87 lines
3.0 KiB
Ruby
87 lines
3.0 KiB
Ruby
require 'concurrent/atomic/atomic_reference'
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module Concurrent
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# A fixed size array with volatile (synchronized, thread safe) getters/setters.
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# Mixes in Ruby's `Enumerable` module for enhanced search, sort, and traversal.
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#
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# @example
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# tuple = Concurrent::Tuple.new(16)
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#
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# tuple.set(0, :foo) #=> :foo | volatile write
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# tuple.get(0) #=> :foo | volatile read
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# tuple.compare_and_set(0, :foo, :bar) #=> true | strong CAS
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# tuple.cas(0, :foo, :baz) #=> false | strong CAS
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# tuple.get(0) #=> :bar | volatile read
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#
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# @see https://en.wikipedia.org/wiki/Tuple Tuple entry at Wikipedia
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# @see http://www.erlang.org/doc/reference_manual/data_types.html#id70396 Erlang Tuple
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# @see http://ruby-doc.org/core-2.2.2/Enumerable.html Enumerable
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class Tuple
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include Enumerable
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# The (fixed) size of the tuple.
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attr_reader :size
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# @!visibility private
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Tuple = defined?(Rubinius::Tuple) ? Rubinius::Tuple : ::Array
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private_constant :Tuple
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# Create a new tuple of the given size.
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#
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# @param [Integer] size the number of elements in the tuple
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def initialize(size)
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@size = size
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@tuple = tuple = Tuple.new(size)
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i = 0
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while i < size
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tuple[i] = Concurrent::AtomicReference.new
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i += 1
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end
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end
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# Get the value of the element at the given index.
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#
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# @param [Integer] i the index from which to retrieve the value
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# @return [Object] the value at the given index or nil if the index is out of bounds
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def get(i)
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return nil if i >= @size || i < 0
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@tuple[i].get
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end
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alias_method :volatile_get, :get
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# Set the element at the given index to the given value
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#
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# @param [Integer] i the index for the element to set
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# @param [Object] value the value to set at the given index
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#
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# @return [Object] the new value of the element at the given index or nil if the index is out of bounds
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def set(i, value)
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return nil if i >= @size || i < 0
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@tuple[i].set(value)
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end
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alias_method :volatile_set, :set
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# Set the value at the given index to the new value if and only if the current
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# value matches the given old value.
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#
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# @param [Integer] i the index for the element to set
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# @param [Object] old_value the value to compare against the current value
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# @param [Object] new_value the value to set at the given index
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#
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# @return [Boolean] true if the value at the given element was set else false
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def compare_and_set(i, old_value, new_value)
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return false if i >= @size || i < 0
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@tuple[i].compare_and_set(old_value, new_value)
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end
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alias_method :cas, :compare_and_set
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# Calls the given block once for each element in self, passing that element as a parameter.
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#
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# @yieldparam [Object] ref the `Concurrent::AtomicReference` object at the current index
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def each
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@tuple.each {|ref| yield ref.get}
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end
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end
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end
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