1 files changed, 45 insertions, 45 deletions

diff --git a/cpp/src/qpid/sys/ConcurrentQueue.h b/cpp/src/qpid/sys/ConcurrentQueue.h
index 917afc5704..cf8199954e 100644
--- a/cpp/src/qpid/sys/ConcurrentQueue.h
+++ b/cpp/src/qpid/sys/ConcurrentQueue.h
@@ -22,7 +22,7 @@
  *
  */
 
-#include "qpid/sys/Monitor.h"
+#include "qpid/sys/Waitable.h"
 #include "qpid/sys/ScopedIncrement.h"
 
 #include <boost/bind.hpp>
@@ -39,73 +39,73 @@ namespace sys {
  *
  * Also allows consuming threads to wait until an item is available.
  */
-template <class T> class ConcurrentQueue {
+template <class T> class ConcurrentQueue : public Waitable {
   public:
-    ConcurrentQueue() : waiters(0), shutdown(false) {}
+    struct ShutdownException {};
+    
+    ConcurrentQueue() : shutdownFlag(false) {}
 
-    /** Threads in wait() are woken with ShutdownException before
-     * destroying the queue.
-     */
-    ~ConcurrentQueue() {
-        Mutex::ScopedLock l(lock);
-        shutdown = true;
-        lock.notifyAll();
-        while (waiters > 0)
-            lock.wait();
+    /** Waiting threads are notified by ~Waitable */
+    ~ConcurrentQueue() { shutdown(); }
+
+    bool shutdown(bool wait=true) {
+        ScopedLock l(lock);
+        if (!shutdownFlag) {
+            shutdownFlag=true;
+            lock.notifyAll();
+            if (wait) lock.waitAll();
+            shutdownFlag=true;
+            return true;
+        }
+        return false;
     }
-    
+
     /** Push a data item onto the back of the queue */
     void push(const T& data) {
         Mutex::ScopedLock l(lock);
         queue.push_back(data);
+        lock.notify();
     }
 
     /** If the queue is non-empty, pop the front item into data and
      * return true. If the queue is empty, return false
      */
-    bool pop(T& data) {
+    bool tryPop(T& data) {
         Mutex::ScopedLock l(lock);
-        return popInternal(data);
+        if (shutdownFlag || queue.empty())
+            return false;
+        data = queue.front();
+        queue.pop_front();
+        return true;
     }
 
-    /** Wait up to deadline for a data item to be available.
-     *@return true if data was available, false if timed out.
+    /** Wait up to a timeout for a data item to be available.
+     *@return true if data was available, false if timed out or shut down.
      *@throws ShutdownException if the queue is destroyed.
      */
-    bool waitPop(T& data, Duration timeout) {
-        Mutex::ScopedLock l(lock);
-        ScopedIncrement<size_t> w(
-            waiters, boost::bind(&ConcurrentQueue::noWaiters, this));
+    bool waitPop(T& data, Duration timeout=TIME_INFINITE) {
+        ScopedLock l(lock);
         AbsTime deadline(now(), timeout);
-        while (queue.empty() && lock.wait(deadline))
-            ;
-        return popInternal(data);
-    }
-
-  private:
-    
-    bool popInternal(T& data) {
-        if (shutdown) 
-            throw ShutdownException();
+        {
+            ScopedWait(*this);
+            while (!shutdownFlag && queue.empty())
+                if (!lock.wait(deadline))
+                    return false;
+        }
         if (queue.empty())
             return false;
-        else {
-            data = queue.front();
-            queue.pop_front();
-            return true;
-        }
+        data = queue.front();
+        queue.pop_front();
+        return true;
     }
+
+    bool isShutdown() { ScopedLock l(lock); return shutdownFlag; }
     
-    void noWaiters() {
-        assert(waiters == 0);
-        if (shutdown)
-            lock.notify();  // Notify dtor thread.
-    }
-        
-    Monitor lock;
+  protected:
+    Waitable lock;
+  private:
     std::deque<T> queue;
-    size_t waiters;
-    bool shutdown;
+    bool shutdownFlag;
 };
 
 }} // namespace qpid::sys