X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?p=controller.git;a=blobdiff_plain;f=opendaylight%2Fmd-sal%2Fsal-akka-raft%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fcluster%2Fraft%2Fbehaviors%2FFollower.java;h=8aee8c1af88c31da507bede83065d3d457b76428;hp=2480a0db8f734bc6d1d0801b1b57e92e73769189;hb=d3c5dc3b0f6bea3fa1c2f964353b87d1a9fcaef8;hpb=630cb61cc1e51a486785162995eab7b541fcf237 diff --git a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Follower.java b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Follower.java index 2480a0db8f..8aee8c1af8 100644 --- a/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Follower.java +++ b/opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/behaviors/Follower.java @@ -9,17 +9,29 @@ package org.opendaylight.controller.cluster.raft.behaviors; import akka.actor.ActorRef; +import akka.actor.ActorSelection; +import akka.actor.Address; +import akka.cluster.Cluster; +import akka.cluster.ClusterEvent.CurrentClusterState; +import akka.cluster.Member; +import akka.cluster.MemberStatus; import akka.japi.Procedure; import com.google.common.annotations.VisibleForTesting; -import com.google.common.base.Preconditions; +import com.google.common.base.Stopwatch; +import java.io.IOException; import java.util.ArrayList; +import java.util.List; +import java.util.Optional; +import java.util.Set; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import javax.annotation.Nullable; import org.opendaylight.controller.cluster.raft.RaftActorContext; import org.opendaylight.controller.cluster.raft.RaftState; import org.opendaylight.controller.cluster.raft.ReplicatedLogEntry; -import org.opendaylight.controller.cluster.raft.ServerConfigurationPayload; -import org.opendaylight.controller.cluster.raft.Snapshot; import org.opendaylight.controller.cluster.raft.base.messages.ApplySnapshot; import org.opendaylight.controller.cluster.raft.base.messages.ElectionTimeout; +import org.opendaylight.controller.cluster.raft.base.messages.TimeoutNow; import org.opendaylight.controller.cluster.raft.messages.AppendEntries; import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply; import org.opendaylight.controller.cluster.raft.messages.InstallSnapshot; @@ -27,10 +39,11 @@ import org.opendaylight.controller.cluster.raft.messages.InstallSnapshotReply; import org.opendaylight.controller.cluster.raft.messages.RaftRPC; import org.opendaylight.controller.cluster.raft.messages.RequestVote; import org.opendaylight.controller.cluster.raft.messages.RequestVoteReply; +import org.opendaylight.controller.cluster.raft.persisted.ServerConfigurationPayload; +import org.opendaylight.controller.cluster.raft.persisted.Snapshot; /** - * The behavior of a RaftActor in the Follower state - *

+ * The behavior of a RaftActor in the Follower raft state. *

*/ public class Follower extends AbstractRaftActorBehavior { - private static final int SYNC_THRESHOLD = 10; + private static final long MAX_ELECTION_TIMEOUT_FACTOR = 18; private final SyncStatusTracker initialSyncStatusTracker; - private final Procedure appendAndPersistCallback = new Procedure() { - @Override - public void apply(ReplicatedLogEntry logEntry) { - context.getReplicatedLog().captureSnapshotIfReady(logEntry); - } - }; - + private final Stopwatch lastLeaderMessageTimer = Stopwatch.createStarted(); private SnapshotTracker snapshotTracker = null; private String leaderId; private short leaderPayloadVersion; - public Follower(RaftActorContext context) { + public Follower(final RaftActorContext context) { this(context, null, (short)-1); } - public Follower(RaftActorContext context, String initialLeaderId, short initialLeaderPayloadVersion) { + public Follower(final RaftActorContext context, final String initialLeaderId, + final short initialLeaderPayloadVersion) { super(context, RaftState.Follower); this.leaderId = initialLeaderId; this.leaderPayloadVersion = initialLeaderPayloadVersion; - initialSyncStatusTracker = new SyncStatusTracker(context.getActor(), getId(), SYNC_THRESHOLD); + initialSyncStatusTracker = new