path: root/qpid/cpp/src/qpid/broker/Queue.cpp

/*
 *
 * 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.
 *
 */

#include "qpid/broker/Broker.h"
#include "qpid/broker/Queue.h"
#include "qpid/broker/QueueEvents.h"
#include "qpid/broker/Exchange.h"
#include "qpid/broker/Fairshare.h"
#include "qpid/broker/DeliverableMessage.h"
#include "qpid/broker/LegacyLVQ.h"
#include "qpid/broker/MessageDeque.h"
#include "qpid/broker/MessageMap.h"
#include "qpid/broker/MessageStore.h"
#include "qpid/broker/NullMessageStore.h"
#include "qpid/broker/QueueRegistry.h"
#include "qpid/broker/QueueFlowLimit.h"
#include "qpid/broker/ThresholdAlerts.h"

#include "qpid/StringUtils.h"
#include "qpid/log/Statement.h"
#include "qpid/management/ManagementAgent.h"
#include "qpid/framing/reply_exceptions.h"
#include "qpid/framing/FieldTable.h"
#include "qpid/sys/ClusterSafe.h"
#include "qpid/sys/Monitor.h"
#include "qpid/sys/Time.h"
#include "qmf/org/apache/qpid/broker/ArgsQueuePurge.h"
#include "qmf/org/apache/qpid/broker/ArgsQueueReroute.h"

#include <iostream>
#include <algorithm>
#include <functional>

#include <boost/bind.hpp>
#include <boost/intrusive_ptr.hpp>


using namespace qpid::broker;
using namespace qpid::sys;
using namespace qpid::framing;
using qpid::management::ManagementAgent;
using qpid::management::ManagementObject;
using qpid::management::Manageable;
using qpid::management::Args;
using std::for_each;
using std::mem_fun;
namespace _qmf = qmf::org::apache::qpid::broker;


namespace 
{
const std::string qpidMaxSize("qpid.max_size");
const std::string qpidMaxCount("qpid.max_count");
const std::string qpidNoLocal("no-local");
const std::string qpidTraceIdentity("qpid.trace.id");
const std::string qpidTraceExclude("qpid.trace.exclude");
const std::string qpidLastValueQueueKey("qpid.last_value_queue_key");
const std::string qpidLastValueQueue("qpid.last_value_queue");
const std::string qpidLastValueQueueNoBrowse("qpid.last_value_queue_no_browse");
const std::string qpidPersistLastNode("qpid.persist_last_node");
const std::string qpidVQMatchProperty("qpid.LVQ_key");
const std::string qpidQueueEventGeneration("qpid.queue_event_generation");
const std::string qpidAutoDeleteTimeout("qpid.auto_delete_timeout");
//following feature is not ready for general use as it doesn't handle
//the case where a message is enqueued on more than one queue well enough:
const std::string qpidInsertSequenceNumbers("qpid.insert_sequence_numbers");

const int ENQUEUE_ONLY=1;
const int ENQUEUE_AND_DEQUEUE=2;
}

Queue::Queue(const string& _name, bool _autodelete, 
             MessageStore* const _store,
             const OwnershipToken* const _owner,
             Manageable* parent,
             Broker* b) :

    name(_name), 
    autodelete(_autodelete),
    store(_store),
    owner(_owner), 
    consumerCount(0),
    exclusive(0),
    noLocal(false),
    persistLastNode(false),
    inLastNodeFailure(false),
    messages(new MessageDeque()),
    persistenceId(0),
    policyExceeded(false),
    mgmtObject(0),
    eventMode(0),
    insertSeqNo(0),
    broker(b),
    deleted(false),
    barrier(*this),
    autoDeleteTimeout(0)
{
    if (parent != 0 && broker != 0) {
        ManagementAgent* agent = broker->getManagementAgent();

        if (agent != 0) {
            mgmtObject = new _qmf::Queue(agent, this, parent, _name, _store != 0, _autodelete, _owner != 0);
            agent->addObject(mgmtObject, 0, store != 0);
        }
    }
}

Queue::~Queue()
{
    if (mgmtObject != 0)
        mgmtObject->resourceDestroy();
}

bool isLocalTo(const OwnershipToken* token, boost::intrusive_ptr<Message>& msg)
{
    return token && token->isLocal(msg->getPublisher());
}

bool Queue::isLocal(boost::intrusive_ptr<Message>& msg)
{
    //message is considered local if it was published on the same
    //connection as that of the session which declared this queue
    //exclusive (owner) or which has an exclusive subscription
    //(exclusive)
    return noLocal && (isLocalTo(owner, msg) || isLocalTo(exclusive, msg));
}

bool Queue::isExcluded(boost::intrusive_ptr<Message>& msg)
{
    return traceExclude.size() && msg->isExcluded(traceExclude);
}

