diff --git a/src/raft.c b/src/raft.c index 02b7253..cfa8a49 100644 --- a/src/raft.c +++ b/src/raft.c @@ -1,944 +1,942 @@ /* * Copyright (C) 2014 Philipp Marek * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This software is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include #include #include #include #include #include "booth.h" #include "timer.h" #include "transport.h" #include "inline-fn.h" #include "config.h" #include "raft.h" #include "ticket.h" #include "log.h" inline static void clear_election(struct ticket_config *tk) { int i; struct booth_site *site; tk_log_debug("clear election"); tk->votes_received = 0; foreach_node(i, site) tk->votes_for[site->index] = NULL; } inline static void record_vote(struct ticket_config *tk, struct booth_site *who, struct booth_site *vote) { tk_log_debug("site %s votes for %s", site_string(who), site_string(vote)); if (!tk->votes_for[who->index]) { tk->votes_for[who->index] = vote; tk->votes_received |= who->bitmask; } else { if (tk->votes_for[who->index] != vote) tk_log_warn("%s voted previously " "for %s and now wants to vote for %s (ignored)", site_string(who), site_string(tk->votes_for[who->index]), site_string(vote)); } } static int cmp_msg_ticket(struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg) { if (my_last_term(tk) != ntohl(msg->ticket.term)) { return my_last_term(tk) - ntohl(msg->ticket.term); } return 0; } static void update_term_from_msg(struct ticket_config *tk, struct boothc_ticket_msg *msg) { uint32_t i; i = ntohl(msg->ticket.term); /* if we failed to start the election, then accept the term * from the leader * */ if (tk->state == ST_CANDIDATE) { tk->current_term = i; } else { tk->current_term = max(i, tk->current_term); } } static void update_ticket_from_msg(struct ticket_config *tk, struct booth_site *sender, struct boothc_ticket_msg *msg) { int duration; tk_log_debug("updating from %s (%d/%d)", site_string(sender), ntohl(msg->ticket.term), ntohl(msg->ticket.term_valid_for)); duration = min(tk->term_duration, ntohl(msg->ticket.term_valid_for)); tk->term_expires = get_secs(NULL) + duration; update_term_from_msg(tk, msg); } static void copy_ticket_from_msg(struct ticket_config *tk, struct boothc_ticket_msg *msg) { tk->term_expires = get_secs(NULL) + ntohl(msg->ticket.term_valid_for); tk->current_term = ntohl(msg->ticket.term); } static void become_follower(struct ticket_config *tk, struct boothc_ticket_msg *msg) { copy_ticket_from_msg(tk, msg); tk->state = ST_FOLLOWER; tk->delay_commit = 0; tk->in_election = 0; /* if we're following and the ticket was granted here * then commit to CIB right away (we're probably restarting) */ if (tk->is_granted) { disown_ticket(tk); ticket_write(tk); } } static void won_elections(struct ticket_config *tk) { tk->leader = local; tk->state = ST_LEADER; tk->term_expires = get_secs(NULL) + tk->term_duration; tk->election_end = 0; tk->voted_for = NULL; if (tk->delay_commit && all_sites_replied(tk)) { tk->delay_commit = 0; tk_log_debug("reset delay commit as all sites replied"); } ticket_broadcast(tk, OP_HEARTBEAT, OP_ACK, RLT_SUCCESS, 0); tk->ticket_updated = 0; } static int is_tie(struct ticket_config *tk) { int i; struct booth_site *v; int count[MAX_NODES] = { 0, }; int max_votes = 0, max_cnt = 0; for(i=0; isite_count; i++) { v = tk->votes_for[i]; if (!v) continue; count[v->index]++; max_votes = max(max_votes, count[v->index]); } for(i=0; isite_count; i++) { if (count[i] == max_votes) max_cnt++; } return max_cnt > 1; } static struct booth_site *majority_votes(struct ticket_config *tk) { int i, n; struct booth_site *v; int count[MAX_NODES] = { 0, }; for(i=0; isite_count; i++) { v = tk->votes_for[i]; if (!v) continue; n = v->index; count[n]++; tk_log_debug("Majority: %d %s wants %d %s => %d", i, site_string(&booth_conf->site[i]), n, site_string(v), count[n]); if (count[n]*2 <= booth_conf->site_count) continue; tk_log_debug("Majority reached: %d of %d for %s", count[n], booth_conf->site_count, site_string(v)); return v; } return NULL; } void elections_end(struct ticket_config *tk) { time_t now; struct booth_site *new_leader; now = get_secs(NULL); if (now > tk->election_end) { /* This is previous election timed out */ tk_log_info("elections finished"); } tk->in_election = 0; new_leader = majority_votes(tk); if (new_leader == local) { tk_log_info("granted successfully here"); won_elections(tk); } else if (new_leader) { tk_log_info("ticket granted at %s", site_string(new_leader)); } else { tk_log_info("nobody won elections, new elections"); notify_client(tk, RLT_MORE); if (!new_election(tk, NULL, is_tie(tk), OR_AGAIN)) { ticket_activate_timeout(tk); } } } static int newer_term(struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg, int in_election) { uint32_t term; /* it may happen that we hear about our newer term */ if (leader == local) return 0; term = ntohl(msg->ticket.term); /* §5.1 */ if (term > tk->current_term) { tk->state = ST_FOLLOWER; if (!in_election) { tk->leader = leader; tk_log_info("from %s: higher term %d vs. %d, following %s", site_string(sender), term, tk->current_term, ticket_leader_string(tk)); } else { tk_log_debug("from %s: higher term %d vs. %d (election)", site_string(sender), term, tk->current_term); } tk->current_term = term; return 1; } return 0; } static int term_too_low(struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg) { uint32_t term; term = ntohl(msg->ticket.term); /* §5.1 */ if (term < tk->current_term) { tk_log_info("sending reject to %s, its term too low " "(%d vs. %d)", site_string(sender), term, tk->current_term ); send_reject(sender, tk, RLT_TERM_OUTDATED, msg); return 1; } return 0; } /* For follower. */ static int answer_HEARTBEAT ( struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg ) { uint32_t term; term = ntohl(msg->ticket.term); tk_log_debug("heartbeat from leader: %s, have %s; term %d vs %d", site_string(leader), ticket_leader_string(tk), term, tk->current_term); if (term < tk->current_term) { if (sender == tk->leader) { tk_log_info("trusting leader %s with a lower term (%d vs %d)", site_string(leader), term, tk->current_term); } else if (is_owned(tk)) { tk_log_warn("different leader %s with a lower term " "(%d vs %d), sending reject", site_string(leader), term, tk->current_term); return send_reject(sender, tk, RLT_TERM_OUTDATED, msg); } } /* got heartbeat, no rejects expected anymore */ tk->expect_more_rejects = 0; /* Needed? */ newer_term(tk, sender, leader, msg, 0); become_follower(tk, msg); /* Racy??? */ assert(sender == leader || !leader); tk->leader = leader; /* Ack the heartbeat (we comply). */ return send_msg(OP_ACK, tk, sender, msg); } static int process_UPDATE ( struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg ) { if (is_owned(tk) && sender != tk->leader) { tk_log_warn("different leader %s wants to update " "our ticket, sending reject", site_string(leader)); return send_reject(sender, tk, RLT_TERM_OUTDATED, msg); } tk_log_debug("leader %s wants to update our ticket", site_string(leader)); become_follower(tk, msg); tk->leader = leader; ticket_write(tk); /* run ticket_cron if the ticket expires */ set_ticket_wakeup(tk); return send_msg(OP_ACK, tk, sender, msg); } static int process_REVOKE ( struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg ) { int rv; if (tk->state == ST_INIT && tk->leader == no_leader) { /* assume that our ack got lost */ rv = send_msg(OP_ACK, tk, sender, msg); } else if (tk->leader != sender) { tk_log_error("%s wants to revoke ticket, " "but it is not granted there (ignoring)", site_string(sender)); return 1; } else if (tk->state != ST_FOLLOWER) { tk_log_error("unexpected ticket revoke from %s " "(in state %s) (ignoring)", site_string(sender), state_to_string(tk->state)); return 1; } else { tk_log_info("%s revokes ticket", site_string(tk->leader)); reset_ticket(tk); tk->leader = no_leader; ticket_write(tk); rv = send_msg(OP_ACK, tk, sender, msg); } return rv; } /* For leader. */ static int process_ACK( struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg ) { uint32_t term; int req; term = ntohl(msg->ticket.term); if (newer_term(tk, sender, leader, msg, 0)) { /* unexpected higher term */ tk_log_warn("got higher term from %s (%d vs. %d)", site_string(sender), term, tk->current_term); return 0; } /* Don't send a reject. */ if (term < tk->current_term) { /* Doesn't know what he's talking about - perhaps * doesn't receive our packets? */ tk_log_warn("unexpected term " "from %s (%d vs. %d) (ignoring)", site_string(sender), term, tk->current_term); return 0; } /* if the ticket is to be revoked, further processing is not * interesting (and dangerous) */ if (tk->next_state == ST_INIT || tk->state == ST_INIT) return 0; req = ntohl(msg->header.request); if ((req == OP_UPDATE || req == OP_HEARTBEAT) && term == tk->current_term && leader == tk->leader) { if (majority_of_bits(tk, tk->acks_received)) { /* OK, at least half of the nodes are reachable; * Update the ticket and send update messages out */ return leader_update_ticket(tk); } } return 0; } static int process_VOTE_FOR( struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg ) { /* leader wants to step down? */ if (leader == no_leader && sender == tk->leader && (tk->state == ST_FOLLOWER || tk->state == ST_CANDIDATE)) { tk_log_info("%s wants to give the ticket away", site_string(tk->leader)); reset_ticket(tk); tk->state = ST_FOLLOWER; if (local->type == SITE) { ticket_write(tk); schedule_election(tk, OR_STEPDOWN); } return 0; } if (tk->state != ST_CANDIDATE) { /* lost candidate status, somebody rejected our proposal */ tk_log_debug("candidate status lost, ignoring vote_for from %s", site_string(sender)); return 0; } if (term_too_low(tk, sender, leader, msg)) return 0; if (newer_term(tk, sender, leader, msg, 0)) { clear_election(tk); } record_vote(tk, sender, leader); /* only if all voted can we take the ticket now, otherwise * wait for timeout in ticket_cron */ if (!tk->acks_expected) { /* §5.2 */ elections_end(tk); } return 0; } static int process_REJECTED( struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg ) { uint32_t rv; rv = ntohl(msg->header.result); if (tk->state == ST_CANDIDATE && leader == local) { /* the sender has us as the leader (!) * the elections will time out, then we can try again */ tk_log_warn("ticket was granted to us " "(and we didn't know)"); tk->expect_more_rejects = 1; return 0; } if (tk->state == ST_CANDIDATE && rv == RLT_TERM_OUTDATED) { tk_log_warn("ticket outdated (term %d), granted to %s", ntohl(msg->ticket.term), site_string(leader) ); tk->leader = leader; tk->expect_more_rejects = 1; become_follower(tk, msg); return 0; } if (tk->state == ST_CANDIDATE && rv == RLT_TERM_STILL_VALID) { if (tk->lost_leader == leader) { if (tk->election_reason == OR_TKT_LOST) { tk_log_warn("%s still has the ticket valid, " "we'll backup a bit", site_string(sender)); } else { tk_log_warn("%s unexpectedly rejects elections", site_string(sender)); } } else { tk_log_warn("ticket was granted to %s " "(and we didn't know)", site_string(leader)); } tk->leader = leader; become_follower(tk, msg); tk->expect_more_rejects = 1; return 0; } if (tk->state == ST_CANDIDATE && rv == RLT_YOU_OUTDATED) { tk->leader = leader; tk->expect_more_rejects = 1; if (leader && leader != no_leader) { tk_log_warn("our ticket is outdated, granted to %s", site_string(leader)); become_follower(tk, msg); } else { tk_log_warn("our ticket is outdated and revoked"); update_ticket_from_msg(tk, sender, msg); tk->state = ST_INIT; } return 0; } if (!tk->expect_more_rejects) { tk_log_warn("from %s: in state %s, got %s (unexpected reject)", site_string(sender), state_to_string(tk->state), state_to_string(rv)); } return 0; } static int ticket_seems_ok(struct ticket_config *tk) { int time_left; time_left = term_time_left(tk); if (!time_left) return 0; /* quite sure */ if (tk->state == ST_CANDIDATE) return 0; /* in state of flux */ if (tk->state == ST_LEADER) return 1; /* quite sure */ if (tk->state == ST_FOLLOWER && time_left >= tk->term_duration/3) return 1; /* almost quite sure */ return 0; } static int test_reason( struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg ) { int reason; reason = ntohl(msg->header.reason); if (reason == OR_TKT_LOST) { if (tk->state == ST_INIT && tk->leader == no_leader) { tk_log_warn("%s claims that the ticket is lost, " "but it's in %s state (reject sent)", site_string(sender), state_to_string(tk->state) ); return RLT_YOU_OUTDATED; } if (ticket_seems_ok(tk)) { tk_log_warn("%s claims that the ticket is lost, " "but it is ok here (reject sent)", site_string(sender)); return RLT_TERM_STILL_VALID; } } return 0; } /* §5.2 */ static int answer_REQ_VOTE( struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg ) { int valid; struct boothc_ticket_msg omsg; cmd_result_t inappr_reason; int reason; inappr_reason = test_reason(tk, sender, leader, msg); if (inappr_reason) return send_reject(sender, tk, inappr_reason, msg); valid = term_time_left(tk); reason = ntohl(msg->header.reason); /* valid tickets are not allowed only if the sender thinks * the ticket got lost */ if (sender != tk->leader && valid && reason == OR_TKT_LOST) { tk_log_warn("election from %s rejected " "(we have %s as ticket owner), ticket still valid for %ds", site_string(sender), site_string(tk->leader), valid); return send_reject(sender, tk, RLT_TERM_STILL_VALID, msg); } if (term_too_low(tk, sender, leader, msg)) return 0; /* set this, so that we know not to send status for the * ticket */ tk->in_election = 1; /* reset ticket's leader on not valid tickets */ if (!valid) tk->leader = NULL; /* if it's a newer term or ... */ if (newer_term(tk, sender, leader, msg, 1)) { clear_election(tk); goto vote_for_sender; } /* ... we didn't vote yet, then vote for the sender */ /* §5.2, §5.4 */ if (!tk->voted_for) { vote_for_sender: tk->voted_for = sender; record_vote(tk, sender, leader); } init_ticket_msg(&omsg, OP_VOTE_FOR, OP_REQ_VOTE, RLT_SUCCESS, 0, tk); omsg.ticket.leader = htonl(get_node_id(tk->voted_for)); return booth_udp_send(sender, &omsg, sizeof(omsg)); } int new_election(struct ticket_config *tk, struct booth_site *preference, int update_term, cmd_reason_t reason) { struct booth_site *new_leader; time_t now; if (local->type != SITE) return 0; get_secs(&now); tk_log_debug("start new election?, now=%" PRIi64 ", end %" PRIi64, (int64_t)wall_ts(now), (int64_t)(wall_ts(tk->election_end))); if (now < tk->election_end) return 1; /* §5.2 */ /* If there was _no_ answer, don't keep incrementing the term number * indefinitely. If there was no peer, there'll probably be no one * listening now either. However, we don't know if we were * invoked due to a timeout (caller does). */ if (update_term) { /* save the previous term, we may need to send out the * MY_INDEX message */ if (tk->state != ST_CANDIDATE) { memcpy(tk->last_valid_tk, tk, sizeof(struct ticket_config)); } tk->current_term++; } - tk->term_expires = 0; tk->election_end = now + tk->timeout; tk->in_election = 1; tk_log_info("starting new election (term=%d)", tk->current_term); clear_election(tk); if(preference) new_leader = preference; else new_leader = (local->type == SITE) ? local : NULL; record_vote(tk, local, new_leader); tk->voted_for = new_leader; - tk->leader = no_leader; tk->state = ST_CANDIDATE; /* some callers may want just to repeat on timeout */ if (reason == OR_AGAIN) { reason = tk->election_reason; } else { tk->election_reason = reason; } ticket_broadcast(tk, OP_REQ_VOTE, OP_VOTE_FOR, RLT_SUCCESS, reason); add_random_delay(tk); return 0; } /* we were a leader and somebody says that they have