diff --git a/include/crm/cluster/election.h b/include/crm/cluster/election.h index 1dcc66c2f8..3eb90825f2 100644 --- a/include/crm/cluster/election.h +++ b/include/crm/cluster/election.h @@ -1,87 +1,85 @@ /* * Copyright 2009-2019 the Pacemaker project contributors * * The version control history for this file may have further details. * * This source code is licensed under the GNU Lesser General Public License * version 2.1 or later (LGPLv2.1+) WITHOUT ANY WARRANTY. */ #ifndef CRM_COMMON_ELECTION__H # define CRM_COMMON_ELECTION__H #ifdef __cplusplus extern "C" { #endif /** * \file * \brief Functions for conducting elections * * An election is useful for a daemon that runs on all nodes but needs any one * instance to perform a special role. * * Elections are closely tied to the cluster peer cache. Peers in the cache that * are active members are eligible to vote. Elections are named for logging * purposes, but only one election may exist at any time, so typically an * election would be created at daemon start-up and freed at shutdown. * * Pacemaker's election procedure has been heavily adapted from the * Invitation Algorithm variant of the Garcia-Molina Bully Algorithm: * * https://en.wikipedia.org/wiki/Bully_algorithm * * Elections are conducted via cluster messages. There are two types of * messages: a "vote" is a declaration of the voting node's candidacy, and is * always broadcast; a "no-vote" is a concession by the responding node, and is * always a reply to the preferred node's vote. (These correspond to "invite" * and "accept" in the traditional algorithm.) * * A vote together with any no-vote replies to it is considered an election * round. Rounds are numbered with a simple counter unique to each node * (this would be the group number in the traditional algorithm). Concurrent * election rounds are possible. * * An election round is started when any node broadcasts a vote. When a node * receives another node's vote, it compares itself against the sending node * according to certain metrics, and either starts a new round (if it prefers * itself) or replies to the other node with a no-vote (if it prefers that * node). * * If a node receives no-votes from all other active nodes, it declares itself * the winner. The library API does not notify other nodes of this; callers * must implement that if desired. - * - * \ingroup core */ typedef struct election_s election_t; /*! Possible election states */ enum election_result { election_start = 0, /*! new election needed */ election_in_progress, /*! election started but not all peers have voted */ election_lost, /*! local node lost most recent election */ election_won, /*! local node won most recent election */ election_error, /*! election message or election object invalid */ }; void election_fini(election_t *e); void election_reset(election_t *e); election_t *election_init(const char *name, const char *uname, guint period_ms, GSourceFunc cb); void election_timeout_set_period(election_t *e, guint period_ms); void election_timeout_stop(election_t *e); void election_vote(election_t *e); bool election_check(election_t *e); void election_remove(election_t *e, const char *uname); enum election_result election_state(election_t *e); enum election_result election_count_vote(election_t *e, xmlNode *vote, bool can_win); void election_clear_dampening(election_t *e); #ifdef __cplusplus } #endif #endif