text: /*
   * Copyright (c) 2008, 2009, 2010, 2012, 2013 Nicira, Inc.
   *
   * Licensed 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 <config.h>
  #include "reconnect.h"
  
  #include <stdlib.h>
  
  #include "openvswitch/poll-loop.h"
  #include "util.h"
  #include "openvswitch/vlog.h"
  
  VLOG_DEFINE_THIS_MODULE(reconnect);
  
  #define STATES                                  \
      STATE(VOID, 1 << 0)                         \
      STATE(BACKOFF, 1 << 1)                      \
      STATE(CONNECTING, 1 << 3)          \
      STATE(ACTIVE, 1 << 4)                       \
      STATE(IDLE, 1 << 5)                         \
      STATE(RECONNECT, 1 << 6)                    \
      STATE(LISTENING, 1 << 7)
  enum state {
  #define STATE(NAME, VALUE) S_##NAME = VALUE,
      STATES
  #undef STATE
  };
  
  static bool
  is_connected_state(enum state state)
  {
      return (state & (S_ACTIVE | S_IDLE)) != 0;
  }
  
  struct reconnect {
      /* Configuration. */
      char *name;
      int min_backoff;
      int max_backoff;
      int probe_interval;
      bool passive;
      enum vlog_level info;       /* Used for informational messages. */
  
      /* State. */
      enum state state;
      long long int state_entered;
      int backoff;
      long long int last_activity;
      long long int last_connected;
      long long int last_disconnected;
      unsigned int max_tries;
      unsigned int backoff_free_tries;
  
      /* These values are simply for statistics reporting, not otherwise used
       * directly by anything internal. */
      long long int creation_time;
      unsigned int n_attempted_connections, n_successful_connections;
      unsigned int total_connected_duration;
      unsigned int seqno;
  };
  
  static void reconnect_transition__(struct reconnect *, long long int now,
                                     enum state state);
  static long long int reconnect_deadline__(const struct reconnect *);
  static bool reconnect_may_retry(struct reconnect *);
  
  static const char *
  reconnect_state_name__(enum state state)
  {
      switch (state) {
  #define STATE(NAME, VALUE) case S_##NAME: return #NAME;
          STATES
  #undef STATE
      }
      return "***ERROR***";
  }
  
  /* Creates and returns a new reconnect FSM with default settings.  The FSM is
   * initially disabled.  The caller will likely want to call reconnect_enable()
   * and reconnect_set_name() on the returned object. */
  struct reconnect *
  reconnect_create(long long int now)
  {
      struct reconnect *fsm = xzalloc(sizeof *fsm);
  
      fsm->name = xstrdup("void");
      fsm->min_backoff = RECONNECT_DEFAULT_MIN_BACKOFF;
      fsm->max_backoff = RECONNECT_DEFAULT_MAX_BACKOFF;
      fsm->probe_interval = RECONNECT_DEFAULT_PROBE_INTERVAL;
      fsm->passive = false;
      fsm->info = VLL_INFO;
  
      fsm->state = S_VOID;
      fsm->state_entered = now;
      fsm->backoff = 0;
      fsm->last_activity = now;
      fsm->last_connected = LLONG_MAX;
      fsm->last_disconnected = LLONG_MAX;
      fsm->max_tries = UINT_MAX;
      fsm->creation_time = now;
  
      return fsm;
  }
  
  /* Frees 'fsm'. */
  void
  reconnect_destroy(struct reconnect *fsm)
  {
      if (fsm) {
          free(fsm->name);
          free(fsm);
      }
  }
  
  /* If 'quiet' is true, 'fsm' will log informational messages at level VLL_DBG,
   * by default keeping them out of log files.  This is appropriate if the
   * connection is one that is expected to be short-lived, so that the log
   * messages are merely distracting.
   *
   * If 'quiet' is false, 'fsm' logs informational messages at level VLL_INFO.
   * This is the default.
   *
   * This setting has no effect on the log level of debugging, warning, or error
   * messages. */
  void
  reconnect_set_quiet(struct reconnect *fsm, bool quiet)
  {
      fsm->info = quiet ? VLL_DBG : VLL_INFO;
  }
  
  /* Returns 'fsm''s name. */
  const char *
  reconnect_get_name(const struct reconnect *fsm)
  {
      return fsm->name;
  }
  
