mirror of
https://github.com/octoleo/syncthing.git
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298 lines
8.3 KiB
Go
298 lines
8.3 KiB
Go
// Copyright (C) 2014 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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package db
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import (
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"github.com/syncthing/syncthing/lib/protocol"
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"github.com/syndtr/goleveldb/leveldb"
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"github.com/syndtr/goleveldb/leveldb/util"
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)
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// Flush batches to disk when they contain this many records.
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const batchFlushSize = 64
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// A readOnlyTransaction represents a database snapshot.
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type readOnlyTransaction struct {
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*leveldb.Snapshot
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db *instance
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}
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func (db *instance) newReadOnlyTransaction() readOnlyTransaction {
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snap, err := db.GetSnapshot()
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if err != nil {
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panic(err)
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}
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return readOnlyTransaction{
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Snapshot: snap,
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db: db,
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}
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}
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func (t readOnlyTransaction) close() {
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t.Release()
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}
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func (t readOnlyTransaction) getFile(folder, device, file []byte) (protocol.FileInfo, bool) {
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return t.getFileByKey(t.db.keyer.GenerateDeviceFileKey(nil, folder, device, file))
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}
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func (t readOnlyTransaction) getFileByKey(key []byte) (protocol.FileInfo, bool) {
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if f, ok := t.getFileTrunc(key, false); ok {
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return f.(protocol.FileInfo), true
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}
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return protocol.FileInfo{}, false
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}
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func (t readOnlyTransaction) getFileTrunc(key []byte, trunc bool) (FileIntf, bool) {
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bs, err := t.Get(key, nil)
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if err == leveldb.ErrNotFound {
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return nil, false
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}
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if err != nil {
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l.Debugln("surprise error:", err)
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return nil, false
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}
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f, err := unmarshalTrunc(bs, trunc)
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if err != nil {
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l.Debugln("unmarshal error:", err)
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return nil, false
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}
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return f, true
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}
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func (t readOnlyTransaction) getGlobal(keyBuf, folder, file []byte, truncate bool) ([]byte, FileIntf, bool) {
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keyBuf = t.db.keyer.GenerateGlobalVersionKey(keyBuf, folder, file)
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bs, err := t.Get(keyBuf, nil)
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if err != nil {
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return keyBuf, nil, false
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}
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vl, ok := unmarshalVersionList(bs)
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if !ok {
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return keyBuf, nil, false
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}
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keyBuf = t.db.keyer.GenerateDeviceFileKey(keyBuf, folder, vl.Versions[0].Device, file)
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if fi, ok := t.getFileTrunc(keyBuf, truncate); ok {
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return keyBuf, fi, true
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}
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return keyBuf, nil, false
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}
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// A readWriteTransaction is a readOnlyTransaction plus a batch for writes.
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// The batch will be committed on close() or by checkFlush() if it exceeds the
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// batch size.
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type readWriteTransaction struct {
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readOnlyTransaction
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*leveldb.Batch
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}
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func (db *instance) newReadWriteTransaction() readWriteTransaction {
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t := db.newReadOnlyTransaction()
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return readWriteTransaction{
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readOnlyTransaction: t,
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Batch: new(leveldb.Batch),
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}
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}
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func (t readWriteTransaction) close() {
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t.flush()
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t.readOnlyTransaction.close()
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}
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func (t readWriteTransaction) checkFlush() {
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if t.Batch.Len() > batchFlushSize {
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t.flush()
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t.Batch.Reset()
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}
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}
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func (t readWriteTransaction) flush() {
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if err := t.db.Write(t.Batch, nil); err != nil {
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panic(err)
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}
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}
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// updateGlobal adds this device+version to the version list for the given
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// file. If the device is already present in the list, the version is updated.
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// If the file does not have an entry in the global list, it is created.
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func (t readWriteTransaction) updateGlobal(gk, keyBuf, folder, device []byte, file protocol.FileInfo, meta *metadataTracker) ([]byte, bool) {
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l.Debugf("update global; folder=%q device=%v file=%q version=%v invalid=%v", folder, protocol.DeviceIDFromBytes(device), file.Name, file.Version, file.IsInvalid())
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var fl VersionList
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if svl, err := t.Get(gk, nil); err == nil {
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fl.Unmarshal(svl) // Ignore error, continue with empty fl
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}
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fl, removedFV, removedAt, insertedAt := fl.update(folder, device, file, t.readOnlyTransaction)
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if insertedAt == -1 {
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l.Debugln("update global; same version, global unchanged")
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return keyBuf, false
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}
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name := []byte(file.Name)
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var global protocol.FileInfo
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if insertedAt == 0 {
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// Inserted a new newest version
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global = file
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} else {
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keyBuf = t.db.keyer.GenerateDeviceFileKey(keyBuf, folder, fl.Versions[0].Device, name)
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if new, ok := t.getFileByKey(keyBuf); ok {
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global = new
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} else {
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panic("This file must exist in the db")
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}
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}
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// Fixup the list of files we need.
