Class: Concurrent::CyclicBarrier

Inherits:
Synchronization::LockableObject
  • Object
show all
Defined in:
lib/concurrent-ruby/concurrent/atomic/cyclic_barrier.rb

Overview

A synchronization aid that allows a set of threads to all wait for each other to reach a common barrier point.

Examples:

barrier = Concurrent::CyclicBarrier.new(3) jobs = Array.new(3) { |i| -> { sleep i; p done: i } } process = -> (i) do # waiting to start at the same time  barrier.wait # execute job  jobs[i].call # wait for others to finish  barrier.wait end threads = 2.times.map do |i| Thread.new(i, &process) end # use main as well process.call 2 # here we can be sure that all jobs are processed

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

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# File 'lib/concurrent-ruby/concurrent/atomic/cyclic_barrier.rb', line 40 def initialize(parties, &block) Utility::NativeInteger.ensure_integer_and_bounds parties Utility::NativeInteger.ensure_positive_and_no_zero parties super(&nil) synchronize { ns_initialize parties, &block } 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

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# File 'lib/concurrent-ruby/concurrent/atomic/cyclic_barrier.rb', line 105 def broken? 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

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# File 'lib/concurrent-ruby/concurrent/atomic/cyclic_barrier.rb', line 54 def number_waiting synchronize { @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

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# File 'lib/concurrent-ruby/concurrent/atomic/cyclic_barrier.rb', line 49 def parties synchronize { @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) 
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# File 'lib/concurrent-ruby/concurrent/atomic/cyclic_barrier.rb', line 95 def reset synchronize { ns_generation_done @generation, :reset } 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

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# File 'lib/concurrent-ruby/concurrent/atomic/cyclic_barrier.rb', line 66 def wait(timeout = nil) synchronize do return false unless @generation.status == :waiting @number_waiting += 1 if @number_waiting == @parties @action.call if @action ns_generation_done @generation, :fulfilled true else generation = @generation if ns_wait_until(timeout) { generation.status != :waiting } generation.status == :fulfilled else ns_generation_done generation, :broken, false false end end end end