  /* Sets 'fsm''s name to 'name'.  If 'name' is null, then "void" is used
   * instead.
   *
   * The name set for 'fsm' is used in log messages. */
  void
  reconnect_set_name(struct reconnect *fsm, const char *name)
  {
      free(fsm->name);
      fsm->name = xstrdup(name ? name : "void");
  }
  
  /* Return the minimum number of milliseconds to back off between consecutive
   * connection attempts.  The default is RECONNECT_DEFAULT_MIN_BACKOFF. */
  int
  reconnect_get_min_backoff(const struct reconnect *fsm)
  {
      return fsm->min_backoff;
  }
  
  /* Return the maximum number of milliseconds to back off between consecutive
   * connection attempts.  The default is RECONNECT_DEFAULT_MAX_BACKOFF. */
  int
  reconnect_get_max_backoff(const struct reconnect *fsm)
  {
      return fsm->max_backoff;
  }
  
  /* Returns the "probe interval" for 'fsm' in milliseconds.  If this is zero, it
   * disables the connection keepalive feature.  If it is nonzero, then if the
   * interval passes while 'fsm' is connected and without reconnect_activity()
   * being called for 'fsm', reconnect_run() returns RECONNECT_PROBE.  If the
   * interval passes again without reconnect_activity() being called,
   * reconnect_run() returns RECONNECT_DISCONNECT for 'fsm'. */
  int
  reconnect_get_probe_interval(const struct reconnect *fsm)
  {
      return fsm->probe_interval;
  }
  
  /* Limits the maximum number of times that 'fsm' will ask the client to try to
   * reconnect to 'max_tries'.  UINT_MAX (the default) means an unlimited number
   * of tries.
   *
   * After the number of tries has expired, the 'fsm' will disable itself
   * instead of backing off and retrying. */
  void
  reconnect_set_max_tries(struct reconnect *fsm, unsigned int max_tries)
  {
      fsm->max_tries = max_tries;
  }
  
  /* Returns the current remaining number of connection attempts, UINT_MAX if
   * the number is unlimited.  */
  unsigned int
  reconnect_get_max_tries(struct reconnect *fsm)
  {
      return fsm->max_tries;
  }
  
  /* Sets the number of connection attempts that will be made without backoff to
   * 'backoff_free_tries'.  Values 0 and 1 both represent a single attempt. */
  void
  reconnect_set_backoff_free_tries(struct reconnect *fsm,
                                   unsigned int backoff_free_tries)
  {
      fsm->backoff_free_tries = backoff_free_tries;
  }
  
  /* Configures the backoff parameters for 'fsm'.  'min_backoff' is the minimum
   * number of milliseconds, and 'max_backoff' is the maximum, between connection
   * attempts.  The current backoff is also the duration that 'fsm' is willing to
   * wait for a given connection to succeed or fail.
   *
   * 'min_backoff' must be at least 1000, and 'max_backoff' must be greater than
   * or equal to 'min_backoff'.
   *
   * Pass 0 for 'min_backoff' or 'max_backoff' or both to use the defaults. */
  void
  reconnect_set_backoff(struct reconnect *fsm, int min_backoff, int max_backoff)
  {
      fsm->min_backoff = MAX(min_backoff, 1000);
      fsm->max_backoff = (max_backoff
                          ? MAX(max_backoff, 1000)
                          : RECONNECT_DEFAULT_MAX_BACKOFF);
      if (fsm->min_backoff > fsm->max_backoff) {
          fsm->max_backoff = fsm->min_backoff;
      }
  
      if (fsm->state == S_BACKOFF && fsm->backoff > max_backoff) {
          fsm->backoff = max_backoff;
      }
  }
  
  /* Sets the "probe interval" for 'fsm' to 'probe_interval', in milliseconds.
   * If this is zero, it disables the connection keepalive feature.  If it is
   * nonzero, then if the interval passes while 'fsm' is connected and without
   * reconnect_activity() being called for 'fsm', reconnect_run() returns
   * RECONNECT_PROBE.  If the interval passes again without reconnect_activity()
   * being called, reconnect_run() returns RECONNECT_DISCONNECT for 'fsm'.
   *
   * If 'probe_interval' is nonzero, then it will be forced to a value of at
   * least 1000 ms. */
  void
  reconnect_set_probe_interval(struct reconnect *fsm, int probe_interval)
  {
      fsm->probe_interval = probe_interval ? MAX(1000, probe_interval) : 0;
  }
  
