@Override public synchronized void persistState(ServerState serverState) { try{ ByteBuffer buffer = ByteBuffer.allocate(Long.BYTES * 2 + Integer.BYTES); buffer.putLong(serverState.getTerm()); buffer.putLong(serverState.getCommitIndex()); buffer.putInt(serverState.getVotedFor()); this.serverStateFile.write(buffer.array()); this.serverStateFile.seek(0); }catch(IOException ioError){ this.logger.error("failed to write to the server state file", ioError); throw new RuntimeException("fatal I/O error while writing to the state file", ioError); } }
@Override public synchronized void persistState(ServerState serverState) { try{ ByteBuffer buffer = ByteBuffer.allocate(Long.BYTES * 2 + Integer.BYTES); buffer.putLong(serverState.getTerm()); buffer.putLong(serverState.getCommitIndex()); buffer.putInt(serverState.getVotedFor()); this.serverStateFile.write(buffer.array()); this.serverStateFile.seek(0); }catch(IOException ioError){ this.logger.error("failed to write to the server state file", ioError); throw new RuntimeException("fatal I/O error while writing to the state file", ioError); } }
private void handleVotingResponse(RaftResponseMessage response){ this.votesResponded += 1; if(this.electionCompleted){ this.logger.info("Election completed, will ignore the voting result from this server"); return; } if(response.isAccepted()){ this.votesGranted += 1; } if(this.votesResponded >= this.peers.size() + 1){ this.electionCompleted = true; } // got a majority set of granted votes if(this.votesGranted > (this.peers.size() + 1) / 2){ this.logger.info("Server is elected as leader for term %d", this.state.getTerm()); this.electionCompleted = true; this.becomeLeader(); } }
private void handleVotingResponse(RaftResponseMessage response){ this.votesResponded += 1; if(this.electionCompleted){ this.logger.info("Election completed, will ignore the voting result from this server"); return; } if(response.isAccepted()){ this.votesGranted += 1; } if(this.votesResponded >= this.peers.size() + 1){ this.electionCompleted = true; } // got a majority set of granted votes if(this.votesGranted > (this.peers.size() + 1) / 2){ this.logger.info("Server is elected as leader for term %d", this.state.getTerm()); this.electionCompleted = true; this.becomeLeader(); } }
private boolean updateTerm(long term){ if(term > this.state.getTerm()){ this.state.setTerm(term); this.state.setVotedFor(-1); this.electionCompleted = false; this.votesGranted = 0; this.votedServers.clear(); this.context.getServerStateManager().persistState(this.state); this.becomeFollower(); return true; } return false; }
private boolean updateTerm(long term){ if(term > this.state.getTerm()){ this.state.setTerm(term); this.state.setVotedFor(-1); this.electionCompleted = false; this.votesGranted = 0; this.votesResponded = 0; this.context.getServerStateManager().persistState(this.state); this.becomeFollower(); return true; } return false; }
private boolean updateTerm(long term){ if(term > this.state.getTerm()){ this.state.setTerm(term); this.state.setVotedFor(-1); this.electionCompleted = false; this.votesGranted = 0; this.votesResponded = 0; this.context.getServerStateManager().persistState(this.state); this.becomeFollower(); return true; } return false; }
private void inviteServerToJoinCluster(){ RaftRequestMessage request = new RaftRequestMessage(); request.setCommitIndex(this.quickCommitIndex); request.setDestination(this.serverToJoin.getId()); request.setSource(this.id); request.setTerm(this.state.getTerm()); request.setMessageType(RaftMessageType.JoinClusterRequest); request.setLastLogIndex(this.logStore.getFirstAvailableIndex() - 1); request.setLogEntries(new LogEntry[] { new LogEntry(this.state.getTerm(), this.config.toBytes(), LogValueType.Configuration) }); this.serverToJoin.SendRequest(request).whenCompleteAsync((RaftResponseMessage response, Throwable error) -> { this.handleExtendedResponse(response, error); }, this.context.getScheduledExecutor()); }
