Golang Value.InitChecksum方法代碼示例

// setupMVCCData writes up to numVersions values at each of numKeys
// keys. The number of versions written for each key is chosen
// randomly according to a uniform distribution. Each successive
// version is written starting at 5ns and then in 5ns increments. This
// allows scans at various times, starting at t=5ns, and continuing to
// t=5ns*(numVersions+1). A version for each key will be read on every
// such scan, but the dynamics of the scan will change depending on
// the historical timestamp. Earlier timestamps mean scans which must
// skip more historical versions; later timestamps mean scans which
// skip fewer.
//
// The creation of the rocksdb database is time consuming, especially
// for larger numbers of versions. The database is persisted between
// runs and stored in the current directory as
// "mvcc_scan_<versions>_<keys>".
func setupMVCCScanData(numVersions, numKeys int, b *testing.B) (*RocksDB, *stop.Stopper) {
	loc := fmt.Sprintf("mvcc_scan_%d_%d", numVersions, numKeys)

	exists := true
	if _, err := os.Stat(loc); os.IsNotExist(err) {
		exists = false
	}

	log.Infof("creating mvcc data: %s", loc)
	const cacheSize = 8 << 30 // 8 GB
	stopper := stop.NewStopper()
	rocksdb := NewRocksDB(roachpb.Attributes{Attrs: []string{"ssd"}}, loc, cacheSize, stopper)
	if err := rocksdb.Open(); err != nil {
		b.Fatalf("could not create new rocksdb db instance at %s: %v", loc, err)
	}

	if exists {
		return rocksdb, stopper
	}

	rng, _ := randutil.NewPseudoRand()
	keys := make([]roachpb.Key, numKeys)
	nvs := make([]int, numKeys)
	for t := 1; t <= numVersions; t++ {
		walltime := int64(5 * t)
		ts := makeTS(walltime, 0)
		batch := rocksdb.NewBatch()
		for i := 0; i < numKeys; i++ {
			if t == 1 {
				keys[i] = roachpb.Key(encoding.EncodeUvarint([]byte("key-"), uint64(i)))
				nvs[i] = int(rand.Int31n(int32(numVersions)) + 1)
			}
			// Only write values if this iteration is less than the random
			// number of versions chosen for this key.
			if t <= nvs[i] {
				value := roachpb.Value{Bytes: randutil.RandBytes(rng, 1024)}
				value.InitChecksum(keys[i])
				if err := MVCCPut(batch, nil, keys[i], ts, value, nil); err != nil {
					b.Fatal(err)
				}
			}
		}
		if err := batch.Commit(); err != nil {
			b.Fatal(err)
		}
		batch.Close()
	}
	rocksdb.CompactRange(nil, nil)

	return rocksdb, stopper
}

// append the given entries to the raft log. Takes the previous values of
// r.mu.lastIndex and r.mu.raftLogSize, and returns new values. We do this
// rather than modifying them directly because these modifications need to be
// atomic with the commit of the batch.
func (r *Replica) append(
	ctx context.Context,
	batch engine.ReadWriter,
	prevLastIndex uint64,
	prevRaftLogSize int64,
	entries []raftpb.Entry,
) (uint64, int64, error) {
	if len(entries) == 0 {
		return prevLastIndex, prevRaftLogSize, nil
	}
	var diff enginepb.MVCCStats
	var value roachpb.Value
	for i := range entries {
		ent := &entries[i]
		key := keys.RaftLogKey(r.RangeID, ent.Index)
		if err := value.SetProto(ent); err != nil {
			return 0, 0, err
		}
		value.InitChecksum(key)
		var err error
		if ent.Index > prevLastIndex {
			err = engine.MVCCBlindPut(ctx, batch, &diff, key, hlc.ZeroTimestamp, value, nil /* txn */)
		} else {
			err = engine.MVCCPut(ctx, batch, &diff, key, hlc.ZeroTimestamp, value, nil /* txn */)
		}
		if err != nil {
			return 0, 0, err
		}
	}

	// Delete any previously appended log entries which never committed.
	lastIndex := entries[len(entries)-1].Index
	for i := lastIndex + 1; i <= prevLastIndex; i++ {
		err := engine.MVCCDelete(ctx, batch, &diff, keys.RaftLogKey(r.RangeID, i),
			hlc.ZeroTimestamp, nil /* txn */)
		if err != nil {
			return 0, 0, err
		}
	}

	if err := setLastIndex(ctx, batch, r.RangeID, lastIndex); err != nil {
		return 0, 0, err
	}

	raftLogSize := prevRaftLogSize + diff.SysBytes

	return lastIndex, raftLogSize, nil
}