a more up * to date ticket * there was probably connectivity loss * tricky */ static int leader_handle_newer_ticket( struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg ) { update_term_from_msg(tk, msg); if (leader != no_leader && leader && leader != local) { /* eek, two leaders, split brain */ /* normally shouldn't happen; run election */ tk_log_error("from %s: ticket granted to %s! (revoking locally)", site_string(sender), site_string(leader) ); } else if (term_time_left(tk)) { /* eek, two leaders, split brain */ /* normally shouldn't happen; run election */ tk_log_error("from %s: ticket granted to %s! (revoking locally)", site_string(sender), site_string(leader) ); } tk->next_state = ST_LEADER; return 0; } /* reply to STATUS */ static int process_MY_INDEX ( struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg ) { int i; int expired; expired = !msg->ticket.term_valid_for; i = cmp_msg_ticket(tk, sender, leader, msg); if (i > 0) { /* let them know about our newer ticket */ /* but if we're voting in elections, our ticket is not * valid yet, don't send it */ if (!tk->in_election) send_msg(OP_MY_INDEX, tk, sender, msg); if (tk->state == ST_LEADER) { tk_log_info("sending ticket update to %s", site_string(sender)); return send_msg(OP_UPDATE, tk, sender, msg); } } /* we have a newer or equal ticket and theirs is expired, * nothing more to do here */ if (i >= 0 && expired) { return 0; } if (tk->state == ST_LEADER) { /* we're the leader, thread carefully */ if (expired) { /* if their ticket is expired, * nothing more to do */ return 0; } if (i < 0) { /* they have a newer ticket, trouble if we're already leader * for it */ tk_log_warn("from %s: more up to date ticket at %s", site_string(sender), site_string(leader) ); return leader_handle_newer_ticket(tk, sender, leader, msg); } else { /* we have the ticket and we don't care */ return 0; } } /* their ticket is either newer or not expired, don't * ignore it */ update_ticket_from_msg(tk, sender, msg); tk->leader = leader; update_ticket_state(tk, sender); set_ticket_wakeup(tk); return 0; } int raft_answer( struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg ) { int cmd, req; int rv; rv = 0; cmd = ntohl(msg->header.cmd); req = ntohl(msg->header.request); if (req) tk_log_debug("got %s (req %s) from %s", state_to_string(cmd), state_to_string(req), site_string(sender)); else tk_log_debug("got %s from %s", state_to_string(cmd), site_string(sender)); switch (cmd) { case OP_REQ_VOTE: rv = answer_REQ_VOTE(tk, sender, leader, msg); break; case OP_VOTE_FOR: rv = process_VOTE_FOR(tk, sender, leader, msg); break; case OP_ACK: if (tk->leader == local && tk->state == ST_LEADER) rv = process_ACK(tk, sender, leader, msg); break; case OP_HEARTBEAT: if ((tk->leader != local || !term_time_left(tk)) && (tk->state == ST_INIT || tk->state == ST_FOLLOWER || tk->state == ST_CANDIDATE)) rv = answer_HEARTBEAT(tk, sender, leader, msg); else { tk_log_warn("unexpected message %s, from %s", state_to_string(cmd), site_string(sender)); if (ticket_seems_ok(tk)) send_reject(sender, tk, RLT_TERM_STILL_VALID, msg); rv = -EINVAL; } break; case OP_UPDATE: if (((tk->leader != local && tk->leader == leader) || !is_owned(tk)) && (tk->state == ST_INIT || tk->state == ST_FOLLOWER || tk->state == ST_CANDIDATE)) { rv = process_UPDATE(tk, sender, leader, msg); } else { tk_log_warn("unexpected message %s, from %s", state_to_string(cmd), site_string(sender)); if (ticket_seems_ok(tk)) send_reject(sender, tk, RLT_TERM_STILL_VALID, msg); rv = -EINVAL; } break; case OP_REJECTED: rv = process_REJECTED(tk, sender, leader, msg); break; case OP_REVOKE: rv = process_REVOKE(tk, sender, leader, msg); break; case OP_MY_INDEX: rv = process_MY_INDEX(tk, sender, leader, msg); break; case OP_STATUS: if (!tk->in_election) rv = send_msg(OP_MY_INDEX, tk, sender, msg); break; default: tk_log_error("unknown message %s, from %s", state_to_string(cmd), site_string(sender)); rv = -EINVAL; } return rv; } diff --git a/src/ticket.c b/src/ticket.c index d9bb7a4..e2dac31 100644 --- a/src/ticket.c +++ b/src/ticket.c @@ -1,1112 +1,1111 @@ /* * Copyright (C) 2011 Jiaju Zhang * Copyright (C) 2013-2014 Philipp Marek * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This software is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include #include #include #include #include #include #include #include #include #include "ticket.h" #include "config.h" #include "pacemaker.h" #include "inline-fn.h" #include "log.h" #include "booth.h" #include "raft.h" #include "handler.h" #define TK_LINE 256 /* Untrusted input, must fit (incl. \0) in a buffer of max chars. */ int check_max_len_valid(const char *s, int max) { int i; for(i=0; iticket_count; i++) { if (!strcmp(booth_conf->ticket[i].name, ticket)) { if (found) *found = booth_conf->ticket + i; return 1; } } return 0; } int check_ticket(char *ticket, struct ticket_config **found) { if (found) *found = NULL; if (!booth_conf) return 0; if (!check_max_len_valid(ticket, sizeof(booth_conf->ticket[0].name))) return 0; return find_ticket_by_name(ticket, found); } int check_site(char *site, int *is_local) { struct booth_site *node; if (!check_max_len_valid(site, sizeof(node->addr_string))) return 