Bug 867030 - QPID-4374: Reduce contention on Queue::messageLock (Jason Dillaman)

Introduce a separate lock for Queue::UsageBarrier.

git-svn-id: https://svn.apache.org/repos/asf/qpid/trunk@1399812 13f79535-47bb-0310-9956-ffa450edef68

2 files changed, 7 insertions, 6 deletions

diff --git a/qpid/cpp/src/qpid/broker/Queue.cpp b/qpid/cpp/src/qpid/broker/Queue.cpp
index 9dc9ec7a6d..f1288ae59e 100644
--- a/qpid/cpp/src/qpid/broker/Queue.cpp
+++ b/qpid/cpp/src/qpid/broker/Queue.cpp
@@ -1576,7 +1576,7 @@ Queue::UsageBarrier::UsageBarrier(Queue& q) : parent(q), count(0) {}
 
 bool Queue::UsageBarrier::acquire()
 {
-    Monitor::ScopedLock l(parent.messageLock);  /** @todo: use a dedicated lock instead of messageLock */
+    Monitor::ScopedLock l(usageLock);
     if (parent.deleted) {
         return false;
     } else {
@@ -1587,15 +1587,15 @@ bool Queue::UsageBarrier::acquire()
 
 void Queue::UsageBarrier::release()
 {
-    Monitor::ScopedLock l(parent.messageLock);
-    if (--count == 0) parent.messageLock.notifyAll();
+    Monitor::ScopedLock l(usageLock);
+    if (--count == 0) usageLock.notifyAll();
 }
 
 void Queue::UsageBarrier::destroy()
 {
-    Monitor::ScopedLock l(parent.messageLock);
+    Monitor::ScopedLock l(usageLock);
     parent.deleted = true;
-    while (count) parent.messageLock.wait();
+    while (count) usageLock.wait();
 }
 
 }}
diff --git a/qpid/cpp/src/qpid/broker/Queue.h b/qpid/cpp/src/qpid/broker/Queue.h
index 32e9201b5b..3fa8391d46 100644
--- a/qpid/cpp/src/qpid/broker/Queue.h
+++ b/qpid/cpp/src/qpid/broker/Queue.h
@@ -83,6 +83,7 @@ class Queue : public boost::enable_shared_from_this<Queue>,
     {
         Queue& parent;
         uint count;
+        qpid::sys::Monitor usageLock;
 
         UsageBarrier(Queue&);
         bool acquire();
@@ -141,7 +142,7 @@ class Queue : public boost::enable_shared_from_this<Queue>,
      *     o  consumerCount  (TBD: move under separate lock)
      *     o  Queue::UsageBarrier (TBD: move under separate lock)
      */
-    mutable qpid::sys::Monitor messageLock;
+    mutable qpid::sys::Mutex messageLock;
     mutable qpid::sys::Mutex ownershipLock;
     mutable uint64_t persistenceId;
     const QueueSettings settings;