private void inviteServerToJoinCluster(){ RaftRequestMessage request = new RaftRequestMessage(); request.setCommitIndex(this.quickCommitIndex); request.setDestination(this.serverToJoin.getId()); request.setSource(this.id); request.setTerm(this.state.getTerm()); request.setMessageType(RaftMessageType.JoinClusterRequest); request.setLastLogIndex(this.logStore.getFirstAvailableIndex() - 1); request.setLogEntries(new LogEntry[] { new LogEntry(this.state.getTerm(), this.config.toBytes(), LogValueType.Configuration) }); this.serverToJoin.SendRequest(request).whenCompleteAsync((RaftResponseMessage response, Throwable error) -> { this.handleExtendedResponse(response, error); }, this.context.getScheduledExecutor()); }
private void inviteServerToJoinCluster(){ RaftRequestMessage request = new RaftRequestMessage(); request.setCommitIndex(this.quickCommitIndex); request.setDestination(this.serverToJoin.getId()); request.setSource(this.id); request.setTerm(this.state.getTerm()); request.setMessageType(RaftMessageType.JoinClusterRequest); request.setLastLogIndex(this.logStore.getFirstAvailableIndex() - 1); request.setLogEntries(new LogEntry[] { new LogEntry(this.state.getTerm(), this.config.toBytes(), LogValueType.Configuration) }); this.serverToJoin.SendRequest(request).whenCompleteAsync((RaftResponseMessage response, Throwable error) -> { this.handleExtendedResponse(response, error); }, this.context.getScheduledExecutor()); }
private void removeServerFromCluster(int serverId){ ClusterConfiguration newConfig = new ClusterConfiguration(); newConfig.setLastLogIndex(this.config.getLogIndex()); newConfig.setLogIndex(this.logStore.getFirstAvailableIndex()); for(ClusterServer server: this.config.getServers()){ if(server.getId() != serverId){ newConfig.getServers().add(server); } } this.logger.info("removed a server from configuration and save the configuration to log store at %d", newConfig.getLogIndex()); this.configChanging = true; this.logStore.append(new LogEntry(this.state.getTerm(), newConfig.toBytes(), LogValueType.Configuration)); this.requestAppendEntries(); }
private void removeServerFromCluster(int serverId){ ClusterConfiguration newConfig = new ClusterConfiguration(); newConfig.setLastLogIndex(this.config.getLogIndex()); newConfig.setLogIndex(this.logStore.getFirstAvailableIndex()); for(ClusterServer server: this.config.getServers()){ if(server.getId() != serverId){ newConfig.getServers().add(server); } } this.logger.info("removed a server from configuration and save the configuration to log store at %d", newConfig.getLogIndex()); this.configChanging = true; this.logStore.append(new LogEntry(this.state.getTerm(), newConfig.toBytes(), LogValueType.Configuration)); this.requestAppendEntries(); }
private void removeServerFromCluster(int serverId){ ClusterConfiguration newConfig = new ClusterConfiguration(); newConfig.setLastLogIndex(this.config.getLogIndex()); newConfig.setLogIndex(this.logStore.getFirstAvailableIndex()); for(ClusterServer server: this.config.getServers()){ if(server.getId() != serverId){ newConfig.getServers().add(server); } } this.logger.info("removed a server from configuration and save the configuration to log store at %d", newConfig.getLogIndex()); this.configChanging = true; this.logStore.append(new LogEntry(this.state.getTerm(), newConfig.toBytes(), LogValueType.Configuration)); this.requestAppendEntries(); }
private RaftResponseMessage handleLeaveClusterRequest(RaftRequestMessage request){ RaftResponseMessage response = new RaftResponseMessage(); response.setSource(this.id); response.setDestination(request.getSource()); response.setTerm(this.state.getTerm()); response.setMessageType(RaftMessageType.LeaveClusterResponse); response.setNextIndex(this.logStore.getFirstAvailableIndex()); if(!this.configChanging){ this.steppingDown = 2; response.setAccepted(true); }else{ response.setAccepted(false); } return response; }
private RaftResponseMessage handleLeaveClusterRequest(RaftRequestMessage request){ RaftResponseMessage response = new RaftResponseMessage(); response.setSource(this.id); response.setDestination(request.getSource()); response.setTerm(this.state.getTerm()); response.setMessageType(RaftMessageType.LeaveClusterResponse); response.setNextIndex(this.logStore.getFirstAvailableIndex()); if(!this.configChanging){ this.steppingDown = 2; response.setAccepted(true); }else{ response.setAccepted(false); } return response; }