void Queue::deliver(boost::intrusive_ptr<Message> msg){
    // Check for deferred delivery in a cluster.
    if (broker && broker->deferDelivery(name, msg))
        return;
    if (msg->isImmediate() && getConsumerCount() == 0) {
        if (alternateExchange) {
            DeliverableMessage deliverable(msg);
            alternateExchange->route(deliverable, msg->getRoutingKey(), msg->getApplicationHeaders());
        }
    } else if (isLocal(msg)) {
        //drop message
        QPID_LOG(info, "Dropping 'local' message from " << getName());
    } else if (isExcluded(msg)) {
        //drop message
        QPID_LOG(info, "Dropping excluded message from " << getName());
    } else {
        enqueue(0, msg);
        push(msg);
        QPID_LOG(debug, "Message " << msg << " enqueued on " << name);
    }
}

void Queue::recoverPrepared(boost::intrusive_ptr<Message>& msg)
{
    if (policy.get()) policy->recoverEnqueued(msg);
}

void Queue::recover(boost::intrusive_ptr<Message>& msg){
    if (policy.get()) policy->recoverEnqueued(msg);

    push(msg, true);
    if (store){ 
        // setup synclist for recovered messages, so they don't get re-stored on lastNodeFailure
        msg->addToSyncList(shared_from_this(), store); 
    }

    if (store && (!msg->isContentLoaded() || msg->checkContentReleasable())) {
        //content has not been loaded, need to ensure that lazy loading mode is set:
        //TODO: find a nicer way to do this
        msg->releaseContent(store);
        // NOTE: The log message in this section are used for flow-to-disk testing (which checks the log for the
        // presence of this message). Do not change this without also checking these tests.
        QPID_LOG(debug, "Message id=\"" << msg->getProperties<MessageProperties>()->getMessageId() << "\"; pid=0x" <<
                        std::hex << msg->getPersistenceId() << std::dec << ": Content released after recovery");
    }
}

void Queue::process(boost::intrusive_ptr<Message>& msg){
    push(msg);
    if (mgmtObject != 0){
        mgmtObject->inc_msgTxnEnqueues ();
        mgmtObject->inc_byteTxnEnqueues (msg->contentSize ());
    }
}

void Queue::requeue(const QueuedMessage& msg){
    assertClusterSafe();
    QueueListeners::NotificationSet copy;
    {    
        Mutex::ScopedLock locker(messageLock);
        if (!isEnqueued(msg)) return;
        messages->reinsert(msg);
        listeners.populate(copy);

        // for persistLastNode - don't force a message twice to disk, but force it if no force before 
        if(inLastNodeFailure && persistLastNode && !msg.payload->isStoredOnQueue(shared_from_this())) {
            msg.payload->forcePersistent();
            if (msg.payload->isForcedPersistent() ){
                boost::intrusive_ptr<Message> payload = msg.payload;
            	enqueue(0, payload);
            }
        }
    }
    copy.notify();
}

bool Queue::acquireMessageAt(const SequenceNumber& position, QueuedMessage& message) 
{
    Mutex::ScopedLock locker(messageLock);
    assertClusterSafe();
    QPID_LOG(debug, "Attempting to acquire message at " << position);
    if (messages->remove(position, message)) {
        QPID_LOG(debug, "Acquired message at " << position << " from " << name);
        return true;
    } else {
        QPID_LOG(debug, "Could not acquire message at " << position << " from " << name << "; no message at that position");
        return false;
    }
}

bool Queue::acquire(const QueuedMessage& msg) {
    QueuedMessage copy = msg;
    return acquireMessageAt(msg.position, copy);
}

void Queue::notifyListener()
{
    assertClusterSafe();
    QueueListeners::NotificationSet set;
    {
        Mutex::ScopedLock locker(messageLock);
        if (messages->size()) {
            listeners.populate(set);
        }
    }
    set.notify();
}

bool Queue::getNextMessage(QueuedMessage& m, Consumer::shared_ptr c)
{
    checkNotDeleted();
    if (c->preAcquires()) {
        switch (consumeNextMessage(m, c)) {
          case CONSUMED:
            return true;
          case CANT_CONSUME:
            notifyListener();//let someone else try
          case NO_MESSAGES:
          default:
            return false;
        }        
    } else {
        return browseNextMessage(m, c);
    }
}

Queue::ConsumeCode Queue::consumeNextMessage(QueuedMessage& m, Consumer::shared_ptr c)
{
    while (true) {
        Mutex::ScopedLock locker(messageLock);
        if (messages->empty()) { 
            QPID_LOG(debug, "No messages to dispatch on queue '" << name << "'");
            listeners.addListener(c);
            return NO_MESSAGES;
        } else {
            QueuedMessage msg = messages->front();
            if (msg.payload->hasExpired()) {
                QPID_LOG(debug, "Message expired from queue '" << name << "'");
                popAndDequeue();
                continue;
            }

