1 files changed, 107 insertions, 0 deletions
diff --git a/src/common/Timer.h b/src/common/Timer.h
new file mode 100644
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--- /dev/null
+++ b/src/common/Timer.h
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+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+/*
+ * Ceph - scalable distributed file system
+ *
+ * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
+ *
+ * This is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License version 2.1, as published by the Free Software
+ * Foundation.  See file COPYING.
+ *
+ */
+
+#ifndef CEPH_TIMER_H
+#define CEPH_TIMER_H
+
+#include <map>
+#include "include/common_fwd.h"
+#include "ceph_time.h"
+#include "ceph_mutex.h"
+#include "fair_mutex.h"
+#include <condition_variable>
+
+class Context;
+
+template <class Mutex> class CommonSafeTimerThread;
+
+template <class Mutex>
+class CommonSafeTimer
+{
+  CephContext *cct;
+  Mutex& lock;
+  std::condition_variable_any cond;
+  bool safe_callbacks;
+
+  friend class CommonSafeTimerThread<Mutex>;
+  class CommonSafeTimerThread<Mutex> *thread;
+
+  void timer_thread();
+  void _shutdown();
+
+  using clock_t = ceph::mono_clock;
+  using scheduled_map_t = std::multimap<clock_t::time_point, Context*>;
+  scheduled_map_t schedule;
+  using event_lookup_map_t = std::map<Context*, scheduled_map_t::iterator>;
+  event_lookup_map_t events;
+  bool stopping;
+
+  void dump(const char *caller = 0) const;
+
+public:
+  // This class isn't supposed to be copied
+  CommonSafeTimer(const CommonSafeTimer&) = delete;
+  CommonSafeTimer& operator=(const CommonSafeTimer&) = delete;
+
+  /* Safe callbacks determines whether callbacks are called with the lock
+   * held.
+   *
+   * safe_callbacks = true (default option) guarantees that a cancelled
+   * event's callback will never be called.
+   *
+   * Under some circumstances, holding the lock can cause lock cycles.
+   * If you are able to relax requirements on cancelled callbacks, then
+   * setting safe_callbacks = false eliminates the lock cycle issue.
+   * */
+  CommonSafeTimer(CephContext *cct, Mutex &l, bool safe_callbacks=true);
+  virtual ~CommonSafeTimer();
+
+  /* Call with the event_lock UNLOCKED.
+   *
+   * Cancel all events and stop the timer thread.
+   *
+   * If there are any events that still have to run, they will need to take
+   * the event_lock first. */
+  void init();
+  void shutdown();
+
+  /* Schedule an event in the future
+   * Call with the event_lock LOCKED */
+  Context* add_event_after(ceph::timespan duration, Context *callback);
+  Context* add_event_after(double seconds, Context *callback);
+  Context* add_event_at(clock_t::time_point when, Context *callback);
+  Context* add_event_at(ceph::real_clock::time_point when, Context *callback);
+  /* Cancel an event.
+   * Call with the event_lock LOCKED
+   *
+   * Returns true if the callback was cancelled.
+   * Returns false if you never added the callback in the first place.
+   */
+  bool cancel_event(Context *callback);
+
+  /* Cancel all events.
+   * Call with the event_lock LOCKED
+   *
+   * When this function returns, all events have been cancelled, and there are no
+   * more in progress.
+   */
+  void cancel_all_events();
+
+};
+
+extern template class CommonSafeTimer<ceph::mutex>;
+extern template class CommonSafeTimer<ceph::fair_mutex>;
+using SafeTimer = class CommonSafeTimer<ceph::mutex>;
+
+#endif