Golang DB.Write方法代码示例

// flush a leveldb batch to database and reset batch to 0
func cacheFlush(db *leveldb.DB, batch *leveldb.Batch) {
	err := db.Write(batch, nil)
	if err != nil {
		log.Fatal(err)
	}
	batch.Reset()
}

func clearItems(db *leveldb.DB) error {
	snap, err := db.GetSnapshot()
	if err != nil {
		return err
	}
	defer snap.Release()

	// Iterate over k2

	it := snap.NewIterator(util.BytesPrefix([]byte{1}), nil)
	defer it.Release()

	batch := new(leveldb.Batch)
	for it.Next() {
		k1 := it.Key()
		k2 := it.Value()

		// k2 should exist
		_, err := snap.Get(k2, nil)
		if err != nil {
			return err
		}

		// Delete the k1 => k2 mapping first
		batch.Delete(k1)
		// Then the k2 => data mapping
		batch.Delete(k2)
	}
	if testing.Verbose() {
		log.Printf("batch write (clear) %p", batch)
	}
	return db.Write(batch, nil)
}

func clearItems(db *leveldb.DB) error {
	snap, err := db.GetSnapshot()
	if err != nil {
		return err
	}
	defer snap.Release()

	// Iterate from the start of k2 space to the end
	it := snap.NewIterator(&util.Range{Start: []byte{2}, Limit: []byte{2, 0xff, 0xff, 0xff, 0xff}}, nil)
	defer it.Release()

	batch := &leveldb.Batch{}
	for it.Next() {
		k2 := it.Key()
		k1 := it.Value()

		// k1 should exist
		_, err := snap.Get(k1, nil)
		if err != nil {
			return err
		}

		// Delete the k2 => k1 mapping first
		batch.Delete(k2)
		// Then the k1 => key mapping
		batch.Delete(k1)
	}
	return db.Write(batch, nil)
}

func ldbCheckGlobals(db *leveldb.DB, folder []byte) {
	defer runtime.GC()

	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	l.Debugf("created snapshot %p", snap)
	defer func() {
		l.Debugf("close snapshot %p", snap)
		snap.Release()
	}()

	start := globalKey(folder, nil)
	limit := globalKey(folder, []byte{0xff, 0xff, 0xff, 0xff})
	dbi := snap.NewIterator(&util.Range{Start: start, Limit: limit}, nil)
	defer dbi.Release()

	batch := new(leveldb.Batch)
	l.Debugf("new batch %p", batch)

	var fk []byte
	for dbi.Next() {
		gk := dbi.Key()
		var vl versionList
		err := vl.UnmarshalXDR(dbi.Value())
		if err != nil {
			panic(err)
		}

		// Check the global version list for consistency. An issue in previous
		// versions of goleveldb could result in reordered writes so that
		// there are global entries pointing to no longer existing files. Here
		// we find those and clear them out.

		name := globalKeyName(gk)
		var newVL versionList
		for _, version := range vl.versions {
			fk = deviceKeyInto(fk[:cap(fk)], folder, version.device, name)
			l.Debugf("snap.Get %p %x", snap, fk)
			_, err := snap.Get(fk, nil)
			if err == leveldb.ErrNotFound {
				continue
			}
			if err != nil {
				panic(err)
			}
			newVL.versions = append(newVL.versions, version)
		}

		if len(newVL.versions) != len(vl.versions) {
			l.Infof("db repair: rewriting global version list for %x %x", gk[1:1+64], gk[1+64:])
			batch.Put(dbi.Key(), newVL.MustMarshalXDR())
		}
	}
	l.Debugf("db check completed for %q", folder)
	db.Write(batch, nil)
}

func ldbUpdate(db *leveldb.DB, repo, node []byte, fs []protocol.FileInfo) uint64 {
	defer runtime.GC()

	batch := new(leveldb.Batch)
	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	defer snap.Release()

	var maxLocalVer uint64
	for _, f := range fs {
		name := []byte(f.Name)
		fk := nodeKey(repo, node, name)
		bs, err := snap.Get(fk, nil)
		if err == leveldb.ErrNotFound {
			if lv := ldbInsert(batch, repo, node, name, f); lv > maxLocalVer {
				maxLocalVer = lv
			}
			if f.IsInvalid() {
				ldbRemoveFromGlobal(snap, batch, repo, node, name)
			} else {
				ldbUpdateGlobal(snap, batch, repo, node, name, f.Version)
			}
			continue
		}