            if (c->filter(msg.payload)) {
                if (c->accept(msg.payload)) {            
                    m = msg;
                    pop();
                    return CONSUMED;
                } else {
                    //message(s) are available but consumer hasn't got enough credit
                    QPID_LOG(debug, "Consumer can't currently accept message from '" << name << "'");
                    return CANT_CONSUME;
                }
            } else {
                //consumer will never want this message
                QPID_LOG(debug, "Consumer doesn't want message from '" << name << "'");
                return CANT_CONSUME;
            } 
        }
    }
}


bool Queue::browseNextMessage(QueuedMessage& m, Consumer::shared_ptr c)
{
    QueuedMessage msg(this);
    while (seek(msg, c)) {
        if (c->filter(msg.payload) && !msg.payload->hasExpired()) {
            if (c->accept(msg.payload)) {
                //consumer wants the message
                c->position = msg.position;
                m = msg;
                return true;
            } else {
                //browser hasn't got enough credit for the message
                QPID_LOG(debug, "Browser can't currently accept message from '" << name << "'");
                return false;
            }
        } else {
            //consumer will never want this message, continue seeking
            c->position = msg.position;
            QPID_LOG(debug, "Browser skipping message from '" << name << "'");
        }
    }
    return false;
}

void Queue::removeListener(Consumer::shared_ptr c)
{
    QueueListeners::NotificationSet set;
    {
        Mutex::ScopedLock locker(messageLock);
        listeners.removeListener(c);
        if (messages->size()) {
            listeners.populate(set);
        }
    }
    set.notify();
}

bool Queue::dispatch(Consumer::shared_ptr c)
{
    QueuedMessage msg(this);
    if (getNextMessage(msg, c)) {
        c->deliver(msg);
        return true;
    } else {
        return false;
    }
}

// Find the next message 
bool Queue::seek(QueuedMessage& msg, Consumer::shared_ptr c) {
    Mutex::ScopedLock locker(messageLock);
    if (messages->next(c->position, msg)) {
        return true;
    } else {
        listeners.addListener(c);
        return false;
    }
}

QueuedMessage Queue::find(SequenceNumber pos) const {

    Mutex::ScopedLock locker(messageLock);
    QueuedMessage msg;
    messages->find(pos, msg);
    return msg;
}

void Queue::consume(Consumer::shared_ptr c, bool requestExclusive){
    assertClusterSafe();
    Mutex::ScopedLock locker(consumerLock);
    if(exclusive) {
        throw ResourceLockedException(
            QPID_MSG("Queue " << getName() << " has an exclusive consumer. No more consumers allowed."));
    } else if(requestExclusive) {
        if(consumerCount) {
            throw ResourceLockedException(
                QPID_MSG("Queue " << getName() << " already has consumers. Exclusive access denied."));
        } else {
            exclusive = c->getSession();
        }
    }
    consumerCount++;
    if (mgmtObject != 0)
        mgmtObject->inc_consumerCount ();
    //reset auto deletion timer if necessary
    if (autoDeleteTimeout && autoDeleteTask) {
        autoDeleteTask->cancel();
    }
}

void Queue::cancel(Consumer::shared_ptr c){
    removeListener(c);
    Mutex::ScopedLock locker(consumerLock);
    consumerCount--;
    if(exclusive) exclusive = 0;
    if (mgmtObject != 0)
        mgmtObject->dec_consumerCount ();
}

QueuedMessage Queue::get(){
    Mutex::ScopedLock locker(messageLock);
    QueuedMessage msg(this);
    messages->pop(msg);
    return msg;
}

bool collect_if_expired(std::deque<QueuedMessage>& expired, QueuedMessage& message)
{
    if (message.payload->hasExpired()) {
        expired.push_back(message);
        return true;
    } else {
        return false;
    }
}

void Queue::purgeExpired()
{
    //As expired messages are discarded during dequeue also, only
    //bother explicitly expiring if the rate of dequeues since last
    //attempt is less than one per second.  

    if (dequeueTracker.sampleRatePerSecond() < 1) {
        std::deque<QueuedMessage> expired;
        {
            Mutex::ScopedLock locker(messageLock);
            messages->removeIf(boost::bind(&collect_if_expired, boost::ref(expired), _1));
        }
        for_each(expired.begin(), expired.end(), boost::bind(&Queue::dequeue, this, (TransactionContext*) 0, _1));
    }
}

/**
 * purge - for purging all or some messages on a queue
 *         depending on the purge_request
 *
 * purge_request == 0 then purge all messages
 *               == N then purge N messages from queue
 * Sometimes purge_request == 1 to unblock the top of queue
 *
 * The dest exchange may be supplied to re-route messages through the exchange.
 * It is safe to re-route messages such that they arrive back on the same queue,
 * even if the queue is ordered by priority.
 */
uint32_t Queue::purge(const uint32_t purge_request, boost::shared_ptr<Exchange> dest)
{
    Mutex::ScopedLock locker(messageLock);
    uint32_t purge_count = purge_request; // only comes into play if  >0 
    std::deque<DeliverableMessage> rerouteQueue;

    uint32_t count = 0;
    // Either purge them all or just the some (purge_count) while the queue isn't empty.
    while((!purge_request || purge_count--) && !messages->empty()) {
        if (dest.get()) {
            //
            // If there is a destination exchange, stage the messages onto a reroute queue
            // so they don't wind up getting purged more than once.
            //
            DeliverableMessage msg(messages->front().payload);
            rerouteQueue.push_back(msg);
        }
        popAndDequeue();
        count++;
    }