0; if (find_site_by_name(site, &node, 0)) { *is_local = node->local; return 1; } return 0; } /* is it safe to commit the grant? * if we didn't hear from all sites on the initial grant, we may * need to delay the commit * * TODO: investigate possibility to devise from history whether a * missing site could be holding a ticket or not */ static int ticket_dangerous(struct ticket_config *tk) { time_t now = get_secs(NULL); /* we may be invoked often, don't spam the log unnecessarily */ static int no_log_delay_msg; if (!tk->delay_commit) return 0; if (tk->delay_commit <= now || all_sites_replied(tk)) { if (tk->leader == local) { tk_log_info("%s, committing to CIB", tk->delay_commit <= now ? "ticket delay expired" : "all sites replied"); } tk->delay_commit = 0; no_log_delay_msg = 0; return 0; } tk_log_debug("delay ticket commit for %ds", (int)(tk->delay_commit - now)); if (!no_log_delay_msg) { tk_log_info("delaying ticket commit to CIB for %ds " "(or all sites are reached)", (int)(tk->delay_commit - now)); no_log_delay_msg = 1; } return 1; } int ticket_write(struct ticket_config *tk) { if (local->type != SITE) return -EINVAL; if (ticket_dangerous(tk)) return 1; if (tk->leader == local) { pcmk_handler.grant_ticket(tk); } else { pcmk_handler.revoke_ticket(tk); } tk->update_cib = 0; return 0; } /* Ask an external program whether getting the ticket * makes sense. * Eg. if the services have a failcount of INFINITY, * we can't serve here anyway. */ int test_external_prog(struct ticket_config *tk, int start_election) { int rv; rv = run_handler(tk, tk->ext_verifier, 1); if (rv) { tk_log_warn("we are not allowed to acquire ticket"); /* Give it to somebody else. * Just send a VOTE_FOR message, so the * others can start elections. */ if (leader_and_valid(tk)) { reset_ticket(tk); ticket_write(tk); if (start_election) { ticket_broadcast(tk, OP_VOTE_FOR, OP_REQ_VOTE, RLT_SUCCESS, OR_LOCAL_FAIL); } } } return rv; } /* Try to acquire a ticket * Could be manual grant or after ticket loss */ int acquire_ticket(struct ticket_config *tk, cmd_reason_t reason) { int rc; if (test_external_prog(tk, 0)) return RLT_EXT_FAILED; rc = new_election(tk, local, 1, reason); return rc ? RLT_SYNC_FAIL : 0; } /** Try to get the ticket for the local site. * */ int do_grant_ticket(struct ticket_config *tk, int options) { int rv; tk_log_info("granting ticket"); if (tk->leader == local) return RLT_SUCCESS; if (is_owned(tk)) return RLT_OVERGRANT; tk->delay_commit = get_secs(NULL) + tk->term_duration + tk->acquire_after; if (options & OPT_IMMEDIATE) { tk_log_warn("granting ticket immediately! If there are " "unreachable sites, _hope_ you are sure that they don't " "have the ticket!"); tk->delay_commit = 0; } rv = acquire_ticket(tk, OR_ADMIN); if (rv) { tk->delay_commit = 0; return rv; } else { return RLT_MORE; } } static void start_revoke_ticket(struct ticket_config *tk) { tk_log_info("revoking ticket"); reset_ticket(tk); tk->leader = no_leader; ticket_write(tk); ticket_broadcast(tk, OP_REVOKE, OP_ACK, RLT_SUCCESS, OR_ADMIN); } /** Ticket revoke. * Only to be started from the leader. */ int do_revoke_ticket(struct ticket_config *tk) { if (tk->acks_expected) { tk_log_info("delay ticket revoke until the current operation finishes"); tk->next_state = ST_INIT; return RLT_MORE; } else { start_revoke_ticket(tk); return RLT_SUCCESS; } } int list_ticket(char **pdata, unsigned int *len) { struct ticket_config *tk; char timeout_str[64]; char pending_str[64]; char *data, *cp; int i, alloc; time_t ts; *pdata = NULL; *len = 0; alloc = 256 + booth_conf->ticket_count * (BOOTH_NAME_LEN * 2 + 128); data = malloc(alloc); if (!data) return -ENOMEM; cp = data; foreach_ticket(i, tk) { if (tk->term_expires != 0) { ts = wall_ts(tk->term_expires); strftime(timeout_str, sizeof(timeout_str), "%F %T", localtime(&ts)); } else strcpy(timeout_str, "INF"); if (tk->leader == local && tk->delay_commit > get_secs(NULL)) { ts = wall_ts(tk->delay_commit); strcpy(pending_str, " (commit pending until "); strftime(pending_str + strlen(" (commit pending until "), sizeof(pending_str) - strlen(" (commit pending until ") - 1, "%F %T", localtime(&ts)); strcat(pending_str, ")"); } else *pending_str = '\0'; cp += snprintf(cp, alloc - (cp - data), "ticket: %s, leader: %s", tk->name, ticket_leader_string(tk)); if (is_owned(tk)) { cp += snprintf(cp, alloc - (cp - data), ", expires: %s%s\n", timeout_str, pending_str); } else { cp += snprintf(cp, alloc - (cp - data), "\n"); } if (alloc - (cp - data) <= 0) return -ENOMEM; } *pdata = data; *len = cp - data; return 0; } void reset_ticket(struct ticket_config *tk) { disown_ticket(tk); no_resends(tk); tk->state = ST_INIT; tk->voted_for = NULL; } static void reacquire_ticket(struct ticket_config *tk) { int valid; const char *where_granted = "\0"; char buff[64]; valid = (tk->term_expires >= get_secs(NULL)); if (tk->leader == local) { where_granted = "granted here"; } else { snprintf(buff, sizeof(buff), "granted to %s", site_string(tk->leader)); where_granted = buff; } if (!valid) { tk_log_warn("%s, but not valid " "anymore (will try to reacquire)", where_granted); } if (tk->is_granted && tk->leader != local) { if (tk->leader && tk->leader != no_leader) { tk_log_error("granted here, but also %s, " "that's really too bad (will try to reacquire)", where_granted); } else { tk_log_warn("granted here, but we're " "not recorded as the grantee (will try to reacquire)"); } } /* try to acquire the * ticket through new elections */ acquire_ticket(tk, OR_REACQUIRE); } void update_ticket_state(struct ticket_config *tk, struct booth_site *sender) { if (tk->state == ST_CANDIDATE) { tk_log_info("learned from %s about " "newer ticket, stopping elections", site_string(sender)); /* there could be rejects coming from others; don't log * warnings unnecessarily */ tk->expect_more_rejects = 1; } if (tk->leader == local || tk->is_granted) { /* message from a live leader with valid ticket? */ if (sender == tk->leader && term_time_left(tk)) { if (tk->is_granted) { tk_log_warn("ticket was granted here, " "but it's live at %s (revoking here)", site_string(sender)); } else { tk_log_info("ticket live at %s", site_string(sender)); } disown_ticket(tk); ticket_write(tk); tk->state = ST_FOLLOWER; tk->next_state = ST_FOLLOWER; } else { if (tk->state == ST_CANDIDATE) { tk->state = ST_FOLLOWER; } tk->next_state = ST_LEADER; } } else { if (!tk->leader || tk->leader == no_leader) { if (sender) tk_log_info("ticket is not granted"); else tk_log_info("ticket is not granted (from CIB)"); tk->state = ST_INIT; } else { if (sender) tk_log_info("ticket granted to %s (says %s)", site_string(tk->leader), site_string(sender)); else tk_log_info("ticket granted to %s (from CIB)", site_string(tk->leader)); tk->state = ST_FOLLOWER; /* just make sure that we check the ticket soon */ tk->next_state = ST_FOLLOWER; } } } int setup_ticket(void) { struct ticket_config *tk; int i; foreach_ticket(i, tk) { reset_ticket(tk); if (local->type == SITE) { if (!pcmk_handler.load_ticket(tk)) { update_ticket_state(tk, NULL); } tk->update_cib = 1; } tk_log_info("broadcasting state query"); /* wait until all send their status (or the first * timeout) */ tk->start_postpone = 1; ticket_broadcast(tk, OP_STATUS, OP_MY_INDEX, RLT_SUCCESS, 0); } return 0; } int ticket_answer_list(int fd, struct boothc_ticket_msg *msg) { char *data; int olen, rv; struct boothc_header hdr; rv = list_ticket(&data, &olen); if (rv < 0) return rv; init_header(&hdr, CL_LIST, 0, 0, RLT_SUCCESS, 0, sizeof(hdr) + olen); return send_header_plus(fd, &hdr, data, olen); } int process_client_request(struct client *req_client, struct boothc_ticket_msg *msg) { int rv; struct ticket_config *tk; int cmd; cmd = ntohl(msg->header.cmd); if (!check_ticket(msg->ticket.id, &tk)) { log_warn("client referenced unknown ticket %s", msg->ticket.id); rv = RLT_INVALID_ARG; goto reply; } if ((cmd == CMD_GRANT) && is_owned(tk)) { log_warn("client wants to grant an (already granted!) ticket %s", msg->ticket.id); rv = RLT_OVERGRANT; goto reply; } if ((cmd == CMD_REVOKE) && !is_owned(tk)) { log_info("client wants to revoke a free ticket %s", msg->ticket.id); rv = RLT_TICKET_IDLE; goto reply; } if ((cmd == CMD_REVOKE) && tk->leader != local) { log_info("the ticket %s is not granted here, " "redirect to %s", msg->ticket.id, ticket_leader_string(tk)); rv = RLT_REDIRECT; goto reply; } if (cmd == CMD_REVOKE) rv = do_revoke_ticket(tk); else rv = do_grant_ticket(tk, ntohl(msg->header.options)); if (rv == RLT_MORE) { /* client may receive further notifications */ tk->req_client = req_client; } reply: init_ticket_msg(msg, CL_RESULT, 0, rv, 0, tk); return send_ticket_msg(req_client->fd, msg); } void notify_client(struct ticket_config *tk, int rv) { struct boothc_ticket_msg omsg; void (*deadfn) (int ci); int rc, ci; if (!tk->req_client) return; init_ticket_msg(&omsg, CL_RESULT, 0, rv, 0, tk); rc = send_ticket_msg(tk->req_client->fd, &omsg); /* we sent a definite answer or there was a write error, drop * the client */ if (rv != RLT_MORE || rc) { deadfn = tk->req_client->deadfn; if(deadfn) { ci = find_client_by_fd(tk->req_client->fd); if (ci >= 0) deadfn(ci); } tk->req_client = NULL; } } int ticket_broadcast(struct ticket_config *tk, cmd_request_t cmd, cmd_request_t expected_reply, cmd_result_t res, cmd_reason_t reason) { struct boothc_ticket_msg msg; init_ticket_msg(&msg, cmd, 0, res, reason, tk); tk_log_debug("broadcasting '%s' (term=%d, valid=%d)", state_to_string(cmd), ntohl(msg.ticket.term), ntohl(msg.ticket.term_valid_for)); tk->last_request = cmd; if (expected_reply) { expect_replies(tk, expected_reply); } ticket_activate_timeout(tk); return transport()->broadcast(&msg, sizeof(msg)); } /* update the ticket on the leader, write it to the CIB, and send out the update message to others with the new expiry time */ int leader_update_ticket(struct ticket_config *tk) { int rv = 0, rv2; time_t now; if (tk->ticket_updated >= 2) return 0; now = get_secs(NULL); if (tk->ticket_updated < 1) { tk->ticket_updated = 1; tk->last_renewal = now; tk->term_expires = now + tk->term_duration; rv = ticket_broadcast(tk, OP_UPDATE, OP_ACK, RLT_SUCCESS, 0); } if (tk->ticket_updated < 2) { rv2 = ticket_write(tk); switch(rv2) { case 0: tk->ticket_updated = 2; notify_client(tk, RLT_SUCCESS); break; case 1: notify_client(tk, RLT_CIB_PENDING); break; default: break; } } return rv; } static void log_lost_servers(struct ticket_config *tk) { struct booth_site *n; int i; if (tk->retry_number > 1) /* log those that we couldn't reach, but do * that only on the first retry */ return; for (i = 0; i < booth_conf->site_count; i++) { n = booth_conf->site + i; if (!