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+// Copyright (c) 2015 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_SCHEDULER_H
+#define BITCOIN_SCHEDULER_H
+
+//
+// NOTE:
+// boost::thread / boost::function / boost::chrono should be ported to
+// std::thread / std::function / std::chrono when we support C++11.
+//
+#include <boost/function.hpp>
+#include <boost/chrono/chrono.hpp>
+#include <boost/thread.hpp>
+#include <map>
+
+//
+// Simple class for background tasks that should be run
+// periodically or once "after a while"
+//
+// Usage:
+//
+// CScheduler* s = new CScheduler();
+// s->scheduleFromNow(doSomething, 11); // Assuming a: void doSomething() { }
+// s->scheduleFromNow(boost::bind(Class::func, this, argument), 3);
+// boost::thread* t = new boost::thread(boost::bind(CScheduler::serviceQueue, s));
+//
+// ... then at program shutdown, clean up the thread running serviceQueue:
+// t->interrupt();
+// t->join();
+// delete t;
+// delete s; // Must be done after thread is interrupted/joined.
+//
+
+class CScheduler
+{
+public:
+ CScheduler();
+ ~CScheduler();
+
+ typedef boost::function<void(void)> Function;
+
+ // Call func at/after time t
+ void schedule(Function f, boost::chrono::system_clock::time_point t);
+
+ // Convenience method: call f once deltaSeconds from now
+ void scheduleFromNow(Function f, int64_t deltaSeconds);
+
+ // Another convenience method: call f approximately
+ // every deltaSeconds forever, starting deltaSeconds from now.
+ // To be more precise: every time f is finished, it
+ // is rescheduled to run deltaSeconds later. If you
+ // need more accurate scheduling, don't use this method.
+ void scheduleEvery(Function f, int64_t deltaSeconds);
+
+ // To keep things as simple as possible, there is no unschedule.
+
+ // Services the queue 'forever'. Should be run in a thread,
+ // and interrupted using boost::interrupt_thread
+ void serviceQueue();
+
+ // Tell any threads running serviceQueue to stop as soon as they're
+ // done servicing whatever task they're currently servicing (drain=false)
+ // or when there is no work left to be done (drain=true)
+ void stop(bool drain=false);
+
+ // Returns number of tasks waiting to be serviced,
+ // and first and last task times
+ size_t getQueueInfo(boost::chrono::system_clock::time_point &first,
+ boost::chrono::system_clock::time_point &last) const;
+
+private:
+ std::multimap<boost::chrono::system_clock::time_point, Function> taskQueue;
+ boost::condition_variable newTaskScheduled;
+ mutable boost::mutex newTaskMutex;
+ int nThreadsServicingQueue;
+ bool stopRequested;
+ bool stopWhenEmpty;
+ bool shouldStop() { return stopRequested || (stopWhenEmpty && taskQueue.empty()); }
+};
+
+#endif