Examples with LogCompactionInfo org.neo4j.causalclustering.core.consensus.RaftMessages.LogCompactionInfo used on opensource projects

Example 1 with LogCompactionInfo

use of org.neo4j.causalclustering.core.consensus.RaftMessages.LogCompactionInfo in project neo4j by neo4j.

the class Leader method handle.

@Override
public Outcome handle(RaftMessages.RaftMessage message, ReadableRaftState ctx, Log log) throws IOException {
    Outcome outcome = new Outcome(LEADER, ctx);
    switch(message.type()) {
        case HEARTBEAT:
            {
                Heartbeat req = (Heartbeat) message;
                if (req.leaderTerm() < ctx.term()) {
                    break;
                }
                stepDownToFollower(outcome);
                log.info("Moving to FOLLOWER state after receiving heartbeat at term %d (my term is " + "%d) from %s", req.leaderTerm(), ctx.term(), req.from());
                Heart.beat(ctx, outcome, (Heartbeat) message, log);
                break;
            }
        case HEARTBEAT_TIMEOUT:
            {
                sendHeartbeats(ctx, outcome);
                break;
            }
        case HEARTBEAT_RESPONSE:
            {
                outcome.addHeartbeatResponse(message.from());
                break;
            }
        case ELECTION_TIMEOUT:
            {
                if (!isQuorum(ctx.votingMembers().size(), ctx.heartbeatResponses().size())) {
                    stepDownToFollower(outcome);
                    log.info("Moving to FOLLOWER state after not receiving heartbeat responses in this election timeout " + "period. Heartbeats received: %s", ctx.heartbeatResponses());
                }
                outcome.getHeartbeatResponses().clear();
                break;
            }
        case APPEND_ENTRIES_REQUEST:
            {
                RaftMessages.AppendEntries.Request req = (RaftMessages.AppendEntries.Request) message;
                if (req.leaderTerm() < ctx.term()) {
                    RaftMessages.AppendEntries.Response appendResponse = new RaftMessages.AppendEntries.Response(ctx.myself(), ctx.term(), false, -1, ctx.entryLog().appendIndex());
                    outcome.addOutgoingMessage(new RaftMessages.Directed(req.from(), appendResponse));
                    break;
                } else if (req.leaderTerm() == ctx.term()) {
                    throw new IllegalStateException("Two leaders in the same term.");
                } else {
                    // There is a new leader in a later term, we should revert to follower. (§5.1)
                    stepDownToFollower(outcome);
                    log.info("Moving to FOLLOWER state after receiving append request at term %d (my term is " + "%d) from %s", req.leaderTerm(), ctx.term(), req.from());
                    Appending.handleAppendEntriesRequest(ctx, outcome, req, log);
                    break;
                }
            }
        case APPEND_ENTRIES_RESPONSE:
            {
                RaftMessages.AppendEntries.Response response = (RaftMessages.AppendEntries.Response) message;
                if (response.term() < ctx.term()) {
                    /* Ignore responses from old terms! */
                    break;
                } else if (response.term() > ctx.term()) {
                    outcome.setNextTerm(response.term());
                    stepDownToFollower(outcome);
                    log.info("Moving to FOLLOWER state after receiving append response at term %d (my term is " + "%d) from %s", response.term(), ctx.term(), response.from());
                    outcome.replaceFollowerStates(new FollowerStates<>());
                    break;
                }
                FollowerState follower = ctx.followerStates().get(response.from());
                if (response.success()) {
                    assert response.matchIndex() <= ctx.entryLog().appendIndex();
                    boolean followerProgressed = response.matchIndex() > follower.getMatchIndex();
                    outcome.replaceFollowerStates(outcome.getFollowerStates().onSuccessResponse(response.from(), max(response.matchIndex(), follower.getMatchIndex())));
                    outcome.addShipCommand(new ShipCommand.Match(response.matchIndex(), response.from()));
                    /*
                     * Matches from older terms can in complicated leadership change / log truncation scenarios
                     * be overwritten, even if they were replicated to a majority of instances. Thus we must only
                     * consider matches from this leader's term when figuring out which have been safely replicated
                     * and are ready for commit.
                     * This is explained nicely in Figure 3.7 of the thesis
                     */
                    boolean matchInCurrentTerm = ctx.entryLog().readEntryTerm(response.matchIndex()) == ctx.term();
                    /*
                     * The quorum situation may have changed only if the follower actually progressed.
                     */
                    if (followerProgressed && matchInCurrentTerm) {
                        // TODO: Test that mismatch between voting and participating members affects commit outcome
                        long quorumAppendIndex = Followers.quorumAppendIndex(ctx.votingMembers(), outcome.getFollowerStates());
                        if (quorumAppendIndex > ctx.commitIndex()) {
                            outcome.setLeaderCommit(quorumAppendIndex);
                            outcome.setCommitIndex(quorumAppendIndex);
                            outcome.addShipCommand(new ShipCommand.CommitUpdate());
                        }
                    }
                } else // Response indicated failure.
                {
                    if (response.appendIndex() > -1 && response.appendIndex() >= ctx.entryLog().prevIndex()) {
                        // Signal a mismatch to the log shipper, which will serve an earlier entry.
                        outcome.addShipCommand(new ShipCommand.Mismatch(response.appendIndex(), response.from()));
                    } else {
                        // There are no earlier entries, message the follower that we have compacted so that
                        // it can take appropriate action.
                        LogCompactionInfo compactionInfo = new LogCompactionInfo(ctx.myself(), ctx.term(), ctx.entryLog().prevIndex());
                        RaftMessages.Directed directedCompactionInfo = new RaftMessages.Directed(response.from(), compactionInfo);
                        outcome.addOutgoingMessage(directedCompactionInfo);
                    }
                }
                break;
            }
        case VOTE_REQUEST:
            {
                RaftMessages.Vote.Request req = (RaftMessages.Vote.Request) message;
                if (req.term() > ctx.term()) {
                    stepDownToFollower(outcome);
                    log.info("Moving to FOLLOWER state after receiving vote request at term %d (my term is " + "%d) from %s", req.term(), ctx.term(), req.from());
                    Voting.handleVoteRequest(ctx, outcome, req);
                    break;
                }
                outcome.addOutgoingMessage(new RaftMessages.Directed(req.from(), new RaftMessages.Vote.Response(ctx.myself(), ctx.term(), false)));
                break;
            }
        case NEW_ENTRY_REQUEST:
            {
                RaftMessages.NewEntry.Request req = (RaftMessages.NewEntry.Request) message;
                ReplicatedContent content = req.content();
                Appending.appendNewEntry(ctx, outcome, content);
                break;
            }
        case NEW_BATCH_REQUEST:
            {
                RaftMessages.NewEntry.BatchRequest req = (RaftMessages.NewEntry.BatchRequest) message;
                List<ReplicatedContent> contents = req.contents();
                Appending.appendNewEntries(ctx, outcome, contents);
                break;
            }
        case PRUNE_REQUEST:
            {
                Pruning.handlePruneRequest(outcome, (RaftMessages.PruneRequest) message);
                break;
            }
        default:
            break;
    }
    return outcome;
}