Im Raft-Paper ist die RPC Funktion AppendEntries folgendermaßen definiert worden:

Im Java Code der Raft-grpc Implementierung ist die Funktion so implementiert worden:

    public AppendEntriesResponse handleAppendEntries(AppendEntriesRequest request) {
        // Reject AppendEntries when suspended
        if (suspended) {
            log.debug("Rejecting AppendEntries - node is suspended");
            return AppendEntriesResponse.newBuilder()
                .setTerm(currentTerm.get())
                .setSuccess(false)
                .build();
        }
        lastHeartbeat = System.currentTimeMillis();
        if (request.getTerm() > currentTerm.get()) {
            becomeFollower(request.getTerm());
        }
        if (request.getTerm() < currentTerm.get()) {
            return AppendEntriesResponse.newBuilder()
                .setTerm(currentTerm.get())
                .setSuccess(false)
                .build();
        }
        if (state != NodeState.FOLLOWER) {
            becomeFollower(request.getTerm());
        }
        currentLeader = request.getLeaderId();
        startElectionTimer();
        if (request.getEntriesCount() == 0) {
            logEvent(RaftEvent.EventType.HEARTBEAT_RECEIVED, 
                "Heartbeat from leader " + request.getLeaderId());
        }
        // Check prevLogIndex/prevLogTerm consistency (logical indices)
        int prevLogIndex = request.getPrevLogIndex();
        if (prevLogIndex >= 0) {
            // Check if we have the entry at prevLogIndex
            int prevLogTerm = getLogTermAt(prevLogIndex);
            if (prevLogTerm == 0 || prevLogTerm != request.getPrevLogTerm()) {
                log.debug("Log consistency check failed at index {}: expected term {}, got {}", 
                         prevLogIndex, request.getPrevLogTerm(), prevLogTerm);
                return AppendEntriesResponse.newBuilder()
                    .setTerm(currentTerm.get())
                    .setSuccess(false)
                    .build();
            }
        }
        // Process new entries (logical indices)
        int newEntryLogicalIndex = prevLogIndex + 1;
        int entriesAdded = 0;
        List<LogEntry> entriesToPersist = new ArrayList<>();
        for (GrpcLogEntry entry : request.getEntriesList()) {
            int physicalIndex = logicalToPhysical(newEntryLogicalIndex);
            // Check for conflicts
            if (physicalIndex >= 0 && physicalIndex < raftLog.size()) {
                if (raftLog.get(physicalIndex).getTerm() != entry.getTerm()) {
                    // Conflict detected - delete conflicting entries
                    synchronized (raftLog) {
                        raftLog.subList(physicalIndex, raftLog.size()).clear();
                        // Persist log deletion (CRITICAL for consistency)
                        persistenceService.deleteLogEntriesFrom(config.getNodeId(), newEntryLogicalIndex);
                    }
                }
            }
            // Append if we don't have this entry
            physicalIndex = logicalToPhysical(newEntryLogicalIndex);
            if (physicalIndex >= raftLog.size()) {
                // Convert gRPC entry back to internal LogEntry
                LogEntry logEntry = convertFromGrpcLogEntry(entry);
                synchronized (raftLog) {
                    raftLog.add(logEntry);
                }
                entriesToPersist.add(logEntry);
                entriesAdded++;
            }
            newEntryLogicalIndex++;
        }
        // Persist all new entries in batch (CRITICAL for durability)
        if (!entriesToPersist.isEmpty()) {
            int startLogicalIndex = prevLogIndex + 1;
            persistenceService.appendLogEntries(config.getNodeId(), startLogicalIndex, entriesToPersist);
        }
        if (entriesAdded > 0) {
            logEvent(RaftEvent.EventType.LOG_REPLICATED, 
                "Replicated " + entriesAdded + " entries from leader " + request.getLeaderId());
        }
        // Update commit index based on leader's commit index (logical indices)
        if (request.getLeaderCommit() > commitIndex.get()) {
            commitIndex.set(Math.min(request.getLeaderCommit(), getLastLogIndex()));
            applyCommittedEntries();
        }
        return AppendEntriesResponse.newBuilder()
            .setTerm(currentTerm.get())
            .setSuccess(true)
            .setMatchIndex(getLastLogIndex())  // Logical index of last entry
            .build();
    }

Mit den folgenden gRPC Messages:

message AppendEntriesRequest {
  int32 term = 1;
  string leaderId = 2;
  int32 prevLogIndex = 3;
  int32 prevLogTerm = 4;
  repeated GrpcLogEntry entries = 5;
  int32 leaderCommit = 6;
}
message AppendEntriesResponse {
  int32 term = 1;
  bool success = 2;
  int32 matchIndex = 3;
}

Welche Aussagen treffen dabei zu?