74 lines
2.9 KiB
Ruby
74 lines
2.9 KiB
Ruby
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module Concurrent
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module Concern
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# Object references in Ruby are mutable. This can lead to serious problems when
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# the `#value` of a concurrent object is a mutable reference. Which is always the
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# case unless the value is a `Fixnum`, `Symbol`, or similar "primitive" data type.
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# Most classes in this library that expose a `#value` getter method do so using the
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# `Dereferenceable` mixin module.
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#
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# @!macro copy_options
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module Dereferenceable
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# NOTE: This module is going away in 2.0. In the mean time we need it to
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# play nicely with the synchronization layer. This means that the
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# including class SHOULD be synchronized and it MUST implement a
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# `#synchronize` method. Not doing so will lead to runtime errors.
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# Return the value this object represents after applying the options specified
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# by the `#set_deref_options` method.
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#
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# @return [Object] the current value of the object
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def value
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synchronize { apply_deref_options(@value) }
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end
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alias_method :deref, :value
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protected
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# Set the internal value of this object
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#
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# @param [Object] value the new value
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def value=(value)
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synchronize{ @value = value }
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end
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# @!macro dereferenceable_set_deref_options
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# Set the options which define the operations #value performs before
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# returning data to the caller (dereferencing).
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#
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# @note Most classes that include this module will call `#set_deref_options`
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# from within the constructor, thus allowing these options to be set at
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# object creation.
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#
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# @param [Hash] opts the options defining dereference behavior.
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# @option opts [String] :dup_on_deref (false) call `#dup` before returning the data
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# @option opts [String] :freeze_on_deref (false) call `#freeze` before returning the data
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# @option opts [String] :copy_on_deref (nil) call the given `Proc` passing
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# the internal value and returning the value returned from the proc
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def set_deref_options(opts = {})
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synchronize{ ns_set_deref_options(opts) }
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end
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# @!macro dereferenceable_set_deref_options
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# @!visibility private
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def ns_set_deref_options(opts)
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@dup_on_deref = opts[:dup_on_deref] || opts[:dup]
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@freeze_on_deref = opts[:freeze_on_deref] || opts[:freeze]
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@copy_on_deref = opts[:copy_on_deref] || opts[:copy]
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@do_nothing_on_deref = !(@dup_on_deref || @freeze_on_deref || @copy_on_deref)
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nil
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end
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# @!visibility private
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def apply_deref_options(value)
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return nil if value.nil?
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return value if @do_nothing_on_deref
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value = @copy_on_deref.call(value) if @copy_on_deref
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value = value.dup if @dup_on_deref
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value = value.freeze if @freeze_on_deref
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value
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end
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end
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end
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end
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