Class: Concurrent::Event

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

Overview

Old school kernel-style event reminiscent of Win32 programming in C++.

When an ‘Event` is created it is in the `unset` state. Threads can choose to `#wait` on the event, blocking until released by another thread. When one thread wants to alert all blocking threads it calls the `#set` method which will then wake up all listeners. Once an `Event` has been set it remains set. New threads calling `#wait` will return immediately. An `Event` may be `#reset` at any time once it has been set.

See Also:

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Event

Creates a new ‘Event` in the unset state. Threads calling `#wait` on the `Event` will block.



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# File 'lib/concurrent/atomic/event.rb', line 20

def initialize
  @set = false
  @mutex = Mutex.new
  @condition = Condition.new
end

Instance Method Details

#reset ⇒ Boolean

Reset a previously set event back to the ‘unset` state. Has no effect if the `Event` has not yet been set.

Returns:

  • (Boolean) —

    should always return ‘true`



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# File 'lib/concurrent/atomic/event.rb', line 70

def reset
  @mutex.lock
  @set = false
  true
ensure
  @mutex.unlock
end

#set ⇒ Boolean

Trigger the event, setting the state to ‘set` and releasing all threads waiting on the event. Has no effect if the `Event` has already been set.

Returns:

  • (Boolean) —

    should always return ‘true`



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# File 'lib/concurrent/atomic/event.rb', line 40

def set
  @mutex.lock
  unless @set
    @set = true
    @condition.broadcast
  end
  true
ensure
  @mutex.unlock
end

#set? ⇒ Boolean

Is the object in the set state?

Returns:

  • (Boolean) —

    indicating whether or not the ‘Event` has been set



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# File 'lib/concurrent/atomic/event.rb', line 29

def set?
  @mutex.lock
  @set
ensure
  @mutex.unlock
end

#try? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/concurrent/atomic/event.rb', line 51

def try?
  @mutex.lock

  if @set
    false
  else
    @set = true
    @condition.broadcast
    true
  end

ensure
  @mutex.unlock
end

#wait(timeout = nil) ⇒ Boolean

Wait a given number of seconds for the ‘Event` to be set by another thread. Will wait forever when no `timeout` value is given. Returns immediately if the `Event` has already been set.

Returns:

  • (Boolean) —

    true if the ‘Event` was set before timeout else false



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# File 'lib/concurrent/atomic/event.rb', line 83

def wait(timeout = nil)
  @mutex.lock

  unless @set
    remaining = Condition::Result.new(timeout)
    while !@set && remaining.can_wait?
      remaining = @condition.wait(@mutex, remaining.remaining_time)
    end
  end

  @set
ensure
  @mutex.unlock
end