  /* Returns true if 'fsm' is in passive mode, false if 'fsm' is in active mode
   * (the default). */
  bool
  reconnect_is_passive(const struct reconnect *fsm)
  {
      return fsm->passive;
  }
  
  /* Configures 'fsm' for active or passive mode.  In active mode (the default),
   * the FSM is attempting to connect to a remote host.  In passive mode, the FSM
   * is listening for connections from a remote host. */
  void
  reconnect_set_passive(struct reconnect *fsm, bool passive, long long int now)
  {
      if (fsm->passive != passive) {
          fsm->passive = passive;
  
          if (passive
              ? fsm->state & (S_CONNECTING | S_RECONNECT)
              : fsm->state == S_LISTENING && reconnect_may_retry(fsm)) {
              reconnect_transition__(fsm, now, S_BACKOFF);
              fsm->backoff = 0;
          }
      }
  }
  
  /* Returns true if 'fsm' has been enabled with reconnect_enable().  Calling
   * another function that indicates a change in connection state, such as
   * reconnect_disconnected() or reconnect_force_reconnect(), will also enable
   * a reconnect FSM. */
  bool
  reconnect_is_enabled(const struct reconnect *fsm)
  {
      return fsm->state != S_VOID;
  }
  
  /* If 'fsm' is disabled (the default for newly created FSMs), enables it, so
   * that the next call to reconnect_run() for 'fsm' will return
   * RECONNECT_CONNECT.
   *
   * If 'fsm' is not disabled, this function has no effect. */
  void
  reconnect_enable(struct reconnect *fsm, long long int now)
  {
      if (fsm->state == S_VOID && reconnect_may_retry(fsm)) {
          reconnect_transition__(fsm, now, S_BACKOFF);
          fsm->backoff = 0;
      }
  }
  
  /* Disables 'fsm'.  Until 'fsm' is enabled again, reconnect_run() will always
   * return 0. */
  void
  reconnect_disable(struct reconnect *fsm, long long int now)
  {
      if (fsm->state != S_VOID) {
          reconnect_transition__(fsm, now, S_VOID);
      }
  }
  
  /* If 'fsm' is enabled and currently connected (or attempting to connect),
   * forces reconnect_run() for 'fsm' to return RECONNECT_DISCONNECT the next
   * time it is called, which should cause the client to drop the connection (or
   * attempt), back off, and then reconnect. */
  void
  reconnect_force_reconnect(struct reconnect *fsm, long long int now)
  {
      if (fsm->state & (S_CONNECTING | S_ACTIVE | S_IDLE)) {
          reconnect_transition__(fsm, now, S_RECONNECT);
      }
  }
  
  /* Tell 'fsm' that the connection dropped or that a connection attempt failed.
   * 'error' specifies the reason: a positive value represents an errno value,
   * EOF indicates that the connection was closed by the peer (e.g. read()
   * returned 0), and 0 indicates no specific error.
   *
   * The FSM will back off, then reconnect. */
  void
  reconnect_disconnected(struct reconnect *fsm, long long int now, int error)
  {
      if (!(fsm->state & (S_BACKOFF | S_VOID))) {
          /* Report what happened. */
          if (fsm->state & (S_ACTIVE | S_IDLE)) {
              if (error > 0) {
                  VLOG_WARN("%s: connection dropped (%s)",
                            fsm->name, ovs_strerror(error));
              } else if (error == EOF) {
                  VLOG(fsm->info, "%s: connection closed by peer", fsm->name);
              } else {
                  VLOG(fsm->info, "%s: connection dropped", fsm->name);
              }
          } else if (fsm->state == S_LISTENING) {
              if (error > 0) {
                  VLOG_WARN("%s: error listening for connections (%s)",
                            fsm->name, ovs_strerror(error));
              } else {
                  VLOG(fsm->info, "%s: error listening for connections",
                       fsm->name);
              }
          } else if (fsm->backoff < fsm->max_backoff) {
              const char *type = fsm->passive ? "listen" : "connection";
              if (error > 0) {
                  VLOG_INFO("%s: %s attempt failed (%s)",
                            fsm->name, type, ovs_strerror(error));
              } else {
                  VLOG(fsm->info, "%s: %s attempt timed out", fsm->name, type);
              }
          } else {
              /* We have reached the maximum backoff, so suppress logging to
               * avoid wastefully filling the log.  (Previously we logged that we
               * were suppressing further logging, see below.) */
          }
  
          if (fsm->state & (S_ACTIVE | S_IDLE)) {
              fsm->last_disconnected = now;
          }
  
          if (!reconnect_may_retry(fsm)) {
              reconnect_transition__(fsm, now, S_VOID);
              return;
          }
  