SyncStatusTracker(context.getActor(), getId(), context.getConfigParams() + .getSyncIndexThreshold()); - if(canStartElection()) { - if (context.getPeerIds().isEmpty() && getLeaderId() == null) { - actor().tell(ElectionTimeout.INSTANCE, actor()); - } else { - scheduleElection(electionDuration()); - } + if (context.getPeerIds().isEmpty() && getLeaderId() == null) { + actor().tell(TimeoutNow.INSTANCE, actor()); + } else { + scheduleElection(electionDuration()); } } @@ -80,8 +87,8 @@ public class Follower extends AbstractRaftActorBehavior { } @VisibleForTesting - protected final void setLeaderId(final String leaderId) { - this.leaderId = Preconditions.checkNotNull(leaderId); + protected final void setLeaderId(@Nullable final String leaderId) { + this.leaderId = leaderId; } @Override @@ -90,63 +97,58 @@ public class Follower extends AbstractRaftActorBehavior { } @VisibleForTesting - protected final void setLeaderPayloadVersion(short leaderPayloadVersion) { + protected final void setLeaderPayloadVersion(final short leaderPayloadVersion) { this.leaderPayloadVersion = leaderPayloadVersion; } - private boolean isLogEntryPresent(long index){ - if(index == context.getReplicatedLog().getSnapshotIndex()){ - return true; + private void restartLastLeaderMessageTimer() { + if (lastLeaderMessageTimer.isRunning()) { + lastLeaderMessageTimer.reset(); } - ReplicatedLogEntry previousEntry = context.getReplicatedLog() - .get(index); - - return previousEntry != null; - + lastLeaderMessageTimer.start(); } - private long getLogEntryTerm(long index){ - if(index == context.getReplicatedLog().getSnapshotIndex()){ - return context.getReplicatedLog().getSnapshotTerm(); + private boolean isLogEntryPresent(final long index) { + if (context.getReplicatedLog().isInSnapshot(index)) { + return true; } - ReplicatedLogEntry previousEntry = context.getReplicatedLog() - .get(index); - - if(previousEntry != null){ - return previousEntry.getTerm(); - } + ReplicatedLogEntry entry = context.getReplicatedLog().get(index); + return entry != null; - return -1; } - private void updateInitialSyncStatus(long currentLeaderCommit, String leaderId){ - initialSyncStatusTracker.update(leaderId, currentLeaderCommit, context.getCommitIndex()); + private void updateInitialSyncStatus(final long currentLeaderCommit, final String newLeaderId) { + initialSyncStatusTracker.update(newLeaderId, currentLeaderCommit, context.getCommitIndex()); } @Override - protected RaftActorBehavior handleAppendEntries(ActorRef sender, AppendEntries appendEntries) { + protected RaftActorBehavior handleAppendEntries(final ActorRef sender, final AppendEntries appendEntries) { int numLogEntries = appendEntries.getEntries() != null ? appendEntries.getEntries().size() : 0; - if(LOG.isTraceEnabled()) { - LOG.trace("{}: handleAppendEntries: {}", logName(), appendEntries); - } else if(LOG.isDebugEnabled() && numLogEntries > 0) { - LOG.debug("{}: handleAppendEntries: {}", logName(), appendEntries); + if (log.isTraceEnabled()) { + log.trace("{}: handleAppendEntries: {}", logName(), appendEntries); + } else if (log.isDebugEnabled() && numLogEntries > 0) { + log.debug("{}: handleAppendEntries: {}", logName(), appendEntries); } // TODO : Refactor this method into a bunch of smaller methods // to make it easier to read. Before refactoring ensure tests // cover the code properly + if (snapshotTracker != null && !snapshotTracker.getLeaderId().equals(appendEntries.getLeaderId())) { + log.debug("{}: snapshot install is in progress but the prior snapshot leaderId {} does not match the " + + "AppendEntries leaderId {}", logName(), snapshotTracker.getLeaderId(), appendEntries.getLeaderId()); + closeSnapshotTracker(); + } + if (snapshotTracker != null || context.getSnapshotManager().isApplying()) { // if snapshot install is in progress, follower should just acknowledge append entries with a reply. AppendEntriesReply reply = new AppendEntriesReply(context.getId(), currentTerm(), true, lastIndex(), lastTerm(), context.getPayloadVersion()); - if(LOG.isDebugEnabled()) { - LOG.debug("{}: snapshot install is in progress, replying immediately with {}", logName(), reply); - } + log.debug("{}: