Class: Redlock::Client::RedisInstance

Inherits:
Object
  • Object
show all
Defined in:
lib/redlock/client.rb,
lib/redlock/testing.rb

Constant Summary collapse

UNLOCK_SCRIPT = 
<<-eos
  if redis.call("get",KEYS[1]) == ARGV[1] then
    return redis.call("del",KEYS[1])
  else
    return 0
  end
eos
LOCK_SCRIPT =

thanks to github.com/sbertrang/redis-distlock/blob/master/lib/Redis/DistLock.pm also github.com/sbertrang/redis-distlock/issues/2 which proposes the value-checking and @maltoe for github.com/leandromoreira/redlock-rb/pull/20#discussion_r38903633

<<-eos
  if redis.call("exists", KEYS[1]) == 0 or redis.call("get", KEYS[1]) == ARGV[1] then
    return redis.call("set", KEYS[1], ARGV[1], "PX", ARGV[2])
  end
eos
EXTEND_LIFE_SCRIPT = 
<<-eos
  if redis.call("get", KEYS[1]) == ARGV[1] then
    redis.call("expire", KEYS[1], ARGV[2])
    return 0
  else
    return 1
  end
eos

Instance Method Summary collapse

Constructor Details

#initialize(connection) ⇒ RedisInstance

Returns a new instance of RedisInstance.



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# File 'lib/redlock/client.rb', line 103

def initialize(connection)
  if connection.respond_to?(:client)
    @redis = connection
  else
    @redis  = Redis.new(connection)
  end

  load_scripts
end

Instance Method Details

#extend(resource, val, ttl) ⇒ Object 



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# File 'lib/redlock/client.rb', line 119

def extend(resource, val, ttl)
  recover_from_script_flush do
    rc = @redis.evalsha @extend_life_script_sha, keys: [resource], argv: [val, ttl]
    rc == 0
  end
end

#load_scripts ⇒ Object 



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# File 'lib/redlock/client.rb', line 136

def load_scripts
  @unlock_script_sha = @redis.script(:load, UNLOCK_SCRIPT)
  @lock_script_sha = @redis.script(:load, LOCK_SCRIPT)
  @extend_life_script_sha = @redis.script(:load, EXTEND_LIFE_SCRIPT)
end

#load_scripts_without_testing ⇒ Object 



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# File 'lib/redlock/testing.rb', line 28

def load_scripts
  @unlock_script_sha = @redis.script(:load, UNLOCK_SCRIPT)
  @lock_script_sha = @redis.script(:load, LOCK_SCRIPT)
  @extend_life_script_sha = @redis.script(:load, EXTEND_LIFE_SCRIPT)
end

#lock(resource, val, ttl) ⇒ Object 



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# File 'lib/redlock/client.rb', line 113

def lock(resource, val, ttl)
  recover_from_script_flush do
    @redis.evalsha @lock_script_sha, keys: [resource], argv: [val, ttl]
  end
end

#unlock(resource, val) ⇒ Object 



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# File 'lib/redlock/client.rb', line 126

def unlock(resource, val)
  recover_from_script_flush do
    @redis.evalsha @unlock_script_sha, keys: [resource], argv: [val]
  end
rescue
  # Nothing to do, unlocking is just a best-effort attempt.
end