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keyBuf = t.updateLocalNeed(keyBuf, folder, name, fl, global)
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if removedAt != 0 && insertedAt != 0 {
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l.Debugf(`new global for "%v" after update: %v`, file.Name, fl)
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t.Put(gk, mustMarshal(&fl))
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return keyBuf, true
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}
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// Remove the old global from the global size counter
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var oldGlobalFV FileVersion
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if removedAt == 0 {
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oldGlobalFV = removedFV
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} else if len(fl.Versions) > 1 {
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// The previous newest version is now at index 1
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oldGlobalFV = fl.Versions[1]
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}
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keyBuf = t.db.keyer.GenerateDeviceFileKey(keyBuf, folder, oldGlobalFV.Device, name)
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if oldFile, ok := t.getFileByKey(keyBuf); ok {
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// A failure to get the file here is surprising and our
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// global size data will be incorrect until a restart...
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meta.removeFile(protocol.GlobalDeviceID, oldFile)
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}
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// Add the new global to the global size counter
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meta.addFile(protocol.GlobalDeviceID, global)
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l.Debugf(`new global for "%v" after update: %v`, file.Name, fl)
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t.Put(gk, mustMarshal(&fl))
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return keyBuf, true
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}
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// updateLocalNeed checks whether the given file is still needed on the local
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// device according to the version list and global FileInfo given and updates
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// the db accordingly.
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func (t readWriteTransaction) updateLocalNeed(keyBuf, folder, name []byte, fl VersionList, global protocol.FileInfo) []byte {
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keyBuf = t.db.keyer.GenerateNeedFileKey(keyBuf, folder, name)
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hasNeeded, _ := t.Has(keyBuf, nil)
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if localFV, haveLocalFV := fl.Get(protocol.LocalDeviceID[:]); need(global, haveLocalFV, localFV.Version) {
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if !hasNeeded {
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l.Debugf("local need insert; folder=%q, name=%q", folder, name)
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t.Put(keyBuf, nil)
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}
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} else if hasNeeded {
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l.Debugf("local need delete; folder=%q, name=%q", folder, name)
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t.Delete(keyBuf)
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}
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return keyBuf
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}
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func need(global FileIntf, haveLocal bool, localVersion protocol.Vector) bool {
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// We never need an invalid file.
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if global.IsInvalid() {
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return false
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}
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// We don't need a deleted file if we don't have it.
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if global.IsDeleted() && !haveLocal {
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return false
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}
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// We don't need the global file if we already have the same version.
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if haveLocal && localVersion.GreaterEqual(global.FileVersion()) {
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return false
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}
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return true
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}
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// removeFromGlobal removes the device from the global version list for the
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// given file. If the version list is empty after this, the file entry is
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// removed entirely.
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func (t readWriteTransaction) removeFromGlobal(gk, keyBuf, folder, device []byte, file []byte, meta *metadataTracker) []byte {
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l.Debugf("remove from global; folder=%q device=%v file=%q", folder, protocol.DeviceIDFromBytes(device), file)
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svl, err := t.Get(gk, nil)
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if err != nil {
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// We might be called to "remove" a global version that doesn't exist
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// if the first update for the file is already marked invalid.
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return keyBuf
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}
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var fl VersionList
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err = fl.Unmarshal(svl)
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if err != nil {
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l.Debugln("unmarshal error:", err)
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return keyBuf
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}
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fl, _, removedAt := fl.pop(device)
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if removedAt == -1 {
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// There is no version for the given device
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return keyBuf
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}
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if removedAt == 0 {
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// A failure to get the file here is surprising and our
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// global size data will be incorrect until a restart...
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keyBuf = t.db.keyer.GenerateDeviceFileKey(keyBuf, folder, device, file)
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if f, ok := t.getFileByKey(keyBuf); ok {
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meta.removeFile(protocol.GlobalDeviceID, f)
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}
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}
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if len(fl.Versions) == 0 {
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keyBuf = t.db.keyer.GenerateNeedFileKey(keyBuf, folder, file)
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t.Delete(keyBuf)
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t.Delete(gk)
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return keyBuf
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}
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if removedAt == 0 {
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keyBuf = t.db.keyer.GenerateDeviceFileKey(keyBuf, folder, fl.Versions[0].Device, file)
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global, ok := t.getFileByKey(keyBuf)
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if !ok {
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panic("This file must exist in the db")
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}
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keyBuf = t.updateLocalNeed(keyBuf, folder, file, fl, global)
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meta.addFile(protocol.GlobalDeviceID, global)
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}
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l.Debugf("new global after remove: %v", fl)
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t.Put(gk, mustMarshal(&fl))
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return keyBuf
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}
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func (t readWriteTransaction) deleteKeyPrefix(prefix []byte) {
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dbi := t.NewIterator(util.BytesPrefix(prefix), nil)
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for dbi.Next() {
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t.Delete(dbi.Key())
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t.checkFlush()
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}
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dbi.Release()
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}
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type marshaller interface {
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Marshal() ([]byte, error)
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}
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func mustMarshal(f marshaller) []byte {
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bs, err := f.Marshal()
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if err != nil {
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panic(err)
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}
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return bs
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}
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