    //
    // Re-route purged messages into the destination exchange.  Note that there's no need
    // to test dest.get() here because if it is NULL, the rerouteQueue will be empty.
    //
    while (!rerouteQueue.empty()) {
        DeliverableMessage msg(rerouteQueue.front());
        rerouteQueue.pop_front();
        dest->routeWithAlternate(msg);
    }

    return count;
}

uint32_t Queue::move(const Queue::shared_ptr destq, uint32_t qty) {
    Mutex::ScopedLock locker(messageLock);
    uint32_t move_count = qty; // only comes into play if  qty >0 
    uint32_t count = 0; // count how many were moved for returning

    while((!qty || move_count--) && !messages->empty()) {
        QueuedMessage qmsg = messages->front();
        boost::intrusive_ptr<Message> msg = qmsg.payload;
        destq->deliver(msg); // deliver message to the destination queue
        pop();
        dequeue(0, qmsg);
        count++;
    }
    return count;
}

void Queue::pop()
{
    assertClusterSafe();
    messages->pop();
    ++dequeueTracker;
}

void Queue::push(boost::intrusive_ptr<Message>& msg, bool isRecovery){
    assertClusterSafe();
    QueueListeners::NotificationSet copy;
    QueuedMessage removed;
    bool dequeueRequired = false;
    {
        Mutex::ScopedLock locker(messageLock);   
        QueuedMessage qm(this, msg, ++sequence);
        if (insertSeqNo) msg->getOrInsertHeaders().setInt64(seqNoKey, sequence);
         
        dequeueRequired = messages->push(qm, removed);
        listeners.populate(copy);
        enqueued(qm);
    }
    copy.notify();
    if (dequeueRequired) {
        if (isRecovery) {
            //can't issue new requests for the store until
            //recovery is complete
            pendingDequeues.push_back(removed);
        } else {
            dequeue(0, removed);
        }
    }
}

void isEnqueueComplete(uint32_t* result, const QueuedMessage& message)
{
    if (message.payload->isIngressComplete()) (*result)++;
}

/** function only provided for unit tests, or code not in critical message path */
uint32_t Queue::getEnqueueCompleteMessageCount() const
{
    Mutex::ScopedLock locker(messageLock);
    uint32_t count = 0;
    messages->foreach(boost::bind(&isEnqueueComplete, &count, _1));
    return count;
}

uint32_t Queue::getMessageCount() const
{
    Mutex::ScopedLock locker(messageLock);
    return messages->size();
}

uint32_t Queue::getConsumerCount() const
{
    Mutex::ScopedLock locker(consumerLock);
    return consumerCount;
}

bool Queue::canAutoDelete() const
{
    Mutex::ScopedLock locker(consumerLock);
    return autodelete && !consumerCount && !owner;
}

void Queue::clearLastNodeFailure()
{
    inLastNodeFailure = false;
}

void Queue::forcePersistent(QueuedMessage& message)
{
    if(!message.payload->isStoredOnQueue(shared_from_this())) {
        message.payload->forcePersistent();
        if (message.payload->isForcedPersistent() ){
            enqueue(0, message.payload);
        }
    }
}

void Queue::setLastNodeFailure()
{
    if (persistLastNode){
        Mutex::ScopedLock locker(messageLock);
        try {
            messages->foreach(boost::bind(&Queue::forcePersistent, this, _1));
        } catch (const std::exception& e) {
            // Could not go into last node standing (for example journal not large enough)
            QPID_LOG(error, "Unable to fail to last node standing for queue: " << name << " : " << e.what());
        }
        inLastNodeFailure = true;
    }
}


// return true if store exists, 
bool Queue::enqueue(TransactionContext* ctxt, boost::intrusive_ptr<Message>& msg, bool suppressPolicyCheck)
{
    ScopedUse u(barrier);
    if (!u.acquired) return false;

    if (policy.get() && !suppressPolicyCheck) {
        std::deque<QueuedMessage> dequeues;
        {
            Mutex::ScopedLock locker(messageLock);
            policy->tryEnqueue(msg);
            policy->getPendingDequeues(dequeues);
        }
        //depending on policy, may have some dequeues that need to performed without holding the lock
        for_each(dequeues.begin(), dequeues.end(), boost::bind(&Queue::dequeue, this, (TransactionContext*) 0, _1));        
    }

    if (inLastNodeFailure && persistLastNode){
        msg->forcePersistent();
    }
       
    if (traceId.size()) {
        //copy on write: take deep copy of message before modifying it
        //as the frames may already be available for delivery on other
        //threads
        boost::intrusive_ptr<Message> copy(new Message(*msg));
        msg = copy;
        msg->addTraceId(traceId);
    }

