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diff --git a/src/mds/Beacon.h b/src/mds/Beacon.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) 2012 Red Hat
+ *
+ * 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 BEACON_STATE_H
+#define BEACON_STATE_H
+
+#include <mutex>
+#include <string_view>
+#include <thread>
+
+#include "include/types.h"
+#include "include/Context.h"
+#include "msg/Dispatcher.h"
+
+#include "messages/MMDSBeacon.h"
+
+class MonClient;
+class MDSRank;
+
+
+/**
+ * One of these per MDS.  Handle beacon logic in this separate class so
+ * that a busy MDS holding its own lock does not hold up sending beacon
+ * messages to the mon and cause false lagginess.
+ *
+ * So that we can continue to operate while the MDS is holding its own lock,
+ * we keep copies of the data needed to generate beacon messages.  The MDS is
+ * responsible for calling Beacon::notify_* when things change.
+ */
+class Beacon : public Dispatcher
+{
+public:
+  using clock = ceph::coarse_mono_clock;
+  using time = ceph::coarse_mono_time;
+
+  Beacon(CephContext *cct, MonClient *monc, std::string_view name);
+  ~Beacon() override;
+
+  void init(const MDSMap &mdsmap);
+  void shutdown();
+
+  bool ms_can_fast_dispatch_any() const override { return true; }
+  bool ms_can_fast_dispatch2(const cref_t<Message>& m) const override;
+  void ms_fast_dispatch2(const ref_t<Message>& m) override;
+  bool ms_dispatch2(const ref_t<Message> &m) override;
+  void ms_handle_connect(Connection *c) override {}
+  bool ms_handle_reset(Connection *c) override {return false;}
+  void ms_handle_remote_reset(Connection *c) override {}
+  bool ms_handle_refused(Connection *c) override {return false;}
+
+  void notify_mdsmap(const MDSMap &mdsmap);
+  void notify_health(const MDSRank *mds);
+
+  void handle_mds_beacon(const cref_t<MMDSBeacon> &m);
+  void send();
+
+  void set_want_state(const MDSMap &mdsmap, MDSMap::DaemonState newstate);
+  MDSMap::DaemonState get_want_state() const;
+
+  /**
+   * Send a beacon, and block until the ack is received from the mon
+   * or `duration` seconds pass, whichever happens sooner.  Useful
+   * for emitting a last message on shutdown.
+   */
+  void send_and_wait(const double duration);
+
+  bool is_laggy();
+  double last_cleared_laggy() const {
+    std::unique_lock lock(mutex);
+    return std::chrono::duration<double>(clock::now()-last_laggy).count();
+  }
+
+private:
+  void _notify_mdsmap(const MDSMap &mdsmap);
+  bool _send();
+
+  mutable std::mutex mutex;
+  std::thread sender;
+  std::condition_variable cvar;
+  time last_send = clock::zero();
+  double beacon_interval = 5.0;
+  bool finished = false;
+  MonClient*    monc;
+
+  // Items we duplicate from the MDS to have access under our own lock
+  std::string name;
+  version_t epoch = 0;
+  CompatSet compat;
+  MDSMap::DaemonState want_state = MDSMap::STATE_BOOT;
+
+  // Internal beacon state
+  version_t last_seq = 0; // last seq sent to monitor
+  std::map<version_t,time>  seq_stamp;    // seq # -> time sent
+  time last_acked_stamp = clock::zero();  // last time we sent a beacon that got acked
+  bool laggy = false;
+  time last_laggy = clock::zero();
+
+  // Health status to be copied into each beacon message
+  MDSHealth health;
+};
+
+#endif // BEACON_STATE_H