(tk->acks_received & n->bitmask)) { tk_log_warn("%s %s didn't acknowledge our %s, " "will retry %d times", (n->type == ARBITRATOR ? "arbitrator" : "site"), site_string(n), state_to_string(tk->last_request), tk->retries); } } } static void resend_msg(struct ticket_config *tk) { struct booth_site *n; int i; if (!(tk->acks_received ^ local->bitmask)) { ticket_broadcast(tk, tk->last_request, 0, RLT_SUCCESS, 0); } else { for (i = 0; i < booth_conf->site_count; i++) { n = booth_conf->site + i; if (!(tk->acks_received & n->bitmask)) { tk_log_debug("resending %s to %s", state_to_string(tk->last_request), site_string(n) ); send_msg(tk->last_request, tk, n, NULL); } } ticket_activate_timeout(tk); } } static void handle_resends(struct ticket_config *tk) { int ack_cnt; if (++tk->retry_number > tk->retries) { tk_log_debug("giving up on sending retries"); no_resends(tk); set_ticket_wakeup(tk); return; } /* try to reach some sites again if we just stepped down */ if (tk->last_request == OP_VOTE_FOR) { tk_log_warn("no answers to our request (try #%d), " "we are alone", tk->retry_number); goto just_resend; } if (!majority_of_bits(tk, tk->acks_received)) { ack_cnt = count_bits(tk->acks_received) - 1; if (!ack_cnt) { tk_log_warn("no answers to our request (try #%d), " "we are alone", tk->retry_number); } else { tk_log_warn("not enough answers to our request (try #%d): " "only got %d answers", tk->retry_number, ack_cnt); } } else { log_lost_servers(tk); } just_resend: resend_msg(tk); } int postpone_ticket_processing(struct ticket_config *tk) { extern time_t start_time; return tk->start_postpone && ((get_secs(NULL) - start_time) < tk->timeout); } static void process_next_state(struct ticket_config *tk) { switch(tk->next_state) { case ST_LEADER: reacquire_ticket(tk); break; case ST_INIT: no_resends(tk); start_revoke_ticket(tk); notify_client(tk, RLT_SUCCESS); break; /* wanting to be follower is not much of an ambition; no * processing, just return; don't reset start_postpone until * we got some replies to status */ case ST_FOLLOWER: return; default: break; } tk->start_postpone = 0; } static void ticket_lost(struct ticket_config *tk) { if (tk->leader != local) { tk_log_warn("lost at %s", site_string(tk->leader)); } else { tk_log_warn("lost majority (revoking locally)"); } tk->lost_leader = tk->leader; reset_ticket(tk); tk->state = ST_FOLLOWER; if (local->type == SITE) { ticket_write(tk); schedule_election(tk, OR_TKT_LOST); } } static void next_action(struct ticket_config *tk) { switch(tk->state) { case ST_INIT: /* init state, handle resends for ticket revoke */ /* and rebroadcast if stepping down */ if (tk->acks_expected) { handle_resends(tk); } break; case ST_FOLLOWER: /* leader/ticket lost? and we didn't vote yet */ tk_log_debug("leader: %s, voted_for: %s", site_string(tk->leader), site_string(tk->voted_for)); if (!tk->leader) { if (!tk->voted_for) { disown_ticket(tk); if (!new_election(tk, NULL, 1, OR_AGAIN)) { ticket_activate_timeout(tk); } } else { /* we should restart elections in case nothing * happens in the meantime */ tk->in_election = 0; ticket_activate_timeout(tk); } } break; case ST_CANDIDATE: /* elections timed out? */ elections_end(tk); break; case ST_LEADER: /* timeout or ticket renewal? */ if (tk->acks_expected) { handle_resends(tk); if (majority_of_bits(tk, tk->acks_received)) { leader_update_ticket(tk); } } else { /* this is ticket renewal, run local test */ if (!test_external_prog(tk, 1)) { ticket_broadcast(tk, OP_HEARTBEAT, OP_ACK, RLT_SUCCESS, 0); tk->ticket_updated = 0; } } break; default: break; } } static void ticket_cron(struct ticket_config *tk) { time_t now; /* don't process the tickets too early after start */ if (postpone_ticket_processing(tk)) { tk_log_debug("ticket processing postponed (start_postpone=%d)", tk->start_postpone); /* but run again soon */ ticket_activate_timeout(tk); return; } /* no need for status resends, we hope we got at least one * my_index back */ if (tk->acks_expected == OP_MY_INDEX) { no_resends(tk); } /* after startup, we need to decide what to do based on the * current ticket state; tk->next_state has a hint * also used for revokes which had to be delayed */ if (tk->next_state) { process_next_state(tk); goto out; } /* Has an owner, has an expiry date, and expiry date in the past? * Losing the ticket must happen in _every_ state. */ now = get_secs(NULL); - if (!tk->in_election && + if (is_owned(tk) && tk->term_expires && - is_owned(tk) && now >= tk->term_expires) { ticket_lost(tk); goto out; } next_action(tk); out: tk->next_state = 0; if (!tk->in_election && tk->update_cib) ticket_write(tk); } void process_tickets(void) { struct ticket_config *tk; int i; timetype now, last_cron; get_time(&now); foreach_ticket(i, tk) { if (time_cmp(&tk->next_cron, &now, >)) continue; tk_log_debug("ticket cron"); last_cron = tk->next_cron; ticket_cron(tk); if (!time_cmp(&last_cron, &tk->next_cron, !