    if ((msg->isPersistent() || msg->checkContentReleasable()) && store) {
        // mark the message as being enqueued - the store MUST CALL msg->enqueueComplete()
        // when it considers the message stored.
        msg->enqueueAsync(shared_from_this(), store);
        boost::intrusive_ptr<PersistableMessage> pmsg = boost::static_pointer_cast<PersistableMessage>(msg);
        store->enqueue(ctxt, pmsg, *this);
        return true;
    }
    if (!store) {
        //Messages enqueued on a transient queue should be prevented
        //from having their content released as it may not be
        //recoverable by these queue for delivery
        msg->blockContentRelease();
    }
    return false;
}

void Queue::enqueueAborted(boost::intrusive_ptr<Message> msg)
{
    Mutex::ScopedLock locker(messageLock);
    if (policy.get()) policy->enqueueAborted(msg);       
}

// return true if store exists, 
bool Queue::dequeue(TransactionContext* ctxt, const QueuedMessage& msg)
{
    ScopedUse u(barrier);
    if (!u.acquired) return false;

    {
        Mutex::ScopedLock locker(messageLock);
        if (!isEnqueued(msg)) return false;
        if (!ctxt) { 
            dequeued(msg);
        }
    }
    // This check prevents messages which have been forced persistent on one queue from dequeuing
    // from another on which no forcing has taken place and thus causing a store error.
    bool fp = msg.payload->isForcedPersistent();
    if (!fp || (fp && msg.payload->isStoredOnQueue(shared_from_this()))) {
        if ((msg.payload->isPersistent() || msg.payload->checkContentReleasable()) && store) {
            msg.payload->dequeueAsync(shared_from_this(), store); //increment to async counter -- for message sent to more than one queue
            boost::intrusive_ptr<PersistableMessage> pmsg = boost::static_pointer_cast<PersistableMessage>(msg.payload);
            store->dequeue(ctxt, pmsg, *this);
            return true;
        }
    }
    return false;
}

void Queue::dequeueCommitted(const QueuedMessage& msg)
{
    Mutex::ScopedLock locker(messageLock);
    dequeued(msg);    
    if (mgmtObject != 0) {
        mgmtObject->inc_msgTxnDequeues();
        mgmtObject->inc_byteTxnDequeues(msg.payload->contentSize());
    }
}

/**
 * Removes a message from the in-memory delivery queue as well
 * dequeing it from the logical (and persistent if applicable) queue
 */
void Queue::popAndDequeue()
{
    QueuedMessage msg = messages->front();
    pop();
    dequeue(0, msg);
}

/**
 * Updates policy and management when a message has been dequeued,
 * expects messageLock to be held
 */
void Queue::dequeued(const QueuedMessage& msg)
{
    if (policy.get()) policy->dequeued(msg);
    mgntDeqStats(msg.payload);
    for (Observers::const_iterator i = observers.begin(); i != observers.end(); ++i) {
        try{
            (*i)->dequeued(msg);
        } catch (const std::exception& e) {
            QPID_LOG(warning, "Exception on notification of dequeue for queue " << getName() << ": " << e.what());
        }
    }
}


void Queue::create(const FieldTable& _settings)
{
    settings = _settings;
    if (store) {
        store->create(*this, _settings);
    }
    configureImpl(_settings);
}


int getIntegerSetting(const qpid::framing::FieldTable& settings, const std::string& key)
{
    qpid::framing::FieldTable::ValuePtr v = settings.get(key);
    if (!v) {
        return 0;
    } else if (v->convertsTo<int>()) {
        return v->get<int>();
    } else if (v->convertsTo<std::string>()){
        std::string s = v->get<std::string>();
        try { 
            return boost::lexical_cast<int>(s); 
        } catch(const boost::bad_lexical_cast&) {
            QPID_LOG(warning, "Ignoring invalid integer value for " << key << ": " << s);
            return 0;
        }
    } else {
        QPID_LOG(warning, "Ignoring invalid integer value for " << key << ": " << *v);
        return 0;
    }
}

void Queue::configure(const FieldTable& _settings)
{
    settings = _settings;
    configureImpl(settings);
}

void Queue::configureImpl(const FieldTable& _settings)
{
    eventMode = _settings.getAsInt(qpidQueueEventGeneration);
    if (eventMode && broker) {
        broker->getQueueEvents().observe(*this, eventMode == ENQUEUE_ONLY);
    }

    if (QueuePolicy::getType(_settings) == QueuePolicy::FLOW_TO_DISK && 
        (!store || NullMessageStore::isNullStore(store) || (broker && !(broker->getQueueEvents().isSync())) )) {
        if ( NullMessageStore::isNullStore(store)) {
            QPID_LOG(warning, "Flow to disk not valid for non-persisted queue:" << getName());
        } else if (broker && !(broker->getQueueEvents().isSync()) ) {
            QPID_LOG(warning, "Flow to disk not valid with async Queue Events:" << getName());
        }
        FieldTable copy(_settings);
        copy.erase(QueuePolicy::typeKey);
        setPolicy(QueuePolicy::createQueuePolicy(getName(), copy));
    } else {
        setPolicy(QueuePolicy::createQueuePolicy(getName(), _settings));
    }
    if (broker && broker->getManagementAgent()) {
        ThresholdAlerts::observe(*this, *(broker->getManagementAgent()), _settings, broker->getOptions().queueThresholdEventRatio);
    }

