Module: RedisQueuedLocks::Acquirer::LockInfo Private

Defined in:
lib/redis_queued_locks/acquirer/lock_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

.lock_info(redis_client, lock_name) ⇒ Hash<String,String|Numeric>, NilClass

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.

rubocop:disable Metrics/MethodLength

Parameters:

  • redis_client (RedisClient)
  • lock_name (String)

Returns:

  • (Hash<String,String|Numeric>, NilClass) —
    • nil is returned when lock key does not exist or expired;
    • result format: { 'lock_key' => "rql:lock:your_lockname", # acquired lock key 'acq_id' => "rql:acq:123/456/789/987/uniqstring", # lock acquirer identifier 'hst_id' => "rql:hst:123/456/987/uniqstring", # lock host identifier 'ts' => 123456789.2649841, # time stamp (epoch, seconds.microseconds) 'ini_ttl' => 123456789, # initial lock key ttl (milliseconds) 'rem_ttl' => 123456789, # remaining lock key ttl (milliseconds) : 'spc_cnt' => 2, # lock reentreing count (if lock was used as reentrant lock) 'l_spc_ts' => 123456.1234 # (epoch) timestamp 'spc_ext_ttl' => 14500, # (milliseconds) the sum of all ttl extensions 'l_spc_ext_ini_ttl' => 5000, # (milliseconds) the last ttl of reentrant lock 'l_spc_ext_ts' => 123456.789 # (epoch) timestamp }

Since:

  • 1.0.0

Version:

  • 1.9.0



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# File 'lib/redis_queued_locks/acquirer/lock_info.rb', line 30

def lock_info(redis_client, lock_name)
  lock_key = RedisQueuedLocks::Resource.prepare_lock_key(lock_name)

  result = redis_client.pipelined do |pipeline|
    pipeline.call('HGETALL', lock_key)
    pipeline.call('PTTL', lock_key)
  end

  if result == nil
    # NOTE:
    #   - nil result means that during transaction invocation the lock is changed (CAS):
    #     - lock is expired;
    #     - lock is released;
    #     - lock is expired + re-obtained;
    nil
  else
    # NOTE: the result of MULTI-command is an array of results of each internal command
    #   - result[0] (HGETALL) (Hash<String,String>)
    #     => (will be mutated further with different value types)
    #   - result[1] (PTTL) (Integer)
    #     => (without any mutation, integer is atomic)

    # @type var result: [Hash[String,String|Float|Integer],Integer]
    hget_cmd_res = result[0]
    pttl_cmd_res = result[1]

    if hget_cmd_res == {} || pttl_cmd_res == -2 # NOTE: key does not exist
      nil
    else
      hget_cmd_res.tap do |lock_data|
        lock_data['lock_key'] = lock_key
        lock_data['ts'] = Float(lock_data['ts'])
        lock_data['ini_ttl'] = Integer(lock_data['ini_ttl'])
        lock_data['rem_ttl'] = ((pttl_cmd_res == -1) ? Float::INFINITY : pttl_cmd_res)
        lock_data['spc_cnt'] = Integer(lock_data['spc_cnt']) if lock_data['spc_cnt']
        lock_data['l_spc_ts'] = Float(lock_data['l_spc_ts']) if lock_data['l_spc_ts']
        lock_data['spc_ext_ttl'] = Integer(lock_data['spc_ext_ttl']) if lock_data['spc_ext_ttl']
        lock_data['l_spc_ext_ini_ttl'] =
          Integer(lock_data['l_spc_ext_ini_ttl']) if lock_data.key?('l_spc_ext_ini_ttl')
        lock_data['l_spc_ext_ts'] =
          Float(lock_data['l_spc_ext_ts']) if lock_data['l_spc_ext_ts']
      end
    end
  end
end