syncthing/lib/db/blockmap.go
2017-02-09 08:04:16 +01:00

229 lines
5.7 KiB
Go

// Copyright (C) 2014 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
package db
import (
"encoding/binary"
"fmt"
"github.com/syncthing/syncthing/lib/osutil"
"github.com/syncthing/syncthing/lib/protocol"
"github.com/syndtr/goleveldb/leveldb"
"github.com/syndtr/goleveldb/leveldb/util"
)
var blockFinder *BlockFinder
const maxBatchSize = 256 << 10
type BlockMap struct {
db *Instance
folder uint32
}
func NewBlockMap(db *Instance, folder uint32) *BlockMap {
return &BlockMap{
db: db,
folder: folder,
}
}
// Add files to the block map, ignoring any deleted or invalid files.
func (m *BlockMap) Add(files []protocol.FileInfo) error {
batch := new(leveldb.Batch)
buf := make([]byte, 4)
var key []byte
for _, file := range files {
if batch.Len() > maxBatchSize {
if err := m.db.Write(batch, nil); err != nil {
return err
}
batch.Reset()
}
if file.IsDirectory() || file.IsDeleted() || file.IsInvalid() {
continue
}
for i, block := range file.Blocks {
binary.BigEndian.PutUint32(buf, uint32(i))
key = m.blockKeyInto(key, block.Hash, file.Name)
batch.Put(key, buf)
}
}
return m.db.Write(batch, nil)
}
// Update block map state, removing any deleted or invalid files.
func (m *BlockMap) Update(files []protocol.FileInfo) error {
batch := new(leveldb.Batch)
buf := make([]byte, 4)
var key []byte
for _, file := range files {
if batch.Len() > maxBatchSize {
if err := m.db.Write(batch, nil); err != nil {
return err
}
batch.Reset()
}
if file.IsDirectory() {
continue
}
if file.IsDeleted() || file.IsInvalid() {
for _, block := range file.Blocks {
key = m.blockKeyInto(key, block.Hash, file.Name)
batch.Delete(key)
}
continue
}
for i, block := range file.Blocks {
binary.BigEndian.PutUint32(buf, uint32(i))
key = m.blockKeyInto(key, block.Hash, file.Name)
batch.Put(key, buf)
}
}
return m.db.Write(batch, nil)
}
// Discard block map state, removing the given files
func (m *BlockMap) Discard(files []protocol.FileInfo) error {
batch := new(leveldb.Batch)
var key []byte
for _, file := range files {
if batch.Len() > maxBatchSize {
if err := m.db.Write(batch, nil); err != nil {
return err
}
batch.Reset()
}
for _, block := range file.Blocks {
key = m.blockKeyInto(key, block.Hash, file.Name)
batch.Delete(key)
}
}
return m.db.Write(batch, nil)
}
// Drop block map, removing all entries related to this block map from the db.
func (m *BlockMap) Drop() error {
batch := new(leveldb.Batch)
iter := m.db.NewIterator(util.BytesPrefix(m.blockKeyInto(nil, nil, "")[:keyPrefixLen+keyFolderLen]), nil)
defer iter.Release()
for iter.Next() {
if batch.Len() > maxBatchSize {
if err := m.db.Write(batch, nil); err != nil {
return err
}
batch.Reset()
}
batch.Delete(iter.Key())
}
if iter.Error() != nil {
return iter.Error()
}
return m.db.Write(batch, nil)
}
func (m *BlockMap) blockKeyInto(o, hash []byte, file string) []byte {
return blockKeyInto(o, hash, m.folder, file)
}
type BlockFinder struct {
db *Instance
}
func NewBlockFinder(db *Instance) *BlockFinder {
if blockFinder != nil {
return blockFinder
}
f := &BlockFinder{
db: db,
}
return f
}
func (f *BlockFinder) String() string {
return fmt.Sprintf("BlockFinder@%p", f)
}
// Iterate takes an iterator function which iterates over all matching blocks
// for the given hash. The iterator function has to return either true (if
// they are happy with the block) or false to continue iterating for whatever
// reason. The iterator finally returns the result, whether or not a
// satisfying block was eventually found.
func (f *BlockFinder) Iterate(folders []string, hash []byte, iterFn func(string, string, int32) bool) bool {
var key []byte
for _, folder := range folders {
folderID := f.db.folderIdx.ID([]byte(folder))
key = blockKeyInto(key, hash, folderID, "")
iter := f.db.NewIterator(util.BytesPrefix(key), nil)
defer iter.Release()
for iter.Next() && iter.Error() == nil {
file := blockKeyName(iter.Key())
index := int32(binary.BigEndian.Uint32(iter.Value()))
if iterFn(folder, osutil.NativeFilename(file), index) {
return true
}
}
}
return false
}
// Fix repairs incorrect blockmap entries, removing the old entry and
// replacing it with a new entry for the given block
func (f *BlockFinder) Fix(folder, file string, index int32, oldHash, newHash []byte) error {
buf := make([]byte, 4)
binary.BigEndian.PutUint32(buf, uint32(index))
folderID := f.db.folderIdx.ID([]byte(folder))
batch := new(leveldb.Batch)
batch.Delete(blockKeyInto(nil, oldHash, folderID, file))
batch.Put(blockKeyInto(nil, newHash, folderID, file), buf)
return f.db.Write(batch, nil)
}
// m.blockKey returns a byte slice encoding the following information:
// keyTypeBlock (1 byte)
// folder (4 bytes)
// block hash (32 bytes)
// file name (variable size)
func blockKeyInto(o, hash []byte, folder uint32, file string) []byte {
reqLen := keyPrefixLen + keyFolderLen + keyHashLen + len(file)
if cap(o) < reqLen {
o = make([]byte, reqLen)
} else {
o = o[:reqLen]
}
o[0] = KeyTypeBlock
binary.BigEndian.PutUint32(o[keyPrefixLen:], folder)
copy(o[keyPrefixLen+keyFolderLen:], hash)
copy(o[keyPrefixLen+keyFolderLen+keyHashLen:], []byte(file))
return o
}
// blockKeyName returns the file name from the block key
func blockKeyName(data []byte) string {
if len(data) < keyPrefixLen+keyFolderLen+keyHashLen+1 {
panic("Incorrect key length")
}
if data[0] != KeyTypeBlock {
panic("Incorrect key type")
}
file := string(data[keyPrefixLen+keyFolderLen+keyHashLen:])
return file
}