Class: Concurrent::CyclicBarrier

Inherits:
Object
  • Object
show all
Defined in:
lib/concurrent/atomic/cyclic_barrier.rb

Instance Method Summary collapse

Constructor Details

#initialize(parties) { ... } ⇒ CyclicBarrier

Create a new ‘CyclicBarrier` that waits for `parties` threads

Parameters:

  • parties (Fixnum) —

    the number of parties

Yields:

  • an optional block that will be executed that will be executed after the last thread arrives and before the others are released

Raises:

  • (ArgumentError) —

    if ‘parties` is not an integer or is less than zero



14
15
16
17
18
19
20
21
22
 
# File 'lib/concurrent/atomic/cyclic_barrier.rb', line 14

def initialize(parties, &block)
  raise ArgumentError.new('count must be in integer greater than or equal zero') if !parties.is_a?(Fixnum) || parties < 1
  @parties = parties
  @mutex = Mutex.new
  @condition = Condition.new
  @number_waiting = 0
  @action = block
  @generation = Generation.new(:waiting)
end

Instance Method Details

#broken? ⇒ Boolean

A barrier can be broken when:

  • a thread called the ‘reset` method while at least one other thread was waiting

  • at least one thread timed out on ‘wait` method

A broken barrier can be restored using ‘reset` it’s safer to create a new one

Returns:

  • (Boolean) —

    true if the barrier is broken otherwise false



74
75
76
 
# File 'lib/concurrent/atomic/cyclic_barrier.rb', line 74

def broken?
  @mutex.synchronize { @generation.status != :waiting }
end

#number_waiting ⇒ Fixnum

Returns the number of threads currently waiting on the barrier.

Returns:

  • (Fixnum) —

    the number of threads currently waiting on the barrier



30
31
32
 
# File 'lib/concurrent/atomic/cyclic_barrier.rb', line 30

def number_waiting
  @number_waiting
end

#parties ⇒ Fixnum

Returns the number of threads needed to pass the barrier.

Returns:

  • (Fixnum) —

    the number of threads needed to pass the barrier



25
26
27
 
# File 'lib/concurrent/atomic/cyclic_barrier.rb', line 25

def parties
  @parties
end

#reset ⇒ nil

resets the barrier to its initial state If there is at least one waiting thread, it will be woken up, the ‘wait` method will return false and the barrier will be broken If the barrier is broken, this method restores it to the original state

Returns:

  • (nil) 


62
63
64
65
66
 
# File 'lib/concurrent/atomic/cyclic_barrier.rb', line 62

def reset
  @mutex.synchronize do
    set_status_and_restore(:reset)
  end
end

#wait(timeout = nil) ⇒ Boolean

Blocks on the barrier until the number of waiting threads is equal to ‘parties` or until `timeout` is reached or `reset` is called If a block has been passed to the constructor, it will be executed once by the last arrived thread before releasing the others

Parameters:

  • timeout (Fixnum) (defaults to: nil) —

    the number of seconds to wait for the counter or ‘nil` to block indefinitely

Returns:

  • (Boolean) —

    ‘true` if the `count` reaches zero else false on `timeout` or on `reset` or if the barrier is broken



38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
 
# File 'lib/concurrent/atomic/cyclic_barrier.rb', line 38

def wait(timeout = nil)
  @mutex.synchronize do

    return false unless @generation.status == :waiting

    @number_waiting += 1

    if @number_waiting == @parties
      @action.call if @action
      set_status_and_restore(:fulfilled)
      true
    else
      wait_for_wake_up(@generation, timeout)
    end
  end
end