1 files changed, 97 insertions, 0 deletions
diff --git a/qpid/cpp/src/qpid/broker/LossyQueue.cpp b/qpid/cpp/src/qpid/broker/LossyQueue.cpp
new file mode 100644
index 0000000000..ee13d7733a
--- /dev/null
+++ b/qpid/cpp/src/qpid/broker/LossyQueue.cpp
@@ -0,0 +1,97 @@
+/*
+ *
+ * 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 "LossyQueue.h"
+#include "QueueDepth.h"
+#include "qpid/framing/reply_exceptions.h"
+#include "qpid/log/Statement.h"
+
+namespace qpid {
+namespace broker {
+
+namespace {
+bool isLowerPriorityThan(uint8_t priority, const Message& m)
+{
+    return m.getPriority() <= priority;
+}
+}
+
+LossyQueue::LossyQueue(const std::string& n, const QueueSettings& s, MessageStore* const ms, management::Manageable* p, Broker* b)
+    : Queue(n, s, ms, p, b) {}
+
+bool LossyQueue::checkDepth(const QueueDepth& increment, const Message& message)
+{
+    if (settings.maxDepth.hasSize() && increment.getSize() > settings.maxDepth.getSize()) {
+        if (mgmtObject) {
+            mgmtObject->inc_discardsOverflow();
+            if (brokerMgmtObject)
+                brokerMgmtObject->inc_discardsOverflow();
+        }
+        throw qpid::framing::ResourceLimitExceededException(QPID_MSG("Message larger than configured maximum depth on "
+                                                                     << name << ": size=" << increment.getSize() << ", max-size=" << settings.maxDepth.getSize()));
+    }
+
+    while (settings.maxDepth && (settings.maxDepth - current < increment)) {
+        QPID_LOG(debug, "purging " << name << ": current depth is [" << current << "], max depth is [" << settings.maxDepth << "], new message has size " << increment.getSize());
+        qpid::sys::Mutex::ScopedUnlock u(messageLock);
+        //TODO: arguably we should try and purge expired messages first but that
+        //is potentially expensive
+
+        // Note: in the case of a priority queue we are only comparing the new mesage
+        // with single lowest-priority message, hence the final parameter maxTests
+        // is 1 in this case, so we only test one message for removal.
+        if (remove(1,
+                   settings.priorities ?
+                   boost::bind(&isLowerPriorityThan, message.getPriority(), _1) :
+                   MessagePredicate(), boost::bind(&reroute, alternateExchange, _1),
+                   PURGE, false,
+                   settings.priorities ? 1 : 0))
+        {
+            if (mgmtObject) {
+                mgmtObject->inc_discardsRing(1);
+                if (brokerMgmtObject)
+                    brokerMgmtObject->inc_discardsRing(1);
+            }
+        } else {
+            //should only be the case for a non-empty queue if we are
+            //testing priority and there was no lower (or equal)
+            //priority message available to purge
+            break;
+        }
+    }
+    if (settings.maxDepth && (settings.maxDepth - current < increment)) {
+        //will only be the case where we were unable to purge another
+        //message, which should only be the case if we are purging
+        //based on priority and there was no message with a lower (or
+        //equal) priority than this one, meaning that we drop this
+        //current message
+        if (mgmtObject) {
+            mgmtObject->inc_discardsRing(1);
+            if (brokerMgmtObject)
+                brokerMgmtObject->inc_discardsRing(1);
+        }
+        return false;
+    } else {
+        //have sufficient space for this message
+        current += increment;
+        return true;
+    }
+}
+}} // namespace qpid::broker