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Contents
module Ohm
# This module is a straight extraction from Ohm. The only difference is
# that this allows for a custom sleep value.
#
# In addition, since future ohm versions might drop mutexes, I thought it
# might be a good idea to preseve this feature as a drop-in module.
module Locking
# Lock the object before executing the block, and release it once the block
# is done.
#
# @example
#
# post = Order.create(:customer => Customer.create)
# post.mutex(0.01) do
# # this block is in a mutex!
# end
def mutex(wait = 0.1)
lock!(wait)
yield
self
ensure
unlock!
end
protected
# Lock the object so no other instances can modify it.
# This method implements the design pattern for locks
# described at: http://code.google.com/p/redis/wiki/SetnxCommand
#
# @see Model#mutex
def lock!(wait = 0.1)
until key[:_lock].setnx(lock_timeout)
next unless lock = key[:_lock].get
sleep(wait) and next unless lock_expired?(lock)
break unless lock = key[:_lock].getset(lock_timeout)
break if lock_expired?(lock)
end
end
# Release the lock.
# @see Model#mutex
def unlock!
key[:_lock].del
end
def lock_timeout
Time.now.to_f + 1
end
def lock_expired? lock
lock.to_f < Time.now.to_f
end
end
end
Version data entries
17 entries across 17 versions & 1 rubygems