=)) { tk_log_debug("nobody set ticket wakeup"); set_ticket_wakeup(tk); } } } void tickets_log_info(void) { struct ticket_config *tk; int i; time_t ts; foreach_ticket(i, tk) { ts = wall_ts(tk->term_expires); tk_log_info("state '%s' " "term %d " "leader %s " "expires %-24.24s", state_to_string(tk->state), tk->current_term, ticket_leader_string(tk), ctime(&ts)); } } static void update_acks( struct ticket_config *tk, struct booth_site *sender, struct booth_site *leader, struct boothc_ticket_msg *msg ) { uint32_t cmd; uint32_t req; cmd = ntohl(msg->header.cmd); req = ntohl(msg->header.request); if (req != tk->last_request || (tk->acks_expected != cmd && tk->acks_expected != OP_REJECTED)) return; /* got an ack! */ tk->acks_received |= sender->bitmask; if (all_replied(tk) || /* we just stepped down, need only one site to start * elections */ (cmd == OP_REQ_VOTE && tk->last_request == OP_VOTE_FOR)) { no_resends(tk); tk->start_postpone = 0; set_ticket_wakeup(tk); } } /* UDP message receiver. */ int message_recv(struct boothc_ticket_msg *msg, int msglen) { uint32_t from; struct booth_site *source; struct ticket_config *tk; struct booth_site *leader; uint32_t leader_u; if (check_boothc_header(&msg->header, sizeof(*msg)) < 0 || msglen != sizeof(*msg)) { log_error("message receive error"); return -1; } from = ntohl(msg->header.from); if (!find_site_by_id(from, &source) || !source) { log_error("unknown sender: %08x", from); return -1; } if (!check_ticket(msg->ticket.id, &tk)) { log_warn("got invalid ticket name %s from %s", msg->ticket.id, site_string(source)); return -EINVAL; } leader_u = ntohl(msg->ticket.leader); if (!find_site_by_id(leader_u, &leader)) { tk_log_error("message with unknown leader %u received", leader_u); return -EINVAL; } update_acks(tk, source, leader, msg); return raft_answer(tk, source, leader, msg); } static void log_next_wakeup(struct ticket_config *tk) { timetype now, res; get_time(&now); time_sub(&tk->next_cron, &now, &res); tk_log_debug("set ticket wakeup in %d.%03d", (int)res.tv_sec, (int)msecs(res)); } /* New vote round; §5.2 */ /* delay the next election start for up to 1s */ void add_random_delay(struct ticket_config *tk) { timetype delay, tv; rand_time_ms(delay, 1000); time_add(&tk->next_cron, &delay, &tv); ticket_next_cron_at(tk, tv); if (ANYDEBUG) { log_next_wakeup(tk); } } void set_ticket_wakeup(struct ticket_config *tk) { timetype tv, now, res; /* At least every hour, perhaps sooner. */ ticket_next_cron_in(tk, 3600); get_time(&now); switch (tk->state) { case ST_LEADER: assert(tk->leader == local); tv = now; tv.tv_sec = next_vote_starts_at(tk); /* If timestamp is in the past, wakeup in * one second. */ if (time_cmp(&tv, &now, <)) { time_sub(&tv, &now, &res); tk_log_debug("next ts in the past (%d.%03d)", (int)res.tv_sec, (int)msecs(res)); tv.tv_sec = now.tv_sec + 1; } ticket_next_cron_at(tk, tv); break; case ST_CANDIDATE: assert(tk->election_end); ticket_next_cron_at_coarse(tk, tk->election_end); break; case ST_INIT: case ST_FOLLOWER: /* If there is (or should be) some owner, check on it later on. * If no one is interested - don't care. */ if (is_owned(tk) && (local->type == SITE)) ticket_next_cron_at_coarse(tk, tk->term_expires + tk->acquire_after); break; default: tk_log_error("unknown ticket state: %d", tk->state); } if (tk->next_state) { /* we need to do something soon here */ if (!tk->acks_expected) { ticket_next_cron_at(tk, now); } else { ticket_activate_timeout(tk); } } if (ANYDEBUG) { log_next_wakeup(tk); } } void schedule_election(struct ticket_config *tk, cmd_reason_t reason) { if (local->type != SITE) return; tk->election_reason = reason; get_time(&tk->next_cron); /* introduce a short delay before starting election */ add_random_delay(tk); } /* Given a state (in host byte order), return a human-readable (char*). * An array is used so that multiple states can be printed in a single printf(). */ char *state_to_string(uint32_t state_ho) { union mu { cmd_request_t s; char c[5]; }; static union mu cache[6] = { { 0 } }, *cur; static int current = 0; current ++; if (current >= sizeof(cache)/sizeof(cache[0])) current = 0; cur = cache + current; cur->s = htonl(state_ho); /* Shouldn't be necessary, union array is initialized with zeroes, and * these bytes never get written. */ cur->c[4] = 0; return cur->c; } int send_reject(struct booth_site *dest, struct ticket_config *tk, cmd_result_t code, struct boothc_ticket_msg *in_msg) { int req = ntohl(in_msg->header.cmd); struct boothc_ticket_msg msg; tk_log_debug("sending reject to %s", site_string(dest)); init_ticket_msg(&msg, OP_REJECTED, req, code, 0, tk); return booth_udp_send(dest, &msg, sizeof(msg)); } int send_msg ( int cmd, struct ticket_config *current_tk, struct booth_site *dest, struct boothc_ticket_msg *in_msg ) { int req = 0; struct ticket_config *tk = current_tk; struct boothc_ticket_msg msg; if (cmd == OP_MY_INDEX) { if (current_tk->state == ST_CANDIDATE && current_tk->last_valid_tk->current_term) { tk = current_tk->last_valid_tk; } tk_log_info("sending status to %s", site_string(dest)); } if (in_msg) req = ntohl(in_msg->header.cmd); init_ticket_msg(&msg, cmd, req, RLT_SUCCESS, 0, tk); return booth_udp_send(dest, &msg, sizeof(msg)); }