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redis_queued_locks

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Distributed locks with "prioritized lock acquisition queue" capabilities based on the Redis Database. Provides flexible invocation flow, parametrized time limits, zombie locks elimination, instrumentation, logging, etc.

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# RedisQueuedLocks &middot; ![Gem Version](https://img.shields.io/gem/v/redis_queued_locks)

[![Tests (RSpec)](https://github.com/0exp/redis_queued_locks/actions/workflows/tests.yml/badge.svg?branch=master)](https://github.com/0exp/redis_queued_locks/actions) [![Lint (Rubocop)](https://github.com/0exp/redis_queued_locks/actions/workflows/lint.yml/badge.svg?branch=master)](https://github.com/0exp/redis_queued_locks/actions) [![TypeCheck (Runtime/RBS)](https://github.com/0exp/redis_queued_locks/actions/workflows/typecheck-runtime.yml/badge.svg?branch=master)](https://github.com/0exp/redis_queued_locks/actions) [![TypeCheck (Static/Steep)](https://github.com/0exp/redis_queued_locks/actions/workflows/typecheck-static.yml/badge.svg?branch=master)](https://github.com/0exp/redis_queued_locks/actions)

<a href="https://redis.io/docs/latest/develop/clients/patterns/distributed-locks/">Distributed locks</a> with "prioritized lock acquisition queue" capabilities based on the Redis Database.

Each lock request is put into the request queue (each lock is hosted by its own queue separately from other queues) and processed in order of their priority (FIFO). Each lock request lives some period of time (RTTL) (with requeue capabilities) which guarantees the request queue will never be stacked.

In addition to the classic `queued` (FIFO) strategy RQL supports `random` (RANDOM) lock obtaining strategy when any acquirer from the lock queue can obtain the lock regardless the position in the queue.

Provides flexible invocation flow, parametrized limits (lock request ttl, lock ttl, queue ttl, lock attempts limit, fast failing, etc), **zombie locks elimination**, support for **reentrant locks**, logging and instrumentation (and much more).

---

## Table of Contents

- [Requirements](#requirements)
- [Experience](#experience)
- [Algorithm](#algorithm)
- [Installation](#installation)
- [Setup](#setup)
- [Configuration](#configuration)
- [Usage](#usage)
  - [lock](#lock---obtain-a-lock)
  - [lock!](#lock---exceptional-lock-obtaining)
  - [lock_series](#lock_series---poc-acquire-a-series-of-locks) (PoC)
  - [lock_series!](#lock_series---poc-exceptional-lock_series) (PoC)
  - [lock_info](#lock_info)
  - [queue_info](#queue_info)
  - [locked?](#locked)
  - [queued?](#queued)
  - [unlock](#unlock---release-a-lock) (aka `release_lock`)
  - [clear_locks](#clear_locks---release-all-locks-and-lock-queues) (aka `release_locks`)
  - [clear_locks_of](#clear_locks_of) (aka `release_locks_of`)
  - [clear_current_locks](#clear_current_locks) (aka `release_current_locks`)
  - [extend_lock_ttl](#extend_lock_ttl)
  - [locks](#locks---get-list-of-obtained-locks)
  - [queues](#queues---get-list-of-lock-request-queues)
  - [keys](#keys---get-list-of-taken-locks-and-queues)
  - [locks_info](#locks_info---get-list-of-locks-with-their-info)
  - [queues_info](#queues_info---get-list-of-queues-with-their-info)
  - [clear_dead_requests](#clear_dead_requests)
  - [current_acquirer_id](#current_acquirer_id)
  - [current_host_id](#current_host_id)
  - [possible_host_ids](#possible_host_ids)
- [Swarm Mode and Zombie Locks](#swarm-mode-and-zombie-locks)
  - [work and usage preview (temporary example-based docs)](#work-and-usage-preview-temporary-example-based-docs)
  - [How to Swarm](#how-to-swarm)
    - [configuration](#)
    - [swarm_status](#swarm_status)
    - [swarm_info](#swarm_info)
    - [swarmize!](#swarmize!)
    - [deswarmize!](#deswarmize!)
    - [probe_hosts](#probe_hosts)
    - [flush_zobmies](#flush_zombies)
  - [zombies_info](#zombies_info)
  - [zombie_locks](#zombie_locks)
  - [zombie_hosts](#zombie_hosts)
  - [zombie_acquirers](#zombie_acquirers)
- [Lock Access Strategies](#lock-access-strategies)
  - [queued](#lock-access-strategies)
  - [random](#lock-access-strategies)
- [Deadlocks and Reentrant locks](#deadlocks-and-reentrant-locks)
- [Logging](#logging)
  - [Logging Configuration](#logging-configuration)
- [Instrumentation](#instrumentation)
  - [Instrumentation Configuration](#instrumentation-configuration)
  - [Instrumentation Events](#instrumentation-events)
    - ["redis_queued_locks.lock_obtained"](#redis_queued_lockslock_hold_and_release)
    - ["redis_queued_locks.extendable_reentrant_lock_obtained"](#redis_queued_locksextendable_reentrant_lock_obtained)
    - ["redis_queued_locks.reentrant_lock_obtained"](#redis_queued_locksreentrant_lock_obtained)
    - ["redis_queued_locks.lock_hold_and_release"](#redis_queued_lockslock_hold_and_release)
    - ["redis_queued_locks.reentrant_lock_hold_completes"](#redis_queued_locksreentrant_lock_hold_completes)
    - ["redis_queued_locks.explicit_lock_release"](#redis_queued_locksexplicit_lock_release)
    - ["redis_queued_locks.explicit_all_locks_release"](#redis_queued_locksexplicit_all_locks_release)
    - ["redis_queued_locks.release_locks_of"](#redis_queued_locksrelease_locks_of)
- [Roadmap](#roadmap)
- [Build and Develop](#build-and-develop)
- [Contributing](#contributing)
- [License](#license)
- [Authors](#authors)

---

### Requirements

\[[back to top](#table-of-contents)\]

- Redis Version: `>= 7`, `~> 8.x`;
- Redis Protocol: `RESP3`;
- gem `redis-client`: `~> 0.20`;
- Ruby: `>= 3.3`;

---

### Experience

\[[back to top](#table-of-contents)\]

- Battle-tested on huge ruby projects in production: `~3000` locks-per-second are obtained and released on an ongoing basis;
- Works well with `hiredis` driver enabled (it is enabled by default on our projects where `redis_queued_locks` are used);

---

### Algorithm

\[[back to top](#table-of-contents)\]

> Each lock request is put into the request queue (each lock is hosted by its own queue separately from other queues) and processed in order of their priority (FIFO). Each lock request lives some period of time (RTTL) which guarantees that the request queue will never be stacked.

> In addition to the classic "queued" (FIFO) strategy RQL supports "random" (RANDOM) lock obtaining strategy when any acquirer from the lock queue can obtain the lock regardless the position in the queue.

**Soon**: detailed explanation.

---

### Installation

\[[back to top](#table-of-contents)\]

```ruby
gem 'redis_queued_locks'
```

```shell
bundle install
# --- or ---
gem install redis_queued_locks
```

```ruby
require 'redis_queued_locks'
```

---

### Setup

\[[back to top](#table-of-contents)\]

```ruby
require 'redis_queued_locks'

# Step 1: initialize RedisClient instance
redis_client = RedisClient.config.new_pool # NOTE: provide your own RedisClient instance

# Step 2: initialize RedisQueuedLock::Client instance
rq_lock_client = RedisQueuedLocks::Client.new(redis_client) do |config|
 # NOTE:
 # - some your application-related configs;
 # - for documentation see <Configuration> section in readme;
end

# Step 3: start to work with locks :)
rq_lock_client.lock("some-lock") { puts "Hello, lock!" }
```

---

### Configuration

\[[back to top](#table-of-contents)\]

```ruby
redis_client = RedisClient.config.new_pool # NOTE: provide your own RedisClient instance

client = RedisQueuedLocks::Client.new(redis_client) do |config|
  # (default: 3) (supports nil)
  # - nil means "infinite retries" and you are only limited by the "try_to_lock_timeout" config;
  config['retry_count'] = 3

# (milliseconds) (default: 200)
  config['retry_delay'] = 200

# (milliseconds) (default: 25)
  config['retry_jitter'] = 25

# (seconds) (supports nil)
  # - nil means "no timeout" and you are only limited by "retry_count" config;
  config['try_to_lock_timeout'] = 10

# (milliseconds) (default: 5_000)
  # - lock's time to live
  config['default_lock_ttl'] = 5_000

# (seconds) (default: 15)
  # - lock request timeout. after this timeout your lock request in queue will be requeued with new position (at the end of the queue);
  config['default_queue_ttl'] = 15

# (boolean) (default: false)
  # - should be all blocks of code are timed by default;
  config['is_timed_by_default'] = false

# (boolean) (default: false)
 # - When the lock acquirement try reached the acquirement time limit (:timeout option) the
 # `RedisQueuedLocks::LockAcquirementTimeoutError` is raised (when `raise_errors` option
 # of the #lock method is set to `true`). The error message contains the lock key name and
 # the timeout value).
 # - <true> option adds the additional details to the error message:
 # - current lock queue state (you can see which acquirer blocks your request and
 # how much acquirers are in queue);
 # - current lock data stored inside (for example: you can check the current acquirer and
 # the lock meta state if you store some additional data there);
 # - Realized as an option because of the additional lock data requires two additional Redis
 # queries: (1) get the current lock from redis and (2) fetch the lock queue state;
 # - These two additional Redis queries has async nature so you can receive
 # inconsistent data of the lock and of the lock queue in your error emssage because:
 # - required lock can be released after the error moment and before the error message build;
 # - required lock can be obtained by other process after the error moment and
 # before the error message build;
 # - required lock queue can reach a state when the blocking acquirer start to obtain the lock
 # and moved from the lock queue after the error moment and before the error message build;
 # - You should consider the async nature of this error message and should use received data
 # from error message correspondingly;
 config['detailed_acq_timeout_error'] = false

# (symbol) (default: :queued)
  # - Defines the way in which the lock should be obitained;
  # - By default it is configured to obtain a lock in classic `queued` way:
  #   you should wait your position in queue in order to obtain a lock;
  # - Can be customized in methods `#lock` and `#lock!` via `:access_strategy` attribute (see method signatures of #lock and #lock! methods);
  # - Supports different strategies:
  #   - `:queued` (FIFO): the classic queued behavior (default), your lock will be obitaned if you are first in queue and the required lock is free;
  #   - `:random` (RANDOM): obtain a lock without checking the positions in the queue (but with checking the limist,
  #     retries, timeouts and so on). if lock is free to obtain - it will be obtained;
  config['default_access_strategy'] = :queued

# (symbol) (default: :wait_for_lock)
 # - Global default conflict strategy mode;
 # - Can be customized in methods `#lock` and `#lock!` via `:conflict_strategy` attribute (see method signatures of #lock and #lock! methods);
 # - Conflict strategy is a logical behavior for cases when the process that obtained the lock want to acquire this lock again;
 # - Realizes "reentrant locks" abstraction (same process conflict / same process deadlock);
 # - By default uses `:wait_for_lock` strategy (classic way);
 # - Strategies:
 # - `:work_through` - continue working under the lock <without> lock's TTL extension;
 # - `:extendable_work_through` - continue working under the lock <with> lock's TTL extension;
 # - `:wait_for_lock` - (default) - work in classic way (with timeouts, retry delays, retry limits, etc - in classic way :));
 # - `:dead_locking` - fail with deadlock exception;
 # - See "Dead locks and Reentrant Locks" documentation section in README.md for details;
 config['default_conflict_strategy'] = :wait_for_lock

# (default: 100)
  # - how many items will be released at a time in #clear_locks and in #clear_dead_requests (uses SCAN);
  # - affects the performance of your Redis and Ruby Application (configure thoughtfully);
  config['lock_release_batch_size'] = 100

# (default: 300)
  # - how many items will be released at a time in #clear_locks_of and in #clear_current_locks methods (uses SCAN for batch extraction and DEL for batch deletion);
  # - affects the ruby's memory (cuz this batch will be stored in Set object in first, and then will be splatted to the DEL redis method invocation) (configure thoughtfully);
  # - affects the performance of your Redis (configure thoughtfully);
  config['clear_locks_of__lock_scan_size'] = 300

# (default: 300)
  # - how many queues will be SCAN'ned at a time in #clear_locks_of and in #clear_current_locks methods (uses SCAN);
  # - affects the performance of your Redis (configure thoughtfully);
  config['clear_locks_of__queue_scan_size'] = 300

# (default: 500)
  # - how many items should be extracted from redis during the #locks, #queues, #keys
  #   #locks_info, and #queues_info operations (uses SCAN);
  # - affects the performance of your Redis and Ruby Application (configure thoughtfully);
  config['key_extraction_batch_size'] = 500

# (default: 1 day)
  # - the default period of time (in milliseconds) after which a lock request is considered dead;
  # - used for `#clear_dead_requests` as default vaule of `:dead_ttl` option;
  config['dead_request_ttl'] = (1 * 24 * 60 * 60 * 1000) # one day in milliseconds

# (default: RedisQueuedLocks::Instrument::VoidNotifier)
 # - instrumentation layer;
 # - you can provide your own instrumenter that should realize `#notify(event, payload = {})` interface:
 # - event: <string> requried;
 # - payload: <hash> requried;
 # - disabled by default via `VoidNotifier`;
 config['instrumenter'] = RedisQueuedLocks::Instrument::ActiveSupport

# (default: -> { RedisQueuedLocks::Resource.calc_uniq_identity })
  # - uniqude idenfitier that is uniq per process/pod;
  # - prevents potential lock-acquirement collisions bettween different process/pods
  #   that have identical process_id/thread_id/fiber_id/ractor_id (identivcal acquirer ids);
  # - it is calculated once per `RedisQueudLocks::Client` instance;
  # - expects the proc object;
  # - `SecureRandom.hex(8)` by default;
  config['uniq_identifier'] = -> { RedisQueuedLocks::Resource.calc_uniq_identity }

# (default: RedisQueuedLocks::Logging::VoidLogger)
  # - the logger object;
  # - should implement `debug(progname = nil, &block)` (minimal requirement) or be an instance of Ruby's `::Logger` class/subclass;
  # - supports `SemanticLogger::Logger` (see "semantic_logger" gem)
  # - at this moment the only debug logs are realised in following cases:
  #   - "[redis_queued_locks.start_lock_obtaining]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
  #   - "[redis_queued_locks.start_try_to_lock_cycle]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
  #   - "[redis_queued_locks.dead_score_reached__reset_acquirer_position]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
  #   - "[redis_queued_locks.lock_obtained]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acq_time", "acs_strat");
  #   - "[redis_queued_locks.extendable_reentrant_lock_obtained]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acq_time", "acs_strat");
  #   - "[redis_queued_locks.reentrant_lock_obtained]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acq_time", "acs_strat");
  #   - "[redis_queued_locks.fail_fast_or_limits_reached_or_deadlock__dequeue]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
  #   - "[redis_queued_locks.expire_lock]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
  #   - "[redis_queued_locks.decrease_lock]" (logs "lock_key", "decreased_ttl", "queue_ttl", "acq_id", "hst_id", "acs_strat");
  # - by default uses VoidLogger that does nothing;
  config['logger'] = RedisQueuedLocks::Logging::VoidLogger

# (default: false)
 # - adds additional debug logs;
 # - enables additional logs for each internal try-retry lock acquiring (a lot of logs can be generated depending on your retry configurations);
 # - it adds following debug logs in addition to the existing:
 # - "[redis_queued_locks.try_lock.start]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
 # - "[redis_queued_locks.try_lock.rconn_fetched]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
 # - "[redis_queued_locks.try_lock.same_process_conflict_detected]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
 # - "[redis_queued_locks.try_lock.same_process_conflict_analyzed]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "spc_status");
 # - "[redis_queued_locks.try_lock.reentrant_lock__extend_and_work_through]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "spc_status", "last_ext_ttl", "last_ext_ts");
 # - "[redis_queued_locks.try_lock.reentrant_lock__work_through]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "spc_status", last_spc_ts);
 # - "[redis_queued_locks.try_lock.acq_added_to_queue]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat")";
 # - "[redis_queued_locks.try_lock.remove_expired_acqs]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
 # - "[redis_queued_locks.try_lock.get_first_from_queue]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "first_acq_id_in_queue");
 # - "[redis_queued_locks.try_lock.exit__queue_ttl_reached]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
 # - "[redis_queued_locks.try_lock.exit__no_first]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "first_acq_id_in_queue", "<current_lock_data>");
 # - "[redis_queued_locks.try_lock.exit__lock_still_obtained]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "first_acq_id_in_queue", "locked_by_acq_id", "<current_lock_data>");
 # - "[redis_queued_locks.try_lock.obtain__free_to_acquire]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
 config['log_lock_try'] = false

# (default: false)
 # - enables <log sampling>: only the configured percent of RQL cases will be logged;
 # - disabled by default;
 # - works in tandem with <config['log_sampling_percent']> and <config['log_sampler']> configs;
 config['log_sampling_enabled'] = false

# (default: 15)
 # - the percent of cases that should be logged;
 # - take an effect when <config['log_sampling_enalbed']> is true;
 # - works in tandem with <config['log_sampling_enabled']> and <config['log_sampler']> configs;
 config['log_sampling_percent'] = 15

# (default: RedisQueuedLocks::Logging::Sampler)
 # - percent-based log sampler that decides should be RQL case logged or not;
 # - works in tandem with <config['log_sampling_enabled']> and <config['log_sampling_percent']> configs;
 # - based on the ultra simple percent-based (weight-based) algorithm that uses SecureRandom.rand
 # method so the algorithm error is ~(0%..13%);
 # - you can provide your own log sampler with bettter algorithm that should realize
 # `sampling_happened?(percent) => boolean` interface (see `RedisQueuedLocks::Logging::Sampler` for example);
 config['log_sampler'] = RedisQueuedLocks::Logging::Sampler

# (default: false)
 # - enables <instrumentaion sampling>: only the configured percent of RQL cases will be instrumented;
 # - disabled by default;
 # - works in tandem with <config['instr_sampling_percent'] and <config['instr_sampler']>;
 config['nstr_sampling_enabled'] = false

# (default: 15)
 # - the percent of cases that should be instrumented;
 # - take an effect when <config['instr_sampling_enalbed']> is true;
 # - works in tandem with <config['instr_sampling_enabled']> and <config['instr_sampler']> configs;
 config['instr_sampling_percent'] = 15

# (default: RedisQueuedLocks::Instrument::Sampler)
 # - percent-based log sampler that decides should be RQL case instrumented or not;
 # - works in tandem with <config['instr_sampling_enabled']> and <config['instr_sampling_percent']> configs;
 # - based on the ultra simple percent-based (weight-based) algorithm that uses SecureRandom.rand
 # method so the algorithm error is ~(0%..13%);
 # - you can provide your own log sampler with bettter algorithm that should realize
 # `sampling_happened?(percent) => boolean` interface (see `RedisQueuedLocks::Instrument::Sampler` for example);
 config['instr_sampler'] = RedisQueuedLocks::Instrument::Sampler
end
```