    //set this regardless of owner to allow use of no-local with exclusive consumers also
    noLocal = _settings.get(qpidNoLocal);
    QPID_LOG(debug, "Configured queue " << getName() << " with no-local=" << noLocal);

    std::string lvqKey = _settings.getAsString(qpidLastValueQueueKey);
    if (lvqKey.size()) {
        QPID_LOG(debug, "Configured queue " <<  getName() << " as Last Value Queue with key " << lvqKey);
        messages = std::auto_ptr<Messages>(new MessageMap(lvqKey));
    } else if (_settings.get(qpidLastValueQueueNoBrowse)) {
        QPID_LOG(debug, "Configured queue " <<  getName() << " as Legacy Last Value Queue with 'no-browse' on");
        messages = LegacyLVQ::updateOrReplace(messages, qpidVQMatchProperty, true, broker);
    } else if (_settings.get(qpidLastValueQueue)) {
        QPID_LOG(debug, "Configured queue " <<  getName() << " as Legacy Last Value Queue");
        messages = LegacyLVQ::updateOrReplace(messages, qpidVQMatchProperty, false, broker);
    } else {
        std::auto_ptr<Messages> m = Fairshare::create(_settings);
        if (m.get()) {
            messages = m;
            QPID_LOG(debug, "Configured queue " <<  getName() << " as priority queue.");
        }
    }
    
    persistLastNode= _settings.get(qpidPersistLastNode);
    if (persistLastNode) QPID_LOG(debug, "Configured queue to Persist data if cluster fails to one node for: " << getName());

    traceId = _settings.getAsString(qpidTraceIdentity);
    std::string excludeList = _settings.getAsString(qpidTraceExclude);
    if (excludeList.size()) {
        split(traceExclude, excludeList, ", ");
    }
    QPID_LOG(debug, "Configured queue " << getName() << " with qpid.trace.id='" << traceId 
             << "' and qpid.trace.exclude='"<< excludeList << "' i.e. " << traceExclude.size() << " elements");

    FieldTable::ValuePtr p =_settings.get(qpidInsertSequenceNumbers);
    if (p && p->convertsTo<std::string>()) insertSequenceNumbers(p->get<std::string>());

    autoDeleteTimeout = getIntegerSetting(_settings, qpidAutoDeleteTimeout);
    if (autoDeleteTimeout) 
        QPID_LOG(debug, "Configured queue " << getName() << " with qpid.auto_delete_timeout=" << autoDeleteTimeout); 

    if (mgmtObject != 0) {
        mgmtObject->set_arguments(ManagementAgent::toMap(_settings));
    }

    QueueFlowLimit::observe(*this, _settings);
}

void Queue::destroyed()
{
    unbind(broker->getExchanges());
    if (alternateExchange.get()) {
        Mutex::ScopedLock locker(messageLock);
        while(!messages->empty()){
            DeliverableMessage msg(messages->front().payload);
            alternateExchange->routeWithAlternate(msg);
            popAndDequeue();
        }
        alternateExchange->decAlternateUsers();
    }

    if (store) {
        barrier.destroy();
        store->flush(*this);
        store->destroy(*this);
        store = 0;//ensure we make no more calls to the store for this queue
    }
    if (autoDeleteTask) autoDeleteTask = boost::intrusive_ptr<TimerTask>();
    notifyDeleted();
}

void Queue::notifyDeleted()
{
    QueueListeners::ListenerSet set;
    {
        Mutex::ScopedLock locker(messageLock);
        listeners.snapshot(set);
        deleted = true;
    }
    set.notifyAll();
}

void Queue::bound(const string& exchange, const string& key,
                  const FieldTable& args)
{
    bindings.add(exchange, key, args);
}

void Queue::unbind(ExchangeRegistry& exchanges)
{
    bindings.unbind(exchanges, shared_from_this());
}

void Queue::setPolicy(std::auto_ptr<QueuePolicy> _policy)
{
    policy = _policy;
}

const QueuePolicy* Queue::getPolicy()
{
    return policy.get();
}

uint64_t Queue::getPersistenceId() const 
{ 
    return persistenceId; 
}

void Queue::setPersistenceId(uint64_t _persistenceId) const
{
    if (mgmtObject != 0 && persistenceId == 0 && externalQueueStore)
    {
        ManagementObject* childObj = externalQueueStore->GetManagementObject();
        if (childObj != 0)
            childObj->setReference(mgmtObject->getObjectId());
    }
    persistenceId = _persistenceId;
}

void Queue::encode(Buffer& buffer) const 
{
    buffer.putShortString(name);
    buffer.put(settings);
    if (policy.get()) { 
        buffer.put(*policy);
    }
    buffer.putShortString(alternateExchange.get() ? alternateExchange->getName() : std::string(""));
}

uint32_t Queue::encodedSize() const
{
    return name.size() + 1/*short string size octet*/
        + (alternateExchange.get() ? alternateExchange->getName().size() : 0) + 1 /* short string */
        + settings.encodedSize()
        + (policy.get() ? (*policy).encodedSize() : 0);
}

