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keyer.go
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keyer.go
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// Copyright (C) 2018 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"
)
const (
keyPrefixLen = 1
keyFolderLen = 4 // indexed
keyDeviceLen = 4 // indexed
keySequenceLen = 8
keyHashLen = 32
maxInt64 int64 = 1<<63 - 1
)
const (
KeyTypeDevice = 0
KeyTypeGlobal = 1
KeyTypeBlock = 2
KeyTypeDeviceStatistic = 3
KeyTypeFolderStatistic = 4
KeyTypeVirtualMtime = 5
KeyTypeFolderIdx = 6
KeyTypeDeviceIdx = 7
KeyTypeIndexID = 8
KeyTypeFolderMeta = 9
KeyTypeMiscData = 10
KeyTypeSequence = 11
KeyTypeNeed = 12
)
type keyer interface {
// device file key stuff
GenerateDeviceFileKey(key, folder, device, name []byte) deviceFileKey
NameFromDeviceFileKey(key []byte) []byte
DeviceFromDeviceFileKey(key []byte) ([]byte, bool)
FolderFromDeviceFileKey(key []byte) ([]byte, bool)
// global version key stuff
GenerateGlobalVersionKey(key, folder, name []byte) globalVersionKey
NameFromGlobalVersionKey(key []byte) []byte
FolderFromGlobalVersionKey(key []byte) ([]byte, bool)
// file need index
GenerateNeedFileKey(key, folder, name []byte) needFileKey
// file sequence index
GenerateSequenceKey(key, folder []byte, seq int64) sequenceKey
SequenceFromSequenceKey(key []byte) int64
// index IDs
GenerateIndexIDKey(key, device, folder []byte) indexIDKey
DeviceFromIndexIDKey(key []byte) ([]byte, bool)
// Mtimes
GenerateMtimesKey(key, folder []byte) mtimesKey
// Folder metadata
GenerateFolderMetaKey(key, folder []byte) folderMetaKey
}
// defaultKeyer implements our key scheme. It needs folder and device
// indexes.
type defaultKeyer struct {
folderIdx *smallIndex
deviceIdx *smallIndex
}
func newDefaultKeyer(folderIdx, deviceIdx *smallIndex) defaultKeyer {
return defaultKeyer{
folderIdx: folderIdx,
deviceIdx: deviceIdx,
}
}
type deviceFileKey []byte
func (k deviceFileKey) WithoutNameAndDevice() []byte {
return k[:keyPrefixLen+keyFolderLen]
}
func (k defaultKeyer) GenerateDeviceFileKey(key, folder, device, name []byte) deviceFileKey {
key = resize(key, keyPrefixLen+keyFolderLen+keyDeviceLen+len(name))
key[0] = KeyTypeDevice
binary.BigEndian.PutUint32(key[keyPrefixLen:], k.folderIdx.ID(folder))
binary.BigEndian.PutUint32(key[keyPrefixLen+keyFolderLen:], k.deviceIdx.ID(device))
copy(key[keyPrefixLen+keyFolderLen+keyDeviceLen:], name)
return key
}
func (k defaultKeyer) NameFromDeviceFileKey(key []byte) []byte {
return key[keyPrefixLen+keyFolderLen+keyDeviceLen:]
}
func (k defaultKeyer) DeviceFromDeviceFileKey(key []byte) ([]byte, bool) {
return k.deviceIdx.Val(binary.BigEndian.Uint32(key[keyPrefixLen+keyFolderLen:]))
}
func (k defaultKeyer) FolderFromDeviceFileKey(key []byte) ([]byte, bool) {
return k.folderIdx.Val(binary.BigEndian.Uint32(key[keyPrefixLen:]))
}
type globalVersionKey []byte
func (k globalVersionKey) WithoutName() []byte {
return k[:keyPrefixLen+keyFolderLen]
}
func (k defaultKeyer) GenerateGlobalVersionKey(key, folder, name []byte) globalVersionKey {
key = resize(key, keyPrefixLen+keyFolderLen+len(name))
key[0] = KeyTypeGlobal
binary.BigEndian.PutUint32(key[keyPrefixLen:], k.folderIdx.ID(folder))
copy(key[keyPrefixLen+keyFolderLen:], name)
return key
}
func (k defaultKeyer) NameFromGlobalVersionKey(key []byte) []byte {
return key[keyPrefixLen+keyFolderLen:]
}
func (k defaultKeyer) FolderFromGlobalVersionKey(key []byte) ([]byte, bool) {
return k.folderIdx.Val(binary.BigEndian.Uint32(key[keyPrefixLen:]))
}
type needFileKey []byte
func (k needFileKey) WithoutName() []byte {
return k[:keyPrefixLen+keyFolderLen]
}
func (k defaultKeyer) GenerateNeedFileKey(key, folder, name []byte) needFileKey {
key = resize(key, keyPrefixLen+keyFolderLen+len(name))
key[0] = KeyTypeNeed
binary.BigEndian.PutUint32(key[keyPrefixLen:], k.folderIdx.ID(folder))
copy(key[keyPrefixLen+keyFolderLen:], name)
return key
}
type sequenceKey []byte
func (k sequenceKey) WithoutSequence() []byte {
return k[:keyPrefixLen+keyFolderLen]
}
func (k defaultKeyer) GenerateSequenceKey(key, folder []byte, seq int64) sequenceKey {
key = resize(key, keyPrefixLen+keyFolderLen+keySequenceLen)
key[0] = KeyTypeSequence
binary.BigEndian.PutUint32(key[keyPrefixLen:], k.folderIdx.ID(folder))
binary.BigEndian.PutUint64(key[keyPrefixLen+keyFolderLen:], uint64(seq))
return key
}
func (k defaultKeyer) SequenceFromSequenceKey(key []byte) int64 {
return int64(binary.BigEndian.Uint64(key[keyPrefixLen+keyFolderLen:]))
}
type indexIDKey []byte
func (k defaultKeyer) GenerateIndexIDKey(key, device, folder []byte) indexIDKey {
key = resize(key, keyPrefixLen+keyDeviceLen+keyFolderLen)
key[0] = KeyTypeIndexID
binary.BigEndian.PutUint32(key[keyPrefixLen:], k.deviceIdx.ID(device))
binary.BigEndian.PutUint32(key[keyPrefixLen+keyDeviceLen:], k.folderIdx.ID(folder))
return key
}
func (k defaultKeyer) DeviceFromIndexIDKey(key []byte) ([]byte, bool) {
return k.deviceIdx.Val(binary.BigEndian.Uint32(key[keyPrefixLen:]))
}
type mtimesKey []byte
func (k defaultKeyer) GenerateMtimesKey(key, folder []byte) mtimesKey {
key = resize(key, keyPrefixLen+keyFolderLen)
key[0] = KeyTypeVirtualMtime
binary.BigEndian.PutUint32(key[keyPrefixLen:], k.folderIdx.ID(folder))
return key
}
type folderMetaKey []byte
func (k defaultKeyer) GenerateFolderMetaKey(key, folder []byte) folderMetaKey {
key = resize(key, keyPrefixLen+keyFolderLen)
key[0] = KeyTypeFolderMeta
binary.BigEndian.PutUint32(key[keyPrefixLen:], k.folderIdx.ID(folder))
return key
}
// resize returns a byte slice of the specified size, reusing bs if possible
func resize(bs []byte, size int) []byte {
if cap(bs) < size {
return make([]byte, size)
}
return bs[:size]
}