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+#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/Mutex.h"
+#include <boost/function.hpp>
+#include <boost/bind.hpp>
+#include <algorithm>
+#include <deque>
+
+namespace qpid {
+
+namespace sys { class Poller; }
+
+namespace sys {
+
+// FIXME aconway 2008-08-11: this could be of more general interest,
+// move to common lib.
+
+/**
+ * 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 {
+ typedef std::deque<T> Queue;
+
+ public:
+ typedef typename Queue::iterator iterator;
+
+ /** Callback to process a range of items. */
+ typedef boost::function<void (const iterator&, const iterator&)> Callback;
+
+ /** Functor tempalate to create a Callback from a functor that handles a single item. */
+ template <class F> struct ForEach {
+ F handleOne;
+ ForEach(const F& f) : handleOne(f) {}
+ void operator()(const iterator& i, const iterator& j) const { std::for_each(i, j, handleOne); }
+ };
+ /** Function to create ForEach instances */
+ template <class F> static ForEach<F> forEach(const F& f) { return ForEach<F>(f); }
+
+ /** When the queue is selected by the poller, values are passed to callback cb. */
+ explicit PollableQueue(const Callback& cb);
+
+ /** Push a value onto the queue. Thread safe */
+ void push(const T& t) { ScopedLock l(lock); queue.push_back(t); condition.set(); }
+
+ /** Start polling. */
+ void start(const boost::shared_ptr<sys::Poller>& poller) { handle.startWatch(poller); }
+
+ /** Stop polling. */
+ void stop() { handle.stopWatch(); }
+
+ private:
+ typedef sys::Mutex::ScopedLock ScopedLock;
+ typedef sys::Mutex::ScopedUnlock ScopedUnlock;
+
+ void dispatch(sys::DispatchHandle&);
+
+ sys::Mutex lock;
+ Callback callback;
+ PollableCondition condition;
+ sys::DispatchHandle handle;
+ Queue queue;
+ Queue batch;
+};
+
+template <class T> PollableQueue<T>::PollableQueue(const Callback& cb) // FIXME aconway 2008-08-12:
+ : callback(cb),
+ handle(condition, boost::bind(&PollableQueue<T>::dispatch, this, _1), 0, 0)
+{}
+
+template <class T> void PollableQueue<T>::dispatch(sys::DispatchHandle& h) {
+ ScopedLock l(lock); // Lock for concurrent push()
+ batch.clear();
+ batch.swap(queue);
+ condition.clear();
+ {
+ // Process outside the lock to allow concurrent push.
+ ScopedUnlock u(lock);
+ callback(batch.begin(), batch.end());
+ h.rewatch();
+ }
+ batch.clear();
+}
+
+}} // namespace qpid::sys
+
+#endif /*!QPID_SYS_POLLABLEQUEUE_H*/