Class: Datadog::Core::Remote::Component::Barrier

Inherits:
Object
  • Object
show all
Defined in:
lib/datadog/core/remote/component.rb

Overview

Barrier provides a mechanism to fence execution until a condition happens

Instance Method Summary collapse

Constructor Details

#initialize(timeout = nil) ⇒ Barrier

Returns a new instance of Barrier.



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# File 'lib/datadog/core/remote/component.rb', line 92

def initialize(timeout = nil)
  @once = false
  @timeout = timeout

  @mutex = Mutex.new
  @condition = ConditionVariable.new
end

Instance Method Details

#lift ⇒ Object

Release all current waiters



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# File 'lib/datadog/core/remote/component.rb', line 136

def lift
  @mutex.lock

  @once ||= true

  @condition.broadcast
ensure
  @mutex.unlock
end

#wait_once(timeout = nil) ⇒ Object

Wait for first lift to happen, otherwise don’t wait



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# File 'lib/datadog/core/remote/component.rb', line 101

def wait_once(timeout = nil)
  # TTAS (Test and Test-And-Set) optimisation
  # Since @once only ever goes from false to true, this is semantically valid
  return :pass if @once

  begin
    @mutex.lock

    return :pass if @once

    timeout ||= @timeout

    # - starting with Ruby 3.2, ConditionVariable#wait returns nil on
    #   timeout and an integer otherwise
    # - before Ruby 3.2, ConditionVariable returns itself
    # so we have to rely on @once having been set
    if RUBY_VERSION >= '3.2'
      lifted = @condition.wait(@mutex, timeout)
    else
      @condition.wait(@mutex, timeout)
      lifted = @once
    end

    if lifted
      :lift
    else
      @once = true
      :timeout
    end
  ensure
    @mutex.unlock
  end
end