Etcd 删除

删除Tombstone,与put差异

func (tw *storeTxnWrite) delete(key []byte) {
	ibytes := newRevBytes()
	idxRev := revision{main: tw.beginRev + 1, sub: int64(len(tw.changes))}
	revToBytes(idxRev, ibytes)
	//boltdb 的key追加一个Tombstone标志
	ibytes = appendMarkTombstone(tw.storeTxnRead.s.lg, ibytes)

	kv := mvccpb.KeyValue{Key: key}

	d, err := kv.Marshal()
	if err != nil {
		tw.storeTxnRead.s.lg.Fatal(
			"failed to marshal mvccpb.KeyValue",
			zap.Error(err),
		)
	}

	tw.tx.UnsafeSeqPut(keyBucketName, ibytes, d)//删除操作, boltdb kv 使用包含Tombstone再put一次
	err = tw.s.kvindex.Tombstone(key, idxRev)//删除索引 treeIndex,实际是操作
	if err != nil {
		tw.storeTxnRead.s.lg.Fatal(
			"failed to tombstone an existing key",
			zap.String("key", string(key)),
			zap.Error(err),
		)
	}
	tw.changes = append(tw.changes, kv)

	item := lease.LeaseItem{Key: string(key)}
	leaseID := tw.s.le.GetLease(item)

	if leaseID != lease.NoLease {
		err = tw.s.le.Detach(leaseID, []lease.LeaseItem{item})
		if err != nil {
			tw.storeTxnRead.s.lg.Error(
				"failed to detach old lease from a key",
				zap.Error(err),
			)
		}
	}
}

追加Tombstone标志’t’

markTombstone     byte = 't'
// appendMarkTombstone appends tombstone mark to normal revision bytes.
func appendMarkTombstone(lg *zap.Logger, b []byte) []byte {
	if len(b) != revBytesLen {
		lg.Panic(
			"cannot append tombstone mark to non-normal revision bytes",
			zap.Int("expected-revision-bytes-size", revBytesLen),
			zap.Int("given-revision-bytes-size", len(b)),
		)
	}
	return append(b, markTombstone)
}