---

### Usage

\[[back to top](#table-of-contents)\]

- [lock](#lock---obtain-a-lock)
- [lock!](#lock---exeptional-lock-obtaining)
- [lock_series](#lock_series---poc-acquire-a-series-of-locks) (PoC)
- [lock_series!](#lock_series---poc-exceptional-lock_series) (PoC)
- [lock_info](#lock_info)
- [queue_info](#queue_info)
- [locked?](#locked)
- [queued?](#queued)
- [unlock](#unlock---release-a-lock)
- [clear_locks](#clear_locks---release-all-locks-and-lock-queues)
- [extend_lock_ttl](#extend_lock_ttl)
- [locks](#locks---get-list-of-obtained-locks)
- [queues](#queues---get-list-of-lock-request-queues)
- [keys](#keys---get-list-of-taken-locks-and-queues)
- [locks_info](#locks_info---get-list-of-locks-with-their-info)
- [queues_info](#queues_info---get-list-of-queues-with-their-info)
- [clear_dead_requests](#clear_dead_requests)
- [current_acquirer_id](#current_acquirer_id)
- [current_host_id](#current_host_id)
- [possible_host_ids](#possible_host_ids)

---

#### #lock - obtain a lock

\[[back to top](#usage)\]

- `#lock` - obtain a lock;
- If block is passed:
  - the obtained lock will be released after the block execution or the lock's ttl (what will happen first);
    - if you want to timeout (fail with timeout) the block execution with lock's TTL use `timed: true` option;
  - the block's result will be returned;
- If block is not passed:
  - the obtained lock will be released after lock's ttl;
  - the lock information will be returned (hash with technical info that contains: lock key, acquirer identifier, acquirement timestamp, lock's ttl, type of obtaining process, etc);

```ruby
def lock(
  lock_name,
  ttl: config['default_lock_ttl'],
  queue_ttl: config['default_queue_ttl'],
  timeout: config['try_to_lock_timeout'],
  timed: config['is_timed_by_default'],
  retry_count: config['retry_count'],
  retry_delay: config['retry_delay'],
  retry_jitter: config['retry_jitter'],
  raise_errors: false,
  fail_fast: false,
  conflict_strategy: config['default_conflict_strategy'],
  access_strategy: config['default_access_strategy'],
  identity: uniq_identity, # (attr_accessor) calculated during client instantiation via config['uniq_identifier'] proc;
  meta: nil,
  detailed_acq_timeout_error: config['detailed_acq_timeout_error'],
  instrument: nil,
  instrumenter: config['instrumenter'],
  logger: config['logger'],
  log_lock_try: config['log_lock_try'],
  log_sampling_enabled: config['log_sampling_enabled'],
  log_sampling_percent: config['log_sampling_percent'],
  log_sampler: config['log_sampler'],
  log_sample_this: false,
  instr_sampling_enabled: config['instr_sampling_enabled'],
  instr_sampling_percent: config['instr_sampling_percent'],
  instr_sampler: config['instr_sampler'],
  instr_sample_this: false,
  &block
)
```

- `lock_name` - (required) `[String]`
 - Lock name to be obtained.
- `ttl` - (optional) - [Integer]
 - Lock's time to live (in milliseconds);
 - pre-configured in `config['default_lock_ttl']`;
- `queue_ttl` - (optional) `[Integer]`
 - Lifetime of the acuier's lock request. In seconds.
 - pre-configured in `config['default_queue_ttl']`;
- `timeout` - (optional) `[Integer,NilClass]`
 - Time period a client should try to acquire the lock (in seconds). Nil means "without timeout".
 - pre-configured in `config['try_to_lock_timeout']`;
- `timed` - (optiona) `[Boolean]`
 - Limit the invocation time period of the passed block of code by the lock's TTL.
 - pre-configured in `config['is_timed_by_default']`;
 - `false` by default;
- `retry_count` - (optional) `[Integer,NilClass]`
 - How many times we should try to acquire a lock. Nil means "infinite retries".
 - pre-configured in `config['retry_count']`;
- `retry_delay` - (optional) `[Integer]`
 - A time-interval between the each retry (in milliseconds).
 - pre-configured in `config['retry_delay']`;
- `retry_jitter` - (optional) `[Integer]`
 - Time-shift range for retry-delay (in milliseconds);
 - pre-configured in `config['retry_jitter']`;
- `instrumenter` - (optional) `[#notify]`
 - See RedisQueuedLocks::Instrument::ActiveSupport for example;
 - See [Instrumentation](#instrumentation) section of docs;
 - pre-configured in `config['isntrumenter']` with void notifier (`RedisQueuedLocks::Instrumenter::VoidNotifier`);
- `instrument` - (optional) `[NilClass,Any]`
 - Custom instrumentation data wich will be passed to the instrumenter's payload with :instrument key;
 - `nil` by default (means "no custom instrumentation data");
- `raise_errors` - (optional) `[Boolean]`
 - Raise errors on library-related limits (such as timeout or retry count limit) and on lock conflicts (such as same-process dead locks);
 - `false` by default;
- `fail_fast` - (optional) `[Boolean]`
 - Should the required lock to be checked before the try and exit immidietly if lock is
 already obtained;
 - Should the logic exit immidietly after the first try if the lock was obtained
 by another process while the lock request queue was initially empty;
 - `false` by default;
- `access_strategy` - (optional) - `[Symbol]`
 - Defines the way in which the lock should be obitained (in queued way, in random way and so on);
 - By default it is configured to obtain a lock in classic `:queued` way: you should wait your position in queue in order to obtain a lock;
 - Supports following strategies:
 - `:queued` (FIFO): (default) the classic queued behavior, your lock will be obitaned if you are first in queue and the required lock is free;
 - `:random` (RANDOM): obtain a lock without checking the positions in the queue (but with checking the limist, retries, timeouts and so on).
 if lock is free to obtain - it will be obtained;
 - pre-configured in `config['default_access_strategy']`;
 - See [Lock Access Strategies](#lock-access-strategies) documentation section for details;
- `conflict_strategy` - (optional) - `[Symbol]`
 - The conflict strategy mode for cases when the process that obtained the lock
 want to acquire this lock again;
 - By default uses `:wait_for_lock` strategy;
 - pre-confured in `config['default_conflict_strategy']`;
 - Strategies:
 - `:work_through` - continue working under the lock **without** lock's TTL extension;
 - `:extendable_work_through` - continue working under the lock **with** lock's TTL extension;
 - `:wait_for_lock` - (default) - work in classic way (with timeouts, retry delays, retry limits, etc - in classic way :));
 - `:dead_locking` - fail with deadlock exception;
 - See [Deadlocks and Reentrant locks](#deadlocks-and-reentrant-locks) documentation section for details;
- `identity` - (optional) `[String]`
 - An unique string that is unique per `RedisQueuedLock::Client` instance. Resolves the
 collisions between the same process_id/thread_id/fiber_id/ractor_id identifiers on different
 pods or/and nodes of your application;
 - It is calculated once during `RedisQueuedLock::Client` instantiation and stored in `@uniq_identity`
 ivar (accessed via `uniq_dentity` accessor method);
 - Identity calculator is pre-configured in `config['uniq_identifier']`;
- `meta` - (optional) `[NilClass,Hash<String|Symbol,Any>]`
 - A custom metadata wich will be passed to the lock data in addition to the existing data;
 - Custom metadata can not contain reserved lock data keys (such as `lock_key`, `acq_id`, `ts`, `ini_ttl`, `rem_ttl`);
 - `nil` by default (means "no metadata");
- `detailed_acq_timeout_error` - (optional) `[Boolean]`
 - When the lock acquirement try reached the acquirement time limit (:timeout option) the
 `RedisQueuedLocks::LockAcquirementTimeoutError` is raised (when `raise_errors` option
 set to `true`). The error message contains the lock key name and the timeout value).
 - <true> option adds the additional details to the error message:
 - current lock queue state (you can see which acquirer blocks your request and how much acquirers are in queue);
 - current lock data stored inside (for example: you can check the current acquirer and the lock meta state if you store some additional data there);
 - Realized as an option because of the additional lock data requires two additional Redis
 queries: (1) get the current lock from redis and (2) fetch the lock queue state;
 - These two additional Redis queries has async nature so you can receive
 inconsistent data of the lock and of the lock queue in your error emssage because:
 - required lock can be released after the error moment and before the error message build;
 - required lock can be obtained by other process after the error moment and
 before the error message build;
 - required lock queue can reach a state when the blocking acquirer start to obtain the lock
 and moved from the lock queue after the error moment and before the error message build;
 - You should consider the async nature of this error message and should use received data
 from error message correspondingly;
 - pre-configred in `config['detailed_acq_timeout_error']`;
- `logger` - (optional) `[::Logger,#debug]`
 - Logger object used for loggin internal mutation oeprations and opertioan results / process progress;
 - pre-configured in `config['logger']` with void logger `RedisQueuedLocks::Logging::VoidLogger`;
- `log_lock_try` - (optional) `[Boolean]`
 - should be logged the each try of lock acquiring (a lot of logs can be generated depending on your retry configurations);
 - pre-configured in `config['log_lock_try']`;
 - `false` by default;
- `log_sampling_enabled` - (optional) `[Boolean]`
 - enables **log sampling**: only the configured percent of RQL cases will be logged;
 - disabled by default;
 - works in tandem with `log_sampling_percent` and `log_sampler` options;
 - pre-configured in `config['log_sampling_enabled']`;
- `log_sampling_percent` - (optional) `[Integer]`
 - the percent of cases that should be logged;
 - take an effect when `log_sampling_enalbed` is true;
 - works in tandem with `log_sampling_enabled` and `log_sampler` options;
 - pre-configured in `config['log_sampling_percent']`;
- `log_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Logging::Sampler>]`
 - percent-based log sampler that decides should be RQL case logged or not;
 - works in tandem with `log_sampling_enabled` and `log_sampling_percent` options;
 - based on the ultra simple percent-based (weight-based) algorithm that uses SecureRandom.rand
 method so the algorithm error is ~(0%..13%);
 - you can provide your own log sampler with bettter algorithm that should realize
 `sampling_happened?(percent) => boolean` interface (see `RedisQueuedLocks::Logging::Sampler` for example);
 - pre-configured in `config['log_sampler']`;
- `log_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be logged despite the enabled log sampling;
 - makes sense when log sampling is enabled;
 - `false` by default;
- `instr_sampling_enabled` - (optional) `[Boolean]`
 - enables **instrumentaion sampling**: only the configured percent of RQL cases will be instrumented;
 - disabled by default;
 - works in tandem with `instr_sampling_percent` and `instr_sampler` options;
 - pre-configured in `config['instr_sampling_enabled']`;
- `instr_sampling_percent` - (optional) `[Integer]`
 - the percent of cases that should be instrumented;
 - take an effect when `instr_sampling_enalbed` is true;
 - works in tandem with `instr_sampling_enabled` and `instr_sampler` options;
 - pre-configured in `config['instr_sampling_percent']`;
- `instr_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Instrument::Sampler>]`
 - percent-based log sampler that decides should be RQL case instrumented or not;
 - works in tandem with `instr_sampling_enabled` and `instr_sampling_percent` options;
 - based on the ultra simple percent-based (weight-based) algorithm that uses SecureRandom.rand
 method so the algorithm error is ~(0%..13%);
 - you can provide your own log sampler with bettter algorithm that should realize
 `sampling_happened?(percent) => boolean` interface (see `RedisQueuedLocks::Instrument::Sampler` for example);
 - pre-configured in `config['instr_sampler']`;
- `instr_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be instrumneted despite the enabled instrumentation sampling;
 - makes sense when instrumentation sampling is enabled;
 - `false` by default;
- `block` - (optional) `[Block]`
 - A block of code that should be executed after the successfully acquired lock.
 - If block is **passed** the obtained lock will be released after the block execution or its ttl (what will happen first);
 - If block is **not passed** the obtained lock will be released after its ttl;
 - If you want the block to have a TTL too and this TTL to be the same as TTL of the lock
 use `timed: true` option (`rql.lock("my_lock", timed: true, ttl: 5_000) { ... }`)

