1 files changed, 566 insertions, 0 deletions

diff --git a/src/mon/Elector.cc b/src/mon/Elector.cc
new file mode 100644
index 00000000..1e364605
--- /dev/null
+++ b/src/mon/Elector.cc
@@ -0,0 +1,566 @@
+// -*- 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 "Elector.h"
+#include "Monitor.h"
+
+#include "common/Timer.h"
+#include "MonitorDBStore.h"
+#include "messages/MMonElection.h"
+
+#include "common/config.h"
+#include "include/ceph_assert.h"
+
+#define dout_subsys ceph_subsys_mon
+#undef dout_prefix
+#define dout_prefix _prefix(_dout, mon, epoch)
+static ostream& _prefix(std::ostream *_dout, Monitor *mon, epoch_t epoch) {
+  return *_dout << "mon." << mon->name << "@" << mon->rank
+		<< "(" << mon->get_state_name()
+		<< ").elector(" << epoch << ") ";
+}
+
+
+void Elector::init()
+{
+  epoch = mon->store->get(Monitor::MONITOR_NAME, "election_epoch");
+  if (!epoch) {
+    dout(1) << "init, first boot, initializing epoch at 1 " << dendl;
+    epoch = 1;
+  } else if (epoch % 2) {
+    dout(1) << "init, last seen epoch " << epoch
+	    << ", mid-election, bumping" << dendl;
+    ++epoch;
+    auto t(std::make_shared<MonitorDBStore::Transaction>());
+    t->put(Monitor::MONITOR_NAME, "election_epoch", epoch);
+    mon->store->apply_transaction(t);
+  } else {
+    dout(1) << "init, last seen epoch " << epoch << dendl;
+  }
+}
+
+void Elector::shutdown()
+{
+  cancel_timer();
+}
+
+void Elector::bump_epoch(epoch_t e) 
+{
+  dout(10) << "bump_epoch " << epoch << " to " << e << dendl;
+  ceph_assert(epoch <= e);
+  epoch = e;
+  auto t(std::make_shared<MonitorDBStore::Transaction>());
+  t->put(Monitor::MONITOR_NAME, "election_epoch", epoch);
+  mon->store->apply_transaction(t);
+
+  mon->join_election();
+
+  // clear up some state
+  electing_me = false;
+  acked_me.clear();
+}
+
+
+void Elector::start()
+{
+  if (!participating) {
+    dout(0) << "not starting new election -- not participating" << dendl;
+    return;
+  }
+  dout(5) << "start -- can i be leader?" << dendl;
+
+  acked_me.clear();
+  init();
+  
+  // start by trying to elect me
+  if (epoch % 2 == 0) {
+    bump_epoch(epoch+1);  // odd == election cycle
+  } else {
+    // do a trivial db write just to ensure it is writeable.
+    auto t(std::make_shared<MonitorDBStore::Transaction>());
+    t->put(Monitor::MONITOR_NAME, "election_writeable_test", rand());
+    int r = mon->store->apply_transaction(t);
+    ceph_assert(r >= 0);
+  }
+  electing_me = true;
+  acked_me[mon->rank].cluster_features = CEPH_FEATURES_ALL;
+  acked_me[mon->rank].mon_release = ceph_release();
+  acked_me[mon->rank].mon_features = ceph::features::mon::get_supported();
+  mon->collect_metadata(&acked_me[mon->rank].metadata);
+  leader_acked = -1;
+
+  // bcast to everyone else
+  for (unsigned i=0; i<mon->monmap->size(); ++i) {
+    if ((int)i == mon->rank) continue;
+    MMonElection *m =
+      new MMonElection(MMonElection::OP_PROPOSE, epoch, mon->monmap);
+    m->mon_features = ceph::features::mon::get_supported();
+    m->mon_release = ceph_release();
+    mon->send_mon_message(m, i);
+  }
+  
+  reset_timer();
+}
+
+void Elector::defer(int who)
+{
+  dout(5) << "defer to " << who << dendl;
+
+  if (electing_me) {
+    // drop out
+    acked_me.clear();
+    electing_me = false;
+  }
+
+  // ack them
+  leader_acked = who;
+  MMonElection *m = new MMonElection(MMonElection::OP_ACK, epoch, mon->monmap);
+  m->mon_features = ceph::features::mon::get_supported();
+  m->mon_release = ceph_release();
+  mon->collect_metadata(&m->metadata);
+
+  mon->send_mon_message(m, who);
+  
+  // set a timer
+  reset_timer(1.0);  // give the leader some extra time to declare victory
+}
+
+
+void Elector::reset_timer(double plus)
+{
+  // set the timer
+  cancel_timer();
+  /**
+   * This class is used as the callback when the expire_event timer fires up.