snapshot install is in progress, replying immediately with {}", logName(), reply); sender.tell(reply, actor()); return this; @@ -156,7 +158,6 @@ public class Follower extends AbstractRaftActorBehavior { leaderId = appendEntries.getLeaderId(); leaderPayloadVersion = appendEntries.getPayloadVersion(); - updateInitialSyncStatus(appendEntries.getLeaderCommit(), appendEntries.getLeaderId()); // First check if the logs are in sync or not long lastIndex = lastIndex(); @@ -164,17 +165,18 @@ public class Follower extends AbstractRaftActorBehavior { // We found that the log was out of sync so just send a negative // reply and return - LOG.debug("{}: Follower is out-of-sync, so sending negative reply, lastIndex: {}, lastTerm: {}", - logName(), lastIndex, lastTerm()); + final AppendEntriesReply reply = new AppendEntriesReply(context.getId(), currentTerm(), false, lastIndex, + lastTerm(), context.getPayloadVersion()); - sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), false, lastIndex, - lastTerm(), context.getPayloadVersion()), actor()); + log.info("{}: Follower is out-of-sync so sending negative reply: {}", logName(), reply); + updateInitialSyncStatus(appendEntries.getLeaderCommit(), appendEntries.getLeaderId()); + sender.tell(reply, actor()); return this; } if (appendEntries.getEntries() != null && appendEntries.getEntries().size() > 0) { - LOG.debug("{}: Number of entries to be appended = {}", logName(), + log.debug("{}: Number of entries to be appended = {}", logName(), appendEntries.getEntries().size()); // 3. If an existing entry conflicts with a new one (same index @@ -186,26 +188,44 @@ public class Follower extends AbstractRaftActorBehavior { // Find the entry up until the one that is not in the follower's log for (int i = 0;i < appendEntries.getEntries().size(); i++, addEntriesFrom++) { ReplicatedLogEntry matchEntry = appendEntries.getEntries().get(i); - ReplicatedLogEntry newEntry = context.getReplicatedLog().get(matchEntry.getIndex()); - if (newEntry == null) { - //newEntry not found in the log + if (!isLogEntryPresent(matchEntry.getIndex())) { + // newEntry not found in the log break; } - if (newEntry.getTerm() == matchEntry.getTerm()) { + long existingEntryTerm = getLogEntryTerm(matchEntry.getIndex()); + + log.debug("{}: matchEntry {} is present: existingEntryTerm: {}", logName(), matchEntry, + existingEntryTerm); + + // existingEntryTerm == -1 means it's in the snapshot and not in the log. We don't know + // what the term was so we'll assume it matches. + if (existingEntryTerm == -1 || existingEntryTerm == matchEntry.getTerm()) { continue; } - if(!context.getRaftPolicy().applyModificationToStateBeforeConsensus()) { + if (!context.getRaftPolicy().applyModificationToStateBeforeConsensus()) { - LOG.debug("{}: Removing entries from log starting at {}", logName(), - matchEntry.getIndex()); + log.info("{}: Removing entries from log starting at {}", logName(), matchEntry.getIndex()); // Entries do not match so remove all subsequent entries - context.getReplicatedLog().removeFromAndPersist(matchEntry.getIndex()); + if (!context.getReplicatedLog().removeFromAndPersist(matchEntry.getIndex())) { + // Could not remove the entries - this means the matchEntry index must be in the + // snapshot and not the log. In this case the prior entries are part of the state + // so we must send back a reply to force a snapshot to completely re-sync the + // follower's log and state. + + log.info("{}: Could not remove entries - sending reply to force snapshot", logName()); + updateInitialSyncStatus(appendEntries.getLeaderCommit(), appendEntries.getLeaderId()); + sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), false, lastIndex, + lastTerm(), context.getPayloadVersion(), true), actor()); + return this; + } + break; } else { + updateInitialSyncStatus(appendEntries.getLeaderCommit(), appendEntries.getLeaderId()); sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), false, lastIndex, lastTerm(), context.getPayloadVersion(), true), actor()); return this; @@ -214,23 +234,42 @@ public class Follower extends AbstractRaftActorBehavior { } lastIndex = lastIndex(); - LOG.debug("{}: After cleanup entries to be added from = {}", logName(), - (addEntriesFrom + lastIndex)); + log.debug("{}: After cleanup, lastIndex: {}, entries to be added from: {}", logName(), + lastIndex, addEntriesFrom); + + // When persistence successfully completes for each new log entry appended, we need to determine if we + // should capture a snapshot to compact the persisted log. shouldCaptureSnapshot tracks whether or not + // one of the log entries has exceeded the log size threshold whereby a snapshot should be taken. However + // we don't initiate the snapshot at that log entry but rather after the last log entry has been persisted. + // This is done because subsequent log entries after the one that tripped the threshold may have been + // applied to the state already, as the persistence callback occurs async, and we want those entries + // purged from the persisted log as well. + final AtomicBoolean shouldCaptureSnapshot = new AtomicBoolean(false); + final Procedure appendAndPersistCallback = logEntry -> { + final ReplicatedLogEntry lastEntryToAppend = appendEntries.getEntries().get( + appendEntries.getEntries().size() - 1); + if (shouldCaptureSnapshot.get() && logEntry == lastEntryToAppend) { + context.getSnapshotManager().capture(context.getReplicatedLog().last(), getReplicatedToAllIndex()); + } + }; // 4. Append any new entries not already in the log for (int i = addEntriesFrom; i < appendEntries.getEntries().size(); i++) { ReplicatedLogEntry entry = appendEntries.getEntries().get(i); - LOG.debug("{}: Append entry to log {}", logName(), entry.getData()); + log.debug("{}: Append entry to log {}", logName(), entry.getData()); + + context.getReplicatedLog().appendAndPersist(entry, appendAndPersistCallback, false); - context.getReplicatedLog().appendAndPersist(entry, appendAndPersistCallback); + shouldCaptureSnapshot.compareAndSet(false, + context.getReplicatedLog().shouldCaptureSnapshot(entry.getIndex())); - if(entry.getData() instanceof ServerConfigurationPayload) { + if (entry.getData() instanceof ServerConfigurationPayload) { context.updatePeerIds((ServerConfigurationPayload)entry.getData()); } } - LOG.debug("{}: Log size is now {}", logName(), context.getReplicatedLog().size()); + log.debug("{}: Log size is now {}", logName(), context.getReplicatedLog().size()); } // 5. If leaderCommit > commitIndex, set commitIndex = @@ -239,38 +278,41 @@ public class Follower extends AbstractRaftActorBehavior { lastIndex = lastIndex(); long prevCommitIndex = context.getCommitIndex(); - context.setCommitIndex(Math.min(appendEntries.getLeaderCommit(), lastIndex)); + if (appendEntries.getLeaderCommit() > prevCommitIndex) { + context.setCommitIndex(Math.min(appendEntries.getLeaderCommit(), lastIndex)); + } if (prevCommitIndex != context.getCommitIndex()) { - LOG.debug("{}: Commit index set to {}", logName(), context.getCommitIndex()); + log.debug("{}: Commit index set to {}", logName(), context.getCommitIndex()); + } + + AppendEntriesReply reply = new AppendEntriesReply(context.getId(), currentTerm(), true, + lastIndex, lastTerm(), context.getPayloadVersion()); + + if (log.isTraceEnabled()) { + log.trace("{}: handleAppendEntries returning : {}", logName(), reply); + } else if (log.isDebugEnabled() && numLogEntries > 0) { + log.debug("{}: handleAppendEntries returning : {}", logName(), reply); } + // Reply to the leader before applying any previous state so as not to hold up leader consensus. + updateInitialSyncStatus(appendEntries.getLeaderCommit(), appendEntries.getLeaderId()); + sender.tell(reply, actor()); + // If commitIndex > lastApplied: increment lastApplied, apply // log[lastApplied] to state machine (§5.3) // check if there are any entries to be applied. last-applied can be equal to last-index - if (appendEntries.getLeaderCommit() > context.getLastApplied() && - context.getLastApplied() < lastIndex) { - if(LOG.isDebugEnabled()) { - LOG.debug("{}: applyLogToStateMachine, " + - "appendEntries.getLeaderCommit(): {}," + - "context.getLastApplied(): {}, lastIndex(): {}", logName(), + if (appendEntries.getLeaderCommit() > context.getLastApplied() + && context.getLastApplied() < lastIndex) { + if (log.isDebugEnabled()) { + log.debug("{}: applyLogToStateMachine, appendEntries.getLeaderCommit(): {}, " + + "context.getLastApplied(): {}, lastIndex(): {}", logName(), appendEntries.getLeaderCommit(), context.getLastApplied(), lastIndex); } applyLogToStateMachine(appendEntries.getLeaderCommit()); } - AppendEntriesReply reply = new AppendEntriesReply(context.getId(), currentTerm(), true, - lastIndex, lastTerm(), context.getPayloadVersion()); - - if(LOG.isTraceEnabled()) { - LOG.trace("{}: handleAppendEntries returning : {}", logName(), reply); - } else if(LOG.isDebugEnabled() && numLogEntries > 0) { - LOG.debug("{}: handleAppendEntries returning : {}", logName(), reply); - } - - sender.tell(reply, actor()); - if (!context.getSnapshotManager().isCapturing()) { super.performSnapshotWithoutCapture(appendEntries.getReplicatedToAllIndex()); } @@ -278,118 +320,217 @@ public class Follower extends AbstractRaftActorBehavior { return this; } - private boolean isOutOfSync(AppendEntries appendEntries) { - - long prevLogTerm = getLogEntryTerm(appendEntries.getPrevLogIndex()); - boolean prevEntryPresent = isLogEntryPresent(appendEntries.getPrevLogIndex()); - long lastIndex = lastIndex(); - int numLogEntries = appendEntries.getEntries() != null ? appendEntries.getEntries().size() : 0; - boolean outOfSync = true; + private boolean isOutOfSync(final AppendEntries appendEntries) { + final long lastIndex = lastIndex(); if (lastIndex == -1 && appendEntries.getPrevLogIndex() != -1) { - // The follower's log is out of sync because the leader does have - // an entry at prevLogIndex and this follower has no entries in - // it's log. - - LOG.debug("{}: The followers log is empty and the senders prevLogIndex is {}", - logName(), appendEntries.getPrevLogIndex()); - } else if (lastIndex > -1 && appendEntries.getPrevLogIndex() != -1 && !prevEntryPresent) { - - // The follower's log is out of sync because the Leader's - // prevLogIndex entry was not found in it's log - - LOG.debug("{}: The log is not empty but the prevLogIndex {} was not found in it", - logName(), appendEntries.getPrevLogIndex()); - } else if (lastIndex > -1 && prevEntryPresent && prevLogTerm != appendEntries.getPrevLogTerm()) { - - // The follower's log is out of sync because the Leader's - // prevLogIndex entry does exist in the follower's log but it has - // a different term in it - - LOG.debug( - "{}: Cannot append entries because previous entry term {} is not equal to append entries prevLogTerm {}", - logName(), prevLogTerm, appendEntries.getPrevLogTerm()); - } else if(appendEntries.getPrevLogIndex() == -1 && appendEntries.getPrevLogTerm() == -1 - && appendEntries.getReplicatedToAllIndex() != -1 - && !isLogEntryPresent(appendEntries.getReplicatedToAllIndex()) - && !context.getReplicatedLog().isInSnapshot(appendEntries.getReplicatedToAllIndex())) { - // This append entry comes from a leader who has it's log aggressively trimmed and so does not have - // the previous entry in it's in-memory journal - - LOG.debug( - "{}: Cannot append entries because the replicatedToAllIndex {} does not appear to be in the in-memory journal", - logName(), appendEntries.getReplicatedToAllIndex()); - } else if(appendEntries.getPrevLogIndex() == -1 && appendEntries.getPrevLogTerm() == -1 - && appendEntries.getReplicatedToAllIndex() != -1 && numLogEntries > 0 - && !isLogEntryPresent(appendEntries.getEntries().get(0).getIndex() - 1) - && !context.getReplicatedLog().isInSnapshot(appendEntries.getEntries().get(0).getIndex() - 1)) { - LOG.debug( - "{}: Cannot append entries because the calculated previousIndex {} was not found in the in-memory journal", - logName(), appendEntries.getEntries().get(0).getIndex() - 1); - } else { - outOfSync = false; + // The follower's log is out of sync because the leader does have an entry at prevLogIndex and this + // follower has no entries in it's log. + + log.info("{}: The followers log is empty and the senders prevLogIndex is {}", logName(), + appendEntries.getPrevLogIndex()); + return