85 lines
2.4 KiB
Go
85 lines
2.4 KiB
Go
// Copyright (C) 2015 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 http://mozilla.org/MPL/2.0/.
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package db
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import (
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"fmt"
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"time"
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"github.com/syndtr/goleveldb/leveldb"
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)
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// This type encapsulates a repository of mtimes for platforms where file mtimes
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// can't be set to arbitrary values. For this to work, we need to store both
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// the mtime we tried to set (the "actual" mtime) as well as the mtime the file
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// has when we're done touching it (the "disk" mtime) so that we can tell if it
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// was changed. So in GetMtime(), it's not sufficient that the record exists --
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// the argument must also equal the "disk" mtime in the record, otherwise it's
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// been touched locally and the "disk" mtime is actually correct.
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type VirtualMtimeRepo struct {
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ns *NamespacedKV
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}
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func NewVirtualMtimeRepo(ldb *leveldb.DB, folder string) *VirtualMtimeRepo {
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prefix := string(KeyTypeVirtualMtime) + folder
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return &VirtualMtimeRepo{
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ns: NewNamespacedKV(ldb, prefix),
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}
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}
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func (r *VirtualMtimeRepo) UpdateMtime(path string, diskMtime, actualMtime time.Time) {
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if debug {
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l.Debugf("virtual mtime: storing values for path:%s disk:%v actual:%v", path, diskMtime, actualMtime)
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}
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diskBytes, _ := diskMtime.MarshalBinary()
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actualBytes, _ := actualMtime.MarshalBinary()
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data := append(diskBytes, actualBytes...)
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r.ns.PutBytes(path, data)
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}
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func (r *VirtualMtimeRepo) GetMtime(path string, diskMtime time.Time) time.Time {
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data, exists := r.ns.Bytes(path)
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if !exists {
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// Absense of debug print is significant enough in itself here
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return diskMtime
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}
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var mtime time.Time
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if err := mtime.UnmarshalBinary(data[:len(data)/2]); err != nil {
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panic(fmt.Sprintf("Can't unmarshal stored mtime at path %s: %v", path, err))
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}
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if mtime.Equal(diskMtime) {
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if err := mtime.UnmarshalBinary(data[len(data)/2:]); err != nil {
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panic(fmt.Sprintf("Can't unmarshal stored mtime at path %s: %v", path, err))
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}
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if debug {
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l.Debugf("virtual mtime: return %v instead of %v for path: %s", mtime, diskMtime, path)
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}
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return mtime
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}
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if debug {
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l.Debugf("virtual mtime: record exists, but mismatch inDisk: %v dbDisk: %v for path: %s", diskMtime, mtime, path)
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}
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return diskMtime
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}
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func (r *VirtualMtimeRepo) DeleteMtime(path string) {
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r.ns.Delete(path)
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}
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func (r *VirtualMtimeRepo) Drop() {
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r.ns.Reset()
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}
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