Return value:

- If block is passed the block's yield result will be returned:
 ```ruby
 result = rql.lock("my_lock") { 1 + 1 }
 result # => 2
 ```
- If block is not passed the lock information will be returned:
 ```ruby
 result = rql.lock("my_lock")
 result # =>
 {
 ok: true,
 result: {
 lock_key: "rql:lock:my_lock",
 acq_id: "rql:acq:26672/2280/2300/2320/70ea5dbf10ea1056",
 ts: 1711909612.653696,
 ttl: 10000,
 process: :lock_obtaining
 }
 }
 ```
- Lock information result:
 - Signature: `[yield, Hash<Symbol,Boolean|Hash<Symbol,Numeric|String>>]`
 - Format: `{ ok: true/false, result: <Symbol|Hash<Symbol,Hash>> }`;
 - Includes the `:process` key that describes a logical type of the lock obtaining process. Possible values:
 - `:lock_obtaining` - classic lock obtaining proces. Default behavior (`conflict_strategy: :wait_for_lock`);
 - `:extendable_conflict_work_through` - reentrant lock acquiring process with lock's TTL extension. Suitable for `conflict_strategy: :extendable_work_through`;
 - `:conflict_work_through` - reentrant lock acquiring process without lock's TTL extension. Suitable for `conflict_strategy: :work_through`;
 - `:dead_locking` - current process tries to acquire a lock that is already acquired by them. Suitalbe for `conflict_startegy: :dead_locking`;
 - For more details see [Deadlocks and Reentrant locks](#deadlocks-and-reentrant-locks) readme section;
 - For successful lock obtaining:
 ```ruby
 {
 ok: true,
 result: {
 lock_key: String, # acquirerd lock key ("rql:lock:your_lock_name")
 acq_id: String, # acquirer identifier ("process_id/thread_id/fiber_id/ractor_id/identity")
 hst_id: String, # host identifier ("process_id/thread_id/ractor_id/identity")
 ts: Float, # time (epoch) when lock was obtained (float, Time#to_f)
 ttl: Integer, # lock's time to live in milliseconds (integer)
 process: Symbol # which logical process has acquired the lock (:lock_obtaining, :extendable_conflict_work_through, :conflict_work_through, :conflict_dead_lock)
 }
 }
 ```

```ruby
 # example:
 {
 ok: true,
 result: {
 lock_key: "rql:lock:my_lock",
 acq_id: "rql:acq:26672/2280/2300/2320/70ea5dbf10ea1056",
 acq_id: "rql:acq:26672/2280/2320/70ea5dbf10ea1056",
 ts: 1711909612.653696,
 ttl: 10000,
 process: :lock_obtaining # for custom conflict strategies may be: :conflict_dead_lock, :conflict_work_through, :extendable_conflict_work_through
 }
 }
 ```
 - For failed lock obtaining:
 ```ruby
 { ok: false, result: :timeout_reached }
 { ok: false, result: :retry_count_reached }
 { ok: false, result: :conflict_dead_lock } # see <conflict_strategy> option for details (:dead_locking strategy)
 { ok: false, result: :fail_fast_no_try } # see <fail_fast> option
 { ok: false, result: :fail_fast_after_try } # see <fail_fast> option
 { ok: false, result: :unknown }
 ```

Examples:

- obtain a lock:

```ruby
rql.lock("my_lock") { print "Hello!" }
```

- obtain a lock with custom lock TTL:

```ruby
rql.lock("my_lock", ttl: 5_000) { print "Hello!" } # for 5 seconds
```

- obtain a lock and limit the passed block of code TTL with lock's TTL:

```ruby
rql.lock("my_lock", ttl: 5_000, timed: true) { sleep(4) }
# => OK

rql.lock("my_lock", ttl: 5_000, timed: true) { sleep(6) }
# => fails with RedisQueuedLocks::TimedLockTimeoutError
```

- infinite lock obtaining (no retry limit, no timeout limit):

```ruby
rql.lock("my_lock", retry_count: nil, timeout: nil)
```

- try to obtain with a custom waiting timeout:

```ruby
# First Ruby Process:
rql.lock("my_lock", ttl: 5_000) { sleep(4) } # acquire a long living lock

# Another Ruby Process:
rql.lock("my_lock", timeout: 2) # try to acquire but wait for a 2 seconds maximum
# =>
{ ok: false, result: :timeout_reached }
```

- obtain a lock and immediatly continue working (the lock will live in the background in Redis with the passed ttl)

```ruby
rql.lock("my_lock", ttl: 6_500) # blocks execution until the lock is obtained
puts "Let's go" # will be called immediately after the lock is obtained
```

- add custom metadata to the lock (via `:meta` option):

```ruby
rql.lock("my_lock", ttl: 123456, meta: { "some" => "data", key: 123.456 })

rql.lock_info("my_lock")
# =>
{
  "lock_key" => "rql:lock:my_lock",
  "acq_id" => "rql:acq:123/456/567/678/374dd74324",
  "hst_id" => "rql:acq:123/456/678/374dd74324",
  "ts" => 123456789,
  "ini_ttl" => 123456,
  "rem_ttl" => 123440,
  "some" => "data",
  "key" => "123.456" # NOTE: returned as a raw string directly from Redis
}
```

- (`:queue_ttl`) setting a short limit of time to the lock request queue position (if a process fails to acquire
  the lock within this period of time (and before timeout/retry_count limits occurs of course) -
  its lock request will be moved to the end of queue):

```ruby
rql.lock("my_lock", queue_ttl: 5, timeout: 10_000, retry_count: nil)
# "queue_ttl: 5": 5 seconds time slot before the lock request moves to the end of queue;
# "timeout" and "retry_count" is used as "endless lock try attempts" example to show the lock queue behavior;

# lock queue: =>
[
 "rql:acq:123/456/567/676/374dd74324",
 "rql:acq:123/456/567/677/374dd74322", # <- long living lock
 "rql:acq:123/456/567/679/374dd74321",
 "rql:acq:123/456/567/683/374dd74322", # <== we are here
 "rql:acq:123/456/567/685/374dd74329", # some other waiting process
]

# ... some period of time (2 seconds later)
# lock queue: =>
[
 "rql:acq:123/456/567/677/374dd74322", # <- long living lock
 "rql:acq:123/456/567/679/374dd74321",
 "rql:acq:123/456/567/683/374dd74322", # <== we are here
 "rql:acq:123/456/567/685/374dd74329", # some other waiting process
]

# ... some period of time (3 seconds later)
# ... queue_ttl time limit is reached
# lock queue: =>
[
 "rql:acq:123/456/567/685/374dd74329", # some other waiting process
 "rql:acq:123/456/567/683/374dd74322", # <== we are here (moved to the end of the queue)
]
```

- obtain a lock in `:random` way (with `:random` strategy): in `:random` strategy
  any acquirer from the lock queue can obtain the lock regardless of the position in the lock queue;

```ruby
# Current Process (process#1)
rql.lock('my_lock', ttl: 2_000, access_strategy: :random)
# => holds the lock

# Another Process (process#2)
rql.lock('my_lock', retry_delay: 7000, ttl: 4000, access_strategy: :random)
# => the lock is not free, stay in a queue and retry...

# Another Process (process#3)
rql.lock('my_lock', retry_delay: 3000, ttl: 3000, access_strategy: :random)
# => the lock is not free, stay in a queue and retry...

# lock queue:
[
 "rql:acq:123/456/567/677/374dd74322", # process#1 (holds the lock)
 "rql:acq:123/456/567/679/374dd74321", # process#2 (waiting for the lock, in retry)
 "rql:acq:123/456/567/683/374dd74322", # process#3 (waiting for the lock, in retry)
]

# ... some period of time
# -> process#1 => released the lock;
# -> process#2 => delayed retry, waiting;
# -> process#3 => preparing for retry (the delay is over);
# lock queue:
[
 "rql:acq:123/456/567/679/374dd74321", # process#2 (waiting for the lock, DELAYED)
 "rql:acq:123/456/567/683/374dd74322", # process#3 (trying to obtain the lock, RETRYING now)
]

# ... some period of time
# -> process#2 => didn't have time to obtain the lock, delayed retry;
# -> process#3 => holds the lock;
# lock queue:
[
 "rql:acq:123/456/567/679/374dd74321", # process#2 (waiting for the lock, DELAYED)
 "rql:acq:123/456/567/683/374dd74322", # process#3 (holds the lock)
]

# `process#3` is the last in queue, but has acquired the lock because his lock request "randomly" came first;
```

---

#### #lock! - exceptional lock obtaining

\[[back to top](#usage)\]

- `#lock!` - exceptional lock obtaining;
- fails when (and with):
  - (`RedisQueuedLocks::LockAlreadyObtainedError`) when `fail_fast` is `true` and lock is already obtained;
  - (`RedisQueuedLocks::LockAcquirementTimeoutError`) `timeout` limit reached before lock is obtained;
  - (`RedisQueuedLocks::LockAcquirementRetryLimitError`) `retry_count` limit reached before lock is obtained;
  - (`RedisQueuedLocks::ConflictLockObtainError`) when `conflict_strategy: :dead_locking` is used and the "same-process-dead-lock" is happened (see [Deadlocks and Reentrant locks](#deadlocks-and-reentrant-locks) for details);

```ruby
def lock!(
  lock_name,
  ttl: config['default_lock_ttl'],
  queue_ttl: config['default_queue_ttl'],
  timeout: config['try_to_lock_timeout'],
  timed: config['is_timed_by_default'],
  retry_count: config['retry_count'],
  retry_delay: config['retry_delay'],
  retry_jitter: config['retry_jitter'],
  fail_fast: false,
  identity: uniq_identity,
  meta: nil,
  detailed_acq_timeout_error: config['detailed_acq_timeout_error']
  logger: config['logger'],
  log_lock_try: config['log_lock_try'],
  instrument: nil,
  instrumenter: config['instrumenter'],
  access_strategy: config['default_access_strategy'],
  conflict_strategy: config['default_conflict_strategy'],
  log_sampling_enabled: config['log_sampling_enabled'],
  log_sampling_percent: config['log_sampling_percent'],
  log_sampler: config['log_sampler'],
  log_sample_this: false,
  instr_sampling_enabled: config['instr_sampling_enabled'],
  instr_sampling_percent: config['instr_sampling_percent'],
  instr_sampler: config['instr_sampler'],
  instr_sample_this: false,
  &block
)
```

See `#lock` method [documentation](#lock---obtain-a-lock).

---

#### #lock_series - (PoC) acquire a series of locks

\[[back to top](#usage)\]

> (IMPORTANT!) "Proof of Concept" realization. Will be reworked in the future.

`lock_series` - acquire a series of locks simultaniously and hold them all while your block of code is executing
or (if block is not passed) while all locks will not expire.

If it is not possible to obtain all locks at the same time (taking into queue ttl, retry attempts count for each lock, etc) no any lock will be acquired.

Method options is the same as for `lock` method: `retry_count`, `retry_jitter`, `ttl`, `queue_ttl`, etc. Each option will be
applied with the same value to the each lock acquirement process (for each lock in a series separately).

**IMPORTANT DETAILS AND LIMITATIONS**:
- (this behavior will be reworked with another algorithm in future);
- each lock will be released with the next formula: 
  - `lock position with reverse numbering` * `ttl`
    - (positions exmaple: ["a", "b", "c"] => "a" position is 3, "b" position is 2, "c" position is 1);
  - this means that in case of 3 locks (`lock_series("x", "y", "z", ttl: 5_000`) with `5 seconds TTL` your locks will be with the next TTL:
    - `"x"` - 15 seconds
    - `"y"` - 10 seconds
    - `"z"` - 5 seconds
- when your block of code has completed their execution - all locks will be released immediatly;
- if you did not pass a block - all locks will be released with their forumla-based TTL described above;
  - **HOW WILL THIS CASE WORK IN FUTURE RELESAE**: all locks will have the same TTL (`5 seconds` for our example, not `15/10/5 seconds`);

##### How to use:

- method signature is the same as the `#lock`;

```ruby
# typical logic-oriented way
client.lock_series("a", "b", "c") { ...some_code... }

# result-oriented way:
# - (block is passed)
detailed_result = client.lock_series('x', 'y', 'z', detailed_result: true) { 1 + 2 }
detailed_result # =>
{
  yield_result: 3, # result of your block of code
  lock_release_strategy: :immediate_release_after_yield, # (block is passed)
  locks_released_at: 1769506100.676884, # (instrumentation) release time, epoch
  locks_acq_time: 7.0, # (instrumentation) time spent to acquire all locks, milliseconds
  locks_hold_time: 0.65, # (instrumentation) lock series hold period (hold preiod of all required locks), milliseconds
  lock_series: ["x", "y", "z"], # your locks
  rql_lock_series: ["rql:lock:x", "rql:lock:y", "rql:lock:z"] # internal RQL lock-keys of your locks
}

# - (block is not passed)
detailed_result = client.lock_series('x', 'y', 'z', detailed_result: true)
detailed_result # =>
{
  yield_result: nil, # block is not given - nothing to return
  lock_release_strategy: :redis_key_ttl, # block is not given - locks are living in redis with their TTL
  locks_released_at: nil, # (instrumentation) # block is not given - locks are living in redis with their TTL
  locks_acq_time: 7.0, # (instrumentation) time spent to acquire all locks, milliseconds
  locks_hold_time: nil, # (instrumentation) # block is not given - locks are living in redis with their TTL
  lock_series: ["x", "y", "z"], # your locks
  rql_lock_series: ["rql:lock:x", "rql:lock:y", "rql:lock:z"] # internal RQL lock-keys of your locks
}
```

```ruby
# (failed lock obtainig) when lock series can not be obtained for some reasons
# for example: one of required lock in series is still obtained and can not be obtained now (and all retries are exhausted)

# - lock 'a' is obtained with long ttl
client.lock('a', ttl: 10_000_000)

# - try to bobtain series of locks with `a` inside the series (`a` can not be obtained for now)
client.lock_seires('c', 'a', 'b') # ... `a` is still obtained 
# =>
{
  ok: false,
  result: {
    error: :failed_to_acquire_lock_series,
    detailed_errors: { 'a' => { ok: false, result: :retry_limit_reached } },
    lock_series: ["c", "a", "b"],
    acquired_locks: ["c"],
    missing_locks: ["a", "b"],
    failed_on_lock: ["a"],
  }
}
```

###### New instrumentaiton events:

```ruby
# NEW instrumentation events (examples)
"redis_queued_locks.lock_series_obtained" => # {lock_keys: ["rql:lock:s", "rql:lock:t", "rql:lock:u"], ttl: 5000, acq_id: "rql:acq:4486/1696/1704/1712/e6fd0da7991e4303", hst_id: "rql:hst:4486/1696/1712/e6fd0da7991e4303", ts: "2026-01-28 22:05:06 +0300", acq_time: 2.61, instrument: nil}
"redis_queued_locks.lock_series_hold_and_release" => # {lock_keys: ["rql:lock:x", "rql:lock:y", "rql:lock:z"], hold_time: 0.29, ttl: 5000, acq_id: "rql:acq:4486/1696/1704/1712/e6fd0da7991e4303", hst_id: "rql:hst:4486/1696/1712/e6fd0da7991e4303", ts: 1769627106.4717052, acq_time: 4.26, instrument: nil}
```