true; } - return outOfSync; + + if (lastIndex > -1) { + if (isLogEntryPresent(appendEntries.getPrevLogIndex())) { + final long prevLogTerm = getLogEntryTerm(appendEntries.getPrevLogIndex()); + if (prevLogTerm != appendEntries.getPrevLogTerm()) { + + // The follower's log is out of sync because the Leader's prevLogIndex entry does exist + // in the follower's log but it has a different term in it + + log.info("{}: The prevLogIndex {} was found in the log but the term {} is not equal to the append " + + "entries prevLogTerm {} - lastIndex: {}, snapshotIndex: {}", logName(), + appendEntries.getPrevLogIndex(), prevLogTerm, appendEntries.getPrevLogTerm(), lastIndex, + context.getReplicatedLog().getSnapshotIndex()); + return true; + } + } else if (appendEntries.getPrevLogIndex() != -1) { + + // The follower's log is out of sync because the Leader's prevLogIndex entry was not found in it's log + + log.info("{}: The log is not empty but the prevLogIndex {} was not found in it - lastIndex: {}, " + + "snapshotIndex: {}", logName(), appendEntries.getPrevLogIndex(), lastIndex, + context.getReplicatedLog().getSnapshotIndex()); + return true; + } + } + + if (appendEntries.getPrevLogIndex() == -1 && appendEntries.getPrevLogTerm() == -1 + && appendEntries.getReplicatedToAllIndex() != -1) { + if (!isLogEntryPresent(appendEntries.getReplicatedToAllIndex())) { + // This append entry comes from a leader who has it's log aggressively trimmed and so does not have + // the previous entry in it's in-memory journal + + log.info("{}: Cannot append entries because the replicatedToAllIndex {} does not appear to be in the " + + "in-memory journal", logName(), appendEntries.getReplicatedToAllIndex()); + return true; + } + + final List entries = appendEntries.getEntries(); + if (entries != null && entries.size() > 0 && !isLogEntryPresent(entries.get(0).getIndex() - 1)) { + log.info("{}: Cannot append entries because the calculated previousIndex {} was not found in the " + + "in-memory journal", logName(), entries.get(0).getIndex() - 1); + return true; + } + } + + return false; } @Override - protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender, - AppendEntriesReply appendEntriesReply) { + protected RaftActorBehavior handleAppendEntriesReply(final ActorRef sender, + final AppendEntriesReply appendEntriesReply) { return this; } @Override - protected RaftActorBehavior handleRequestVoteReply(ActorRef sender, - RequestVoteReply requestVoteReply) { + protected RaftActorBehavior handleRequestVoteReply(final ActorRef sender, + final RequestVoteReply requestVoteReply) { return this; } @Override - public RaftActorBehavior handleMessage(ActorRef sender, Object originalMessage) { - if (originalMessage instanceof ElectionTimeout) { - if (canStartElection()) { - LOG.debug("{}: Received ElectionTimeout - switching to Candidate", logName()); + public RaftActorBehavior handleMessage(final ActorRef sender, final Object message) { + if (message instanceof ElectionTimeout || message instanceof TimeoutNow) { + return handleElectionTimeout(message); + } + + if (!(message instanceof RaftRPC)) { + // The rest of the processing requires the message to be a RaftRPC + return null; + } + + final RaftRPC rpc = (RaftRPC) message; + // If RPC request or response contains term T > currentTerm: + // set currentTerm = T, convert to follower (§5.1) + // This applies to all RPC messages and responses + if (rpc.getTerm() > context.getTermInformation().getCurrentTerm()) { + log.info("{}: Term {} in \"{}\" message is greater than follower's term {} - updating term", + logName(), rpc.getTerm(), rpc, context.getTermInformation().getCurrentTerm()); + + context.getTermInformation().updateAndPersist(rpc.getTerm(), null); + } + + if (rpc instanceof InstallSnapshot) { + handleInstallSnapshot(sender, (InstallSnapshot) rpc); + restartLastLeaderMessageTimer(); + scheduleElection(electionDuration()); + return this; + } + + if (!