lib/reconnect.h

   1 /*
   2  * Copyright (c) 2009 Nicira Networks.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef RECONNECT_H
  18 #define RECONNECT_H 1
  19
  20 /* This library implements a finite-state machine for connecting and
  21  * reconnecting to a network resource with exponential backoff.  It also
  22  * provides optional support for detecting a connection on which the peer is no
  23  * longer responding.
  24  *
  25  * The library does not implement anything networking related, only an FSM for
  26  * networking code to use.
  27  *
  28  * Many "reconnect" functions take a "now" argument.  This makes testing easier
  29  * since there is no hidden state.  When not testing, just pass the return
  30  * value of time_msec() from timeval.h.  (Perhaps this design should be
  31  * revisited later.) */
  32
  33 #include <stdbool.h>
  34
  35 struct reconnect *reconnect_create(long long int now);
  36 void reconnect_destroy(struct reconnect *);
  37
  38 const char *reconnect_get_name(const struct reconnect *);
  39 void reconnect_set_name(struct reconnect *, const char *name);
  40
  41 int reconnect_get_min_backoff(const struct reconnect *);
  42 int reconnect_get_max_backoff(const struct reconnect *);
  43 int reconnect_get_probe_interval(const struct reconnect *);
  44
  45 void reconnect_set_max_tries(struct reconnect *, unsigned int max_tries);
  46 unsigned int reconnect_get_max_tries(struct reconnect *);
  47
  48 void reconnect_set_backoff(struct reconnect *,
  49                            int min_backoff, int max_backoff);
  50 void reconnect_set_probe_interval(struct reconnect *, int probe_interval);
  51
  52 bool reconnect_is_enabled(const struct reconnect *);
  53 void reconnect_enable(struct reconnect *, long long int now);
  54 void reconnect_disable(struct reconnect *, long long int now);
  55
  56 void reconnect_force_reconnect(struct reconnect *, long long int now);
  57
  58 bool reconnect_is_connected(const struct reconnect *);
  59 unsigned int reconnect_get_connection_duration(const struct reconnect *,
  60                                                long long int now);
  61
  62 void reconnect_disconnected(struct reconnect *, long long int now, int error);
  63 void reconnect_connecting(struct reconnect *, long long int now);
  64 void reconnect_connected(struct reconnect *, long long int now);
  65 void reconnect_connect_failed(struct reconnect *, long long int now,
  66                               int error);
  67 void reconnect_received(struct reconnect *, long long int now);
  68
  69 enum reconnect_action {
  70     RECONNECT_CONNECT = 1,
  71     RECONNECT_DISCONNECT,
  72     RECONNECT_PROBE,
  73 };
  74 enum reconnect_action reconnect_run(struct reconnect *, long long int now);
  75 void reconnect_wait(struct reconnect *, long long int now);
  76 int reconnect_timeout(struct reconnect *, long long int now);
  77
  78 struct reconnect_stats {
  79     /* All times and durations in this structure are in milliseconds. */
  80     long long int creation_time;  /* Time reconnect_create() called. */
  81     long long int last_received; /* Last call to reconnect_received(). */
  82     long long int last_connected; /* Last call to reconnect_connected(). */
  83     int backoff;                  /* Current backoff duration.  */
  84
  85     unsigned int seqno;         /* # of connections + # of disconnections. */
  86
  87     bool is_connected;          /* Currently connected? */
  88     unsigned int current_connection_duration; /* Time of current connection. */
  89     unsigned int total_connected_duration;    /* Sum of all connections. */
  90     unsigned int n_attempted_connections;
  91     unsigned int n_successful_connections;
  92
  93     /* These should only be provided to a human user for debugging purposes.
  94      * The client should not attempt to interpret them. */
  95     const char *state;            /* FSM state. */
  96     unsigned int state_elapsed;   /* Time since FSM state entered. */
  97 };
  98
  99 void reconnect_get_stats(const struct reconnect *, long long int now,
 100                          struct reconnect_stats *);
 101
 102 #endif /* reconnect.h */