1 files changed, 152 insertions, 0 deletions
diff --git a/RC9/qpid/cpp/src/qpid/sys/PollableQueue.h b/RC9/qpid/cpp/src/qpid/sys/PollableQueue.h
new file mode 100644
index 0000000000..7f11cc35a9
--- /dev/null
+++ b/RC9/qpid/cpp/src/qpid/sys/PollableQueue.h
@@ -0,0 +1,152 @@
+#ifndef QPID_SYS_POLLABLEQUEUE_H
+#define QPID_SYS_POLLABLEQUEUE_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/PollableCondition.h"
+#include "qpid/sys/Dispatcher.h"
+#include "qpid/sys/DispatchHandle.h"
+#include "qpid/sys/Monitor.h"
+#include <boost/function.hpp>
+#include <boost/bind.hpp>
+#include <algorithm>
+#include <deque>
+
+namespace qpid {
+namespace sys {
+
+class Poller;
+
+/**
+ * A queue that can be polled by sys::Poller.  Any thread can push to
+ * the queue, on wakeup the poller thread processes all items on the
+ * queue by passing them to a callback in a batch.
+ */
+template <class T>
+class PollableQueue {
+  public:
+    typedef std::deque<T> Queue;
+
+    /**
+     * Callback to process a batch of items from the queue.
+     * @param values to process, any items remaining after call are put back on the queue.
+     */
+    typedef boost::function<void (Queue& values)> Callback;
+
+    /** When the queue is selected by the poller, values are passed to callback cb. */
+    PollableQueue(const Callback& cb, const boost::shared_ptr<sys::Poller>& poller);
+
+    ~PollableQueue();
+    
+    /** Push a value onto the queue. Thread safe */
+    void push(const T& t);
+
+    /** Start polling. */ 
+    void start();
+
+    /** Stop polling and wait for the current callback, if any, to complete. */
+    void stop();
+
+    /** Are we currently stopped?*/
+    bool isStopped() const { ScopedLock l(lock); return stopped; }
+
+    size_t size() { ScopedLock l(lock); return queue.size(); }
+    bool empty() { ScopedLock l(lock); return queue.empty(); }
+    
+  private:
+    typedef sys::Monitor::ScopedLock ScopedLock;
+    typedef sys::Monitor::ScopedUnlock ScopedUnlock;
+
+    void dispatch(sys::DispatchHandle&);
+    
+    mutable sys::Monitor lock;
+    Callback callback;
+    boost::shared_ptr<sys::Poller> poller;
+    PollableCondition condition;
+    DispatchHandle handle;
+    Queue queue, batch;
+    Thread dispatcher;
+    bool stopped;
+};
+
+template <class T> PollableQueue<T>::PollableQueue(
+    const Callback& cb, const boost::shared_ptr<sys::Poller>& p) 
+    : callback(cb), poller(p),
+      handle(condition, boost::bind(&PollableQueue<T>::dispatch, this, _1), 0, 0), stopped(true)
+{
+    handle.startWatch(poller);
+    handle.unwatch();
+}
+
+template <class T> void PollableQueue<T>::start() {
+    ScopedLock l(lock);
+    if (!stopped) return;
+    stopped = false;
+    if (!queue.empty()) condition.set();
+    handle.rewatch();
+}
+
+template <class T> PollableQueue<T>::~PollableQueue() {
+    handle.stopWatch();
+}
+
+template <class T> void PollableQueue<T>::push(const T& t) {
+    ScopedLock l(lock);
+    if (queue.empty()) condition.set();
+    queue.push_back(t);
+}
+
+template <class T> void PollableQueue<T>::dispatch(sys::DispatchHandle& h) {
+    ScopedLock l(lock);
+    assert(dispatcher.id() == 0);
+    dispatcher = Thread::current();
+    while (!stopped && !queue.empty()) {
+        assert(batch.empty());
+        batch.swap(queue);
+        {
+            ScopedUnlock u(lock);   // Allow concurrent push to queue.
+            callback(batch);
+        }
+        if (!batch.empty()) {
+            queue.insert(queue.begin(), batch.begin(), batch.end()); // put back unprocessed items.
+            batch.clear();
+        }
+    }
+    dispatcher = Thread();
+    if (queue.empty()) condition.clear();
+    if (stopped) lock.notifyAll();
+    else h.rewatch();
+}
+
+template <class T> void PollableQueue<T>::stop() {
+    ScopedLock l(lock);
+    if (stopped) return;
+    handle.unwatch();
+    stopped = true;
+    // Avoid deadlock if stop is called from the dispatch thread
+    while (dispatcher.id() && dispatcher.id() != Thread::current().id())
+        lock.wait();
+}
+
+}} // namespace qpid::sys
+
+#endif  /*!QPID_SYS_POLLABLEQUEUE_H*/