Update to periodic purge of expired messages: check the dequeue rate to avoid interfering unnecessarily where the dequeing is sufficient to remove expired messages.

git-svn-id: https://svn.apache.org/repos/asf/incubator/qpid/trunk/qpid@704461 13f79535-47bb-0310-9956-ffa450edef68

4 files changed, 123 insertions, 10 deletions

diff --git a/cpp/src/qpid/broker/Queue.cpp b/cpp/src/qpid/broker/Queue.cpp
index 355f822b57..1f508a1cc7 100644
--- a/cpp/src/qpid/broker/Queue.cpp
+++ b/cpp/src/qpid/broker/Queue.cpp
@@ -405,19 +405,24 @@ QueuedMessage Queue::get(){
 
 void Queue::purgeExpired()
 {
-    Messages expired;
-    {
-        Mutex::ScopedLock locker(messageLock);
-        for (Messages::iterator i = messages.begin(); i != messages.end();) {
-            if (i->payload->hasExpired()) {
-                expired.push_back(*i);
-                i = messages.erase(i);
-            } else {
-                ++i;
+    //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) {
+        Messages expired;
+        {
+            Mutex::ScopedLock locker(messageLock);
+            for (Messages::iterator i = messages.begin(); i != messages.end();) {
+                if (i->payload->hasExpired()) {
+                    expired.push_back(*i);
+                    i = messages.erase(i);
+                } else {
+                    ++i;
+                }
             }
         }
+        for_each(expired.begin(), expired.end(), bind(&Queue::dequeue, this, (TransactionContext*) 0, _1));
     }
-    for_each(expired.begin(), expired.end(), bind(&Queue::dequeue, this, (TransactionContext*) 0, _1));
 }
 
 /**
@@ -465,6 +470,7 @@ void Queue::popMsg(QueuedMessage& qmsg)
         lvq.erase(key);
     }
     messages.pop_front();
+    ++dequeueTracker;
 }
 
 void Queue::push(boost::intrusive_ptr<Message>& msg){
diff --git a/cpp/src/qpid/broker/Queue.h b/cpp/src/qpid/broker/Queue.h
index fc628bbbc0..d9af63d3d9 100644
--- a/cpp/src/qpid/broker/Queue.h
+++ b/cpp/src/qpid/broker/Queue.h
@@ -27,6 +27,7 @@
 #include "PersistableQueue.h"
 #include "QueuePolicy.h"
 #include "QueueBindings.h"
+#include "RateTracker.h"
 
 #include "qpid/framing/FieldTable.h"
 #include "qpid/sys/Monitor.h"
@@ -94,6 +95,7 @@ namespace qpid {
             boost::shared_ptr<Exchange> alternateExchange;
             framing::SequenceNumber sequence;
             qmf::org::apache::qpid::broker::Queue* mgmtObject;
+            RateTracker dequeueTracker;
 
             void push(boost::intrusive_ptr<Message>& msg);
             void setPolicy(std::auto_ptr<QueuePolicy> policy);
diff --git a/cpp/src/qpid/broker/RateTracker.cpp b/cpp/src/qpid/broker/RateTracker.cpp
new file mode 100644
index 0000000000..5377bcfc0b
--- /dev/null
+++ b/cpp/src/qpid/broker/RateTracker.cpp
@@ -0,0 +1,48 @@
+/*
+ *
+ * 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 "RateTracker.h"
+
+using qpid::sys::AbsTime;
+using qpid::sys::Duration;
+using qpid::sys::TIME_SEC;
+
+namespace qpid {
+namespace broker {
+
+RateTracker::RateTracker() : currentCount(0), lastCount(0), lastTime(AbsTime::now()) {}
+
+RateTracker& RateTracker::operator++()
+{
+    ++currentCount;
+    return *this;
+}
+
+double RateTracker::sampleRatePerSecond()
+{
+    int32_t increment = currentCount - lastCount;    
+    AbsTime now = AbsTime::now();
+    Duration interval(lastTime, now);
+    lastCount = currentCount;
+    lastTime = now;
+    return increment ? increment / (interval / TIME_SEC) : 0;
+}
+
+}} // namespace qpid::broker
diff --git a/cpp/src/qpid/broker/RateTracker.h b/cpp/src/qpid/broker/RateTracker.h
new file mode 100644
index 0000000000..0c20b37312
--- /dev/null
+++ b/cpp/src/qpid/broker/RateTracker.h
@@ -0,0 +1,57 @@
+#ifndef QPID_BROKER_RATETRACKER_H
+#define QPID_BROKER_RATETRACKER_H
+
+/*
+ *
+ * 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/sys/Time.h"
+
+namespace qpid {
+namespace broker {
+
+/**
+ * Simple rate tracker: represents some value that can be incremented,
+ * then can periodcially sample the rate of increments.
+ */
+class RateTracker
+{
+  public:
+    RateTracker();
+    /**
+     * Increments the count being tracked. Can be called concurrently
+     * with other calls to this operator as well as with calls to
+     * sampleRatePerSecond().
+     */
+    RateTracker& operator++();
+    /**
+     * Returns the rate of increments per second since last
+     * called. Calls to this method should be serialised, but can be
+     * called concurrently with the increment operator
+     */
+    double sampleRatePerSecond();
+  private:
+    volatile int32_t currentCount;
+    int32_t lastCount;
+    qpid::sys::AbsTime lastTime;
+};
+}} // namespace qpid::broker
+
+#endif  /*!QPID_BROKER_RATETRACKER_H*/