###### New logs:

```shell
# NEW logs (examples)
[redis_queued_locks.start_lock_series_obtaining] lock_keys => '["rql:lock:a", "rql:lock:b"]'queue_ttl => 15 acq_id => 'rql:acq:4486/1696/1704/1712/e6fd0da7991e4303' hst_id => 'rql:hst:4486/1696/1712/e6fd0da7991e4303' acs_strat => 'queued'
[redis_queued_locks.lock_series_obtained] lock_keys => '["rql:lock:a", "rql:lock:b"]' queue_ttl => 15 acq_id => 'rql:acq:4486/1696/1704/1712/e6fd0da7991e4303' hst_id => 'rql:hst:4486/1696/1712/e6fd0da7991e4303' acs_strat => 'queued' acq_time => 2.55 (ms)
[redis_queued_locks.expire_lock_series] lock_keys => '["rql:lock:x", "rql:lock:y", "rql:lock:z"]' queue_ttl => 15 acq_id => 'rql:acq:4486/1696/1704/1712/e6fd0da7991e4303' hst_id => 'rql:hst:4486/1696/1712/e6fd0da7991e4303' acs_strat => 'queued'
```

----

#### #lock_series! - (PoC) exceptional `lock_series`

\[[back to top](#usage)\]

> (IMPORTANT!) "Proof of Concept" realization. Will be reworked in the future (very-very soon)

For more details see `lock_series` [docs](#lock_series---poc-acquire-a-series-of-locks)

```ruby
client.lock_series!("x", "y", "z") { ...some_code... }
```

----

#### #lock_info

\[[back to top](#usage)\]

- get the lock information;
- returns `nil` if lock does not exist;
- lock data (`Hash<String,String|Integer>`):
 - `"lock_key"` - `string` - lock key in redis;
 - `"acq_id"` - `string` - acquirer identifier (process_id/thread_id/fiber_id/ractor_id/identity);
 - `"hst_id"` - `string` - host identifier (process_id/thread_id/ractor_id/identity);
 - `"ts"` - `numeric`/`epoch` - the time when lock was obtained;
 - `"init_ttl"` - `integer` - (milliseconds) initial lock key ttl;
 - `"rem_ttl"` - `integer` - (milliseconds) remaining lock key ttl;
 - `<custom metadata>`- `string`/`integer` - custom metadata passed to the `lock`/`lock!` methods via `meta:` keyword argument (see [lock]((#lock---obtain-a-lock)) method documentation);
 - additional keys for **reentrant locks** and **extendable reentrant locks**:
 - for any type of reentrant locks:
 - `"spc_cnt"` - `integer` - how many times the lock was obtained as reentrant lock;
 - for non-extendable reentrant locks:
 - `"l_spc_ts"` - `numeric`/`epoch` - timestamp of the last **non-extendable** reentrant lock obtaining;
 - for extendalbe reentrant locks:
 - `"spc_ext_ttl"` - `integer` - (milliseconds) sum of TTL of the each **extendable** reentrant lock (the total TTL extension time);
 - `"l_spc_ext_ini_ttl"` - `integer` - (milliseconds) TTL of the last reentrant lock;
 - `"l_spc_ext_ts"` - `numeric`/`epoch` - timestamp of the last extendable reentrant lock obtaining;

```ruby
# <without custom metadata>
rql.lock_info("your_lock_name")

```ruby
# <with custom metadata>
rql.lock("your_lock_name", meta: { "kek" => "pek", "bum" => 123 })
rql.lock_info("your_lock_name")

```ruby
# <for reentrant locks>
# (see `conflict_strategy:` kwarg attribute of #lock/#lock! methods and `config['default_conflict_strategy']` config)

rql.lock("your_lock_name", ttl: 5_000)
rql.lock("your_lock_name", ttl: 3_000)
rql.lock("your_lock_name", ttl: 2_000)
rql.lock_info("your_lock_name")

# =>
{
 "lock_key" => "rql:lock:your_lock_name",
 "acq_id" => "rql:acq:123/456/567/678/374dd74324",
 "hst_id" => "rql:acq:123/456/678/374dd74324",
 "ts" => 123456789.12345,
 "ini_ttl" => 5_000,
 "rem_ttl" => 9_444,
 # ==> keys for any type of reentrant lock:
 "spc_count" => 2, # how many times the lock was obtained as reentrant lock
 # ==> keys for extendable reentarnt locks with `:extendable_work_through` strategy:
 "spc_ext_ttl" => 5_000, # sum of TTL of the each <extendable> reentrant lock (3_000 + 2_000)
 "l_spc_ext_ini_ttl" => 2_000, # TTL of the last <extendable> reentrant lock
 "l_spc_ext_ts" => 123456792.12345, # timestamp of the last <extendable> reentrant lock obtaining
 # ==> keys for non-extendable locks with `:work_through` strategy:
 "l_spc_ts" => 123456.789 # timestamp of the last <non-extendable> reentrant lock obtaining
}
```

---

#### #queue_info

\[[back to top](#usage)\]

Returns an information about the required lock queue by the lock name. The result
represnts the ordered lock request queue that is ordered by score (Redis Sets) and shows
lock acquirers and their position in queue. Async nature with redis communcation can lead
the situation when the queue becomes empty during the queue data extraction. So sometimes
you can receive the lock queue info with empty queue value (an empty array).

- get the lock queue information;
- queue represents the ordered set of lock key reqests:
 - set is ordered by score in ASC manner (inside the Redis Set);
 - score is represented as a timestamp when the lock request was made;
 - represents the acquirer identifier and their score as an array of hashes;
- returns `nil` if lock queue does not exist;
- lock queue data (`Hash<String,String|Array<Hash<String|Numeric>>`):
 - `"lock_queue"` - `string` - lock queue key in redis;
 - `"queue"` - `array` - an array of lock requests (array of hashes):
 - `"acq_id"` - `string` - acquirer identifier (process_id/thread_id/fiber_id/ractor_id/identity by default);
 - `"score"` - `float`/`epoch` - time when the lock request was made (epoch);

```ruby
rql.queue_info("your_lock_name")

# =>
{
  "lock_queue" => "rql:lock_queue:your_lock_name",
  "queue" => [
    { "acq_id" => "rql:acq:123/456/567/678/fa76df9cc2", "score" => 1711606640.540842},
    { "acq_id" => "rql:acq:123/567/456/679/c7bfcaf4f9", "score" => 1711606640.540906},
    { "acq_id" => "rql:acq:555/329/523/127/7329553b11", "score" => 1711606640.540963},
    # ...etc
  ]
}
```

---

#### #locked?

\[[back to top](#usage)\]

- is the lock obtaied or not?

```ruby
rql.locked?("your_lock_name") # => true/false
```

---

#### #queued?

\[[back to top](#usage)\]

- is the lock queued for obtain / has requests for obtain?

```ruby
rql.queued?("your_lock_name") # => true/false
```

---

#### #unlock - release a lock

\[[back to top](#usage)\]

- release the concrete lock with lock request queue;
- queue will be relased first;
- has an alias: `#release_lock`;
- accepts:
 - `lock_name` - (required) `[String]` - the lock name that should be released.
 - `:logger` - (optional) `[::Logger,#debug]`
 - custom logger object;
 - pre-configured in `config['logger']`;
 - `:instrumenter` - (optional) `[#notify]`
 - custom instrumenter object;
 - pre-configured in `config['instrumetner']`;
 - `:instrument` - (optional) `[NilClass,Any]`;
 - custom instrumentation data wich will be passed to the instrumenter's payload with :instrument key;
 - `nil` by default (no additional data);
 - `:log_sampling_enabled` - (optional) `[Boolean]`
 - enables **log sampling**;
 - pre-configured in `config['log_sampling_enabled']`;
 - `:log_sampling_percent` - (optional) `[Integer]`
 - **log sampling**:the percent of cases that should be logged;
 - pre-configured in `config['log_sampling_percent']`;
 - `:log_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Logging::Sampler>]`
 - **log sampling**: percent-based log sampler that decides should be RQL case logged or not;
 - pre-configured in `config['log_sampler']`;
 - `log_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be logged despite the enabled log sampling;
 - makes sense when log sampling is enabled;
 - `false` by default;
 - `:instr_sampling_enabled` - (optional) `[Boolean]`
 - enables **instrumentaion sampling**;
 - pre-configured in `config['instr_sampling_enabled']`;
 - `instr_sampling_percent` - (optional) `[Integer]`
 - the percent of cases that should be instrumented;
 - pre-configured in `config['instr_sampling_percent']`;
 - `instr_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Instrument::Sampler>]`
 - percent-based log sampler that decides should be RQL case instrumented or not;
 - pre-configured in `config['instr_sampler']`;
 - `instr_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be instrumneted despite the enabled instrumentation sampling;
 - makes sense when instrumentation sampling is enabled;
 - `false` by default;
- if you try to unlock non-existent lock you will receive `ok: true` result with operation timings
 and `:nothing_to_release` result factor inside;

Return:
- `[Hash<Symbol,Boolean|Hash<Symbol,Numeric|String|Symbol>>]` (`{ ok: true/false, result: Hasn }`);
- `:result` format;
 - `:rel_time` - `Float` - time spent to process redis commands (in seconds);
 - `:rel_key` - `String` - released lock key (RedisQueudLocks-internal lock key name from Redis);
 - `:rel_queue` - `String` - released lock queue key (RedisQueuedLocks-internal queue key name from Redis);
 - `:queue_res` - `Symbol` - `:released` (or `:nothing_to_release` if the required queue does not exist);
 - `:lock_res` - `Symbol` - `:released` (or `:nothing_to_release` if the required lock does not exist);

Consider that `lock_res` and `queue_res` can have different value because of the async nature of invoked Redis'es commands.

```ruby
rql.unlock("your_lock_name")

# =>
{
  ok: true,
  result: {
    rel_time: 0.02, # time spent to lock release (in seconds)
    rel_key: "rql:lock:your_lock_name", # released lock key
    rel_queue: "rql:lock_queue:your_lock_name", # released lock key queue
    queue_res: :released, # or :nothing_to_release
    lock_res: :released # or :nothing_to_release
  }
}
```

---

#### #clear_locks - release all locks and lock queues

\[[back to top](#usage)\]

- release all obtained locks and related lock request queues;
- queues will be released first;
- has an alias: `#release_locks`;
- accepts:
 - `:batch_size` - (optional) `[Integer]`
 - the size of batch of locks and lock queus that should be cleared under the one pipelined redis command at once;
 - pre-configured in `config['lock_release_batch_size']`;
 - `:logger` - (optional) `[::Logger,#debug]`
 - custom logger object;
 - pre-configured value in `config['logger']`;
 - `:instrumenter` - (optional) `[#notify]`
 - custom instrumenter object;
 - pre-configured value in `config['isntrumenter']`;
 - `:instrument` - (optional) `[NilClass,Any]`
 - custom instrumentation data wich will be passed to the instrumenter's payload with `:instrument` key;
 - `:log_sampling_enabled` - (optional) `[Boolean]`
 - enables **log sampling**;
 - pre-configured in `config['log_sampling_enabled']`;
 - `:log_sampling_percent` - (optional) `[Integer]`
 - **log sampling**:the percent of cases that should be logged;
 - pre-configured in `config['log_sampling_percent']`;
 - `:log_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Logging::Sampler>]`
 - **log sampling**: percent-based log sampler that decides should be RQL case logged or not;
 - pre-configured in `config['log_sampler']`;
 - `log_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be logged despite the enabled log sampling;
 - makes sense when log sampling is enabled;
 - `false` by default;
 - `:instr_sampling_enabled` - (optional) `[Boolean]`
 - enables **instrumentaion sampling**;
 - pre-configured in `config['instr_sampling_enabled']`;
 - `instr_sampling_percent` - (optional) `[Integer]`
 - the percent of cases that should be instrumented;
 - pre-configured in `config['instr_sampling_percent']`;
 - `instr_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Instrument::Sampler>]`
 - percent-based log sampler that decides should be RQL case instrumented or not;
 - pre-configured in `config['instr_sampler']`;
 - `instr_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be instrumneted despite the enabled instrumentation sampling;
 - makes sense when instrumentation sampling is enabled;
 - `false` by default;
- returns:
 - `[Hash<Symbol,Numeric>]` - Format: `{ ok: true, result: Hash<Symbol,Numeric> }`;
 - result data:
 - `:rel_time` - `Numeric` - time spent to release all locks and related queus;
 - `:rel_key_cnt` - `Integer` - the number of released Redis keys (queues+locks);

```ruby
rql.clear_locks

# =>
{
  ok: true,
  result: {
    rel_time: 3.07,
    rel_key_cnt: 1234
  }
}
```

---

#### #clear_locks_of

\[[back to top](#usage)\]

- release all locks of the passed acquirer/host and remove this acquirer/host from all queues (locks will be released first)
- this is a cleanup helper intended for operational and debugging scenarios (for example: your
 current puma request thread is killed by Rack::Timeout and you need to cleanup all zombie RQL
 locks and lock reuqests obtained during the request processing);
- acquirer/host dentifiers can be extracted via:
 - `#current_host_id`
 - `#current_acquirer_id`
 - `#possible_host_ids`
 - from lock data (extracted via `#lock_info`, `#locks_info`, `#queue_info`, `#queues_info`);
- produces `"redis_queued_locks.release_locks_of"` instrumentation event;
- accepts:
 - `:host_id` - (required) `[String]`
 - host indentifier whose locks we want to release and which we want to remove from all locks queues;
 - `:acquirer_id` - (required) `[String]`
 - acquirer indentifier whose locks we want to release and which we want to remove from all locks queues;
 - `:lock_scan_size` - (optional) `[Integer]`
 - how many items will be released at a time (uses `SCAN `for batch extraction and `DEL` for batch deletion);
 - pre-configuerd value in `config['clear_locks_of__lock_scan_size']`;
 - `:queue_scan_size` - (optional) `[Integer]`
 - how many queues will be SCAN'ned at a time (uses `SCAN)`;
 - pre-configuerd value in `config['clear_locks_of__queue_scan_size']`;
 - `:logger` - (optional) `[::Logger,#debug]`
 - custom logger object;
 - pre-configured value in `config['logger']`;
 - `:instrumenter` - (optional) `[#notify]`
 - custom instrumenter object;
 - pre-configured value in `config['isntrumenter']`;
 - `:instrument` - (optional) `[NilClass,Any]`
 - custom instrumentation data wich will be passed to the instrumenter's payload with `:instrument` key;
 - `:log_sampling_enabled` - (optional) `[Boolean]`
 - enables **log sampling**;
 - pre-configured in `config['log_sampling_enabled']`;
 - `:log_sampling_percent` - (optional) `[Integer]`
 - **log sampling**:the percent of cases that should be logged;
 - pre-configured in `config['log_sampling_percent']`;
 - `:log_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Logging::Sampler>]`
 - **log sampling**: percent-based log sampler that decides should be RQL case logged or not;
 - pre-configured in `config['log_sampler']`;
 - `log_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be logged despite the enabled log sampling;
 - makes sense when log sampling is enabled;
 - `false` by default;
 - `:instr_sampling_enabled` - (optional) `[Boolean]`
 - enables **instrumentaion sampling**;
 - pre-configured in `config['instr_sampling_enabled']`;
 - `instr_sampling_percent` - (optional) `[Integer]`
 - the percent of cases that should be instrumented;
 - pre-configured in `config['instr_sampling_percent']`;
 - `instr_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Instrument::Sampler>]`
 - percent-based log sampler that decides should be RQL case instrumented or not;
 - pre-configured in `config['instr_sampler']`;
 - `instr_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be instrumneted despite the enabled instrumentation sampling;
 - makes sense when instrumentation sampling is enabled;
 - `false` by default;
- returns:
 - `[Hash<Symbol,Numeric>]` - Format: `{ ok: true, result: Hash<Symbol,Numeric> }`;
 - result data:
 - `:rel_time` - `Numeric` - time spent;
 - `:rel_key_cnt` - `Integer` - the count of released locks;
 - `:tch_queue_cnt` - `Integer` - the count of touched (modified) queues (the number of queues from which the acquirer/host was removed);

```ruby
rql.clear_locks_of(
  host_id: "rql:hst:41478/4320/4360/848818f09d8c3420",
  acquirer_id: "rql:acq:41478/4320/4340/4360/848818f09d8c3420"
)
# -- or (alias) --
rql.release_locks_of(
  host_id: "rql:hst:41478/4320/4360/848818f09d8c3420",
  acquirer_id: "rql:acq:41478/4320/4340/4360/848818f09d8c3420"
)

# -> result
{
  ok: true,
  result: {
    rel_key_cnt: 123,
    tch_queue_cnt: 2,
    rel_time: 0.1
  }
}
```

```ruby
# clear locks and queues of the current acquirer:
rql.clear_locks_of(
  host_id: rql.current_host_id,
  acquirer_id: rql.current_acquirer_id
)

# equivalent:
rql.clear_current_locks

# -> result
{
  ok: true,
  result: {
    rel_key_cnt: 43,
    tch_queue_cnt: 3,
    rel_time: 0.2
  }
}
```

