syncthing/lib/db/meta.go
Jakob Borg b50d57b7fd
lib/db: Refactor: use a Lowlevel type underneath Instance (ref #5198) (#5212)
This adds a thin type that holds the state associated with the
leveldb.DB, leaving the huge Instance type more or less stateless. Also
moves some keying stuff into the DB package so that other packages need
not know the keying specifics.

(This does not, yet, fix the cmd/stindex program, in order to keep the
diff size down. Hence the keying constants are still exported.)
2018-10-10 11:34:24 +02:00

325 lines
7.5 KiB
Go

// Copyright (C) 2017 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 (
"bytes"
"math/bits"
"time"
"github.com/syncthing/syncthing/lib/protocol"
"github.com/syncthing/syncthing/lib/sync"
)
// metadataTracker keeps metadata on a per device, per local flag basis.
type metadataTracker struct {
mut sync.RWMutex
counts CountsSet
indexes map[metaKey]int // device ID + local flags -> index in counts
dirty bool
}
type metaKey struct {
dev protocol.DeviceID
flags uint32
}
func newMetadataTracker() *metadataTracker {
return &metadataTracker{
mut: sync.NewRWMutex(),
indexes: make(map[metaKey]int),
}
}
// Unmarshal loads a metadataTracker from the corresponding protobuf
// representation
func (m *metadataTracker) Unmarshal(bs []byte) error {
if err := m.counts.Unmarshal(bs); err != nil {
return err
}
// Initialize the index map
for i, c := range m.counts.Counts {
m.indexes[metaKey{protocol.DeviceIDFromBytes(c.DeviceID), c.LocalFlags}] = i
}
return nil
}
// Unmarshal returns the protobuf representation of the metadataTracker
func (m *metadataTracker) Marshal() ([]byte, error) {
return m.counts.Marshal()
}
// toDB saves the marshalled metadataTracker to the given db, under the key
// corresponding to the given folder
func (m *metadataTracker) toDB(db *instance, folder []byte) error {
key := db.keyer.GenerateFolderMetaKey(nil, folder)
m.mut.RLock()
defer m.mut.RUnlock()
if !m.dirty {
return nil
}
bs, err := m.Marshal()
if err != nil {
return err
}
err = db.Put(key, bs, nil)
if err == nil {
m.dirty = false
}
return err
}
// fromDB initializes the metadataTracker from the marshalled data found in
// the database under the key corresponding to the given folder
func (m *metadataTracker) fromDB(db *instance, folder []byte) error {
key := db.keyer.GenerateFolderMetaKey(nil, folder)
bs, err := db.Get(key, nil)
if err != nil {
return err
}
return m.Unmarshal(bs)
}
// countsPtr returns a pointer to the corresponding Counts struct, if
// necessary allocating one in the process
func (m *metadataTracker) countsPtr(dev protocol.DeviceID, flags uint32) *Counts {
// must be called with the mutex held
key := metaKey{dev, flags}
idx, ok := m.indexes[key]
if !ok {
idx = len(m.counts.Counts)
m.counts.Counts = append(m.counts.Counts, Counts{DeviceID: dev[:], LocalFlags: flags})
m.indexes[key] = idx
}
return &m.counts.Counts[idx]
}
// addFile adds a file to the counts, adjusting the sequence number as
// appropriate
func (m *metadataTracker) addFile(dev protocol.DeviceID, f FileIntf) {
if f.IsInvalid() && f.FileLocalFlags() == 0 {
// This is a remote invalid file; it does not count.
return
}
m.mut.Lock()
m.dirty = true
if flags := f.FileLocalFlags(); flags == 0 {
// Account regular files in the zero-flags bucket.
m.addFileLocked(dev, 0, f)
} else {
// Account in flag specific buckets.
eachFlagBit(flags, func(flag uint32) {
m.addFileLocked(dev, flag, f)
})
}
m.mut.Unlock()
}
func (m *metadataTracker) addFileLocked(dev protocol.DeviceID, flags uint32, f FileIntf) {
cp := m.countsPtr(dev, flags)
switch {
case f.IsDeleted():
cp.Deleted++
case f.IsDirectory() && !f.IsSymlink():
cp.Directories++
case f.IsSymlink():
cp.Symlinks++
default:
cp.Files++
}
cp.Bytes += f.FileSize()
if seq := f.SequenceNo(); seq > cp.Sequence {
cp.Sequence = seq
}
}
// removeFile removes a file from the counts
