qpid/cpp/src/qpid/cluster/exp/QueueContext.cpp

/*
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 * 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
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#include "QueueContext.h"
#include "Multicaster.h"
#include "qpid/framing/ProtocolVersion.h"
#include "qpid/framing/ClusterQueueResubscribeBody.h"
#include "qpid/framing/ClusterQueueSubscribeBody.h"
#include "qpid/framing/ClusterQueueUnsubscribeBody.h"
#include "qpid/broker/Broker.h"
#include "qpid/broker/Queue.h"
#include "qpid/log/Statement.h"
#include "qpid/sys/Timer.h"

namespace qpid {
namespace cluster {


class OwnershipTimeout : public sys::TimerTask {
    QueueContext& queueContext;

  public:
    OwnershipTimeout(QueueContext& qc, const sys::Duration& interval) :
        TimerTask(interval, "QueueContext::OwnershipTimeout"), queueContext(qc) {}

    // FIXME aconway 2011-07-27: thread safety on deletion?
    void fire() { queueContext.timeout(); }
};

QueueContext::QueueContext(broker::Queue& q, Multicaster& m)
    : timer(q.getBroker()->getTimer()), queue(q), mcast(m), consumers(0)
{
    q.setClusterContext(boost::intrusive_ptr<QueueContext>(this));
    q.stop();  // Initially stopped.
}

QueueContext::~QueueContext() {
    // FIXME aconway 2011-07-27: revisit shutdown logic.
    // timeout() could be called concurrently with destructor.
    sys::Mutex::ScopedLock l(lock);
    if (timerTask) timerTask->cancel();
}

void QueueContext::replicaState(QueueOwnership state) {
    sys::Mutex::ScopedLock l(lock);
    switch (state) {
      case UNSUBSCRIBED:
      case SUBSCRIBED:
        break;
      case SOLE_OWNER:
        queue.start();
        if (timerTask) {        // no need for timeout.
            timerTask->cancel();
            timerTask = 0;
        }
        break;
      case SHARED_OWNER:
        queue.start();
        if (timerTask) timerTask->cancel();
        // FIXME aconway 2011-07-28: configurable interval.
        timerTask = new OwnershipTimeout(*this, 100*sys::TIME_MSEC);
        timer.add(timerTask);
        break;
    }
}

// FIXME aconway 2011-07-27: Dont spin token on an empty queue. Cancel timer.

// Called in connection threads when a consumer is added
void QueueContext::consume(size_t n) {
    sys::Mutex::ScopedLock l(lock);
    consumers = n;
    if (n == 1) mcast.mcast(
        framing::ClusterQueueSubscribeBody(framing::ProtocolVersion(), queue.getName()));
}

// Called in connection threads when a consumer is cancelled
void QueueContext::cancel(size_t n) {
    sys::Mutex::ScopedLock l(lock);
    consumers = n;
    if (n == 0) queue.stop(); // FIXME aconway 2011-07-28: Ok inside lock?
}

void QueueContext::timeout() {
    QPID_LOG(critical, "FIXME Ownership timeout on queue " << queue.getName());
    queue.stop();
    // When all threads have stopped, queue will call stopped()
}


// Callback set up by queue.stop(), called when no threads are dispatching from the queue.
// Release the queue.
void QueueContext::stopped() {
    sys::Mutex::ScopedLock l(lock);
    // FIXME aconway 2011-07-28: review thread safety of state.
    // Deffered call to stopped doesn't sit well.
    // queueActive is invalid while stop is in progress?
    if (consumers == 0)
        mcast.mcast(framing::ClusterQueueUnsubscribeBody(
                        framing::ProtocolVersion(), queue.getName()));
    else
        mcast.mcast(framing::ClusterQueueResubscribeBody(
                        framing::ProtocolVersion(), queue.getName()));
}

boost::intrusive_ptr<QueueContext> QueueContext::get(broker::Queue& q) {
    return boost::intrusive_ptr<QueueContext>(
        static_cast<QueueContext*>(q.getClusterContext().get()));
}



}} // namespace qpid::cluster