---

#### #clear_current_locks

\[[back to top](#usage)\]

- release all locks of the current acquirer/host and remove the current acquirer/host from all queues (locks will be released first);
- this is a cleanup helper intended for operational and debugging scenarios (for example: your
 current puma request thread is killed by Rack::Timeout and you need to cleanup all zombie RQL
 locks and lock reuqests obtained during the request processing);
- representes an equivalent invocation:
 ```ruby
 rql.clear_locks_of(host_id: rql.current_host_id, acquirer_id: rql.current_acquirer_id)
 ```
- produces `"redis_queued_locks.release_locks_of"` instrumentation event;
 - `:lock_scan_size` - (optional) `[Integer]`
 - how many items will be released at a time (uses `SCAN `for batch extraction and `DEL` for batch deletion);
 - pre-configuerd value in `config['clear_locks_of__lock_scan_size']`;
 - `:queue_scan_size` - (optional) `[Integer]`
 - how many queues will be SCAN'ned at a time (uses `SCAN)`;
 - pre-configuerd value in `config['clear_locks_of__queue_scan_size']`;
 - `:logger` - (optional) `[::Logger,#debug]`
 - custom logger object;
 - pre-configured value in `config['logger']`;
 - `:instrumenter` - (optional) `[#notify]`
 - custom instrumenter object;
 - pre-configured value in `config['isntrumenter']`;
 - `:instrument` - (optional) `[NilClass,Any]`
 - custom instrumentation data wich will be passed to the instrumenter's payload with `:instrument` key;
 - `:log_sampling_enabled` - (optional) `[Boolean]`
 - enables **log sampling**;
 - pre-configured in `config['log_sampling_enabled']`;
 - `:log_sampling_percent` - (optional) `[Integer]`
 - **log sampling**:the percent of cases that should be logged;
 - pre-configured in `config['log_sampling_percent']`;
 - `:log_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Logging::Sampler>]`
 - **log sampling**: percent-based log sampler that decides should be RQL case logged or not;
 - pre-configured in `config['log_sampler']`;
 - `log_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be logged despite the enabled log sampling;
 - makes sense when log sampling is enabled;
 - `false` by default;
 - `:instr_sampling_enabled` - (optional) `[Boolean]`
 - enables **instrumentaion sampling**;
 - pre-configured in `config['instr_sampling_enabled']`;
 - `instr_sampling_percent` - (optional) `[Integer]`
 - the percent of cases that should be instrumented;
 - pre-configured in `config['instr_sampling_percent']`;
 - `instr_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Instrument::Sampler>]`
 - percent-based log sampler that decides should be RQL case instrumented or not;
 - pre-configured in `config['instr_sampler']`;
 - `instr_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be instrumneted despite the enabled instrumentation sampling;
 - makes sense when instrumentation sampling is enabled;
 - `false` by default;
- returns:
 - `[Hash<Symbol,Numeric>]` - Format: `{ ok: true, result: Hash<Symbol,Numeric> }`;
 - result data:
 - `:rel_time` - `Numeric` - time spent;
 - `:rel_key_cnt` - `Integer` - the count of released locks;
 - `:tch_queue_cnt` - `Integer` - the count of touched (modified) queues (the number of queues from which the acquirer/host was removed);

```ruby
rql.clear_current_locks
# -- or (alias) --
rql.release_current_locks
# equivalent:
rql.release_locks_of(host_id: rql.current_host_id, acquirer_id: rql.current_acquirer_id)

# -> result
{
  ok: true,
  result: {
    rel_key_cnt: 43,
    tch_queue_cnt: 3,
    rel_time: 0.2
  }
}
```

---

#### #extend_lock_ttl

\[[back to top](#usage)\]

- extends lock ttl by the required number of milliseconds;
- expects the lock name and the number of milliseconds;
- accepts:
 - `lock_name` - (required) `[String]`
 - the lock name which ttl should be extended;
 - `milliseconds` - (required) `[Integer]`
 - how many milliseconds should be added to the lock's TTL;
 - `:instrumenter` - (optional) `[#notify]`
 - custom instrumenter object;
 - pre-configured in `config['instrumetner']`;
 - `:instrument` - (optional) `[NilClass,Any]`;
 - custom instrumentation data wich will be passed to the instrumenter's payload with :instrument key;
 - `nil` by default (no additional data);
 - `:logger` - (optional) `[::Logger,#debug]`
 - custom logger object;
 - pre-configured in `config['logger']`;
 - `:log_sampling_enabled` - (optional) `[Boolean]`
 - enables **log sampling**;
 - pre-configured in `config['log_sampling_enabled']`;
 - `:log_sampling_percent` - (optional) `[Integer]`
 - **log sampling**:the percent of cases that should be logged;
 - pre-configured in `config['log_sampling_percent']`;
 - `:log_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Logging::Sampler>]`
 - **log sampling**: percent-based log sampler that decides should be RQL case logged or not;
 - pre-configured in `config['log_sampler']`;
 - `log_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be logged despite the enabled log sampling;
 - makes sense when log sampling is enabled;
 - `false` by default;
 - `:instr_sampling_enabled` - (optional) `[Boolean]`
 - enables **instrumentaion sampling**;
 - pre-configured in `config['instr_sampling_enabled']`;
 - `instr_sampling_percent` - (optional) `[Integer]`
 - the percent of cases that should be instrumented;
 - pre-configured in `config['instr_sampling_percent']`;
 - `instr_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Instrument::Sampler>]`
 - percent-based log sampler that decides should be RQL case instrumented or not;
 - pre-configured in `config['instr_sampler']`;
 - `instr_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be instrumneted despite the enabled instrumentation sampling;
 - makes sense when instrumentation sampling is enabled;
 - `false` by default;
- returns `{ ok: true, result: :ttl_extended }` when ttl is extended;
- returns `{ ok: false, result: :async_expire_or_no_lock }` when a lock not found or a lock is already expired during
 some steps of invocation (see **Important** section below);
- **Important**:
 - the method is non-atomic cuz redis does not provide an atomic function for TTL/PTTL extension;
 - the method consists of two commands:
 - (1) read current pttl;
 - (2) set new ttl that is calculated as "current pttl + additional milliseconds";
 - the method uses Redis'es **CAS** (check-and-set) behavior;
 - what can happen during these steps:
 - lock is expired between commands or before the first command;
 - lock is expired before the second command;
 - lock is expired AND newly acquired by another process (so you will extend the
 totally new lock with fresh PTTL);
 - use it at your own risk and consider the async nature when calling this method;

```ruby
rql.extend_lock_ttl("my_lock", 5_000) # NOTE: add 5_000 milliseconds

# => `ok` case
{ ok: true, result: :ttl_extended }

# => `failed` case
{ ok: false, result: :async_expire_or_no_lock }
```

---

#### #locks - get list of obtained locks

\[[back to top](#usage)\]

- get list of obtained locks;
- uses redis `SCAN` under the hood;
- accepts:
 - `:scan_size` - `Integer` - (`config['key_extraction_batch_size']` by default);
 - `:with_info` - `Boolean` - `false` by default (for details see [#locks_info](#locks_info---get-list-of-locks-with-their-info));
- returns:
 - `Set<String>` (for `with_info: false`);
 - `Set<Hash<Symbol,Any>>` (for `with_info: true`). See [#locks_info](#locks_info---get-list-of-locks-with-their-info) for details;

```ruby
rql.locks # or rql.locks(scan_size: 123)

=>
#<Set:
 {"rql:lock:locklock75",
 "rql:lock:locklock9",
 "rql:lock:locklock108",
 "rql:lock:locklock7",
 "rql:lock:locklock48",
 "rql:lock:locklock104",
 "rql:lock:locklock13",
 "rql:lock:locklock62",
 "rql:lock:locklock80",
 "rql:lock:locklock28",
 ...}>
```

---

#### #queues - get list of lock request queues

\[[back to top](#usage)\]

- get list of lock request queues;
- uses redis `SCAN` under the hood;
- accepts
 - `:scan_size` - `Integer` - (`config['key_extraction_batch_size']` by default);
 - `:with_info` - `Boolean` - `false` by default (for details see [#queues_info](#queues_info---get-list-of-queues-with-their-info));
- returns:
 - `Set<String>` (for `with_info: false`);
 - `Set<Hash<Symbol,Any>>` (for `with_info: true`). See [#locks_info](#locks_info---get-list-of-locks-with-their-info) for details;

```ruby
rql.queues # or rql.queues(scan_size: 123)

=>
#<Set:
 {"rql:lock_queue:locklock75",
 "rql:lock_queue:locklock9",
 "rql:lock_queue:locklock108",
 "rql:lock_queue:locklock7",
 "rql:lock_queue:locklock48",
 "rql:lock_queue:locklock104",
 "rql:lock_queue:locklock13",
 "rql:lock_queue:locklock62",
 "rql:lock_queue:locklock80",
 "rql:lock_queue:locklock28",
 ...}>
```

---

#### #keys - get list of taken locks and queues

\[[back to top](#usage)\]

- get list of taken locks and queues;
- uses redis `SCAN` under the hood;
- accepts:
 `:scan_size` - `Integer` - (`config['key_extraction_batch_size']` by default);
- returns: `Set<String>`

```ruby
rql.keys # or rql.keys(scan_size: 123)

=>
#<Set:
 {"rql:lock_queue:locklock75",
 "rql:lock_queue:locklock9",
 "rql:lock:locklock9",
 "rql:lock_queue:locklock108",
 "rql:lock_queue:locklock7",
 "rql:lock:locklock7",
 "rql:lock_queue:locklock48",
 "rql:lock_queue:locklock104",
 "rql:lock:locklock104",
 "rql:lock_queue:locklock13",
 "rql:lock_queue:locklock62",
 "rql:lock_queue:locklock80",
 "rql:lock:locklock80",
 "rql:lock_queue:locklock28",
 ...}>
```

---

#### #locks_info - get list of locks with their info

\[[back to top](#usage)\]

- get list of locks with their info;
- uses redis `SCAN` under the hod;
- accepts `scan_size:`/`Integer` option (`config['key_extraction_batch_size']` by default);
- returns `Set<Hash<Symbol,Any>>` (see [#lock_info](#lock_info) and examples below for details).
 - contained data: `{ lock: String, status: Symbol, info: Hash<String,Any> }`;
 - `:lock` - `String` - lock key in Redis;
 - `:status` - `Symbol`- `:released` or `:alive`
 - the lock may become relased durign the lock info extraction process;
 - `:info` for `:released` keys is empty (`{}`);
 - `:info` - `Hash<String,Any>`
 - lock data stored in the lock key in Redis;
 - See [#lock_info](#lock_info) for details;

```ruby
rql.locks_info # or rql.locks_info(scan_size: 123)

# =>
=> #<Set:
 {{:lock=>"rql:lock:some-lock-123",
 :status=>:alive,
 :info=>{
 "acq_id"=>"rql:acq:41478/4320/4340/4360/848818f09d8c3420",
 "hst_id"=>"rql:hst:41478/4320/4360/848818f09d8c3420",
 "ts"=>1711607112.670343,
 "ini_ttl"=>15000,
 "rem_ttl"=>13998}},
 {:lock=>"rql:lock:some-lock-456",
 :status=>:released,
 :info=>{},
 ...}>
```

---

#### #queues_info - get list of queues with their info

\[[back to top](#usage)\]

- get list of queues with their info;
- uses redis `SCAN` under the hod;
- accepts `scan_size:`/`Integer` option (`config['key_extraction_batch_size']` by default);
- returns `Set<Hash<Symbol,Any>>` (see [#queue_info](#queue_info) and examples below for details).
 - contained data: `{ queue: String, requests: Array<Hash<String,Any>> }`
 - `:queue` - `String` - lock key queue in Redis;
 - `:requests` - `Array<Hash<String,Any>>` - lock requests in the que with their acquirer id and score.

```ruby
rql.queues_info # or rql.qeuues_info(scan_size: 123)

=> #<Set:
 {{:queue=>"rql:lock_queue:some-lock-123",
 :requests=>
 [{"acq_id"=>"rql:acq:38529/4500/4520/4360/66093702f24a3129", "score"=>1711606640.540842},
 {"acq_id"=>"rql:acq:38529/4580/4600/4360/66093702f24a3129", "score"=>1711606640.540906},
 {"acq_id"=>"rql:acq:38529/4620/4640/4360/66093702f24a3129", "score"=>1711606640.5409632}]},
 {:queue=>"rql:lock_queue:some-lock-456",
 :requests=>
 [{"acq_id"=>"rql:acq:38529/4380/4400/4360/66093702f24a3129", "score"=>1711606640.540722},
 {"acq_id"=>"rql:acq:38529/4420/4440/4360/66093702f24a3129", "score"=>1711606640.5407748},
 {"acq_id"=>"rql:acq:38529/4460/4480/4360/66093702f24a3129", "score"=>1711606640.540808}]},
 ...}>
```
---

#### #clear_dead_requests

\[[back to top](#usage)\]

In some cases your lock requests may become "dead". It means that your lock request lives in lock queue in Redis without
any processing. It can happen when your processs that are enqueeud to the lock queue is failed unexpectedly (for some reason)
before the lock acquire moment occurs and when no any other process does not need this lock anymore.
For this case your lock reuquest will be cleared only when any process will try
to acquire this lock again (cuz lock acquirement triggers the removement of expired requests).

In order to help with these dead requests you may periodically call `#clear_dead_requests`
with corresponding `:dead_ttl` option, that is pre-configured by default via `config['dead_request_ttl']`.

`:dead_ttl` option is required because of it is no any **fast** and **resource-free** way to understand which request
is dead now and is it really dead cuz each request queue can host their requests with
a custom queue ttl for each request differently.