+   *
+   * If the expire_event is fired, then it means that we had an election going,
+   * either started by us or by some other participant, but it took too long,
+   * thus expiring.
+   *
+   * When the election expires, we will check if we were the ones who won, and
+   * if so we will declare victory. If that is not the case, then we assume
+   * that the one we defered to didn't declare victory quickly enough (in fact,
+   * as far as we know, we may even be dead); so, just propose ourselves as the
+   * Leader.
+   */
+  expire_event = mon->timer.add_event_after(
+    g_conf()->mon_election_timeout + plus,
+    new C_MonContext(mon, [this](int) {
+	expire();
+      }));
+}
+
+
+void Elector::cancel_timer()
+{
+  if (expire_event) {
+    mon->timer.cancel_event(expire_event);
+    expire_event = 0;
+  }
+}
+
+void Elector::expire()
+{
+  dout(5) << "election timer expired" << dendl;
+  
+  // did i win?
+  if (electing_me &&
+      acked_me.size() > (unsigned)(mon->monmap->size() / 2)) {
+    // i win
+    victory();
+  } else {
+    // whoever i deferred to didn't declare victory quickly enough.
+    if (mon->has_ever_joined)
+      start();
+    else
+      mon->bootstrap();
+  }
+}
+
+
+void Elector::victory()
+{
+  leader_acked = -1;
+  electing_me = false;
+
+  uint64_t cluster_features = CEPH_FEATURES_ALL;
+  mon_feature_t mon_features = ceph::features::mon::get_supported();
+  set<int> quorum;
+  map<int,Metadata> metadata;
+  int min_mon_release = -1;
+  for (map<int, elector_info_t>::iterator p = acked_me.begin();
+       p != acked_me.end();
+       ++p) {
+    quorum.insert(p->first);
+    cluster_features &= p->second.cluster_features;
+    mon_features &= p->second.mon_features;
+    metadata[p->first] = p->second.metadata;
+    if (min_mon_release < 0 || p->second.mon_release < min_mon_release) {
+      min_mon_release = p->second.mon_release;
+    }
+  }
+
+  cancel_timer();
+  
+  ceph_assert(epoch % 2 == 1);  // election
+  bump_epoch(epoch+1);     // is over!
+
+  // tell everyone!