          /* Back off. */
          if (fsm->backoff_free_tries > 1) {
              fsm->backoff_free_tries--;
              fsm->backoff = 0;
          } else if (fsm->state & (S_ACTIVE | S_IDLE)
                     && (fsm->last_activity - fsm->last_connected >= fsm->backoff
                         || fsm->passive)) {
              fsm->backoff = fsm->passive ? 0 : fsm->min_backoff;
          } else {
              if (fsm->backoff < fsm->min_backoff) {
                  fsm->backoff = fsm->min_backoff;
              } else if (fsm->backoff < fsm->max_backoff / 2) {
                  fsm->backoff *= 2;
                  VLOG(fsm->info, "%s: waiting %.3g seconds before %s",
                       fsm->name, fsm->backoff / 1000.0,
                       fsm->passive ? "trying to listen again" : "reconnect");
              } else {
                  if (fsm->backoff < fsm->max_backoff) {
                      VLOG_INFO("%s: continuing to %s in the background but "
                                "suppressing further logging", fsm->name,
                                fsm->passive ? "try to listen" : "reconnect");
                  }
                  fsm->backoff = fsm->max_backoff;
              }
          }
          reconnect_transition__(fsm, now, S_BACKOFF);
      }
  }
  
  /* Tell 'fsm' that a connection or listening attempt is in progress.
   *
   * The FSM will start a timer, after which the connection or listening attempt
   * will be aborted (by returning RECONNECT_DISCONNECT from
   * reconnect_run()).  */
  void
  reconnect_connecting(struct reconnect *fsm, long long int now)
  {
      if (fsm->state != S_CONNECTING) {
          if (fsm->passive) {
              VLOG(fsm->info, "%s: listening...", fsm->name);
          } else if (fsm->backoff < fsm->max_backoff) {
              VLOG(fsm->info, "%s: connecting...", fsm->name);
          }
          reconnect_transition__(fsm, now, S_CONNECTING);
      }
  }
  
  /* Tell 'fsm' that the client is listening for connection attempts.  This state
   * last indefinitely until the client reports some change.
   *
   * The natural progression from this state is for the client to report that a
   * connection has been accepted or is in progress of being accepted, by calling
   * reconnect_connecting() or reconnect_connected().
   *
   * The client may also report that listening failed (e.g. accept() returned an
   * unexpected error such as ENOMEM) by calling reconnect_listen_error(), in
   * which case the FSM will back off and eventually return RECONNECT_CONNECT
   * from reconnect_run() to tell the client to try listening again. */
  void
  reconnect_listening(struct reconnect *fsm, long long int now)
  {
      if (fsm->state != S_LISTENING) {
          VLOG(fsm->info, "%s: listening...", fsm->name);
          reconnect_transition__(fsm, now, S_LISTENING);
      }
  }
  
  /* Tell 'fsm' that the client's attempt to accept a connection failed
   * (e.g. accept() returned an unexpected error such as ENOMEM).
   *
   * If the FSM is currently listening (reconnect_listening() was called), it
   * will back off and eventually return RECONNECT_CONNECT from reconnect_run()
   * to tell the client to try listening again.  If there is an active
   * connection, this will be delayed until that connection drops. */
  void
  reconnect_listen_error(struct reconnect *fsm, long long int now, int error)
  {
      if (fsm->state == S_LISTENING) {
          reconnect_disconnected(fsm, now, error);
      }
  }
  
  /* Tell 'fsm' that the connection was successful.
   *
   * The FSM will start the probe interval timer, which is reset by
   * reconnect_activity().  If the timer expires, a probe will be sent (by
   * returning RECONNECT_PROBE from reconnect_run()).  If the timer expires
   * again without being reset, the connection will be aborted (by returning
   * RECONNECT_DISCONNECT from reconnect_run()). */
  void
  reconnect_connected(struct reconnect *fsm, long long int now)
  {
      if (!is_connected_state(fsm->state)) {
          reconnect_connecting(fsm, now);
  
          VLOG(fsm->info, "%s: connected", fsm->name);
          reconnect_transition__(fsm, now, S_ACTIVE);
          fsm->last_connected = now;
      }
  }
  