		var ef protocol.FileInfoTruncated
		err = ef.UnmarshalXDR(bs)
		if err != nil {
			panic(err)
		}
		// Flags might change without the version being bumped when we set the
		// invalid flag on an existing file.
		if ef.Version != f.Version || ef.Flags != f.Flags {
			if lv := ldbInsert(batch, repo, node, name, f); lv > maxLocalVer {
				maxLocalVer = lv
			}
			if f.IsInvalid() {
				ldbRemoveFromGlobal(snap, batch, repo, node, name)
			} else {
				ldbUpdateGlobal(snap, batch, repo, node, name, f.Version)
			}
		}
	}

	err = db.Write(batch, nil)
	if err != nil {
		panic(err)
	}

	return maxLocalVer
}

func setItems(db *leveldb.DB) error {
	batch := new(leveldb.Batch)
	for _, k1 := range keys {
		k2 := randomData(2)
		// k2 -> data
		batch.Put(k2, randomData(42))
		// k1 -> k2
		batch.Put(k1, k2)
	}
	if testing.Verbose() {
		log.Printf("batch write (set) %p", batch)
	}
	return db.Write(batch, nil)
}

func setItems(db *leveldb.DB) error {
	snap, err := db.GetSnapshot()
	if err != nil {
		return err
	}
	defer snap.Release()

	batch := &leveldb.Batch{}
	for k2, k1 := range keys {
		// Create k1 => item mapping first
		batch.Put(makeK1(k1), items[k1])
		// Then the k2 => k1 mapping
		batch.Put(makeK2(k2), makeK1(k1))
	}
	return db.Write(batch, nil)
}

func ldbWithAllFolderTruncated(db *leveldb.DB, folder []byte, fn func(device []byte, f FileInfoTruncated) bool) {
	runtime.GC()

	start := deviceKey(folder, nil, nil)                                                  // before all folder/device files
	limit := deviceKey(folder, protocol.LocalDeviceID[:], []byte{0xff, 0xff, 0xff, 0xff}) // after all folder/device files
	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	if debugDB {
		l.Debugf("created snapshot %p", snap)
	}
	defer func() {
		if debugDB {
			l.Debugf("close snapshot %p", snap)
		}
		snap.Release()
	}()

	dbi := snap.NewIterator(&util.Range{Start: start, Limit: limit}, nil)
	defer dbi.Release()

	for dbi.Next() {
		device := deviceKeyDevice(dbi.Key())
		var f FileInfoTruncated
		err := f.UnmarshalXDR(dbi.Value())
		if err != nil {
			panic(err)
		}

		switch f.Name {
		case "", ".", "..", "/": // A few obviously invalid filenames
			l.Infof("Dropping invalid filename %q from database", f.Name)
			batch := new(leveldb.Batch)
			ldbRemoveFromGlobal(db, batch, folder, device, nil)
			batch.Delete(dbi.Key())
			db.Write(batch, nil)
			continue
		}

		if cont := fn(device, f); !cont {
			return
		}
	}
}

func ldbUpdate(db *leveldb.DB, repo, node []byte, fs []protocol.FileInfo) uint64 {
	defer runtime.GC()

	batch := new(leveldb.Batch)
	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	defer snap.Release()

	var maxLocalVer uint64
	for _, f := range fs {
		name := []byte(f.Name)
		fk := nodeKey(repo, node, name)
		bs, err := snap.Get(fk, nil)
		if err == leveldb.ErrNotFound {
			if lv := ldbInsert(batch, repo, node, name, f); lv > maxLocalVer {
				maxLocalVer = lv
			}
			ldbUpdateGlobal(snap, batch, repo, node, name, f.Version)
			continue
		}

		var ef protocol.FileInfoTruncated
		err = ef.UnmarshalXDR(bs)
		if err != nil {
			panic(err)
		}
		if ef.Version != f.Version {
			if lv := ldbInsert(batch, repo, node, name, f); lv > maxLocalVer {
				maxLocalVer = lv
			}
			ldbUpdateGlobal(snap, batch, repo, node, name, f.Version)
		}
	}

	err = db.Write(batch, nil)
	if err != nil {
		panic(err)
	}

	return maxLocalVer
}

func ldbUpdate(db *leveldb.DB, repo, node []byte, fs []protocol.FileInfo) bool {
	batch := new(leveldb.Batch)
	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	defer snap.Release()

	for _, f := range fs {
		name := []byte(f.Name)
		fk := nodeKey(repo, node, name)
		bs, err := snap.Get(fk, nil)
		if err == leveldb.ErrNotFound {
			ldbInsert(batch, repo, node, name, f)
			ldbUpdateGlobal(snap, batch, repo, node, name, f.Version)
			continue
		}