+  for (set<int>::iterator p = quorum.begin();
+       p != quorum.end();
+       ++p) {
+    if (*p == mon->rank) continue;
+    MMonElection *m = new MMonElection(MMonElection::OP_VICTORY, epoch,
+				       mon->monmap);
+    m->quorum = quorum;
+    m->quorum_features = cluster_features;
+    m->mon_features = mon_features;
+    m->sharing_bl = mon->get_local_commands_bl(mon_features);
+    m->mon_release = min_mon_release;
+    mon->send_mon_message(m, *p);
+  }
+
+  // tell monitor
+  mon->win_election(epoch, quorum,
+                    cluster_features, mon_features, min_mon_release,
+		    metadata);
+}
+
+
+void Elector::handle_propose(MonOpRequestRef op)
+{
+  op->mark_event("elector:handle_propose");
+  MMonElection *m = static_cast<MMonElection*>(op->get_req());
+  dout(5) << "handle_propose from " << m->get_source() << dendl;
+  int from = m->get_source().num();
+
+  ceph_assert(m->epoch % 2 == 1); // election
+  uint64_t required_features = mon->get_required_features();
+  mon_feature_t required_mon_features = mon->get_required_mon_features();
+
+  dout(10) << __func__ << " required features " << required_features
+           << " " << required_mon_features
+           << ", peer features " << m->get_connection()->get_features()
+           << " " << m->mon_features
+           << dendl;
+
+  if ((required_features ^ m->get_connection()->get_features()) &
+      required_features) {
+    dout(5) << " ignoring propose from mon" << from
+	    << " without required features" << dendl;
+    nak_old_peer(op);
+    return;
+  } else if (mon->monmap->min_mon_release > m->mon_release) {
+    dout(5) << " ignoring propose from mon" << from
+	    << " release " << (int)m->mon_release
+	    << " < min_mon_release " << (int)mon->monmap->min_mon_release
+	    << dendl;
+    nak_old_peer(op);
+    return;
+  } else if (!m->mon_features.contains_all(required_mon_features)) {
+    // all the features in 'required_mon_features' not in 'm->mon_features'
+    mon_feature_t missing = required_mon_features.diff(m->mon_features);
+    dout(5) << " ignoring propose from mon." << from
+            << " without required mon_features " << missing
+            << dendl;
+    nak_old_peer(op);
+  } else if (m->epoch > epoch) {
+    bump_epoch(m->epoch);
+  } else if (m->epoch < epoch) {
+    // got an "old" propose,
+    if (epoch % 2 == 0 &&    // in a non-election cycle
+	mon->quorum.count(from) == 0) {  // from someone outside the quorum
+      // a mon just started up, call a new election so they can rejoin!
+      dout(5) << " got propose from old epoch, quorum is " << mon->quorum 
+	      << ", " << m->get_source() << " must have just started" << dendl;
+      // we may be active; make sure we reset things in the monitor appropriately.
+      mon->start_election();
+    } else {
+      dout(5) << " ignoring old propose" << dendl;
+    }
+    return;
+  }
+
+  if (mon->rank < from) {
+    // i would win over them.
+    if (leader_acked >= 0) {        // we already acked someone
+      ceph_assert(leader_acked < from);  // and they still win, of course
+      dout(5) << "no, we already acked " << leader_acked << dendl;
+    } else {
+      // wait, i should win!
+      if (!electing_me) {
+	mon->start_election();
+      }
+    }
+  } else {
+    // they would win over me
+    if (leader_acked < 0 ||      // haven't acked anyone yet, or
+	leader_acked > from ||   // they would win over who you did ack, or
+	leader_acked == from) {  // this is the guy we're already deferring to
+      defer(from);
+    } else {
+      // ignore them!
+      dout(5) << "no, we already acked " << leader_acked << dendl;
+    }
+  }
+}
+
+void Elector::handle_ack(MonOpRequestRef op)
+{
+  op->mark_event("elector:handle_ack");
+  MMonElection *m = static_cast<MMonElection*>(op->get_req());
+  dout(5) << "handle_ack from " << m->get_source() << dendl;
+  int from = m->get_source().num();
+
+  ceph_assert(m->epoch % 2 == 1); // election
+  if (m->epoch > epoch) {
+    dout(5) << "woah, that's a newer epoch, i must have rebooted.  bumping and re-starting!" << dendl;
+    bump_epoch(m->epoch);
+    start();
+    return;
+  }
+  ceph_assert(m->epoch == epoch);
+  uint64_t required_features = mon->get_required_features();
+  if ((required_features ^ m->get_connection()->get_features()) &
+      required_features) {
+    dout(5) << " ignoring ack from mon" << from
+	    << " without required features" << dendl;
+    return;
+  }
+
+  mon_feature_t required_mon_features = mon->get_required_mon_features();
+  if (!m->mon_features.contains_all(required_mon_features)) {
+    mon_feature_t missing = required_mon_features.diff(m->mon_features);
+    dout(5) << " ignoring ack from mon." << from
+            << " without required mon_features " << missing
+            << dendl;
+    return;
+  }
+
+  if (electing_me) {
+    // thanks
+    acked_me[from].cluster_features = m->get_connection()->get_features();
+    acked_me[from].mon_features = m->mon_features;
+    acked_me[from].mon_release = m->mon_release;
+    acked_me[from].metadata = m->metadata;
+    dout(5) << " so far i have {";
+    for (map<int, elector_info_t>::const_iterator p = acked_me.begin();
+         p != acked_me.end();
+         ++p) {
+      if (p != acked_me.begin())
+        *_dout << ",";
+      *_dout << " mon." << p->first << ":"
+             << " features " << p->second.cluster_features
+             << " " << p->second.mon_features;
+    }
+    *_dout << " }" << dendl;
+
+    // is that _everyone_?
