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# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
module Qpid::Proton
# A thread-safe queue of work for multi-threaded programs.
#
# A {Container} can have multiple threads calling {Container#run}
# The container ensures that work associated with a single {Connection} or
# {Listener} is _serialized_ - two threads will never concurrently call
# handlers associated with the same object.
#
# To have your own code serialized in the same, add a block to the connection's
# {WorkQueue}. The block will be invoked as soon as it is safe to do so.
#
# A {Connection} and the objects associated with it ({Session}, {Sender},
# {Receiver}, {Delivery}, {Tracker}) are not thread safe, so if you have
# multiple threads calling {Container#run} or if you want to affect objects
# managed by the container from non-container threads you need to use the
# {WorkQueue}
#
class WorkQueue
# Error raised if work is added after the queue has been stopped.
class StoppedError < Qpid::Proton::StoppedError
def initialize() super("WorkQueue has been stopped"); end
end
# Add a block of code to be invoked in sequence.
#
# @yield [ ] the block will be invoked with no parameters in the appropriate thread context
# @note Thread Safe: may be called in any thread.
# @return [void]
# @raise [StoppedError] if the queue is closed and cannot accept more work
def add(&block)
schedule(0, &block)
end
# Schedule a block to be invoked at a certain time.
#
# @param at [Time] Invoke block as soon as possible after Time +at+
# @param at [Numeric] Invoke block after a delay of +at+ seconds from now
# @yield [ ] (see #add)
# @note (see #add)
# @return (see #add)
# @raise (see #add)
def schedule(at, &block)
raise ArgumentError, "no block" unless block_given?
@lock.synchronize do
raise @closed if @closed
@schedule.insert(at, block)
end
@container.send :wake
end
# @private
def initialize(container)
@lock = Mutex.new
@schedule = Schedule.new
@container = container
@closed = nil
end
# @private
def close() @lock.synchronize { @closed = StoppedError.new } end
# @private
def process(now)
while p = @lock.synchronize { @schedule.pop(now) }
p.call
end
end
# @private
def next_tick() @lock.synchronize { @schedule.next_tick } end
# @private
def empty?() @lock.synchronize { @schedule.empty? } end
# @private
def clear() @lock.synchronize { @schedule.clear } end
end
end
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