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# encoding: utf-8
# utilities.rb : General-purpose utility classes which don't fit anywhere else
#
# Copyright August 2012, Alex Dowad. All Rights Reserved.
#
# This is free software. Please see the LICENSE and COPYING files for details.
require 'thread'
module Prawn
# Throughout the Prawn codebase, repeated calculations which can benefit from caching are made
# In some cases, caching and reusing results can not only save CPU cycles but also greatly
# reduce memory requirements
# But at the same time, we don't want to throw away thread safety
# We have two interchangeable thread-safe cache implementations:
# @private
class SynchronizedCache
# As an optimization, this could access the hash directly on VMs with a global interpreter lock (like MRI)
def initialize
@cache = {}
@mutex = Mutex.new
end
def [](key)
@mutex.synchronize { @cache[key] }
end
def []=(key,value)
@mutex.synchronize { @cache[key] = value }
end
end
# @private
class ThreadLocalCache
def initialize
@cache_id = "cache_#{self.object_id}".to_sym
end
def [](key)
(Thread.current[@cache_id] ||= {})[key]
end
def []=(key,value)
(Thread.current[@cache_id] ||= {})[key] = value
end
end
end
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