		var ef protocol.FileInfo
		err = ef.UnmarshalXDR(bs)
		if err != nil {
			panic(err)
		}
		if ef.Version != f.Version {
			ldbInsert(batch, repo, node, name, f)
			ldbUpdateGlobal(snap, batch, repo, node, name, f.Version)
		}
	}

	err = db.Write(batch, nil)
	if err != nil {
		panic(err)
	}

	return true
}

func ldbUpdate(db *leveldb.DB, folder, device []byte, fs []protocol.FileInfo) int64 {
	runtime.GC()

	batch := new(leveldb.Batch)
	if debugDB {
		l.Debugf("new batch %p", batch)
	}
	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	if debugDB {
		l.Debugf("created snapshot %p", snap)
	}
	defer func() {
		if debugDB {
			l.Debugf("close snapshot %p", snap)
		}
		snap.Release()
	}()

	var maxLocalVer int64
	var fk []byte
	for _, f := range fs {
		name := []byte(f.Name)
		fk = deviceKeyInto(fk[:cap(fk)], folder, device, name)
		if debugDB {
			l.Debugf("snap.Get %p %x", snap, fk)
		}
		bs, err := snap.Get(fk, nil)
		if err == leveldb.ErrNotFound {
			if lv := ldbInsert(batch, folder, device, f); lv > maxLocalVer {
				maxLocalVer = lv
			}
			if f.IsInvalid() {
				ldbRemoveFromGlobal(snap, batch, folder, device, name)
			} else {
				ldbUpdateGlobal(snap, batch, folder, device, f)
			}
			continue
		}

		var ef FileInfoTruncated
		err = ef.UnmarshalXDR(bs)
		if err != nil {
			panic(err)
		}
		// Flags might change without the version being bumped when we set the
		// invalid flag on an existing file.
		if !ef.Version.Equal(f.Version) || ef.Flags != f.Flags {
			if lv := ldbInsert(batch, folder, device, f); lv > maxLocalVer {
				maxLocalVer = lv
			}
			if f.IsInvalid() {
				ldbRemoveFromGlobal(snap, batch, folder, device, name)
			} else {
				ldbUpdateGlobal(snap, batch, folder, device, f)
			}
		}

		// Write out and reuse the batch every few records, to avoid the batch
		// growing too large and thus allocating unnecessarily much memory.
		if batch.Len() > batchFlushSize {
			if debugDB {
				l.Debugf("db.Write %p", batch)
			}

			err = db.Write(batch, nil)
			if err != nil {
				panic(err)
			}

			batch.Reset()
		}
	}

	if debugDB {
		l.Debugf("db.Write %p", batch)
	}
	err = db.Write(batch, nil)
	if err != nil {
		panic(err)
	}

	return maxLocalVer
}

//.........这里部分代码省略.........
		moreFs := fsi < len(fs)

		if !moreDb && !moreFs {
			break
		}

		if moreFs {
			newName = []byte(fs[fsi].Name)
		}

		if moreDb {
			oldName = deviceKeyName(dbi.Key())
		}

		cmp := bytes.Compare(newName, oldName)

		if debugDB {
			l.Debugf("generic replace; folder=%q device=%v moreFs=%v moreDb=%v cmp=%d newName=%q oldName=%q", folder, protocol.DeviceIDFromBytes(device), moreFs, moreDb, cmp, newName, oldName)
		}

		switch {
		case moreFs && (!moreDb || cmp == -1):
			if debugDB {
				l.Debugln("generic replace; missing - insert")
			}
			// Database is missing this file. Insert it.
			if lv := ldbInsert(batch, folder, device, fs[fsi]); lv > maxLocalVer {
				maxLocalVer = lv
			}
			if fs[fsi].IsInvalid() {
				ldbRemoveFromGlobal(snap, batch, folder, device, newName)
			} else {
				ldbUpdateGlobal(snap, batch, folder, device, fs[fsi])
			}
			fsi++

		case moreFs && moreDb && cmp == 0:
			// File exists on both sides - compare versions. We might get an
			// update with the same version and different flags if a device has
			// marked a file as invalid, so handle that too.
			if debugDB {
				l.Debugln("generic replace; exists - compare")
			}
			var ef FileInfoTruncated
			ef.UnmarshalXDR(dbi.Value())
			if !fs[fsi].Version.Equal(ef.Version) || fs[fsi].Flags != ef.Flags {
				if debugDB {
					l.Debugln("generic replace; differs - insert")
				}
				if lv := ldbInsert(batch, folder, device, fs[fsi]); lv > maxLocalVer {
					maxLocalVer = lv
				}
				if fs[fsi].IsInvalid() {
					ldbRemoveFromGlobal(snap, batch, folder, device, newName)
				} else {
					ldbUpdateGlobal(snap, batch, folder, device, fs[fsi])
				}
			} else if debugDB {
				l.Debugln("generic replace; equal - ignore")
			}

