76 lines
1.5 KiB
Ruby
76 lines
1.5 KiB
Ruby
# frozen_string_literal: true
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# Released under the MIT License.
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# Copyright, 2017-2024, by Samuel Williams.
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# Copyright, 2017, by Kent Gruber.
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require "fiber"
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require_relative "list"
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module Async
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# A synchronization primitive, which allows fibers to wait until a particular condition is (edge) triggered.
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# @public Since *Async v1*.
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class Condition
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# Create a new condition.
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def initialize
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@waiting = List.new
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end
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class FiberNode < List::Node
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def initialize(fiber)
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@fiber = fiber
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end
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def transfer(*arguments)
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@fiber.transfer(*arguments)
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end
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def alive?
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@fiber.alive?
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end
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end
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private_constant :FiberNode
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# Queue up the current fiber and wait on yielding the task.
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# @returns [Object]
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def wait
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@waiting.stack(FiberNode.new(Fiber.current)) do
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Fiber.scheduler.transfer
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end
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end
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# @deprecated Replaced by {#waiting?}
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def empty?
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@waiting.empty?
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end
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# @returns [Boolean] Is any fiber waiting on this notification?
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def waiting?
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@waiting.size > 0
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end
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# Signal to a given task that it should resume operations.
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# @parameter value [Object | Nil] The value to return to the waiting fibers.
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def signal(value = nil)
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return if @waiting.empty?
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waiting = self.exchange
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waiting.each do |fiber|
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Fiber.scheduler.resume(fiber, value) if fiber.alive?
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end
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return nil
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end
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protected
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def exchange
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waiting = @waiting
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@waiting = List.new
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return waiting
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end
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end
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end
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