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Diffstat (limited to 'src/mon/PaxosService.cc')
| -rw-r--r-- | src/mon/PaxosService.cc | 441 |
1 files changed, 441 insertions, 0 deletions
diff --git a/src/mon/PaxosService.cc b/src/mon/PaxosService.cc new file mode 100644 index 00000000..06776635 --- /dev/null +++ b/src/mon/PaxosService.cc @@ -0,0 +1,441 @@ +// -*- 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) 2004-2006 Sage Weil <sage@newdream.net> + * + * 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. + * + */ + +#include "PaxosService.h" +#include "common/Clock.h" +#include "common/config.h" +#include "include/stringify.h" +#include "include/ceph_assert.h" +#include "mon/MonOpRequest.h" + +#define dout_subsys ceph_subsys_paxos +#undef dout_prefix +#define dout_prefix _prefix(_dout, mon, paxos, service_name, get_first_committed(), get_last_committed()) +static ostream& _prefix(std::ostream *_dout, Monitor *mon, Paxos *paxos, string service_name, + version_t fc, version_t lc) { + return *_dout << "mon." << mon->name << "@" << mon->rank + << "(" << mon->get_state_name() + << ").paxosservice(" << service_name << " " << fc << ".." << lc << ") "; +} + +bool PaxosService::dispatch(MonOpRequestRef op) +{ + ceph_assert(op->is_type_service() || op->is_type_command()); + PaxosServiceMessage *m = static_cast<PaxosServiceMessage*>(op->get_req()); + op->mark_event("psvc:dispatch"); + + dout(10) << __func__ << " " << m << " " << *m + << " from " << m->get_orig_source_inst() + << " con " << m->get_connection() << dendl; + + if (mon->is_shutdown()) { + return true; + } + + // make sure this message isn't forwarded from a previous election epoch + if (m->rx_election_epoch && + m->rx_election_epoch < mon->get_epoch()) { + dout(10) << " discarding forwarded message from previous election epoch " + << m->rx_election_epoch << " < " << mon->get_epoch() << dendl; + return true; + } + + // make sure the client is still connected. note that a proxied + // connection will be disconnected with a null message; don't drop + // those. also ignore loopback (e.g., log) messages. + if (m->get_connection() && + !m->get_connection()->is_connected() && + m->get_connection() != mon->con_self && + m->get_connection()->get_messenger() != NULL) { + dout(10) << " discarding message from disconnected client " + << m->get_source_inst() << " " << *m << dendl; + return true; + } + + // make sure our map is readable and up to date + if (!is_readable(m->version)) { + dout(10) << " waiting for paxos -> readable (v" << m->version << ")" << dendl; + wait_for_readable(op, new C_RetryMessage(this, op), m->version); + return true; + } + + // preprocess + if (preprocess_query(op)) + return true; // easy! + + // leader? + if (!mon->is_leader()) { + mon->forward_request_leader(op); + return true; + } + + // writeable? + if (!is_writeable()) { + dout(10) << " waiting for paxos -> writeable" << dendl; + wait_for_writeable(op, new C_RetryMessage(this, op)); + return true; + } + + // update + if (!prepare_update(op)) { + // no changes made. + return true; + } + + if (need_immediate_propose) { + dout(10) << __func__ << " forced immediate propose" << dendl; + need_immediate_propose = false; + propose_pending(); + return true; + } + + double delay = 0.0; + if (!should_propose(delay)) { + dout(10) << " not proposing" << dendl; + return true; + } + + if (delay == 0.0) { + propose_pending(); + return true; + } + + // delay a bit + if (!proposal_timer) { + /** + * Callback class used to propose the pending value once the proposal_timer + * fires up. + */ + auto do_propose = new C_MonContext(mon, [this](int r) { + proposal_timer = 0; + if (r >= 0) { + propose_pending(); + } else if (r == -ECANCELED || r == -EAGAIN) { + return; + } else { + ceph_abort_msg("bad return value for proposal_timer"); + } + }); + dout(10) << " setting proposal_timer " << do_propose + << " with delay of " << delay << dendl; + proposal_timer = mon->timer.add_event_after(delay, do_propose); + } else { + dout(10) << " proposal_timer already set" << dendl; + } + return true; +} + +void PaxosService::refresh(bool *need_bootstrap) +{ + // update cached versions + cached_first_committed = mon->store->get(get_service_name(), first_committed_name); + cached_last_committed = mon->store->get(get_service_name(), last_committed_name); + + version_t new_format = get_value("format_version"); + if (new_format != format_version) { + dout(1) << __func__ << " upgraded, format " << format_version << " -> " << new_format << dendl; + on_upgrade(); + } + format_version = new_format; + + dout(10) << __func__ << dendl; + + update_from_paxos(need_bootstrap); +} + +void PaxosService::post_refresh() +{ + dout(10) << __func__ << dendl; + + post_paxos_update(); + + if (mon->is_peon() && !waiting_for_finished_proposal.empty()) { + finish_contexts(g_ceph_context, waiting_for_finished_proposal, -EAGAIN); + } +} + +bool PaxosService::should_propose(double& delay) +{ + // simple default policy: quick startup, then some damping. + if (get_last_committed() <= 1) { + delay = 0.0; + } else { + utime_t now = ceph_clock_now(); + if ((now - paxos->last_commit_time) > g_conf()->paxos_propose_interval) + delay = (double)g_conf()->paxos_min_wait; + else + delay = (double)(g_conf()->paxos_propose_interval + paxos->last_commit_time + - now); + } + return true; +} + + +void PaxosService::propose_pending() +{ + dout(10) << __func__ << dendl; + ceph_assert(have_pending); + ceph_assert(!proposing); + ceph_assert(mon->is_leader()); + ceph_assert(is_active()); + + if (proposal_timer) { + dout(10) << " canceling proposal_timer " << proposal_timer << dendl; + mon->timer.cancel_event(proposal_timer); + proposal_timer = NULL; + } + + /** + * @note What we contribute to the pending Paxos transaction is + * obtained by calling a function that must be implemented by + * the class implementing us. I.e., the function + * encode_pending will be the one responsible to encode + * whatever is pending on the implementation class into a + * bufferlist, so we can then propose that as a value through + * Paxos. + */ + MonitorDBStore::TransactionRef t = paxos->get_pending_transaction(); + + if (should_stash_full()) + encode_full(t); + + encode_pending(t); + have_pending = false; + + if (format_version > 0) { + t->put(get_service_name(), "format_version", format_version); + } + + // apply to paxos + proposing = true; + /** + * Callback class used to mark us as active once a proposal finishes going + * through Paxos. + * + * We should wake people up *only* *after* we inform the service we + * just went active. And we should wake people up only once we finish + * going active. This is why we first go active, avoiding to wake up the + * wrong people at the wrong time, such as waking up a C_RetryMessage + * before waking up a C_Active, thus ending up without a pending value. + */ + class C_Committed : public Context { + PaxosService *ps; + public: + explicit C_Committed(PaxosService *p) : ps(p) { } + void finish(int r) override { + ps->proposing = false; + if (r >= 0) + ps->_active(); + else if (r == -ECANCELED || r == -EAGAIN) + return; + else + ceph_abort_msg("bad return value for C_Committed"); + } + }; + paxos->queue_pending_finisher(new C_Committed(this)); + paxos->trigger_propose(); +} + +bool PaxosService::should_stash_full() +{ + version_t latest_full = get_version_latest_full(); + /* @note The first member of the condition is moot and it is here just for + * clarity's sake. The second member would end up returing true + * nonetheless because, in that event, + * latest_full == get_trim_to() == 0. + */ + return (!latest_full || + (latest_full <= get_trim_to()) || + (get_last_committed() - latest_full > (version_t)g_conf()->paxos_stash_full_interval)); +} + +void PaxosService::restart() +{ + dout(10) << __func__ << dendl; + if (proposal_timer) { + dout(10) << " canceling proposal_timer " << proposal_timer << dendl; + mon->timer.cancel_event(proposal_timer); + proposal_timer = 0; + } + + finish_contexts(g_ceph_context, waiting_for_finished_proposal, -EAGAIN); + + if (have_pending) { + discard_pending(); + have_pending = false; + } + proposing = false; + + on_restart(); +} + +void PaxosService::election_finished() +{ + dout(10) << __func__ << dendl; + + finish_contexts(g_ceph_context, waiting_for_finished_proposal, -EAGAIN); + + // make sure we update our state + _active(); +} + +void PaxosService::_active() +{ + if (is_proposing()) { + dout(10) << __func__ << " - proposing" << dendl; + return; + } + if (!is_active()) { + dout(10) << __func__ << " - not active" << dendl; + /** + * Callback used to make sure we call the PaxosService::_active function + * whenever a condition is fulfilled. + * + * This is used in multiple situations, from waiting for the Paxos to commit + * our proposed value, to waiting for the Paxos to become active once an + * election is finished. + */ + class C_Active : public Context { + PaxosService *svc; + public: + explicit C_Active(PaxosService *s) : svc(s) {} + void finish(int r) override { + if (r >= 0) + svc->_active(); + } + }; + wait_for_active_ctx(new C_Active(this)); + return; + } + dout(10) << __func__ << dendl; + + // create pending state? + if (mon->is_leader()) { + dout(7) << __func__ << " creating new pending" << dendl; + if (!have_pending) { + create_pending(); + have_pending = true; + } + + if (get_last_committed() == 0) { + // create initial state + create_initial(); + propose_pending(); + return; + } + } else { + dout(7) << __func__ << " we are not the leader, hence we propose nothing!" << dendl; + } + + // wake up anyone who came in while we were proposing. note that + // anyone waiting for the previous proposal to commit is no longer + // on this list; it is on Paxos's. + finish_contexts(g_ceph_context, waiting_for_finished_proposal, 0); + + if (mon->is_leader()) + upgrade_format(); + + // NOTE: it's possible that this will get called twice if we commit + // an old paxos value. Implementations should be mindful of that. + on_active(); +} + + +void PaxosService::shutdown() +{ + cancel_events(); + + if (proposal_timer) { + dout(10) << " canceling proposal_timer " << proposal_timer << dendl; + mon->timer.cancel_event(proposal_timer); + proposal_timer = 0; + } + + finish_contexts(g_ceph_context, waiting_for_finished_proposal, -EAGAIN); + + on_shutdown(); +} + +void PaxosService::maybe_trim() +{ + if (!is_writeable()) + return; + + version_t trim_to = get_trim_to(); + if (trim_to < get_first_committed()) + return; + + version_t to_remove = trim_to - get_first_committed(); + if (g_conf()->paxos_service_trim_min > 0 && + to_remove < (version_t)g_conf()->paxos_service_trim_min) { + dout(10) << __func__ << " trim_to " << trim_to << " would only trim " << to_remove + << " < paxos_service_trim_min " << g_conf()->paxos_service_trim_min << dendl; + return; + } + + if (g_conf()->paxos_service_trim_max > 0 && + to_remove > (version_t)g_conf()->paxos_service_trim_max) { + dout(10) << __func__ << " trim_to " << trim_to << " would only trim " << to_remove + << " > paxos_service_trim_max, limiting to " << g_conf()->paxos_service_trim_max + << dendl; + trim_to = get_first_committed() + g_conf()->paxos_service_trim_max; + to_remove = g_conf()->paxos_service_trim_max; + } + + dout(10) << __func__ << " trimming to " << trim_to << ", " << to_remove << " states" << dendl; + MonitorDBStore::TransactionRef t = paxos->get_pending_transaction(); + trim(t, get_first_committed(), trim_to); + put_first_committed(t, trim_to); + cached_first_committed = trim_to; + + // let the service add any extra stuff + encode_trim_extra(t, trim_to); + + paxos->trigger_propose(); +} + +void PaxosService::trim(MonitorDBStore::TransactionRef t, + version_t from, version_t to) +{ + dout(10) << __func__ << " from " << from << " to " << to << dendl; + ceph_assert(from != to); + + for (version_t v = from; v < to; ++v) { + dout(20) << __func__ << " " << v << dendl; + t->erase(get_service_name(), v); + + string full_key = mon->store->combine_strings("full", v); + if (mon->store->exists(get_service_name(), full_key)) { + dout(20) << __func__ << " " << full_key << dendl; + t->erase(get_service_name(), full_key); + } + } + if (g_conf()->mon_compact_on_trim) { + dout(20) << " compacting prefix " << get_service_name() << dendl; + t->compact_range(get_service_name(), stringify(from - 1), stringify(to)); + t->compact_range(get_service_name(), + mon->store->combine_strings(full_prefix_name, from - 1), + mon->store->combine_strings(full_prefix_name, to)); + } +} + +void PaxosService::load_health() +{ + bufferlist bl; + mon->store->get("health", service_name, bl); + if (bl.length()) { + auto p = bl.cbegin(); + decode(health_checks, p); + } +} |