func (m *metadataTracker) removeFile(dev protocol.DeviceID, f FileIntf) {
if f.IsInvalid() && f.FileLocalFlags() == 0 {
// This is a remote invalid file; it does not count.
return
}
m.mut.Lock()
m.dirty = true
if flags := f.FileLocalFlags(); flags == 0 {
// Remove regular files from the zero-flags bucket
m.removeFileLocked(dev, 0, f)
} else {
// Remove from flag specific buckets.
eachFlagBit(flags, func(flag uint32) {
m.removeFileLocked(dev, flag, f)
})
}
m.mut.Unlock()
}
func (m *metadataTracker) removeFileLocked(dev protocol.DeviceID, flags uint32, f FileIntf) {
cp := m.countsPtr(dev, f.FileLocalFlags())
switch {
case f.IsDeleted():
cp.Deleted--
case f.IsDirectory() && !f.IsSymlink():
cp.Directories--
case f.IsSymlink():
cp.Symlinks--
default:
cp.Files--
}
cp.Bytes -= f.FileSize()
// If we've run into an impossible situation, correct it for now and set
// the created timestamp to zero. Next time we start up the metadata
// will be seen as infinitely old and recalculated from scratch.
if cp.Deleted < 0 {
cp.Deleted = 0
m.counts.Created = 0
}
if cp.Files < 0 {
cp.Files = 0
m.counts.Created = 0
}
if cp.Directories < 0 {
cp.Directories = 0
m.counts.Created = 0
}
if cp.Symlinks < 0 {
cp.Symlinks = 0
m.counts.Created = 0
}
}
// resetAll resets all metadata for the given device
func (m *metadataTracker) resetAll(dev protocol.DeviceID) {
m.mut.Lock()
m.dirty = true
for i, c := range m.counts.Counts {
if bytes.Equal(c.DeviceID, dev[:]) {
m.counts.Counts[i] = Counts{
DeviceID: c.DeviceID,
LocalFlags: c.LocalFlags,
}
}
}
m.mut.Unlock()
}
// resetCounts resets the file, dir, etc. counters, while retaining the
// sequence number
func (m *metadataTracker) resetCounts(dev protocol.DeviceID) {
m.mut.Lock()
m.dirty = true
for i, c := range m.counts.Counts {
if bytes.Equal(c.DeviceID, dev[:]) {
m.counts.Counts[i] = Counts{
DeviceID: c.DeviceID,
Sequence: c.Sequence,
LocalFlags: c.LocalFlags,
}
}
}
m.mut.Unlock()
}
// Counts returns the counts for the given device ID and flag. `flag` should
// be zero or have exactly one bit set.
func (m *metadataTracker) Counts(dev protocol.DeviceID, flag uint32) Counts {
if bits.OnesCount32(flag) > 1 {
panic("incorrect usage: set at most one bit in flag")
}
m.mut.RLock()
defer m.mut.RUnlock()
idx, ok := m.indexes[metaKey{dev, flag}]
if !ok {
return Counts{}
}
return m.counts.Counts[idx]
}
// nextSeq allocates a new sequence number for the given device
func (m *metadataTracker) nextSeq(dev protocol.DeviceID) int64 {
m.mut.Lock()
defer m.mut.Unlock()
c := m.countsPtr(dev, 0)
c.Sequence++
return c.Sequence
}
// devices returns the list of devices tracked, excluding the local device
// (which we don't know the ID of)
func (m *metadataTracker) devices() []protocol.DeviceID {
devs := make(map[protocol.DeviceID]struct{}, len(m.counts.Counts))
m.mut.RLock()
for _, dev := range m.counts.Counts {
if dev.Sequence > 0 {
id := protocol.DeviceIDFromBytes(dev.DeviceID)
if id == protocol.GlobalDeviceID || id == protocol.LocalDeviceID {
continue
}
devs[id] = struct{}{}
}
}
m.mut.RUnlock()
devList := make([]protocol.DeviceID, 0, len(devs))
for dev := range devs {
devList = append(devList, dev)
}
return devList
}
func (m *metadataTracker) Created() time.Time {
m.mut.RLock()
defer m.mut.RUnlock()
return time.Unix(0, m.counts.Created)
}
func (m *metadataTracker) SetCreated() {
m.mut.Lock()
m.counts.Created = time.Now().UnixNano()
m.dirty = true
m.mut.Unlock()
}
// eachFlagBit calls the function once for every bit that is set in flags
func eachFlagBit(flags uint32, fn func(flag uint32)) {
// Test each bit from the right, as long as there are bits left in the
// flag set. Clear any bits found and stop testing as soon as there are
// no more bits set.
currentBit := uint32(1 << 0)
for flags != 0 {
if flags&currentBit != 0 {
fn(currentBit)
flags &^= currentBit
}
currentBit <<= 1
}
}