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|
begin
require 'thread'
rescue LoadError
# Threads not available. Monitor will do nothing.
end
module Ref
# The Monitor class in Ruby 1.8 has some bugs and also threads may not be available on all
# runtimes. This class provides a simple, safe re-entrant mutex as an alternative.
class SafeMonitor
def initialize
@owner = nil
@count = 0
@mutex = defined?(Mutex) ? Mutex.new : nil
end
# Acquire an exclusive lock.
def lock
if @mutex
if @owner != Thread.current.object_id
@mutex.lock
@owner = Thread.current.object_id
end
@count += 1
end
true
end
# Release the exclusive lock.
def unlock
if @mutex
if @owner == Thread.current.object_id
@count -= 1
if @count == 0
@owner = nil
@mutex.unlock
end
end
end
end
# Run a block of code with an exclusive lock.
def synchronize
lock
yield
ensure
unlock
end
end
end
|