Accepts:
- `:dead_ttl` - (optional) `[Integer]`
 - lock request ttl after which a lock request is considered dead;
 - has a preconfigured value in `config['dead_request_ttl']` (1 day by default);
- `:scan_size` - (optional) `[Integer]`
 - the batch of scanned keys for Redis'es SCAN command;
 - has a preconfigured valie in `config['lock_release_batch_size']`;
- `:logger` - (optional) `[::Logger,#debug]`
 - custom logger object;
 - pre-configured in `config['logger']`;
- `:instrumenter` - (optional) `[#notify]`
 - custom instrumenter object;
 - pre-configured in `config['isntrumenter']`;
- `:instrument` - (optional) `[NilClass,Any]`
 - custom instrumentation data wich will be passed to the instrumenter's payload with :instrument key;
 - `nil` by default (no additional data);
- `:log_sampling_enabled` - (optional) `[Boolean]`
 - enables **log sampling**;
 - pre-configured in `config['log_sampling_enabled']`;
- `:log_sampling_percent` - (optional) `[Integer]`
 - **log sampling**:the percent of cases that should be logged;
 - pre-configured in `config['log_sampling_percent']`;
- `:log_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Logging::Sampler>]`
 - **log sampling**: percent-based log sampler that decides should be RQL case logged or not;
 - pre-configured in `config['log_sampler']`;
- `log_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be logged despite the enabled log sampling;
 - makes sense when log sampling is enabled;
 - `false` by default;
- `:instr_sampling_enabled` - (optional) `[Boolean]`
 - enables **instrumentaion sampling**;
 - pre-configured in `config['instr_sampling_enabled']`;
- `instr_sampling_percent` - (optional) `[Integer]`
 - the percent of cases that should be instrumented;
 - pre-configured in `config['instr_sampling_percent']`;
- `instr_sampler` - (optional) `[#sampling_happened?,Module<RedisQueuedLocks::Instrument::Sampler>]`
 - percent-based log sampler that decides should be RQL case instrumented or not;
 - pre-configured in `config['instr_sampler']`;
- `instr_sample_this` - (optional) `[Boolean]`
 - marks the method that everything should be instrumneted despite the enabled instrumentation sampling;
 - makes sense when instrumentation sampling is enabled;
 - `false` by default;

Returns: `{ ok: true, processed_queues: Set<String> }` returns the list of processed lock queues;

```ruby
rql.clear_dead_requests(dead_ttl: 60 * 60 * 1000) # 1 hour in milliseconds

# =>
{
  ok: true,
  processed_queues: [
    "rql:lock_queue:some-lock-123",
    "rql:lock_queue:some-lock-456",
    "rql:lock_queue:your-other-lock",
    ...
  ]
}
```

---

#### #current_acquirer_id

\[[back to top](#usage)\]

- (aliases: `#current_acq_id`, `#acq_id`);
- get the current acquirer identifier in RQL notation that you can use for debugging purposes during the lock analyzation;
- acquirer identifier format:
  ```ruby
    "rql:acq:#{process_id}/#{thread_id}/#{fiber_id}/#{ractor_id}/#{identity}"
  ```
- because of the moment that `#lock`/`#lock!` gives you a possibility to customize `process_id`,
  `fiber_id`, `thread_id`, `ractor_id` and `unique identity` identifiers the `#current_acquirer_id` method provides this possibility too;

Accepts:

- `process_id:` - (optional) `[Integer,Any]`
  - `::Process.pid` by default;
- `thread_id:` - (optional) `[Integer,Any]`;
  - `::Thread.current.object_id` by default;
- `fiber_id:` - (optional) `[Integer,Any]`;
  - `::Fiber.current.object_id` by default;
- `ractor_id:` - (optional) `[Integer,Any]`;
  - `::Ractor.current.object_id` by default;
- `identity:` - (optional) `[String,Any]`;
  - this value is calculated once during `RedisQueuedLock::Client` instantiation and stored in `@uniq_identity`;
  - this value can be accessed from `RedisQueuedLock::Client#uniq_identity`;
  - [Configuration](#configuration) documentation: see `config['uniq_identifier']`;
  - [#lock](#lock---obtain-a-lock) method documentation: see `uniq_identifier`;

```ruby
rql.current_acquirer_id

# =>
"rql:acq:38529/4500/4520/4360/66093702f24a3129"
```

---

#### #current_host_id

\[[back to top](#usage)\]

- (aliases: `#current_hst_id`, `#hst_id`);
- get a current host identifier in RQL notation that you can use for debugging purposes during the lock analyzis;
- the host is a ruby worker (a combination of process/thread/ractor/identity) that is alive and can obtain locks;
- the host is limited to `process`/`thread`/`ractor` (without `fiber`) combination cuz we have no abilities to extract
  all fiber objects from the current ruby process when at least one ractor object is defined (**ObjectSpace** loses
  abilities to extract `Fiber` and `Thread` objects after the any ractor is created) (`Thread` objects are analyzed
  via `Thread.list` API which does not lose their abilites);
- host identifier format:
  ```ruby
    "rql:hst:#{process_id}/#{thread_id}/#{ractor_id}/#{uniq_identity}"
  ```
- because of the moment that `#lock`/`#lock!` gives you a possibility to customize `process_id`,
  `fiber_id`, `thread_id`, `ractor_id` and `unique identity` identifiers the `#current_host_id` method provides this possibility too
  (except the `fiber_id` correspondingly);

Accepts:

- `process_id:` - (optional) `[Integer,Any]`
  - `::Process.pid` by default;
- `thread_id:` - (optional) `[Integer,Any]`;
  - `::Thread.current.object_id` by default;
- `ractor_id:` - (optional) `[Integer,Any]`;
  - `::Ractor.current.object_id` by default;
- `identity:` - (optional) `[String]`;
  - this value is calculated once during `RedisQueuedLock::Client` instantiation and stored in `@uniq_identity`;
  - this value can be accessed from `RedisQueuedLock::Client#uniq_identity`;
  - [Configuration](#configuration) documentation: see `config['uniq_identifier']`;
  - [#lock](#lock---obtain-a-lock) method documentation: see `uniq_identifier`;

```ruby
rql.current_host_id

# =>
"rql:acq:38529/4500/4360/66093702f24a3129"
```

---

#### #possible_host_ids

\[[back to top](#usage)\]

- return the list (`Array<String>`) of possible host identifiers that can be reached from the current ractor;
- the host is a ruby worker (a combination of process/thread/ractor/identity) that is alive and can obtain locks;
- the host is limited to `process`/`thread`/`ractor` (without `fiber`) combination cuz we have no abilities to extract
 all fiber objects from the current ruby process when at least one ractor object is defined (**ObjectSpace** loses
 abilities to extract `Fiber` and `Thread` objects after the any ractor is created) (`Thread` objects are analyzed
 via `Thread.list` API which does not lose their abilites);
- host identifier format:
 ```ruby
 "rql:hst:#{process_id}/#{thread_id}/#{ractor_id}/#{uniq_identity}"
 ```

Accepts:

- `identity` - (optional) `[String]`;
  - this value is calculated once during `RedisQueuedLock::Client` instantiation and stored in `@uniq_identity`;
  - this value can be accessed from `RedisQueuedLock::Client#uniq_identity`;
  - [Configuration](#configuration) documentation: see `config['uniq_identifier']`;
  - [#lock](#lock---obtain-a-lock) method documentation: see `uniq_identifier`;

```ruby
rql.possible_host_ids

# =>
[
  "rql:hst:18814/2300/2280/5ce0c4582fc59c06", # process id / thread id / ractor id / uniq identity
  "rql:hst:18814/2320/2280/5ce0c4582fc59c06", # ...
  "rql:hst:18814/2340/2280/5ce0c4582fc59c06", # ...
  "rql:hst:18814/2360/2280/5ce0c4582fc59c06", # ...
  "rql:hst:18814/2380/2280/5ce0c4582fc59c06", # ...
  "rql:hst:18814/2400/2280/5ce0c4582fc59c06"
]
```
---

## Swarm Mode and Zombie Locks

\[[back to top](#table-of-contents)\]

> Eliminate zombie locks with a swarm.

**This documentation section is in progress!** (see the changelog and the usage preview for details at this moment)

[(work and usage preview (temporary example-based docs))](#work-and-usage-preview-temporary-example-based-docs)

- [How to Swarm](#how-to-swarm)
  - [configuration](#)
  - [swarm_status](#swarm_status)
  - [swarm_info](#swarm_info)
  - [swarmize!](#swarmize!)
  - [deswarmize!](#deswarmize!)
  - [probe_hosts](#probe_hosts)
  - [flush_zobmies](#flush_zombies)
- [zombies_info](#zombies_info)
- [zombie_locks](#zombie_locks)
- [zombie_hosts](#zombie_hosts)
- [zombie_acquirers](#zombie_acquirers)

<hr>

#### Work and Usage Preview (temporary example-based docs)

\[[back to top](#swarm-mode-and-zombie-locks)\]

<details>
 <summary>configuration</summary>

```ruby
  redis_client = RedisClient.config.new_pool # NOTE: provide your own RedisClient instance

clinet = RedisQueuedLocks::Client.new(redis_client) do |config|
    # NOTE: auto-swarm your RQL client after initalization (run swarm elements and their supervisor)
    config['swarm.auto_swarm'] = false

# supervisor configs
    config['swarm.supervisor.liveness_probing_period'] = 2 # NOTE: in seconds

# (probe_hosts) host probing configuration
    config['swarm.probe_hosts.enabled_for_swarm'] = true # NOTE: run host-probing from or not
    config['swarm.probe_hosts.probe_period'] = 2 # NOTE: (in seconds) the period of time when the probing process is triggered
    # (probe_hosts) individual redis config
    config['swarm.probe_hosts.redis_config.sentinel'] = false # NOTE: individual redis config
    config['swarm.probe_hosts.redis_config.pooled'] = false # NOTE: individual redis config
    config['swarm.probe_hosts.redis_config.config'] = {} # NOTE: individual redis config
    config['swarm.probe_hosts.redis_config.pool_config'] = {} # NOTE: individual redis config

# (flush_zombies) zombie flushing configuration
 config['swarm.flush_zombies.enabled_for_swarm'] = true # NOTE: run zombie flushing or not
 config['swarm.flush_zombies.zombie_flush_period'] = 10 # NOTE: (in seconds) period of time when the zombie flusher is triggered
 config['swarm.flush_zombies.zombie_ttl'] = 15_000 # NOTE: (in milliseconds) when the lock/host/acquirer is considered a zombie
 config['swarm.flush_zombies.zombie_lock_scan_size'] = 500 # NOTE: scan sizec during zombie flushing
 config['swarm.flush_zombies.zombie_queue_scan_size'] = 500 # NOTE: scan sizec during zombie flushing
 # (flush_zombies) individual redis config
 config['swarm.flush_zombies.redis_config.sentinel'] = false # NOTE: individual redis config
 config['swarm.flush_zombies.redis_config.pooled'] = false # NOTE: individual redis config
 config['swarm.flush_zombies.redis_config.config'] = {} # NOTE: individual redis config
 config['swarm.flush_zombies.redis_config.pool_config'] = {} # NOTE: individual redis config
 end
 ```
</details>

<details>
 <summary>seed a zombie</summary>

- obtain some long living lock and kill the host process which will lead the lock becoming a zombie:

```ruby
 daiver => ~/Projects/redis_queued_locks  master [$]
 ➜ bin/console
 [1] pry(main)> rql = RedisQueuedLocks::Client.new(RedisClient.new);
 [2] pry(main)> rql.swarmize!
 /Users/daiver/Projects/redis_queued_locks/lib/redis_queued_locks/swarm/flush_zombies.rb:107: warning: Ractor is experimental, and the behavior may change in future versions of Ruby! Also there are many implementation issues.
 => {:ok=>true, :result=>:swarming}
 [3] pry(main)> rql.lock('kekpek', ttl: 1111111111)
 => {:ok=>true,
 :result=>
 {:lock_key=>"rql:lock:kekpek",
 :acq_id=>"rql:acq:17580/2260/2380/2280/3f16b93973612580",
 :hst_id=>"rql:hst:17580/2260/2280/3f16b93973612580",
 :ts=>1720305351.069259,
 :ttl=>1111111111,
 :process=>:lock_obtaining}}
 [4] pry(main)> exit
 ```
</details>

<details>
 <summary>find zombies</summary>

- start another process, fetch the swarm info, see that our last process is a zombie now and their hosted lock is a zombie too:

```ruby
 daiver => ~/Projects/redis_queued_locks  master [$] took 27.2s
 ➜ bin/console
 [1] pry(main)> rql = RedisQueuedLocks::Client.new(RedisClient.new);
 [2] pry(main)> rql.swarm_info
 => {"rql:hst:17580/2260/2280/3f16b93973612580"=>{:zombie=>true, :last_probe_time=>2024-07-07 01:35:53 12897/262144 +0300, :last_probe_score=>1720305353.0491982},
 "rql:hst:17580/2300/2280/3f16b93973612580"=>{:zombie=>true, :last_probe_time=>2024-07-07 01:35:53 211107/4194304 +0300, :last_probe_score=>1720305353.0503318},
 "rql:hst:17580/2320/2280/3f16b93973612580"=>{:zombie=>true, :last_probe_time=>2024-07-07 01:35:53 106615/2097152 +0300, :last_probe_score=>1720305353.050838},
 "rql:hst:17580/2260/2340/3f16b93973612580"=>{:zombie=>true, :last_probe_time=>2024-07-07 01:35:53 26239/524288 +0300, :last_probe_score=>1720305353.050047},
 "rql:hst:17580/2300/2340/3f16b93973612580"=>{:zombie=>true, :last_probe_time=>2024-07-07 01:35:53 106359/2097152 +0300, :last_probe_score=>1720305353.050716},
 "rql:hst:17580/2320/2340/3f16b93973612580"=>{:zombie=>true, :last_probe_time=>2024-07-07 01:35:53 213633/4194304 +0300, :last_probe_score=>1720305353.050934},
 "rql:hst:17580/2360/2280/3f16b93973612580"=>{:zombie=>true, :last_probe_time=>2024-07-07 01:35:53 214077/4194304 +0300, :last_probe_score=>1720305353.05104},
 "rql:hst:17580/2360/2340/3f16b93973612580"=>{:zombie=>true, :last_probe_time=>2024-07-07 01:35:53 214505/4194304 +0300, :last_probe_score=>1720305353.051142},
 "rql:hst:17580/2400/2280/3f16b93973612580"=>{:zombie=>true, :last_probe_time=>2024-07-07 01:35:53 53729/1048576 +0300, :last_probe_score=>1720305353.05124},
 "rql:hst:17580/2400/2340/3f16b93973612580"=>{:zombie=>true, :last_probe_time=>2024-07-07 01:35:53 3365/65536 +0300, :last_probe_score=>1720305353.0513458}}
 [3] pry(main)> rql.swarm_status
 => {:auto_swarm=>false,
 :supervisor=>{:running=>false, :state=>"non_initialized", :observable=>"non_initialized"},
 :probe_hosts=>{:enabled=>true, :thread=>{:running=>false, :state=>"non_initialized"}, :main_loop=>{:running=>false, :state=>"non_initialized"}},
 :flush_zombies=>{:enabled=>true, :ractor=>{:running=>false, :state=>"non_initialized"}, :main_loop=>{:running=>false, :state=>"non_initialized"}}}
 [4] pry(main)> rql.zombies_info
 => {:zombie_hosts=>
 #<Set:
 {"rql:hst:17580/2260/2280/3f16b93973612580",
 "rql:hst:17580/2300/2280/3f16b93973612580",
 "rql:hst:17580/2320/2280/3f16b93973612580",
 "rql:hst:17580/2260/2340/3f16b93973612580",
 "rql:hst:17580/2300/2340/3f16b93973612580",
 "rql:hst:17580/2320/2340/3f16b93973612580",
 "rql:hst:17580/2360/2280/3f16b93973612580",
 "rql:hst:17580/2360/2340/3f16b93973612580",
 "rql:hst:17580/2400/2280/3f16b93973612580",
 "rql:hst:17580/2400/2340/3f16b93973612580"}>,
 :zombie_acquirers=>#<Set: {"rql:acq:17580/2260/2380/2280/3f16b93973612580"}>,
 :zombie_locks=>#<Set: {"rql:lock:kekpek"}>}
 [5] pry(main)> rql.zombie_locks
 => #<Set: {"rql:lock:kekpek"}>
 [6] pry(main)> rql.zombie_acquirers
 => #<Set: {"rql:acq:17580/2260/2380/2280/3f16b93973612580"}>
 [7] pry(main)> rql.zombie_hosts
 => #<Set:
 {"rql:hst:17580/2260/2280/3f16b93973612580",
 "rql:hst:17580/2300/2280/3f16b93973612580",
 "rql:hst:17580/2320/2280/3f16b93973612580",
 "rql:hst:17580/2260/2340/3f16b93973612580",
 "rql:hst:17580/2300/2340/3f16b93973612580",
 "rql:hst:17580/2320/2340/3f16b93973612580",
 "rql:hst:17580/2360/2280/3f16b93973612580",
 "rql:hst:17580/2360/2340/3f16b93973612580",
 "rql:hst:17580/2400/2280/3f16b93973612580",
 "rql:hst:17580/2400/2340/3f16b93973612580"}>
 ```
</details>

