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diff --git a/src/common/HeartbeatMap.h b/src/common/HeartbeatMap.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) 2011 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_HEARTBEATMAP_H
+#define CEPH_HEARTBEATMAP_H
+
+#include <list>
+#include <atomic>
+#include <string>
+#include <pthread.h>
+
+#include "common/ceph_time.h"
+#include "common/ceph_mutex.h"
+#include "include/common_fwd.h"
+
+namespace ceph {
+
+/*
+ * HeartbeatMap -
+ *
+ * Maintain a set of handles for internal subsystems to periodically
+ * check in with a health check and timeout.  Each user can register
+ * and get a handle they can use to set or reset a timeout.  
+ *
+ * A simple is_healthy() method checks for any users who are not within
+ * their grace period for a heartbeat.
+ */
+
+struct heartbeat_handle_d {
+  const std::string name;
+  pthread_t thread_id = 0;
+  using clock = ceph::coarse_mono_clock;
+  using time = ceph::coarse_mono_time;
+  std::atomic<time> timeout = clock::zero();
+  std::atomic<time> suicide_timeout = clock::zero();
+  ceph::timespan grace = ceph::timespan::zero();
+  ceph::timespan suicide_grace = ceph::timespan::zero();
+  std::list<heartbeat_handle_d*>::iterator list_item;
+
+  explicit heartbeat_handle_d(const std::string& n)
+    : name(n)
+  { }
+};
+
+class HeartbeatMap {
+ public:
+  // register/unregister
+  heartbeat_handle_d *add_worker(const std::string& name, pthread_t thread_id);
+  void remove_worker(const heartbeat_handle_d *h);
+
+  // reset the timeout so that it expects another touch within grace amount of time
+  void reset_timeout(heartbeat_handle_d *h,
+		     ceph::timespan grace,
+		     ceph::timespan suicide_grace);
+  // clear the timeout so that it's not checked on
+  void clear_timeout(heartbeat_handle_d *h);
+
+  // return false if any of the timeouts are currently expired.
+  bool is_healthy();
+
+  // touch cct->_conf->heartbeat_file if is_healthy()
+  void check_touch_file();
+
+  // get the number of unhealthy workers
+  int get_unhealthy_workers() const;
+
+  // get the number of total workers
+  int get_total_workers() const;
+
+  explicit HeartbeatMap(CephContext *cct);
+  ~HeartbeatMap();
+
+ private:
+  using clock = ceph::coarse_mono_clock;
+  CephContext *m_cct;
+  ceph::shared_mutex m_rwlock =
+    ceph::make_shared_mutex("HeartbeatMap::m_rwlock");
+  clock::time_point m_inject_unhealthy_until;
+  std::list<heartbeat_handle_d*> m_workers;
+  std::atomic<unsigned> m_unhealthy_workers = { 0 };
+  std::atomic<unsigned> m_total_workers = { 0 };
+
+  bool _check(const heartbeat_handle_d *h, const char *who,
+	      ceph::coarse_mono_time now);
+};
+
+}
+#endif