+    if (acked_me.size() == mon->monmap->size()) {
+      // if yes, shortcut to election finish
+      victory();
+    }
+  } else {
+    // ignore, i'm deferring already.
+    ceph_assert(leader_acked >= 0);
+  }
+}
+
+
+void Elector::handle_victory(MonOpRequestRef op)
+{
+  op->mark_event("elector:handle_victory");
+  MMonElection *m = static_cast<MMonElection*>(op->get_req());
+  dout(5) << "handle_victory from " << m->get_source()
+          << " quorum_features " << m->quorum_features
+          << " " << m->mon_features
+          << dendl;
+  int from = m->get_source().num();
+
+  ceph_assert(from < mon->rank);
+  ceph_assert(m->epoch % 2 == 0);  
+
+  leader_acked = -1;
+
+  // i should have seen this election if i'm getting the victory.
+  if (m->epoch != epoch + 1) { 
+    dout(5) << "woah, that's a funny epoch, i must have rebooted.  bumping and re-starting!" << dendl;
+    bump_epoch(m->epoch);
+    start();
+    return;
+  }
+
+  bump_epoch(m->epoch);
+
+  // they win
+  mon->lose_election(epoch, m->quorum, from,
+                     m->quorum_features, m->mon_features, m->mon_release);
+
+  // cancel my timer
+  cancel_timer();
+
+  // stash leader's commands
+  ceph_assert(m->sharing_bl.length());
+  vector<MonCommand> new_cmds;
+  auto bi = m->sharing_bl.cbegin();
+  MonCommand::decode_vector(new_cmds, bi);
+  mon->set_leader_commands(new_cmds);
+}
+
+void Elector::nak_old_peer(MonOpRequestRef op)
+{
+  op->mark_event("elector:nak_old_peer");
+  MMonElection *m = static_cast<MMonElection*>(op->get_req());
+  uint64_t supported_features = m->get_connection()->get_features();
+  uint64_t required_features = mon->get_required_features();
+  mon_feature_t required_mon_features = mon->get_required_mon_features();
+  dout(10) << "sending nak to peer " << m->get_source()
+	   << " supports " << supported_features << " " << m->mon_features
+	   << ", required " << required_features << " " << required_mon_features
+	   << ", release " << (int)m->mon_release
+	   << " vs required " << (int)mon->monmap->min_mon_release
+	   << dendl;
+  MMonElection *reply = new MMonElection(MMonElection::OP_NAK, m->epoch,
+                                         mon->monmap);
+  reply->quorum_features = required_features;
+  reply->mon_features = required_mon_features;
+  reply->mon_release = mon->monmap->min_mon_release;
+  mon->features.encode(reply->sharing_bl);
+  m->get_connection()->send_message(reply);
+}
+
+void Elector::handle_nak(MonOpRequestRef op)
+{
+  op->mark_event("elector:handle_nak");
+  MMonElection *m = static_cast<MMonElection*>(op->get_req());
+  dout(1) << "handle_nak from " << m->get_source()
+	  << " quorum_features " << m->quorum_features
+          << " " << m->mon_features
+	  << " min_mon_release " << (int)m->mon_release
+          << dendl;
+
+  if (m->mon_release > ceph_release()) {
+    derr << "Shutting down because I am release " << (int)ceph_release()
+	 << " < min_mon_release " << (int)m->mon_release << dendl;
+  } else {
+    CompatSet other;
+    auto bi = m->sharing_bl.cbegin();
+    other.decode(bi);
+    CompatSet diff = Monitor::get_supported_features().unsupported(other);
+
+    mon_feature_t mon_supported = ceph::features::mon::get_supported();
+    // all features in 'm->mon_features' not in 'mon_supported'
+    mon_feature_t mon_diff = m->mon_features.diff(mon_supported);
+
+    derr << "Shutting down because I lack required monitor features: { "
+	 << diff << " } " << mon_diff << dendl;
+  }
+  exit(0);
+  // the end!
