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=cc2e55d51b115cc124890c3e643ed810244a7c24;hp=1bdcc8bdb4296c2ceea270ffaa4b261740e1ed00;hb=3591817114661bb7971d6d355186ff1b39636fcd;hpb=26cd54f2cbe0737db6e82aa96cd31671c6f6bf7e 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 1bdcc8bdb4..cc2e55d51b 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 @@ -9,54 +9,353 @@ package org.opendaylight.controller.cluster.raft.behaviors; import akka.actor.ActorRef; +import com.google.common.annotations.VisibleForTesting; +import com.google.protobuf.ByteString; +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.messages.AppendEntries; import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply; -import org.opendaylight.controller.cluster.raft.messages.RequestVote; +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; + public Follower(RaftActorContext context) { super(context); + + scheduleElection(electionDuration()); } - @Override protected RaftState handleAppendEntries(ActorRef sender, - AppendEntries appendEntries, RaftState suggestedState) { - return suggestedState; + private boolean isLogEntryPresent(long index){ + if(index == context.getReplicatedLog().getSnapshotIndex()){ + return true; + } + + ReplicatedLogEntry previousEntry = context.getReplicatedLog() + .get(index); + + return previousEntry != null; + } - @Override protected RaftState handleAppendEntriesReply(ActorRef sender, - AppendEntriesReply appendEntriesReply, RaftState suggestedState) { - return suggestedState; + 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; } - @Override protected RaftState handleRequestVote(ActorRef sender, - RequestVote requestVote, RaftState suggestedState) { - return suggestedState; + @Override protected RaftActorBehavior handleAppendEntries(ActorRef sender, + AppendEntries appendEntries) { + + if(appendEntries.getEntries() != null && appendEntries.getEntries().size() > 0) { + if(LOG.isDebugEnabled()) { + LOG.debug(appendEntries.toString()); + } + } + + // TODO : Refactor this method into a bunch of smaller methods + // to make it easier to read. Before refactoring ensure tests + // cover the code properly + + // 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()); + + + boolean outOfSync = true; + + // First check if the logs are in sync or not + 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. + + if(LOG.isDebugEnabled()) { + LOG.debug("The followers log is empty and the senders prevLogIndex is {}", + 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 + + if(LOG.isDebugEnabled()) { + LOG.debug("The log is not empty but the prevLogIndex {} was not found in it", + 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 + + if (LOG.isDebugEnabled()) { + LOG.debug( + "Cannot append entries because previous entry term {} is not equal to append entries prevLogTerm {}" + , 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 + if(LOG.isDebugEnabled()) { + LOG.debug("Follower ({}) is out-of-sync, " + + "so sending negative reply, lastIndex():{}, lastTerm():{}", + context.getId(), lastIndex(), lastTerm() + ); + } + sender.tell( + new AppendEntriesReply(context.getId(), currentTerm(), false, + lastIndex(), lastTerm()), actor() + ); + return this; + } + + if (appendEntries.getEntries() != null + && appendEntries.getEntries().size() > 0) { + if(LOG.isDebugEnabled()) { + LOG.debug( + "Number of entries to be appended = {}", 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; + } + + if(LOG.isDebugEnabled()) { + LOG.debug( + "Removing entries from log starting at {}", matchEntry.getIndex() + ); + } + + // Entries do not match so remove all subsequent entries + context.getReplicatedLog() + .removeFromAndPersist(matchEntry.getIndex()); + break; + } + } + + if(LOG.isDebugEnabled()) { + LOG.debug("After cleanup entries to be added from = {}", (addEntriesFrom + lastIndex()) + ); + } + + // 4. Append any new entries not already in the log + for (int i = addEntriesFrom; + i < appendEntries.getEntries().size(); i++) { + + if(LOG.isDebugEnabled()) { + LOG.debug("Append entry to log {}", appendEntries.getEntries().get(i).getData()); + } + context.getReplicatedLog().appendAndPersist(appendEntries.getEntries().get(i)); + } + + if(LOG.isDebugEnabled()) { + LOG.debug("Log size is now {}", context.getReplicatedLog().size()); + } + } + + + // 5. If leaderCommit > commitIndex, set commitIndex = + // min(leaderCommit, index of last new entry) + + long prevCommitIndex = context.getCommitIndex(); + + context.setCommitIndex(Math.min(appendEntries.getLeaderCommit(), + context.getReplicatedLog().lastIndex())); + + if (prevCommitIndex != context.getCommitIndex()) { + if(LOG.isDebugEnabled()) { + LOG.debug("Commit index set to {}", 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():{}", + appendEntries.getLeaderCommit(), context.getLastApplied(), lastIndex() + ); + } + + applyLogToStateMachine(appendEntries.getLeaderCommit()); + } + + sender.tell(new AppendEntriesReply(context.getId(), currentTerm(), true, + lastIndex(), lastTerm()), actor()); + + return this; } - @Override protected RaftState handleRequestVoteReply(ActorRef sender, - RequestVoteReply requestVoteReply, RaftState suggestedState) { - return suggestedState; + @Override protected RaftActorBehavior handleAppendEntriesReply(ActorRef sender, + AppendEntriesReply appendEntriesReply) { + return this; } - @Override protected RaftState state() { + @Override protected RaftActorBehavior handleRequestVoteReply(ActorRef sender, + RequestVoteReply requestVoteReply) { + return this; + } + + @Override public RaftState state() { return RaftState.Follower; } - @Override public RaftState handleMessage(ActorRef sender, Object message) { + @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()) { + context.getTermInformation().updateAndPersist(rpc.getTerm(), null); + } + } + + if (message instanceof ElectionTimeout) { + return switchBehavior(new Candidate(context)); + + } else if (message instanceof InstallSnapshot) { + InstallSnapshot installSnapshot = (InstallSnapshot) message; + handleInstallSnapshot(sender, installSnapshot); + } + + scheduleElection(electionDuration()); + return super.handleMessage(sender, message); } + + private void handleInstallSnapshot(ActorRef sender, InstallSnapshot installSnapshot) { + + if(LOG.isDebugEnabled()) { + LOG.debug("InstallSnapshot received by follower " + + "datasize:{} , Chunk:{}/{}", installSnapshot.getData().size(), + installSnapshot.getChunkIndex(), installSnapshot.getTotalChunks() + ); + } + + if(snapshotTracker == null){ + snapshotTracker = new SnapshotTracker(LOG, installSnapshot.getTotalChunks()); + } + + 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; + + } + + sender.tell(new InstallSnapshotReply( + currentTerm(), context.getId(), installSnapshot.getChunkIndex(), + true), actor()); + + } catch (SnapshotTracker.InvalidChunkException e) { + + sender.tell(new InstallSnapshotReply(currentTerm(), context.getId(), + -1, false), actor()); + snapshotTracker = null; + + } catch (Exception e){ + + LOG.error(e, "Exception in InstallSnapshot of follower:"); + //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 + ByteString getSnapshotChunksCollected(){ + return snapshotTracker != null ? snapshotTracker.getCollectedChunks() : ByteString.EMPTY; + } + + }