79 lines
1.9 KiB
Ruby
79 lines
1.9 KiB
Ruby
# frozen_string_literal: true
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# Released under the MIT License.
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# Copyright, 2019-2024, by Samuel Williams.
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require_relative "list"
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require_relative "task"
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module Async
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# A general purpose synchronisation primitive, which allows one task to wait for a number of other tasks to complete. It can be used in conjunction with {Semaphore}.
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#
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# @public Since *Async v1*.
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class Barrier
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# Initialize the barrier.
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# @parameter parent [Task | Semaphore | Nil] The parent for holding any children tasks.
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# @public Since *Async v1*.
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def initialize(parent: nil)
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@tasks = List.new
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@parent = parent
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end
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class TaskNode < List::Node
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def initialize(task)
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@task = task
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end
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attr :task
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end
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private_constant :TaskNode
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# Number of tasks being held by the barrier.
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def size
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@tasks.size
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end
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# All tasks which have been invoked into the barrier.
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attr :tasks
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# Execute a child task and add it to the barrier.
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# @asynchronous Executes the given block concurrently.
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def async(*arguments, parent: (@parent or Task.current), **options, &block)
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task = parent.async(*arguments, **options, &block)
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@tasks.append(TaskNode.new(task))
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return task
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end
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# Whether there are any tasks being held by the barrier.
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# @returns [Boolean]
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def empty?
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@tasks.empty?
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end
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# Wait for all tasks to complete by invoking {Task#wait} on each waiting task, which may raise an error. As long as the task has completed, it will be removed from the barrier.
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# @asynchronous Will wait for tasks to finish executing.
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def wait
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@tasks.each do |waiting|
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task = waiting.task
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begin
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task.wait
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ensure
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@tasks.remove?(waiting) unless task.alive?
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end
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end
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end
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# Stop all tasks held by the barrier.
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# @asynchronous May wait for tasks to finish executing.
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def stop
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@tasks.each do |waiting|
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waiting.task.stop
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end
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end
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end
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end
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