+}
+
+void Elector::dispatch(MonOpRequestRef op)
+{
+  op->mark_event("elector:dispatch");
+  ceph_assert(op->is_type_election());
+
+  switch (op->get_req()->get_type()) {
+    
+  case MSG_MON_ELECTION:
+    {
+      if (!participating) {
+        return;
+      }
+      if (op->get_req()->get_source().num() >= mon->monmap->size()) {
+	dout(5) << " ignoring bogus election message with bad mon rank " 
+		<< op->get_req()->get_source() << dendl;
+	return;
+      }
+
+      MMonElection *em = static_cast<MMonElection*>(op->get_req());
+
+      // assume an old message encoding would have matched
+      if (em->fsid != mon->monmap->fsid) {
+	dout(0) << " ignoring election msg fsid " 
+		<< em->fsid << " != " << mon->monmap->fsid << dendl;
+	return;
+      }
+
+      if (!mon->monmap->contains(em->get_source_addr())) {
+	dout(1) << "discarding election message: " << em->get_source_addr()
+		<< " not in my monmap " << *mon->monmap << dendl;
+	return;
+      }
+
+      MonMap peermap;
+      peermap.decode(em->monmap_bl);
+      if (peermap.epoch > mon->monmap->epoch) {
+	dout(0) << em->get_source_inst() << " has newer monmap epoch " << peermap.epoch
+		<< " > my epoch " << mon->monmap->epoch 
+		<< ", taking it"
+		<< dendl;
+	mon->monmap->decode(em->monmap_bl);
+        auto t(std::make_shared<MonitorDBStore::Transaction>());
+        t->put("monmap", mon->monmap->epoch, em->monmap_bl);
+        t->put("monmap", "last_committed", mon->monmap->epoch);
+        mon->store->apply_transaction(t);
+	//mon->monmon()->paxos->stash_latest(mon->monmap->epoch, em->monmap_bl);
+	cancel_timer();
+	mon->bootstrap();
+	return;
+      }
+      if (peermap.epoch < mon->monmap->epoch) {
+	dout(0) << em->get_source_inst() << " has older monmap epoch " << peermap.epoch
+		<< " < my epoch " << mon->monmap->epoch 
+		<< dendl;
+      } 
+
+      switch (em->op) {
+      case MMonElection::OP_PROPOSE:
+	handle_propose(op);
+	return;
+      }
+
+      if (em->epoch < epoch) {
+	dout(5) << "old epoch, dropping" << dendl;
+	break;
+      }
+
+      switch (em->op) {
+      case MMonElection::OP_ACK:
+	handle_ack(op);
+	return;
+      case MMonElection::OP_VICTORY:
+	handle_victory(op);
+	return;
+      case MMonElection::OP_NAK:
+	handle_nak(op);
+	return;
+      default:
+	ceph_abort();
+      }
+    }
+    break;
+    
+  default: 
+    ceph_abort();
+  }
+}
+
+void Elector::start_participating()
+{
+  if (!participating) {
+    participating = true;
+  }
+}