			fsi++
			moreDb = dbi.Next()

		case moreDb && (!moreFs || cmp == 1):
			if debugDB {
				l.Debugln("generic replace; exists - remove")
			}
			if lv := deleteFn(snap, batch, folder, device, oldName, dbi); lv > maxLocalVer {
				maxLocalVer = lv
			}
			moreDb = dbi.Next()
		}

		// Write out and reuse the batch every few records, to avoid the batch
		// growing too large and thus allocating unnecessarily much memory.
		if batch.Len() > batchFlushSize {
			if debugDB {
				l.Debugf("db.Write %p", batch)
			}

			err = db.Write(batch, nil)
			if err != nil {
				panic(err)
			}

			batch.Reset()
		}
	}

	if debugDB {
		l.Debugf("db.Write %p", batch)
	}
	err = db.Write(batch, nil)
	if err != nil {
		panic(err)
	}

	return maxLocalVer
}

func ldbGenericReplace(db *leveldb.DB, repo, node []byte, fs []protocol.FileInfo, deleteFn deletionHandler) bool {
	sort.Sort(fileList(fs)) // sort list on name, same as on disk

	start := nodeKey(repo, node, nil)                            // before all repo/node files
	limit := nodeKey(repo, node, []byte{0xff, 0xff, 0xff, 0xff}) // after all repo/node files

	batch := new(leveldb.Batch)
	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	defer snap.Release()
	dbi := snap.NewIterator(&util.Range{Start: start, Limit: limit}, nil)
	defer dbi.Release()

	moreDb := dbi.Next()
	fsi := 0
	changed := false

	for {
		var newName, oldName []byte
		moreFs := fsi < len(fs)

		if !moreDb && !moreFs {
			break
		}

		if !moreFs && deleteFn == nil {
			// We don't have any more updated files to process and deletion
			// has not been requested, so we can exit early
			break
		}

		if moreFs {
			newName = []byte(fs[fsi].Name)
		}

		if moreDb {
			oldName = nodeKeyName(dbi.Key())
		}

		cmp := bytes.Compare(newName, oldName)

		if debug {
			l.Debugf("generic replace; repo=%q node=%x moreFs=%v moreDb=%v cmp=%d newName=%q oldName=%q", repo, node, moreFs, moreDb, cmp, newName, oldName)
		}

		switch {
		case moreFs && (!moreDb || cmp == -1):
			changed = true
			// Disk is missing this file. Insert it.
			ldbInsert(batch, repo, node, newName, fs[fsi])
			ldbUpdateGlobal(snap, batch, repo, node, newName, fs[fsi].Version)
			fsi++

		case cmp == 0:
			// File exists on both sides - compare versions.
			var ef protocol.FileInfo
			ef.UnmarshalXDR(dbi.Value())
			if fs[fsi].Version > ef.Version {
				ldbInsert(batch, repo, node, newName, fs[fsi])
				ldbUpdateGlobal(snap, batch, repo, node, newName, fs[fsi].Version)
				changed = true
			}
			// Iterate both sides.
			fsi++
			moreDb = dbi.Next()

		case moreDb && (!moreFs || cmp == 1):
			if deleteFn != nil {
				if deleteFn(snap, batch, repo, node, oldName, dbi) {
					changed = true
				}
			}
			moreDb = dbi.Next()
		}
	}

	err = db.Write(batch, nil)
	if err != nil {
		panic(err)
	}

	return changed
}

func ldbGenericReplace(db *leveldb.DB, repo, node []byte, fs []protocol.FileInfo, deleteFn deletionHandler) uint64 {
	defer runtime.GC()

	sort.Sort(fileList(fs)) // sort list on name, same as on disk

	start := nodeKey(repo, node, nil)                            // before all repo/node files
	limit := nodeKey(repo, node, []byte{0xff, 0xff, 0xff, 0xff}) // after all repo/node files

	batch := new(leveldb.Batch)
	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	defer snap.Release()
	dbi := snap.NewIterator(&util.Range{Start: start, Limit: limit}, nil)
	defer dbi.Release()