Queue::shared_ptr Queue::restore( QueueRegistry& queues, Buffer& buffer )
{
    string name;
    buffer.getShortString(name);
    FieldTable settings;
    buffer.get(settings);
    boost::shared_ptr<Exchange> alternate;
    std::pair<Queue::shared_ptr, bool> result = queues.declare(name, true, false, 0, alternate, settings, true);
    if (result.first->policy.get() && buffer.available() >= result.first->policy->encodedSize()) {
        buffer.get ( *(result.first->policy) );
    }
    if (buffer.available()) {
        string altExch;
        buffer.getShortString(altExch);
        result.first->alternateExchangeName.assign(altExch);
    }

    return result.first;
}


void Queue::setAlternateExchange(boost::shared_ptr<Exchange> exchange)
{
    alternateExchange = exchange;
    if (mgmtObject) {
        if (exchange.get() != 0)
            mgmtObject->set_altExchange(exchange->GetManagementObject()->getObjectId());
        else
            mgmtObject->clr_altExchange();
    }
}

boost::shared_ptr<Exchange> Queue::getAlternateExchange()
{
    return alternateExchange;
}

void tryAutoDeleteImpl(Broker& broker, Queue::shared_ptr queue)
{
    if (broker.getQueues().destroyIf(queue->getName(), 
                                     boost::bind(boost::mem_fn(&Queue::canAutoDelete), queue))) {
        QPID_LOG(debug, "Auto-deleting " << queue->getName());
        queue->destroyed();
    }
}

struct AutoDeleteTask : qpid::sys::TimerTask
{
    Broker& broker;
    Queue::shared_ptr queue;

    AutoDeleteTask(Broker& b, Queue::shared_ptr q, AbsTime fireTime) 
        : qpid::sys::TimerTask(fireTime, "DelayedAutoDeletion"), broker(b), queue(q) {}

    void fire()
    {
        //need to detect case where queue was used after the task was
        //created, but then became unused again before the task fired;
        //in this case ignore this request as there will have already
        //been a later task added
        tryAutoDeleteImpl(broker, queue);
    }
};

void Queue::tryAutoDelete(Broker& broker, Queue::shared_ptr queue)
{
    if (queue->autoDeleteTimeout && queue->canAutoDelete()) {
        AbsTime time(now(), Duration(queue->autoDeleteTimeout * TIME_SEC));
        queue->autoDeleteTask = boost::intrusive_ptr<qpid::sys::TimerTask>(new AutoDeleteTask(broker, queue, time));
        broker.getClusterTimer().add(queue->autoDeleteTask);        
        QPID_LOG(debug, "Timed auto-delete for " << queue->getName() << " initiated");
    } else {
        tryAutoDeleteImpl(broker, queue);
    }
}

bool Queue::isExclusiveOwner(const OwnershipToken* const o) const 
{ 
    Mutex::ScopedLock locker(ownershipLock);
    return o == owner; 
}

void Queue::releaseExclusiveOwnership() 
{ 
    Mutex::ScopedLock locker(ownershipLock);
    owner = 0; 
}

bool Queue::setExclusiveOwner(const OwnershipToken* const o) 
{ 
    //reset auto deletion timer if necessary
    if (autoDeleteTimeout && autoDeleteTask) {
        autoDeleteTask->cancel();
    }
    Mutex::ScopedLock locker(ownershipLock);
    if (owner) {
        return false;
    } else {
        owner = o; 
        return true;
    }
}

bool Queue::hasExclusiveOwner() const 
{ 
    Mutex::ScopedLock locker(ownershipLock);
    return owner != 0; 
}

bool Queue::hasExclusiveConsumer() const 
{ 
    return exclusive; 
}

void Queue::setExternalQueueStore(ExternalQueueStore* inst) {
    if (externalQueueStore!=inst && externalQueueStore) 
        delete externalQueueStore; 
    externalQueueStore = inst;

    if (inst) {
        ManagementObject* childObj = inst->GetManagementObject();
        if (childObj != 0 && mgmtObject != 0)
            childObj->setReference(mgmtObject->getObjectId());
    }
}

ManagementObject* Queue::GetManagementObject (void) const
{
    return (ManagementObject*) mgmtObject;
}

Manageable::status_t Queue::ManagementMethod (uint32_t methodId, Args& args, string& etext)
{
    Manageable::status_t status = Manageable::STATUS_UNKNOWN_METHOD;

