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#--
# =============================================================================
# Copyright (c) 2004, Jamis Buck (jgb3@email.byu.edu)
# All rights reserved.
#
# This source file is distributed as part of the Needle dependency injection
# library for Ruby. This file (and the library as a whole) may be used only as
# allowed by either the BSD license, or the Ruby license (or, by association
# with the Ruby license, the GPL). See the "doc" subdirectory of the Needle
# distribution for the texts of these licenses.
# -----------------------------------------------------------------------------
# needle website : http://needle.rubyforge.org
# project website: http://rubyforge.org/projects/needle
# =============================================================================
#++
require 'needle/pipeline/element'
require 'needle/thread'
module Needle
module Lifecycle
# The instantiation pipeline element that enforces the multiton
# multiplicity. "Multiton" multiplicity is like singleton multiplicity,
# except that the guarded instance is unique for each unique set of
# arguments passed to the multiton.
class Multiton < Needle::Pipeline::Element
set_default_priority 100
# Creates the mutex to use and initializes the cache.
def initialize_element
@mutex = QueryableMutex.new
@cached = Hash.new
@is_cached = Hash.new( false )
end
# Returns the cached reference for the given arguments, if it has been
# previously cached. Otherwise, invokes the next element in the pipeline
# and caches the result. The cached reference is returned.
def call( container, point, *args )
unless @is_cached[ args ]
@mutex.synchronize do
unless @is_cached[ args ]
@cached[ args ] = succ.call( container, point, *args )
@is_cached[ args ] = true
end
end
end
@cached[ args ]
end
# Resets the caches for this multiton object.
def reset!
@mutex.synchronize do
@cached = Hash.new
@is_cached = Hash.new( false )
end
end
end
end
end
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