<details>
 <summary>kill zombies in a background</summary>

- swarmize the new current ruby process that should run the flush zombies element that will drop zombie locks, zombie hosts and their lock requests in a background:

```ruby
 [8] pry(main)> rql.swarmize!
 /Users/daiver/Projects/redis_queued_locks/lib/redis_queued_locks/swarm/flush_zombies.rb:107: warning: Ractor is experimental, and the behavior may change in future versions of Ruby! Also there are many implementation issues.
 => {:ok=>true, :result=>:swarming}
 [9] pry(main)> rql.swarm_info
 => {"rql:hst:17752/2260/2280/89beef198021f16d"=>{:zombie=>false, :last_probe_time=>2024-07-07 01:36:39 4012577/4194304 +0300, :last_probe_score=>1720305399.956673},
 "rql:hst:17752/2300/2280/89beef198021f16d"=>{:zombie=>false, :last_probe_time=>2024-07-07 01:36:39 4015233/4194304 +0300, :last_probe_score=>1720305399.9573061},
 "rql:hst:17752/2320/2280/89beef198021f16d"=>{:zombie=>false, :last_probe_time=>2024-07-07 01:36:39 4016755/4194304 +0300, :last_probe_score=>1720305399.957669},
 "rql:hst:17752/2260/2340/89beef198021f16d"=>{:zombie=>false, :last_probe_time=>2024-07-07 01:36:39 1003611/1048576 +0300, :last_probe_score=>1720305399.957118},
 "rql:hst:17752/2300/2340/89beef198021f16d"=>{:zombie=>false, :last_probe_time=>2024-07-07 01:36:39 2008027/2097152 +0300, :last_probe_score=>1720305399.957502},
 "rql:hst:17752/2320/2340/89beef198021f16d"=>{:zombie=>false, :last_probe_time=>2024-07-07 01:36:39 2008715/2097152 +0300, :last_probe_score=>1720305399.95783},
 "rql:hst:17752/2360/2280/89beef198021f16d"=>{:zombie=>false, :last_probe_time=>2024-07-07 01:36:39 4018063/4194304 +0300, :last_probe_score=>1720305399.9579809},
 "rql:hst:17752/2360/2340/89beef198021f16d"=>{:zombie=>false, :last_probe_time=>2024-07-07 01:36:39 1004673/1048576 +0300, :last_probe_score=>1720305399.9581308}}
 [10] pry(main)> rql.swarm_status
 => {:auto_swarm=>false,
 :supervisor=>{:running=>true, :state=>"sleep", :observable=>"initialized"},
 :probe_hosts=>{:enabled=>true, :thread=>{:running=>true, :state=>"sleep"}, :main_loop=>{:running=>true, :state=>"sleep"}},
 :flush_zombies=>{:enabled=>true, :ractor=>{:running=>true, :state=>"running"}, :main_loop=>{:running=>true, :state=>"sleep"}}}
 [11] pry(main)> rql.zombies_info
 => {:zombie_hosts=>#<Set: {}>, :zombie_acquirers=>#<Set: {}>, :zombie_locks=>#<Set: {}>}
 [12] pry(main)> rql.zombie_acquirers
 => #<Set: {}>
 [13] pry(main)> rql.zombie_hosts
 => #<Set: {}>
 [14] pry(main)>
 ```
</details>

<details>
 <summary>swarm hosts key in Redis</summary>

```ruby
 "rql:swarm:hsts"
 ```
</details>

---

## Lock Access Strategies

\[[back to top](#table-of-contents)\]

- **this documentation section is in progress**;
- (little details for a context of the current implementation and feautres):
  - defines the way in which the lock should be obitained;
  - by default it is configured to obtain a lock in classic `queued` way: you should wait your position in queue in order to obtain a lock;
  - can be customized in methods `#lock` and `#lock!` via `:access_strategy` attribute (see method signatures of #lock and #lock! methods);
  - supports different strategies:
    - `:queued` (FIFO): the classic queued behavior (default), your lock will be obitaned if you are first in queue and the required lock is free;
    - `:random` (RANDOM): obtain a lock without checking the positions in the queue (but with checking the limist, retries, timeouts and so on). if lock is free to obtain - it will be obtained;
  - for current implementation detalis check:
    - [Configuration](#configuration) documentation: see `config['default_access_strategy']` config docs;
    - [#lock](#lock---obtain-a-lock) method documentation: see `access_strategy` attribute docs;

---

## Deadlocks and Reentrant locks

\[[back to top](#table-of-contents)\]

- **this documentation section is in progress**;
- (little details for a context of the current implementation and feautres):
  - at this moment we support only **reentrant locks**: they works via customizable conflict strategy behavior
    (`:wait_for_lock` (default), `:work_through`, `:extendable_work_through`, `:dead_locking`);
  - by default behavior (`:wait_for_lock`) your lock obtaining process will work in a classic way (limits, retries, etc);
  - `:work_through`, `:extendable_work_through` works with limits too (timeouts, delays, etc), but the decision of
    "is your lock are obtained or not" is made as you work with **reentrant locks** (your process continues to use the lock without/with
    lock's TTL extension accordingly);
  - for current implementation details check:
    - [Configuration](#configuration) documentation: see `config['default_conflict_strategy']` config docs;
    - [#lock](#lock---obtain-a-lock) method documentation: see `conflict_strategy` attribute docs and the method result data;

---

## Logging

\[[back to top](#table-of-contents)\]

- [Logging Configuration](#logging-configuration)

- default logs (raised from `#lock`/`#lock!`):

```ruby
"[redis_queued_locks.start_lock_obtaining]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
"[redis_queued_locks.start_try_to_lock_cycle]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
"[redis_queued_locks.dead_score_reached__reset_acquirer_position]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
"[redis_queued_locks.lock_obtained]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acq_time");
"[redis_queued_locks.extendable_reentrant_lock_obtained]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "acq_time");
"[redis_queued_locks.reentrant_lock_obtained]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "acq_time");
"[redis_queued_locks.fail_fast_or_limits_reached_or_deadlock__dequeue]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
"[redis_queued_locks.expire_lock]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
"[redis_queued_locks.decrease_lock]" # (logs "lock_key", "decreased_ttl", "queue_ttl", "acq_id", "hst_id", "acs_strat");
```

- additional logs (raised from `#lock`/`#lock!` with `confg[:log_lock_try] == true`):

```ruby
"[redis_queued_locks.try_lock.start]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
"[redis_queued_locks.try_lock.rconn_fetched]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
"[redis_queued_locks.try_lock.same_process_conflict_detected]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
"[redis_queued_locks.try_lock.same_process_conflict_analyzed]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "spc_status");
"[redis_queued_locks.try_lock.reentrant_lock__extend_and_work_through]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "spc_status", "last_ext_ttl", "last_ext_ts");
"[redis_queued_locks.try_lock.reentrant_lock__work_through]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "spc_status", last_spc_ts);
"[redis_queued_locks.try_lock.single_process_lock_conflict__dead_lock]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "spc_status", "last_spc_ts");
"[redis_queued_locks.try_lock.acq_added_to_queue]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
"[redis_queued_locks.try_lock.remove_expired_acqs]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
"[redis_queued_locks.try_lock.get_first_from_queue]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "first_acq_id_in_queue");
"[redis_queued_locks.try_lock.exit__queue_ttl_reached]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
"[redis_queued_locks.try_lock.exit__no_first]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "first_acq_id_in_queue", "<current_lock_data>");
"[redis_queued_locks.try_lock.exit__lock_still_obtained]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "first_acq_id_in_queue", "locked_by_acq_id", "<current_lock_data>");
"[redis_queued_locks.try_lock.obtain__free_to_acquire]" # (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
```

---

### Logging Configuration

\[[back to top](#table-of-contents)\]

**NOTICE**: logging can be sampled via:
- `config['log_samplign_enabled'] = true` (**false** by default);
- `config['log_sampler'] = RedisQueuedLocks::Logging::Sampler` (used by default);
- see **RedisQueuedLocks::Logging::Sampler** implementation in source code for customization details;

```ruby
# (default: RedisQueuedLocks::Logging::VoidLogger)
# - the logger object;
# - should implement `debug(progname = nil, &block)` (minimal requirement) or be an instance of Ruby's `::Logger` class/subclass;
# - supports `SemanticLogger::Logger` (see "semantic_logger" gem)
# - at this moment the only debug logs are realised in following cases:
#   - "[redis_queued_locks.start_lock_obtaining]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
#   - "[redis_queued_locks.start_try_to_lock_cycle]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
#   - "[redis_queued_locks.dead_score_reached__reset_acquirer_position]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
#   - "[redis_queued_locks.lock_obtained]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acq_time", "acs_strat");
#   - "[redis_queued_locks.extendable_reentrant_lock_obtained]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acq_time", "acs_strat");
#   - "[redis_queued_locks.reentrant_lock_obtained]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acq_time", "acs_strat");
#   - "[redis_queued_locks.fail_fast_or_limits_reached_or_deadlock__dequeue]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
#   - "[redis_queued_locks.expire_lock]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
#   - "[redis_queued_locks.decrease_lock]" (logs "lock_key", "decreased_ttl", "queue_ttl", "acq_id", "hst_id", "acs_strat");
# - by default uses VoidLogger that does nothing;
config['logger'] = RedisQueuedLocks::Logging::VoidLogger

# (default: false)
# - adds additional debug logs;
# - enables additional logs for each internal try-retry lock acquiring (a lot of logs can be generated depending on your retry configurations);
# - it adds following debug logs in addition to the existing:
# - "[redis_queued_locks.try_lock.start]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
# - "[redis_queued_locks.try_lock.rconn_fetched]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
# - "[redis_queued_locks.try_lock.same_process_conflict_detected]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
# - "[redis_queued_locks.try_lock.same_process_conflict_analyzed]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "spc_status");
# - "[redis_queued_locks.try_lock.reentrant_lock__extend_and_work_through]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "spc_status", "last_ext_ttl", "last_ext_ts");
# - "[redis_queued_locks.try_lock.reentrant_lock__work_through]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "spc_status", last_spc_ts);
# - "[redis_queued_locks.try_lock.acq_added_to_queue]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat")";
# - "[redis_queued_locks.try_lock.remove_expired_acqs]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
# - "[redis_queued_locks.try_lock.get_first_from_queue]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "first_acq_id_in_queue");
# - "[redis_queued_locks.try_lock.exit__queue_ttl_reached]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
# - "[redis_queued_locks.try_lock.exit__no_first]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "first_acq_id_in_queue", "<current_lock_data>");
# - "[redis_queued_locks.try_lock.exit__lock_still_obtained]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat", "first_acq_id_in_queue", "locked_by_acq_id", "<current_lock_data>");
# - "[redis_queued_locks.try_lock.obtain__free_to_acquire]" (logs "lock_key", "queue_ttl", "acq_id", "hst_id", "acs_strat");
config['log_lock_try'] = false

# (default: false)
# - enables <log sampling>: only the configured percent of RQL cases will be logged;
# - disabled by default;
# - works in tandem with <config['log_sampling_percent']> and <config['log_sampler']> configs;
config['log_sampling_enabled'] = false

# (default: 15)
# - the percent of cases that should be logged;
# - take an effect when <config['log_sampling_enalbed']> is true;
# - works in tandem with <config['log_sampling_enabled']> and <config['log_sampler']> configs;
config['log_sampling_percent'] = 15

# (default: RedisQueuedLocks::Logging::Sampler)
# - percent-based log sampler that decides should be RQL case logged or not;
# - works in tandem with <config['log_sampling_enabled']> and <config['log_sampling_percent']> configs;
# - based on the ultra simple percent-based (weight-based) algorithm that uses SecureRandom.rand
# method so the algorithm error is ~(0%..13%);
# - you can provide your own log sampler with bettter algorithm that should realize
# `sampling_happened?(percent) => boolean` interface (see `RedisQueuedLocks::Logging::Sampler` for example);
config['log_sampler'] = RedisQueuedLocks::Logging::Sampler
```

---

## Instrumentation

\[[back to top](#table-of-contents)\]

- [Instrumentation Events](#instrumentation-events)
- [Instrumentation Configuration](#instrumentation-configuration)

An instrumentation layer is incapsulated in `instrumenter` object stored in [config](#configuration) (`RedisQueuedLocks::Client#config['instrumenter']`).

Instrumentation can be **sampled**. See [Instrumentation Configuration](#instrumentation-configuration) section for details.

Instrumenter object should provide `notify(event, payload)` method with the following signarue:

- `event` - `string`;
- `payload` - `hash<Symbol,Any>`;

**RQL** provides two instrumenters:

- `RedisQueuedLocks::Instrument::ActiveSupport` - **ActiveSupport::Notifications** instrumenter that instrument events via **ActiveSupport::Notifications** API;
- `RedisQueuedLocks::Instrument::VoidNotifier` - instrumenter that does nothing;

By default `RedisQueuedLocks::Client` is configured with the void notifier (which means "instrumentation is disabled").

