Module: RedisQueuedLocks::Acquirer::QueueInfo Private

Defined in:
lib/redis_queued_locks/acquirer/queue_info.rb

Overview

This module is part of a private API. You should avoid using this module if possible, as it may be removed or be changed in the future.

Since:

  • 1.0.0

Class Method Summary collapse

Class Method Details

.queue_info(redis_client, lock_name) ⇒ Hash<String,Array<Hash<String,String|Numeric>>,NilClass] - `nil` is returned when lock queue does not exist; - result format: { "lock_queue" => "rql:lock_queue:your_lock_name", #lockk queue key in redis, "queue" => [ { "acq_id" => "rql:acq:123/456/789/987/identity", "score" => 123.456 }, { "acq_id" => "rql:acq:123/686/789/987/identity", "score" => 456.789 }, ... ] #orderedd set (by score) with information about an acquirer and their position in queue }

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

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 sitaution when the queue becomes empty during the queue data extraction. So sometimes you can receive the lock queue info with empty queue.

Parameters:

  • redis_client (RedisClient)
  • lock_name (String)

Returns:

  • (Hash<String,Array<Hash<String,String|Numeric>>,NilClass] - `nil` is returned when lock queue does not exist; - result format: { "lock_queue" => "rql:lock_queue:your_lock_name", #lockk queue key in redis, "queue" => [ { "acq_id" => "rql:acq:123/456/789/987/identity", "score" => 123.456 }, { "acq_id" => "rql:acq:123/686/789/987/identity", "score" => 456.789 }, ... ] #orderedd set (by score) with information about an acquirer and their position in queue }) —

    Hash<String,Array<Hash<String,String|Numeric>>,NilClass]

    • nil is returned when lock queue does not exist;
    • result format: { "lock_queue" => "rql:lock_queue:your_lock_name", # lock queue key in redis, "queue" => [ { "acq_id" => "rql:acq:123/456/789/987/identity", "score" => 123.456 }, { "acq_id" => "rql:acq:123/686/789/987/identity", "score" => 456.789 }, ... ] # ordered set (by score) with information about an acquirer and their position in queue }

Since:

  • 1.0.0



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# File 'lib/redis_queued_locks/acquirer/queue_info.rb', line 28

def queue_info(redis_client, lock_name)
  lock_key_queue = RedisQueuedLocks::Resource.prepare_lock_queue(lock_name)

  result = redis_client.pipelined do |pipeline|
    pipeline.call('EXISTS', lock_key_queue)
    pipeline.call('ZRANGE', lock_key_queue, '0', '-1', 'WITHSCORES')
  end

  # @type var result: [Integer,Array[[String,Integer|Float]]]
  exists_cmd_res = result[0]
  zrange_cmd_res = result[1]

  if exists_cmd_res == 1
    # NOTE: queue existed during the piepline invocation
    {
      'lock_queue' => lock_key_queue,
      'queue' => zrange_cmd_res.map { |val| { 'acq_id' => val[0], 'score' => val[1] } }
    }
  else
    # NOTE: queue did not exist during the pipeline invocation
    nil
  end
end