Class: MiniScheduler::DistributedMutex

Inherits:
Object
  • Object
show all
Defined in:
lib/mini_scheduler/distributed_mutex.rb

Defined Under Namespace

Classes: Timeout

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(key, redis) ⇒ DistributedMutex

Returns a new instance of DistributedMutex.

Raises:

  • (ArgumentError) 


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# File 'lib/mini_scheduler/distributed_mutex.rb', line 17

def initialize(key, redis)
  raise ArgumentError.new('redis argument is nil') if redis.nil?
  @key = key
  @redis = redis
  @mutex = Mutex.new
end

Class Method Details

.redis=(redis) ⇒ Object 



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# File 'lib/mini_scheduler/distributed_mutex.rb', line 9

def self.redis=(redis)
  @default_redis = redis
end

.synchronize(key, redis = nil, &blk) ⇒ Object 



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# File 'lib/mini_scheduler/distributed_mutex.rb', line 13

def self.synchronize(key, redis = nil, &blk)
  self.new(key, redis || @default_redis).synchronize(&blk)
end

Instance Method Details

#synchronize ⇒ Object

NOTE wrapped in mutex to maintain its semantics



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# File 'lib/mini_scheduler/distributed_mutex.rb', line 29

def synchronize
  @mutex.lock

  attempts = 0
  sleep_duration = BASE_SLEEP_DURATION
  while !try_to_get_lock

    sleep(sleep_duration)

    if sleep_duration < MAX_SLEEP_DURATION
      sleep_duration = [sleep_duration * 2, MAX_SLEEP_DURATION].min
    end

    attempts += 1
    raise Timeout if attempts >= MAX_POLLING_ATTEMPTS
  end

  yield

ensure
  @redis.del @key
  @mutex.unlock
end