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Contents
# lifted from the ruby programming language book, thx matz!
# Obtain the Mutex associated with the object o, and then evaluate
# the block under the protection of that Mutex.
# This works like the synchronized keyword of Java.
def synchronized(o)
o.mutex.synchronize { yield }
end
# Object.mutex does not actually exist. We've got to define it.
# This method returns a unique Mutex for every object, and
# always returns the same Mutex for any particular object.
# It creates Mutexes lazily, which requires synchronization for
# thread safety.
class Object
# Return the Mutex for this object, creating it if necessary.
# The tricky part is making sure that two threads don't call
# this at the same time and end up creating two different mutexes.
def mutex
# If this object already has a mutex, just return it
return @__mutex if @__mutex
# Otherwise, we've got to create a mutex for the object.
# To do this safely we've got to synchronize on our class object.
synchronized(self.class) {
# Check again: by the time we enter this synchronized block,
# some other thread might have already created the mutex.
@__mutex = @__mutex || Mutex.new
}
# The return value is @__mutex
end
end
# The Object.mutex method defined above needs to lock the class
# if the object doesn't have a Mutex yet. If the class doesn't have
# its own Mutex yet, then the class of the class (the Class object)
# will be locked. In order to prevent infinite recursion, we must
# ensure that the Class object has a mutex.
Class.instance_eval { @__mutex = Mutex.new }
Version data entries
5 entries across 5 versions & 2 rubygems