(rpc instanceof RequestVote) || canGrantVote((RequestVote) rpc)) { + restartLastLeaderMessageTimer(); + scheduleElection(electionDuration()); + } + + return super.handleMessage(sender, rpc); + } + + private RaftActorBehavior handleElectionTimeout(final Object message) { + // If the message is ElectionTimeout, verify we haven't actually seen a message from the leader + // during the election timeout interval. It may that the election timer expired b/c this actor + // was busy and messages got delayed, in which case leader messages would be backed up in the + // queue but would be processed before the ElectionTimeout message and thus would restart the + // lastLeaderMessageTimer. + long lastLeaderMessageInterval = lastLeaderMessageTimer.elapsed(TimeUnit.MILLISECONDS); + long electionTimeoutInMillis = context.getConfigParams().getElectionTimeOutInterval().toMillis(); + boolean noLeaderMessageReceived = !lastLeaderMessageTimer.isRunning() + || lastLeaderMessageInterval >= electionTimeoutInMillis; + + if (canStartElection()) { + if (message instanceof TimeoutNow) { + log.debug("{}: Received TimeoutNow - switching to Candidate", logName()); return internalSwitchBehavior(RaftState.Candidate); + } else if (noLeaderMessageReceived) { + // Check the cluster state to see if the leader is known to be up before we go to Candidate. + // However if we haven't heard from the leader in a long time even though the cluster state + // indicates it's up then something is wrong - leader might be stuck indefinitely - so switch + // to Candidate, + long maxElectionTimeout = electionTimeoutInMillis * MAX_ELECTION_TIMEOUT_FACTOR; + if (isLeaderAvailabilityKnown() && lastLeaderMessageInterval < maxElectionTimeout) { + log.debug("{}: Received ElectionTimeout but leader appears to be available", logName()); + scheduleElection(electionDuration()); + } else { + log.debug("{}: Received ElectionTimeout - switching to Candidate", logName()); + return internalSwitchBehavior(RaftState.Candidate); + } } else { - return this; + log.debug("{}: Received ElectionTimeout but lastLeaderMessageInterval {} < election timeout {}", + logName(), lastLeaderMessageInterval, context.getConfigParams().getElectionTimeOutInterval()); + scheduleElection(electionDuration()); + } + } else if (message instanceof ElectionTimeout) { + if (noLeaderMessageReceived) { + setLeaderId(null); } + + scheduleElection(electionDuration()); } - final Object message = fromSerializableMessage(originalMessage); - if (message instanceof RaftRPC) { - RaftRPC rpc = (RaftRPC) message; - // If RPC request or response contains term T > currentTerm: - // set currentTerm = T, convert to follower (§5.1) - // This applies to all RPC messages and responses - if (rpc.getTerm() > context.getTermInformation().getCurrentTerm()) { - LOG.debug("{}: Term {} in \"{}\" message is greater than follower's term {} - updating term", - logName(), rpc.getTerm(), rpc, context.getTermInformation().getCurrentTerm()); - - context.getTermInformation().updateAndPersist(rpc.getTerm(), null); - } + return this; + } + + private boolean isLeaderAvailabilityKnown() { + if (leaderId == null) { + return false; } - if (message instanceof InstallSnapshot) { - InstallSnapshot installSnapshot = (InstallSnapshot) message; - handleInstallSnapshot(sender, installSnapshot); + Optional cluster = context.getCluster(); + if (!cluster.isPresent()) { + return false; } - if (message instanceof RaftRPC && (!(message instanceof RequestVote) || (canGrantVote((RequestVote) message)))){ - scheduleElection(electionDuration()); + ActorSelection leaderActor = context.getPeerActorSelection(leaderId); + if (leaderActor == null) { + return false; } - return super.handleMessage(sender, message); + Address leaderAddress = leaderActor.anchorPath().address(); + + CurrentClusterState state = cluster.get().state(); + Set unreachable = state.getUnreachable(); + + log.debug("{}: Checking for leader {} in the cluster unreachable set {}", logName(), leaderAddress, + unreachable); + + for (Member m: unreachable) { + if (leaderAddress.equals(m.address())) { + log.info("{}: Leader {} is unreachable", logName(), leaderAddress); + return false; + } + } + + for (Member m: state.getMembers()) { + if (leaderAddress.equals(m.address())) { + if (m.status() == MemberStatus.up() || m.status() == MemberStatus.weaklyUp()) { + log.debug("{}: Leader {} cluster status is {} - leader is available", logName(), + leaderAddress, m.status()); + return true; + } else { + log.debug("{}: Leader {} cluster status is {} - leader is unavailable", logName(), + leaderAddress, m.status()); + return false; + } + } + } + + log.debug("{}: Leader {} not found in the cluster member set", logName(), leaderAddress); + + return false; } - private void handleInstallSnapshot(final ActorRef sender, InstallSnapshot installSnapshot) { + private void handleInstallSnapshot(final ActorRef sender, final InstallSnapshot installSnapshot) { - LOG.debug("{}: handleInstallSnapshot: {}", logName(), installSnapshot); + log.debug("{}: handleInstallSnapshot: {}", logName(), installSnapshot); leaderId = installSnapshot.getLeaderId(); - if(snapshotTracker == null){ - snapshotTracker = new SnapshotTracker(LOG, installSnapshot.getTotalChunks()); + if (snapshotTracker == null) { + snapshotTracker = new SnapshotTracker(log, installSnapshot.getTotalChunks(), installSnapshot.getLeaderId(), + context); } updateInitialSyncStatus(installSnapshot.getLastIncludedIndex(), installSnapshot.getLeaderId()); @@ -398,22 +539,26 @@ public class Follower extends AbstractRaftActorBehavior { final InstallSnapshotReply reply = new InstallSnapshotReply( currentTerm(), context.getId(), installSnapshot.getChunkIndex(), true); - if(snapshotTracker.addChunk(installSnapshot.getChunkIndex(), installSnapshot.getData(), - installSnapshot.getLastChunkHashCode())){ - Snapshot snapshot = Snapshot.create(snapshotTracker.getSnapshot(), - new ArrayList(), + if (snapshotTracker.addChunk(installSnapshot.getChunkIndex(), installSnapshot.getData(), + installSnapshot.getLastChunkHashCode())) { + + log.info("{}: Snapshot installed from leader: {}", logName(), installSnapshot.getLeaderId()); + + Snapshot snapshot = Snapshot.create( + context.getSnapshotManager().convertSnapshot(snapshotTracker.getSnapshotBytes()), + new ArrayList<>(), installSnapshot.getLastIncludedIndex(), installSnapshot.getLastIncludedTerm(), installSnapshot.getLastIncludedIndex(), installSnapshot.getLastIncludedTerm(), context.getTermInformation().getCurrentTerm(), context.getTermInformation().getVotedFor(), - context.getPeerServerInfo(true)); + installSnapshot.getServerConfig().orNull()); ApplySnapshot.Callback applySnapshotCallback = new ApplySnapshot.Callback() { @Override public void onSuccess() { - LOG.debug("{}: handleInstallSnapshot returning: {}", logName(), reply); + log.debug("{}: handleInstallSnapshot returning: {}", logName(), reply); sender.tell(reply, actor()); } @@ -426,36 +571,37 @@ public class Follower extends AbstractRaftActorBehavior { actor().tell(new ApplySnapshot(snapshot, applySnapshotCallback), actor()); - snapshotTracker = null; + closeSnapshotTracker(); } else { - LOG.debug("{}: handleInstallSnapshot returning: {}", logName(), reply); + log.debug("{}: handleInstallSnapshot returning: {}", logName(), reply); sender.tell(reply, actor()); } - } catch (SnapshotTracker.InvalidChunkException e) { - LOG.debug("{}: Exception in InstallSnapshot of follower", logName(), e); + } catch (IOException e) { + log.debug("{}: Exception in InstallSnapshot of follower", logName(), e); sender.tell(new InstallSnapshotReply(currentTerm(), context.getId(), -1, false), actor()); - snapshotTracker = null; - - } catch (Exception e){ - LOG.error("{}: Exception in InstallSnapshot of follower", logName(), e); - //send reply with success as false. The chunk will be sent again on failure - sender.tell(new InstallSnapshotReply(currentTerm(), context.getId(), - installSnapshot.getChunkIndex(), false), actor()); + closeSnapshotTracker(); + } + } + private void closeSnapshotTracker() { + if (snapshotTracker != null) { + snapshotTracker.close(); + snapshotTracker = null; } } @Override public void close() { + closeSnapshotTracker(); stopElection(); } @VisibleForTesting - SnapshotTracker getSnapshotTracker(){ + SnapshotTracker getSnapshotTracker() { return snapshotTracker; } }