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Contents
module Concurrent
# A synchronization point at which threads can pair and swap elements within
# pairs. Each thread presents some object on entry to the exchange method,
# matches with a partner thread, and receives its partner's object on return.
#
# Uses `MVar` to manage synchronization of the individual elements.
# Since `MVar` is also a `Dereferenceable`, the exchanged values support all
# dereferenceable options. The constructor options hash will be passed to
# the `MVar` constructors.
#
# @see Concurrent::MVar
# @see Concurrent::Concern::Dereferenceable
# @see http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/Exchanger.html java.util.concurrent.Exchanger
#
# @!macro edge_warning
class Exchanger
EMPTY = Object.new
# Create a new `Exchanger` object.
#
# @param [Hash] opts the options controlling how the managed references
# will be processed
def initialize(opts = {})
@first = MVar.new(EMPTY, opts)
@second = MVar.new(MVar::EMPTY, opts)
end
# Waits for another thread to arrive at this exchange point (unless the
# current thread is interrupted), and then transfers the given object to
# it, receiving its object in return.
#
# @param [Object] value the value to exchange with an other thread
# @param [Numeric] timeout the maximum time in second to wait for one other
# thread. nil (default value) means no timeout
# @return [Object] the value exchanged by the other thread; nil if timed out
def exchange(value, timeout = nil)
first = @first.take(timeout)
if first == MVar::TIMEOUT
nil
elsif first == EMPTY
@first.put value
second = @second.take timeout
if second == MVar::TIMEOUT
nil
else
second
end
else
@first.put EMPTY
@second.put value
first
end
end
end
end
Version data entries
21 entries across 19 versions & 5 rubygems