private RaftResponseMessage handleLeaveClusterRequest(RaftRequestMessage request){ RaftResponseMessage response = new RaftResponseMessage(); response.setSource(this.id); response.setDestination(request.getSource()); response.setTerm(this.state.getTerm()); response.setMessageType(RaftMessageType.LeaveClusterResponse); response.setNextIndex(this.logStore.getFirstAvailableIndex()); if(!this.configChanging){ this.steppingDown = 2; response.setAccepted(true); }else{ response.setAccepted(false); } return response; }
private void becomeLeader(){ this.stopElectionTimer(); this.role = ServerRole.Leader; this.leader = this.id; this.serverToJoin = null; for(PeerServer server : this.peers.values()){ server.setNextLogIndex(this.logStore.getFirstAvailableIndex()); server.setSnapshotInSync(null); server.setFree(); this.enableHeartbeatForPeer(server); } // if current config is not committed, try to commit it if(this.config.getLogIndex() == 0){ this.config.setLogIndex(this.logStore.getFirstAvailableIndex()); this.logStore.append(new LogEntry(this.state.getTerm(), this.config.toBytes(), LogValueType.Configuration)); this.logger.info("add initial configuration to log store"); this.configChanging = true; } this.requestAppendEntries(); }
private void becomeLeader(){ this.stopElectionTimer(); this.role = ServerRole.Leader; this.leader = this.id; this.serverToJoin = null; for(PeerServer server : this.peers.values()){ server.setNextLogIndex(this.logStore.getFirstAvailableIndex()); server.setSnapshotInSync(null); server.setFree(); this.enableHeartbeatForPeer(server); } // if current config is not committed, try to commit it if(this.config.getLogIndex() == 0){ this.config.setLogIndex(this.logStore.getFirstAvailableIndex()); this.logStore.append(new LogEntry(this.state.getTerm(), this.config.toBytes(), LogValueType.Configuration)); this.logger.info("add initial configuration to log store"); this.configChanging = true; } this.requestAppendEntries(); }
private void becomeLeader(){ this.stopElectionTimer(); this.role = ServerRole.Leader; this.leader = this.id; this.serverToJoin = null; for(PeerServer server : this.peers.values()){ server.setNextLogIndex(this.logStore.getFirstAvailableIndex()); server.setSnapshotInSync(null); server.setFree(); this.enableHeartbeatForPeer(server); } // if current config is not committed, try to commit it if(this.config.getLogIndex() == 0){ this.config.setLogIndex(this.logStore.getFirstAvailableIndex()); this.logStore.append(new LogEntry(this.state.getTerm(), this.config.toBytes(), LogValueType.Configuration)); this.logger.info("add initial configuration to log store"); this.configChanging = true; } this.requestAppendEntries(); }
private synchronized RaftResponseMessage handleVoteRequest(RaftRequestMessage request){ // we allow the server to be continue after term updated to save a round message this.updateTerm(request.getTerm()); // Reset stepping down value to prevent this server goes down when leader crashes after sending a LeaveClusterRequest if(this.steppingDown > 0){ this.steppingDown = 2; } RaftResponseMessage response = new RaftResponseMessage(); response.setMessageType(RaftMessageType.RequestVoteResponse); response.setSource(this.id); response.setDestination(request.getSource()); response.setTerm(this.state.getTerm()); boolean logOkay = request.getLastLogTerm() > this.logStore.getLastLogEntry().getTerm() || (request.getLastLogTerm() == this.logStore.getLastLogEntry().getTerm() && this.logStore.getFirstAvailableIndex() - 1 <= request.getLastLogIndex()); boolean grant = request.getTerm() == this.state.getTerm() && logOkay && (this.state.getVotedFor() == request.getSource() || this.state.getVotedFor() == -1); response.setAccepted(grant); if(grant){ this.state.setVotedFor(request.getSource()); this.context.getServerStateManager().persistState(this.state); } return response; }