etcdserver: change the snapshot + compact into sync operation

server/etcdserver/server.go

@@ -2126,65 +2126,63 @@ func (s *EtcdServer) snapshot(snapi uint64, confState raftpb.ConfState) {
 	// the go routine created below.
 	s.KV().Commit()
 
-	s.GoAttach(func() {
-		lg := s.Logger()
+	lg := s.Logger()
 
-		// For backward compatibility, generate v2 snapshot from v3 state.
-		snap, err := s.r.raftStorage.CreateSnapshot(snapi, &confState, d)
-		if err != nil {
-			// the snapshot was done asynchronously with the progress of raft.
-			// raft might have already got a newer snapshot.
-			if err == raft.ErrSnapOutOfDate {
-				return
-			}
-			lg.Panic("failed to create snapshot", zap.Error(err))
+	// For backward compatibility, generate v2 snapshot from v3 state.
+	snap, err := s.r.raftStorage.CreateSnapshot(snapi, &confState, d)
+	if err != nil {
+		// the snapshot was done asynchronously with the progress of raft.
+		// raft might have already got a newer snapshot.
+		if err == raft.ErrSnapOutOfDate {
+			return
 		}
+		lg.Panic("failed to create snapshot", zap.Error(err))
+	}
 
-		verifyConsistentIndexIsLatest(lg, snap, s.consistIndex.ConsistentIndex())
+	verifyConsistentIndexIsLatest(lg, snap, s.consistIndex.ConsistentIndex())
 
-		// SaveSnap saves the snapshot to file and appends the corresponding WAL entry.
-		if err = s.r.storage.SaveSnap(snap); err != nil {
-			lg.Panic("failed to save snapshot", zap.Error(err))
-		}
-		if err = s.r.storage.Release(snap); err != nil {
-			lg.Panic("failed to release wal", zap.Error(err))
-		}
+	// SaveSnap saves the snapshot to file and appends the corresponding WAL entry.
+	if err = s.r.storage.SaveSnap(snap); err != nil {
+		lg.Panic("failed to save snapshot", zap.Error(err))
+	}
+	if err = s.r.storage.Release(snap); err != nil {
+		lg.Panic("failed to release wal", zap.Error(err))
+	}
 
-		lg.Info(
-			"saved snapshot",
-			zap.Uint64("snapshot-index", snap.Metadata.Index),
-		)
+	lg.Info(
+		"saved snapshot",
+		zap.Uint64("snapshot-index", snap.Metadata.Index),
+	)
 
-		// When sending a snapshot, etcd will pause compaction.
-		// After receives a snapshot, the slow follower needs to get all the entries right after
-		// the snapshot sent to catch up. If we do not pause compaction, the log entries right after
-		// the snapshot sent might already be compacted. It happens when the snapshot takes long time
-		// to send and save. Pausing compaction avoids triggering a snapshot sending cycle.
-		if atomic.LoadInt64(&s.inflightSnapshots) != 0 {
-			lg.Info("skip compaction since there is an inflight snapshot")
-			return
-		}
+	// When sending a snapshot, etcd will pause compaction.
+	// After receives a snapshot, the slow follower needs to get all the entries right after
+	// the snapshot sent to catch up. If we do not pause compaction, the log entries right after
+	// the snapshot sent might already be compacted. It happens when the snapshot takes long time
+	// to send and save. Pausing compaction avoids triggering a snapshot sending cycle.
+	if atomic.LoadInt64(&s.inflightSnapshots) != 0 {
+		lg.Info("skip compaction since there is an inflight snapshot")
+		return
+	}
 
-		// keep some in memory log entries for slow followers.
-		compacti := uint64(1)
-		if snapi > s.Cfg.SnapshotCatchUpEntries {
-			compacti = snapi - s.Cfg.SnapshotCatchUpEntries
-		}
+	// keep some in memory log entries for slow followers.
+	compacti := uint64(1)
+	if snapi > s.Cfg.SnapshotCatchUpEntries {
+		compacti = snapi - s.Cfg.SnapshotCatchUpEntries
+	}
 
-		err = s.r.raftStorage.Compact(compacti)
-		if err != nil {
-			// the compaction was done asynchronously with the progress of raft.
-			// raft log might already been compact.
-			if err == raft.ErrCompacted {
-				return
-			}
-			lg.Panic("failed to compact", zap.Error(err))
+	err = s.r.raftStorage.Compact(compacti)
+	if err != nil {
+		// the compaction was done asynchronously with the progress of raft.
+		// raft log might already been compact.
+		if err == raft.ErrCompacted {
+			return
 		}
-		lg.Info(
-			"compacted Raft logs",
-			zap.Uint64("compact-index", compacti),
-		)
-	})
+		lg.Panic("failed to compact", zap.Error(err))
+	}
+	lg.Info(
+		"compacted Raft logs",
+		zap.Uint64("compact-index", compacti),
+	)
 }
 
 // CutPeer drops messages to the specified peer.