---

### Instrumentation Configuration

\[[back to top](#table-of-contents)\]

**NOTICE**: instrumentation can be sampled via:
- `config['instr_sampling_enabled'] = true` (**false** by default);
- `config['instr_sampler'] = RedisQueuedLocks::Instrument::Sampler` (used by default);
- see **RedisQueuedLocks::Instrument::Sampler** implementation in source code for customization details;

```ruby
# (default: RedisQueuedLocks::Instrument::VoidNotifier)
# - instrumentation layer;
# - you can provide your own instrumenter that should realize `#notify(event, payload = {})` interface:
# - event: <string> requried;
# - payload: <hash> requried;
# - disabled by default via `VoidNotifier`;
config['instrumenter'] = RedisQueuedLocks::Instrument::ActiveSupport

# (default: false)
# - enables <instrumentaion sampling>: only the configured percent of RQL cases will be instrumented;
# - disabled by default;
# - works in tandem with <config['instr_sampling_percent']> and <config['instr_sampler']>;
config['instr_sampling_enabled'] = false

# (default: 15)
# - the percent of cases that should be instrumented;
# - take an effect when <config['instr_sampling_enalbed']> is true;
# - works in tandem with <config['instr_sampling_enabled']> and <config['instr_sampler']> configs;
config['instr_sampling_percent'] = 15

# (default: RedisQueuedLocks::Instrument::Sampler)
# - percent-based log sampler that decides should be RQL case instrumented or not;
# - works in tandem with <config['instr_sampling_enabled']> and <config['instr_sampling_percent']> configs;
# - based on the ultra simple percent-based (weight-based) algorithm that uses SecureRandom.rand
# method so the algorithm error is ~(0%..13%);
# - you can provide your own log sampler with bettter algorithm that should realize
# `sampling_happened?(percent) => boolean` interface (see `RedisQueuedLocks::Instrument::Sampler` for example);
config['instr_sampler'] = RedisQueuedLocks::Instrument::Sampler
```

---

### Instrumentation Events

\[[back to top](#instrumentation)\]

List of instrumentation events

- ["redis_queued_locks.lock_obtained"](#redis_queued_lockslock_hold_and_release)
- ["redis_queued_locks.extendable_reentrant_lock_obtained"](#redis_queued_locksextendable_reentrant_lock_obtained)
- ["redis_queued_locks.reentrant_lock_obtained"](#redis_queued_locksreentrant_lock_obtained)
- ["redis_queued_locks.lock_hold_and_release"](#redis_queued_lockslock_hold_and_release)
- ["redis_queued_locks.reentrant_lock_hold_completes"](#redis_queued_locksreentrant_lock_hold_completes)
- ["redis_queued_locks.explicit_lock_release"](#redis_queued_locksexplicit_lock_release)
- ["redis_queued_locks.explicit_all_locks_release"](#redis_queued_locksexplicit_all_locks_release)
- ["redis_queued_locks.release_locks_of"](#redis_queued_locksrelease_locks_of)

Detalized event semantics and payload structure:

##### `"redis_queued_locks.lock_obtained"`
- \[[back to the list](#instrumentation-events)\]
- a moment when the lock was obtained;
- raised from `#lock`/`#lock!`;
- payload:
 - `:ttl` - `integer`/`milliseconds` - lock ttl;
 - `:acq_id` - `string` - lock acquirer identifier;
 - `:hst_id` - `string` - lock's host identifier;
 - `:lock_key` - `string` - lock name;
 - `:ts` - `numeric`/`epoch` - the time when the lock was obtaiend;
 - `:acq_time` - `float`/`milliseconds` - time spent on lock acquiring;
 - `:instrument` - `nil`/`Any` - custom data passed to the `#lock`/`#lock!` method as `:instrument` attribute;

##### `"redis_queued_locks.extendable_reentrant_lock_obtained"`
- \[[back to the list](#instrumentation-events)\]
- an event signalizes about the "extendable reentrant lock" obtaining is happened;
- raised from `#lock`/`#lock!` when the lock was obtained as reentrant lock;
- payload:
 - `:lock_key` - `string` - lock name;
 - `:ttl` - `integer`/`milliseconds` - last lock ttl by reentrant locking;
 - `:acq_id` - `string` - lock acquirer identifier;
 - `:hst_id` - `string` - lock's host identifier;
 - `:ts` - `numeric`/`epoch` - the time when the lock was obtaiend as extendable reentrant lock;
 - `:acq_time` - `float`/`milliseconds` - time spent on lock acquiring;
 - `:instrument` - `nil`/`Any` - custom data passed to the `#lock`/`#lock!` method as `:instrument` attribute;

##### `"redis_queued_locks.reentrant_lock_obtained"`
- \[[back to the list](#instrumentation-events)\]
- an event signalizes about the "reentrant lock" obtaining is happened (without TTL extension);
- raised from `#lock`/`#lock!` when the lock was obtained as reentrant lock;
- payload:
 - `:lock_key` - `string` - lock name;
 - `:ttl` - `integer`/`milliseconds` - last lock ttl by reentrant locking;
 - `:acq_id` - `string` - lock acquirer identifier;
 - `:hst_id` - `string` - lock's host identifier;
 - `:ts` - `numeric`/`epoch` - the time when the lock was obtaiend as reentrant lock;
 - `:acq_time` - `float`/`milliseconds` - time spent on lock acquiring;
 - `:instrument` - `nil`/`Any` - custom data passed to the `#lock`/`#lock!` method as `:instrument` attribute;

##### `"redis_queued_locks.lock_hold_and_release"`
- \[[back to the list](#instrumentation-events)\]
- an event signalizes about the "hold+and+release" process is finished;
- raised from `#lock`/`#lock!` when invoked with a block of code;
- payload:
 - `:hold_time` - `float`/`milliseconds` - lock hold time;
 - `:ttl` - `integer`/`milliseconds` - lock ttl;
 - `:acq_id` - `string` - lock acquirer identifier;
 - `:hst_id` - `string` - lock's host identifier;
 - `:lock_key` - `string` - lock name;
 - `:ts` - `numeric`/`epoch` - the time when lock was obtained;
 - `:acq_time` - `float`/`milliseconds` - time spent on lock acquiring;
 - `:instrument` - `nil`/`Any` - custom data passed to the `#lock`/`#lock!` method as `:instrument` attribute;

##### `"redis_queued_locks.reentrant_lock_hold_completes"`
- \[[back to the list](#instrumentation-events)\]
- an event signalizes about the "reentrant lock hold" is complete (both extendable and non-extendable);
- lock re-entering can happen many times and this event happens for each of them separately;
- raised from `#lock`/`#lock!` when the lock was obtained as reentrant lock;
- payload:
 - `:hold_time` - `float`/`milliseconds` - lock hold time;
 - `:ttl` - `integer`/`milliseconds` - last lock ttl by reentrant locking;
 - `:acq_id` - `string` - lock acquirer identifier;
 - `:hst_id` - `string` - lock's host identifier;
 - `:ts` - `numeric`/`epoch` - the time when the lock was obtaiend as reentrant lock;
 - `:lock_key` - `string` - lock name;
 - `:acq_time` - `float`/`milliseconds` - time spent on lock acquiring;
 - `:instrument` - `nil`/`Any` - custom data passed to the `#lock`/`#lock!` method as `:instrument` attribute;

##### `"redis_queued_locks.explicit_lock_release"`
- \[[back to the list](#instrumentation-events)\]
- an event signalizes about the explicit lock release (invoked via `RedisQueuedLock#unlock`);
- raised from `#unlock`;
- payload:
 - `:at` - `float`/`epoch` - the time when the lock was released;
 - `:rel_time` - `float`/`milliseconds` - time spent on lock releasing;
 - `:lock_key` - `string` - released lock (lock name);
 - `:lock_key_queue` - `string` - released lock queue (lock queue name);

##### `"redis_queued_locks.explicit_all_locks_release"`
- \[[back to the list](#instrumentation-events)\]
- an event signalizes about the explicit all locks release (invoked via `RedisQueuedLock#clear_locks`);
- raised from `#clear_locks`;
- payload:
 - `:rel_time` - `float`/`milliseconds` - time spent on "realese all locks" operation;
 - `:at` - `float`/`epoch` - the time when the operation has ended;
 - `:rel_keys` - `integer` - released redis keys count (`released queue keys` + `released lock keys`);

##### `"redis_queued_locks.release_locks_of"`
- \[[back to the list](#instrumentation-events)\]
- an event signalizes about the released locks (and removement from lock queues) of the concrete host and acquirer;
- raised from `#clear_locks_of` and `#clear_current_locks` (`#release_locks_of` and `#release_current_locks` respectively);
- payload:
 - `:rel_time` - `float`/`milliseconds` - time spent on "release locks of" operation;
 - `:at` - `float`/`epoch` - the time when the opertaion has ended; 
 - `:acq_id` - `string` - refused acquirer identifier;
 - `:hst_id` - `string` - refused host identifier;
 - `:rel_key_cnt` - `integer` - released locks count;
 - `:tch_queue_cnt` - `:integer` - the number of queues from which the concrete host/acquirer was removed;

---

## Roadmap

\[[back to top](#table-of-contents)\]

- **Major**:
  - Swarm:
    - circuit-breaker for long-living failures of your infrastructure inside the swarm elements and supervisor:
      the supervisor will stop (for some period of time or while the some factor will return `true`)
      trying to ressurect unexpectedly terminated swarm elements, and will notify about this;
    - swarm logs (thread/ractor has some limitations so the initial implementation does not include swarm logging);
    - swarm instrumentation (thread/ractor has some limitations so the initial implementation does not include swarm instrumentation);
  - isolated timeouts which are independent of internal Ruby's timeout implementation (where all timeouts are hostend inside
    the global "timeout request" queue and managed by a single global "timeout wathcer" thread). it should prevent any logic and timeout intersections,
    some GVL-related things and problem situations when the global watcher thread is "dead";
  - lock request prioritization;
  - **strict redlock algorithm support** (support for many `RedisClient` instances that are fully independent (distributed redis instances));
  - #lock_series` - acquire a series of locks:
    - (NOTE: "Proof of Concept" implementation is ready to use);
    ```ruby
    rql.lock_series('lock_a', 'lock_b', 'lock_c') { puts 'locked' }
    ```
  - an ability to release all locks and all requests of the concrete acquirer id or host id (or both in validation-orianted combination);
  - detailed lock informotion inside the error object in cases of exceptions (at the moment we have this info inside the error message only that hard to analyze in work);
  - a convenient way to mark any `lock` invocation as "non-instrumentable" / "non-loggable" (as an alternative to `VoidNotifier` and to `VoidLogger`);
  - `Read`/`Write` semantics: you can mark your locks as `read` or `write` lock in order to simulate `read`/`write` lock behavior:
    - `read` - watis - `write`;
    - `read` - not waits - `read`;
    - `write` - waits - `read`;
    - `write` - waits - `write`;
    - **write** mode is a default behavior for all RQL locks;
  - `README`-section `Issues with other Libs` about issues in other libraries that can broke RQL features:
    - `Sentry`'s' bugs with Ractors:
      - `Sentry`-OpenTelemetry problems with its global mutexes and non-sharable objects that is not accessible from the ractors (sentry tyies to
        intercept all `redis-client` invocations managing their logic via global Mutex instance that brokes `swarm-mode` with `non-sharable` memory
        access errors, cuz RQL's swarm works using its own RedisClient-instnace, that fails isnide the `Sentry`'s patch: Sentry tries to use the same
        Mutex (instantiated inside the main Ractor) from the our non-main Ractor (swar-mode works under the non-main ractor) and this process fails\
        on non-sharable memory error);
- **Minor**:
  - an ability to return all insturmentation metrics from the `lock` invocation (and after block `yield`ing);
  - think about a PG-like `stats`-data/table, that should be helpful for lock history acquirement analyzation :thinking: (suitable for cases when we want
    to check if the lock was acquired by some different parallel process durign the some period of time in the past or not);
  - think about "thread priority" configuration :thinking:;
  - add `hst_id` to all methods that works with queues info;
  - try to return the `fiber object id` to the lock host identifier (we cant use fiber object id cuz `ObjectSpace` has no access to the fiber object space after the any ractor object initialization)
  - named RQL's threads (`Thread#name`) and RQL's ractors (`Ractor#name`) in order to have an ability to find and work with RQL's threads and ractors outside of RQL logic (stop threads before process forking, for example);
  - `#lock`/`#lock!` - `timeout:` option: support for granular periods (it supports only `seconds` at the moment, but we need `milliseconds`);
  - Add `after timeout hook` ability for timeout errors with an ability to access the binding context (if it possibly) of the thread where it failed;
  - Add `ignore timeout errors` ability (for debug purposes);
  - A special explicit documentation section that will explain and clarify which exceptions can be occured and what cases occurs them (at the moment such cases are explained inside the lock methods documentation that is not really convinient);
  - Renaming of some exceptions (such as `RedisQueuedLocks::TimedLockTimeoutError`) to make the related problem more quickly, faster and easier to understand;
  - Support for detailed `OpenTelemetry` tracing;
  - `light mode`: an ability to work without any debug and instrumentation logic and data (totally reduced debugging and instrumenting possibilities, but better performance);
  - support for `Dragonfly` database backend (https://github.com/dragonflydb/dragonfly) (https://www.dragonflydb.io/);
  - (_research_) GVL-isolation for lock acquirement logic (try to bypass Ruby's "context-switching" in order to prevent any time-based affects on lock-acquirement logic);
  - Semantic error objects for unexpected Redis errors;
  - **Experimental feature**: (non-`timed` locks): per-ruby-block-holding-the-lock sidecar `Ractor` and `in progress queue` in RedisDB that will extend
    the acquired lock for long-running blocks of code (that invoked "under" the lock
    whose ttl may expire before the block execution completes). It makes sense for non-`timed` locks *only*;
  - sized lock queues (with an ability of dynamically growing size);
  - better code stylization (+ some refactorings);
  - `RedisQueuedLocks::Acquirer::Try.try_to_lock` - detailed successful result analization;
  - Support for LIFO strategy;
  - specs refactoring with 100% test coverage (total specs rework);
  - statistics with UI;
  - JSON log formatter;
  - **automatic** deadlock detection;
  - `go`-lang implementation;
  - (_research_) simplification and speedup of the internal "redis-communuication-and-data-storing"-based algorithms;
  - `unlock_on:`-option in lock/lock! logic in order to support auto-unlocking on any exception rasaied under the invoked block (invoked under the lock);
  - **Research**: support for `Valkey` database backend (https://github.com/valkey-io/valkey) (https://valkey.io/);
  - **Research**: support for `Garnet` database backend (https://microsoft.github.io/) (https://github.com/microsoft/garnet);
  - add a library-level exception, when RQL-related key in Redis (required for its logic) has incompatible type (means: some other program uses our key with their own type and logic and RQL can't work properly);
  - yardoc docs with CI check (full doc coverage check);
  - split *exception* inheritance to the groups: `lock obtaining errors`, `block invocation errors`, `swarm errors`, and other groups (research possible groups):
    - in some cases we need to intercept "Lock Obtaining Process Erros", in other cases: "Block Invocation Errors", and so on (in `Lock Serirs PoC` for example);
  - think about `#debounce` and `#throttle` mechanisms;

---

## Build and Develop

- Tests (`RSpec`):
```shell
bundle exec rake rspec
```

- Linting (`Rubocop`+`RBS`):
```shell
bundle exec rake rubocop
```

- `Static` TypeChecking (`Steep`):
```shell
bundle exec rake steep:check
```

- `Runtime` TypeChecking (`RBS`):
```shell
bundle exec rbs collection install && RBS_TEST_RAISE=true RUBYOPT='-rrbs/test/setup' RBS_TEST_OPT='-I sig' RBS_TEST_LOGLEVEL=error RBS_TEST_TARGET='RedisQueuedLocks::*' bundle exec rspec --failure-exit-code=0
```

---

## Contributing

\[[back to top](#table-of-contents)\]

- Fork it ( https://github.com/0exp/redis_queued_locks )
- Create your feature branch (`git checkout -b feature/my-new-feature`)
- Commit your changes (`git commit -am '[feature_context] Add some feature'`)
- Push to the branch (`git push origin feature/my-new-feature`)
- Create new Pull Request

## License

\[[back to top](#table-of-contents)\]

Released under MIT License.

## Authors

\[[back to top](#table-of-contents)\]

[Rustam Ibragimov](https://github.com/0exp)

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