  /* Tell 'fsm' that the connection attempt failed.
   *
   * The FSM will back off and attempt to reconnect. */
  void
  reconnect_connect_failed(struct reconnect *fsm, long long int now, int error)
  {
      reconnect_connecting(fsm, now);
      reconnect_disconnected(fsm, now, error);
  }
  
  /* Tell 'fsm' that some activity has occurred on the connection.  This resets
   * the probe interval timer, so that the connection is known not to be idle. */
  void
  reconnect_activity(struct reconnect *fsm, long long int now)
  {
      if (fsm->state != S_ACTIVE) {
          reconnect_transition__(fsm, now, S_ACTIVE);
      }
      fsm->last_activity = now;
  }
  
  static void
  reconnect_transition__(struct reconnect *fsm, long long int now,
                         enum state state)
  {
      if (fsm->state == S_CONNECTING) {
          fsm->n_attempted_connections++;
          if (state == S_ACTIVE) {
              fsm->n_successful_connections++;
          }
      }
      if (is_connected_state(fsm->state) != is_connected_state(state)) {
          if (is_connected_state(fsm->state)) {
              fsm->total_connected_duration += now - fsm->last_connected;
          }
          fsm->seqno++;
      }
  
      VLOG_DBG("%s: entering %s", fsm->name, reconnect_state_name__(state));
      fsm->state = state;
      fsm->state_entered = now;
  }
  
  static long long int
  reconnect_deadline__(const struct reconnect *fsm)
  {
      ovs_assert(fsm->state_entered != LLONG_MIN);
      switch (fsm->state) {
      case S_VOID:
      case S_LISTENING:
          return LLONG_MAX;
  
      case S_BACKOFF:
          return fsm->state_entered + fsm->backoff;
  
      case S_CONNECTING:
          return fsm->state_entered + MAX(1000, fsm->backoff);
  
      case S_ACTIVE:
          if (fsm->probe_interval) {
              long long int base = MAX(fsm->last_activity, fsm->state_entered);
              return base + fsm->probe_interval;
          }
          return LLONG_MAX;
  
      case S_IDLE:
          if (fsm->probe_interval) {
              return fsm->state_entered + fsm->probe_interval;
          }
          return LLONG_MAX;
  
      case S_RECONNECT:
          return fsm->state_entered;
      }
  
      OVS_NOT_REACHED();
  }
  
  /* Assesses whether any action should be taken on 'fsm'.  The return value is
   * one of:
   *
   *     - 0: The client need not take any action.
   *
   *     - Active client, RECONNECT_CONNECT: The client should start a connection
   *       attempt and indicate this by calling reconnect_connecting().  If the
   *       connection attempt has definitely succeeded, it should call
   *       reconnect_connected().  If the connection attempt has definitely
   *       failed, it should call reconnect_connect_failed().
   *
   *       The FSM is smart enough to back off correctly after successful
   *       connections that quickly abort, so it is OK to call
   *       reconnect_connected() after a low-level successful connection
   *       (e.g. connect()) even if the connection might soon abort due to a
   *       failure at a high-level (e.g. SSL negotiation failure).
   *
   *     - Passive client, RECONNECT_CONNECT: The client should try to listen for
   *       a connection, if it is not already listening.  It should call
   *       reconnect_listening() if successful, otherwise reconnect_connecting()
   *       or reconnected_connect_failed() if the attempt is in progress or
   *       definitely failed, respectively.
   *
   *       A listening passive client should constantly attempt to accept a new
   *       connection and report an accepted connection with
   *       reconnect_connected().
   *
   *     - RECONNECT_DISCONNECT: The client should abort the current connection
   *       or connection attempt or listen attempt and call
   *       reconnect_disconnected() or reconnect_connect_failed() to indicate it.
   *
   *     - RECONNECT_PROBE: The client should send some kind of request to the
   *       peer that will elicit a response, to ensure that the connection is
   *       indeed in working order.  (This will only be returned if the "probe
   *       interval" is nonzero--see reconnect_set_probe_interval()).
   */
  enum reconnect_action
  reconnect_run(struct reconnect *fsm, long long int now)
  {
      if (now >= reconnect_deadline__(fsm)) {
          switch (fsm->state) {
          case S_VOID:
              return 0;
  
          case S_BACKOFF:
              return RECONNECT_CONNECT;
  