    QPID_LOG (debug, "Queue::ManagementMethod [id=" << methodId << "]");

    switch (methodId) {
    case _qmf::Queue::METHOD_PURGE :
        {
            _qmf::ArgsQueuePurge& purgeArgs = (_qmf::ArgsQueuePurge&) args;
            purge(purgeArgs.i_request);
            status = Manageable::STATUS_OK;
        }
        break;

    case _qmf::Queue::METHOD_REROUTE :
        {
            _qmf::ArgsQueueReroute& rerouteArgs = (_qmf::ArgsQueueReroute&) args;
            boost::shared_ptr<Exchange> dest;
            if (rerouteArgs.i_useAltExchange)
                dest = alternateExchange;
            else {
                try {
                    dest = broker->getExchanges().get(rerouteArgs.i_exchange);
                } catch(const std::exception&) {
                    status = Manageable::STATUS_PARAMETER_INVALID;
                    etext = "Exchange not found";
                    break;
                }
            }

            purge(rerouteArgs.i_request, dest);
            status = Manageable::STATUS_OK;
        }
        break;
    }

    return status;
}

void Queue::setPosition(SequenceNumber n) {
    Mutex::ScopedLock locker(messageLock);
    sequence = n;
}

SequenceNumber Queue::getPosition() {
    return sequence;
}

int Queue::getEventMode() { return eventMode; }

void Queue::recoveryComplete(ExchangeRegistry& exchanges)
{
    // set the alternate exchange
    if (!alternateExchangeName.empty()) {
        try {
            Exchange::shared_ptr ae = exchanges.get(alternateExchangeName);
            setAlternateExchange(ae);
        } catch (const NotFoundException&) {
            QPID_LOG(warning, "Could not set alternate exchange \"" << alternateExchangeName << "\" on queue \"" << name << "\": exchange does not exist.");
        }
    }
    //process any pending dequeues
    for_each(pendingDequeues.begin(), pendingDequeues.end(), boost::bind(&Queue::dequeue, this, (TransactionContext*) 0, _1));
    pendingDequeues.clear();
}

void Queue::insertSequenceNumbers(const std::string& key)
{
    seqNoKey = key;
    insertSeqNo = !seqNoKey.empty();
    QPID_LOG(debug, "Inserting sequence numbers as " << key);
}

void Queue::enqueued(const QueuedMessage& m)
{
    for (Observers::iterator i = observers.begin(); i != observers.end(); ++i) {
        try {
            (*i)->enqueued(m);
        } catch (const std::exception& e) {
            QPID_LOG(warning, "Exception on notification of enqueue for queue " << getName() << ": " << e.what());
        }
    }
    if (policy.get()) {
        policy->enqueued(m);
    }
    mgntEnqStats(m.payload);
}

void Queue::updateEnqueued(const QueuedMessage& m)
{
    if (m.payload) {
        boost::intrusive_ptr<Message> payload = m.payload;
        enqueue ( 0, payload, true );
        if (policy.get()) {
            policy->recoverEnqueued(payload);
        }
        enqueued(m);
    } else {
        QPID_LOG(warning, "Queue informed of enqueued message that has no payload");
    }
}

bool Queue::isEnqueued(const QueuedMessage& msg)
{
    return !policy.get() || policy->isEnqueued(msg);
}

QueueListeners& Queue::getListeners() { return listeners; }
Messages& Queue::getMessages() { return *messages; }
const Messages& Queue::getMessages() const { return *messages; }

void Queue::checkNotDeleted()
{
    if (deleted) {
        throw ResourceDeletedException(QPID_MSG("Queue " << getName() << " has been deleted."));
    }
}

void Queue::addObserver(boost::shared_ptr<QueueObserver> observer)
{
    observers.insert(observer);
}

void Queue::flush()
{
    ScopedUse u(barrier);
    if (u.acquired && store) store->flush(*this);
}


bool Queue::bind(boost::shared_ptr<Exchange> exchange, const std::string& key,
                 const qpid::framing::FieldTable& arguments)
{
    if (exchange->bind(shared_from_this(), key, &arguments)) {
        bound(exchange->getName(), key, arguments);
        if (exchange->isDurable() && isDurable()) {
            store->bind(*exchange, *this, key, arguments);
        }
        return true;
    } else {
        return false;
    }
}


const Broker* Queue::getBroker()
{
    return broker;
}


Queue::UsageBarrier::UsageBarrier(Queue& q) : parent(q), count(0) {}

bool Queue::UsageBarrier::acquire()
{
    Monitor::ScopedLock l(parent.messageLock);
    if (parent.deleted) {
        return false;
    } else {
        ++count;
        return true;
    }
}

void Queue::UsageBarrier::release()
{
    Monitor::ScopedLock l(parent.messageLock);
    if (--count == 0) parent.messageLock.notifyAll();
}

void Queue::UsageBarrier::destroy()
{
    Monitor::ScopedLock l(parent.messageLock);
    parent.deleted = true;
    while (count) parent.messageLock.wait();
}