57 lines
1.6 KiB
Ruby
57 lines
1.6 KiB
Ruby
# frozen_string_literal: true
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# Released under the MIT License.
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# Copyright, 2020-2024, by Samuel Williams.
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require_relative "local/version"
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require 'fiber/storage'
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class Fiber
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module Local
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def self.extended(klass)
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attribute_name = klass.name.gsub('::', '_').gsub(/\W/, '').downcase.to_sym
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# This is used for the general interface and fiber storage key:
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klass.instance_variable_set(:@fiber_local_attribute_name, attribute_name)
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klass.singleton_class.attr :fiber_local_attribute_name
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# This is used for reading and writing directly to the thread instance variables:
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klass.instance_variable_set(:@fiber_local_variable_name, :"@#{attribute_name}")
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Thread.attr_accessor(attribute_name)
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end
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# Instantiate a new thread-local object.
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# By default, invokes {new} to generate the instance.
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# @returns [Object]
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def local
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self.new
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end
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# Get the current thread-local instance. Create it if required.
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# @returns [Object] The thread-local instance.
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def instance
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# This is considered a local "override" in the dynamic scope of the fiber:
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if instance = Fiber[@fiber_local_attribute_name]
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return instance
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end
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# This is generally the fast path:
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thread = Thread.current
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unless instance = thread.instance_variable_get(@fiber_local_variable_name)
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if instance = self.local
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thread.instance_variable_set(@fiber_local_variable_name, instance)
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end
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end
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return instance
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end
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# Assigns to the fiber-local instance.
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# @parameter instance [Object] The object that will become the thread-local instance.
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def instance= instance
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Fiber[@fiber_local_attribute_name] = instance
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end
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end
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end
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