          case S_CONNECTING:
              return RECONNECT_DISCONNECT;
  
          case S_ACTIVE:
              VLOG_DBG("%s: idle %lld ms, sending inactivity probe", fsm->name,
                       now - MAX(fsm->last_activity, fsm->state_entered));
              reconnect_transition__(fsm, now, S_IDLE);
              return RECONNECT_PROBE;
  
          case S_IDLE:
              VLOG_ERR("%s: no response to inactivity probe after %.3g "
                       "seconds, disconnecting",
                       fsm->name, (now - fsm->state_entered) / 1000.0);
              return RECONNECT_DISCONNECT;
  
          case S_RECONNECT:
              return RECONNECT_DISCONNECT;
  
          case S_LISTENING:
              return 0;
          }
  
          OVS_NOT_REACHED();
      } else {
          return 0;
      }
  }
  
  /* Causes the next call to poll_block() to wake up when reconnect_run() should
   * be called on 'fsm'. */
  void
  reconnect_wait(struct reconnect *fsm, long long int now)
  {
      int timeout = reconnect_timeout(fsm, now);
      if (timeout >= 0) {
          poll_timer_wait(timeout);
      }
  }
  
  /* Returns the number of milliseconds after which reconnect_run() should be
   * called on 'fsm' if nothing else notable happens in the meantime, or a
   * negative number if this is currently unnecessary. */
  int
  reconnect_timeout(struct reconnect *fsm, long long int now)
  {
      long long int deadline = reconnect_deadline__(fsm);
      if (deadline != LLONG_MAX) {
          long long int remaining = deadline - now;
          return MAX(0, MIN(INT_MAX, remaining));
      }
      return -1;
  }
  
  /* Returns true if 'fsm' is currently believed to be connected, that is, if
   * reconnect_connected() was called more recently than any call to
   * reconnect_connect_failed() or reconnect_disconnected() or
   * reconnect_disable(), and false otherwise.  */
  bool
  reconnect_is_connected(const struct reconnect *fsm)
  {
      return is_connected_state(fsm->state);
  }
  
  /* Returns the number of milliseconds since 'fsm' last successfully connected
   * to its peer (even if it has since disconnected). Returns UINT_MAX if never
   * connected. */
  unsigned int
  reconnect_get_last_connect_elapsed(const struct reconnect *fsm,
                                     long long int now)
  {
      return fsm->last_connected == LLONG_MAX ? UINT_MAX
          : now - fsm->last_connected;
  }
  
  /* Returns the number of milliseconds since 'fsm' last disconnected
   * from its peer (even if it has since reconnected). Returns UINT_MAX if never
   * disconnected. */
  unsigned int
  reconnect_get_last_disconnect_elapsed(const struct reconnect *fsm,
                                        long long int now)
  {
      return fsm->last_disconnected == LLONG_MAX ? UINT_MAX
          : now - fsm->last_disconnected;
  }
  
  /* Copies various statistics for 'fsm' into '*stats'. */
  void
  reconnect_get_stats(const struct reconnect *fsm, long long int now,
                      struct reconnect_stats *stats)
  {
      stats->creation_time = fsm->creation_time;
      stats->last_activity = fsm->last_activity;
      stats->last_connected = fsm->last_connected;
      stats->last_disconnected = fsm->last_disconnected;
      stats->backoff = fsm->backoff;
      stats->seqno = fsm->seqno;
      stats->is_connected = reconnect_is_connected(fsm);
      stats->msec_since_connect
          = reconnect_get_last_connect_elapsed(fsm, now);
      stats->msec_since_disconnect
          = reconnect_get_last_disconnect_elapsed(fsm, now);
      stats->total_connected_duration = fsm->total_connected_duration
          + (is_connected_state(fsm->state)
             ? reconnect_get_last_connect_elapsed(fsm, now) : 0);
      stats->n_attempted_connections = fsm->n_attempted_connections;
      stats->n_successful_connections = fsm->n_successful_connections;
      stats->state = reconnect_state_name__(fsm->state);
      stats->state_elapsed = now - fsm->state_entered;
  }
  
  static bool
  reconnect_may_retry(struct reconnect *fsm)
  {
      bool may_retry = fsm->max_tries > 0;
      if (may_retry && fsm->max_tries != UINT_MAX) {
          fsm->max_tries--;
      }
      return may_retry;
  }
  