X-Git-Url: https://git.opendaylight.org/gerrit/gitweb?a=blobdiff_plain;f=opendaylight%2Fmd-sal%2Fsal-akka-raft%2Fsrc%2Fmain%2Fjava%2Forg%2Fopendaylight%2Fcontroller%2Fcluster%2Fraft%2Fbehaviors%2FFollower.java;h=1cfdf9dba8b912a5bc23f78b85c447621298d908;hb=2a31c2cacb9ad8f015a49708261ea93d256f0f60;hp=4c97d933c8c5d0a2698469fa9e1d2d79a6b7a26e;hpb=cf5be659d906cc80d52647cb516bbab435156742;p=controller.git 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 4c97d933c8..a1174d70dc 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 @@ -9,18 +9,396 @@ package org.opendaylight.controller.cluster.raft.behaviors; import akka.actor.ActorRef; +import com.google.common.annotations.VisibleForTesting; +import java.util.ArrayList; 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.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.FollowerInitialSyncUpStatus; +import org.opendaylight.controller.cluster.raft.messages.AppendEntries; +import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply; +import org.opendaylight.controller.cluster.raft.messages.InstallSnapshot; +import org.opendaylight.controller.cluster.raft.messages.InstallSnapshotReply; +import org.opendaylight.controller.cluster.raft.messages.RaftRPC; +import org.opendaylight.controller.cluster.raft.messages.RequestVoteReply; /** * The behavior of a RaftActor in the Follower state + *

+ *

*/ public class Follower extends AbstractRaftActorBehavior { + + + + private SnapshotTracker snapshotTracker = null; + + private final InitialSyncStatusTracker initialSyncStatusTracker; + public Follower(RaftActorContext context) { - super(context); + super(context, RaftState.Follower); + + initialSyncStatusTracker = new InitialSyncStatusTracker(context.getActor()); + + if(context.getPeerAddresses().isEmpty()){ + actor().tell(ELECTION_TIMEOUT, actor()); + } else { + scheduleElection(electionDuration()); + } + + } + + private boolean isLogEntryPresent(long index){ + if(index == context.getReplicatedLog().getSnapshotIndex()){ + return true; + } + + ReplicatedLogEntry previousEntry = context.getReplicatedLog() + .get(index); + + return previousEntry != null; + + } + + private long getLogEntryTerm(long index){ + if(index == context.getReplicatedLog().getSnapshotIndex()){ + return context.getReplicatedLog().getSnapshotTerm(); + } + + ReplicatedLogEntry previousEntry = context.getReplicatedLog() + .get(index); + + if(previousEntry != null){ + return previousEntry.getTerm(); + } + + return -1; + } + + private void updateInitialSyncStatus(long currentLeaderCommit, String leaderId){ + initialSyncStatusTracker.update(leaderId, currentLeaderCommit, context.getCommitIndex()); + } + + @Override protected RaftActorBehavior handleAppendEntries(ActorRef sender, + 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); + } + + // 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) { + // 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()); + + if(LOG.isDebugEnabled()) { + LOG.debug("{}: snapshot install is in progress, replying immediately with {}", logName(), reply); + } + sender.tell(reply, actor()); + + return this; + } + + // 1. Reply false if term < currentTerm (§5.1) + // This is handled in the appendEntries method of the base class + + // If we got here then we do appear to be talking to the leader + leaderId = appendEntries.getLeaderId(); + + // 2. Reply false if log doesn’t contain an entry at prevLogIndex + // whose term matches prevLogTerm (§5.3) + + long prevLogTerm = getLogEntryTerm(appendEntries.getPrevLogIndex()); + boolean prevEntryPresent = isLogEntryPresent(appendEntries.getPrevLogIndex()); + + updateInitialSyncStatus(appendEntries.getLeaderCommit(), appendEntries.getLeaderId()); + + boolean outOfSync = true; + + // First check if the logs are in sync or not + 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 { + outOfSync = false; + } + + if (outOfSync) { + // 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()); + + sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), false, lastIndex, + lastTerm()), actor()); + return this; + } + + if (appendEntries.getEntries() != null && appendEntries.getEntries().size() > 0) { + + LOG.debug("{}: Number of entries to be appended = {}", logName(), + appendEntries.getEntries().size()); + + // 3. If an existing entry conflicts with a new one (same index + // but different terms), delete the existing entry and all that + // follow it (§5.3) + int addEntriesFrom = 0; + if (context.getReplicatedLog().size() > 0) { + + // Find the entry up until which 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 + break; + } + + if (newEntry.getTerm() == matchEntry.getTerm()) { + continue; + } + + LOG.debug("{}: Removing entries from log starting at {}", logName(), + matchEntry.getIndex()); + + // Entries do not match so remove all subsequent entries + context.getReplicatedLog().removeFromAndPersist(matchEntry.getIndex()); + break; + } + } + + lastIndex = lastIndex(); + LOG.debug("{}: After cleanup entries to be added from = {}", logName(), + (addEntriesFrom + lastIndex)); + + // 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()); + + context.getReplicatedLog().appendAndPersist(entry); + } + + LOG.debug("{}: Log size is now {}", logName(), context.getReplicatedLog().size()); + } + + // 5. If leaderCommit > commitIndex, set commitIndex = + // min(leaderCommit, index of last new entry) + + lastIndex = lastIndex(); + long prevCommitIndex = context.getCommitIndex(); + + context.setCommitIndex(Math.min(appendEntries.getLeaderCommit(), lastIndex)); + + if (prevCommitIndex != context.getCommitIndex()) { + LOG.debug("{}: Commit index set to {}", logName(), context.getCommitIndex()); + } + + // 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(), + appendEntries.getLeaderCommit(), context.getLastApplied(), lastIndex); + } + + applyLogToStateMachine(appendEntries.getLeaderCommit()); + } + + AppendEntriesReply reply = new AppendEntriesReply(context.getId(), currentTerm(), true, + lastIndex, lastTerm()); + + 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.isSnapshotCaptureInitiated()) { + super.performSnapshotWithoutCapture(appendEntries.getReplicatedToAllIndex()); + } + + return this; + } + + @Override protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender, + AppendEntriesReply appendEntriesReply) { + return this; + } + + @Override protected RaftActorBehavior handleRequestVoteReply(ActorRef sender, + RequestVoteReply requestVoteReply) { + return this; + } + + @Override public RaftActorBehavior handleMessage(ActorRef sender, Object originalMessage) { + + 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); + } + } + + if (message instanceof ElectionTimeout) { + LOG.debug("{}: Received ElectionTimeout - switching to Candidate", logName()); + return switchBehavior(new Candidate(context)); + + } else if (message instanceof InstallSnapshot) { + InstallSnapshot installSnapshot = (InstallSnapshot) message; + handleInstallSnapshot(sender, installSnapshot); + } + + scheduleElection(electionDuration()); + + return super.handleMessage(sender, message); } - @Override public RaftState handleMessage(ActorRef sender, Object message) { - return RaftState.Follower; + private void handleInstallSnapshot(ActorRef sender, InstallSnapshot installSnapshot) { + + LOG.debug("{}: InstallSnapshot received from leader {}, datasize: {} , Chunk: {}/{}", + logName(), installSnapshot.getLeaderId(), installSnapshot.getData().size(), + installSnapshot.getChunkIndex(), installSnapshot.getTotalChunks()); + + if(snapshotTracker == null){ + snapshotTracker = new SnapshotTracker(LOG, installSnapshot.getTotalChunks()); + } + + updateInitialSyncStatus(installSnapshot.getLastIncludedIndex(), installSnapshot.getLeaderId()); + + try { + if(snapshotTracker.addChunk(installSnapshot.getChunkIndex(), installSnapshot.getData(), + installSnapshot.getLastChunkHashCode())){ + Snapshot snapshot = Snapshot.create(snapshotTracker.getSnapshot(), + new ArrayList(), + installSnapshot.getLastIncludedIndex(), + installSnapshot.getLastIncludedTerm(), + installSnapshot.getLastIncludedIndex(), + installSnapshot.getLastIncludedTerm()); + + actor().tell(new ApplySnapshot(snapshot), actor()); + + snapshotTracker = null; + + } + + InstallSnapshotReply reply = new InstallSnapshotReply( + currentTerm(), context.getId(), installSnapshot.getChunkIndex(), true); + + LOG.debug("{}: handleInstallSnapshot returning: {}", logName(), reply); + + sender.tell(reply, actor()); + + } catch (SnapshotTracker.InvalidChunkException 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()); + + } + } + + @Override + public void close() throws Exception { + stopElection(); + } + + @VisibleForTesting + SnapshotTracker getSnapshotTracker(){ + return snapshotTracker; + } + + private class InitialSyncStatusTracker { + + private static final long INVALID_LOG_INDEX = -2L; + private long initialLeaderCommit = INVALID_LOG_INDEX; + private boolean initialSyncUpDone = false; + private String syncedLeaderId = null; + private final ActorRef actor; + + public InitialSyncStatusTracker(ActorRef actor) { + this.actor = actor; + } + + public void update(String leaderId, long leaderCommit, long commitIndex){ + + if(!leaderId.equals(syncedLeaderId)){ + initialSyncUpDone = false; + initialLeaderCommit = INVALID_LOG_INDEX; + syncedLeaderId = leaderId; + } + + if(!initialSyncUpDone){ + if(initialLeaderCommit == INVALID_LOG_INDEX){ + actor.tell(new FollowerInitialSyncUpStatus(false, getId()), ActorRef.noSender()); + initialLeaderCommit = leaderCommit; + } else if(commitIndex >= initialLeaderCommit){ + actor.tell(new FollowerInitialSyncUpStatus(true, getId()), ActorRef.noSender()); + initialSyncUpDone = true; + } + } + } } }