	moreDb := dbi.Next()
	fsi := 0
	var maxLocalVer uint64

	for {
		var newName, oldName []byte
		moreFs := fsi < len(fs)

		if !moreDb && !moreFs {
			break
		}

		if !moreFs && deleteFn == nil {
			// We don't have any more updated files to process and deletion
			// has not been requested, so we can exit early
			break
		}

		if moreFs {
			newName = []byte(fs[fsi].Name)
		}

		if moreDb {
			oldName = nodeKeyName(dbi.Key())
		}

		cmp := bytes.Compare(newName, oldName)

		if debug {
			l.Debugf("generic replace; repo=%q node=%v moreFs=%v moreDb=%v cmp=%d newName=%q oldName=%q", repo, protocol.NodeIDFromBytes(node), moreFs, moreDb, cmp, newName, oldName)
		}

		switch {
		case moreFs && (!moreDb || cmp == -1):
			// Disk is missing this file. Insert it.
			if lv := ldbInsert(batch, repo, node, newName, fs[fsi]); lv > maxLocalVer {
				maxLocalVer = lv
			}
			if fs[fsi].IsInvalid() {
				ldbRemoveFromGlobal(snap, batch, repo, node, newName)
			} else {
				ldbUpdateGlobal(snap, batch, repo, node, newName, fs[fsi].Version)
			}
			fsi++

		case moreFs && moreDb && cmp == 0:
			// File exists on both sides - compare versions. We might get an
			// update with the same version and different flags if a node has
			// marked a file as invalid, so handle that too.
			var ef protocol.FileInfoTruncated
			ef.UnmarshalXDR(dbi.Value())
			if fs[fsi].Version > ef.Version || fs[fsi].Version != ef.Version {
				if lv := ldbInsert(batch, repo, node, newName, fs[fsi]); lv > maxLocalVer {
					maxLocalVer = lv
				}
				if fs[fsi].IsInvalid() {
					ldbRemoveFromGlobal(snap, batch, repo, node, newName)
				} else {
					ldbUpdateGlobal(snap, batch, repo, node, newName, fs[fsi].Version)
				}
			}
			// Iterate both sides.
			fsi++
			moreDb = dbi.Next()

		case moreDb && (!moreFs || cmp == 1):
			if deleteFn != nil {
				if lv := deleteFn(snap, batch, repo, node, oldName, dbi); lv > maxLocalVer {
					maxLocalVer = lv
				}
			}
			moreDb = dbi.Next()
		}
	}

	err = db.Write(batch, nil)
	if err != nil {
		panic(err)
	}

	return maxLocalVer
}

func ldbUpdate(db *leveldb.DB, folder, device []byte, fs []protocol.FileInfo) uint64 {
	runtime.GC()

	batch := new(leveldb.Batch)
	if debugDB {
		l.Debugf("new batch %p", batch)
	}
	snap, err := db.GetSnapshot()
	if err != nil {
		panic(err)
	}
	if debugDB {
		l.Debugf("created snapshot %p", snap)
	}
	defer func() {
		if debugDB {
			l.Debugf("close snapshot %p", snap)
		}
		snap.Release()
	}()

	var maxLocalVer uint64
	for _, f := range fs {
		name := []byte(f.Name)
		fk := deviceKey(folder, device, name)
		if debugDB {
			l.Debugf("snap.Get %p %x", snap, fk)
		}
		bs, err := snap.Get(fk, nil)
		if err == leveldb.ErrNotFound {
			if lv := ldbInsert(batch, folder, device, f); lv > maxLocalVer {
				maxLocalVer = lv
			}
			if f.IsInvalid() {
				ldbRemoveFromGlobal(snap, batch, folder, device, name)
			} else {
				ldbUpdateGlobal(snap, batch, folder, device, name, f.Version)
			}
			continue
		}

		var ef protocol.FileInfoTruncated
		err = ef.UnmarshalXDR(bs)
		if err != nil {
			panic(err)
		}
		// Flags might change without the version being bumped when we set the
		// invalid flag on an existing file.
		if ef.Version != f.Version || ef.Flags != f.Flags {
			if lv := ldbInsert(batch, folder, device, f); lv > maxLocalVer {
				maxLocalVer = lv
			}
			if f.IsInvalid() {
				ldbRemoveFromGlobal(snap, batch, folder, device, name)
			} else {
				ldbUpdateGlobal(snap, batch, folder, device, name, f.Version)
			}
		}
	}

	if debugDB {
		l.Debugf("db.Write %p", batch)
	}
	err = db.Write(batch, nil)
	if err != nil {
		panic(err)
	}

	return maxLocalVer
}