syncthing/lib/versioner/staggered.go

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// 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
// 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/.
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package versioner
import (
"context"
"fmt"
"sort"
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"strconv"
"time"
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"github.com/syncthing/syncthing/lib/config"
"github.com/syncthing/syncthing/lib/fs"
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)
func init() {
// Register the constructor for this type of versioner with the name "staggered"
factories["staggered"] = newStaggered
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}
type interval struct {
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step int64
end int64
}
type staggered struct {
folderFs fs.Filesystem
versionsFs fs.Filesystem
interval [4]interval
copyRangeMethod fs.CopyRangeMethod
}
func newStaggered(cfg config.FolderConfiguration) Versioner {
params := cfg.Versioning.Params
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maxAge, err := strconv.ParseInt(params["maxAge"], 10, 0)
if err != nil {
maxAge = 31536000 // Default: ~1 year
}
versionsFs := versionerFsFromFolderCfg(cfg)
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s := &staggered{
folderFs: cfg.Filesystem(nil),
versionsFs: versionsFs,
interval: [4]interval{
{30, 60 * 60}, // first hour -> 30 sec between versions
{60 * 60, 24 * 60 * 60}, // next day -> 1 h between versions
{24 * 60 * 60, 30 * 24 * 60 * 60}, // next 30 days -> 1 day between versions
{7 * 24 * 60 * 60, maxAge}, // next year -> 1 week between versions
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},
copyRangeMethod: cfg.CopyRangeMethod,
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}
Implement facility based logger, debugging via REST API This implements a new debug/trace infrastructure based on a slightly hacked up logger. Instead of the traditional "if debug { ... }" I've rewritten the logger to have no-op Debugln and Debugf, unless debugging has been enabled for a given "facility". The "facility" is just a string, typically a package name. This will be slightly slower than before; but not that much as it's mostly a function call that returns immediately. For the cases where it matters (the Debugln takes a hex.Dump() of something for example, and it's not in a very occasional "if err != nil" branch) there is an l.ShouldDebug(facility) that is fast enough to be used like the old "if debug". The point of all this is that we can now toggle debugging for the various packages on and off at runtime. There's a new method /rest/system/debug that can be POSTed a set of facilities to enable and disable debug for, or GET from to get a list of facilities with descriptions and their current debug status. Similarly a /rest/system/log?since=... can grab the latest log entries, up to 250 of them (hardcoded constant in main.go) plus the initial few. Not implemented in this commit (but planned) is a simple debug GUI available on /debug that shows the current log in an easily pasteable format and has checkboxes to enable the various debug facilities. The debug instructions to a user then becomes "visit this URL, check these boxes, reproduce your problem, copy and paste the log". The actual log viewer on the hypothetical /debug URL can poll regularly for new log entries and this bypass the 250 line limit. The existing STTRACE=foo variable is still obeyed and just sets the start state of the system.
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l.Debugf("instantiated %#v", s)
return s
}
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func (v *staggered) Clean(ctx context.Context) error {
l.Debugln("Versioner clean: Cleaning", v.versionsFs)
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if _, err := v.versionsFs.Stat("."); fs.IsNotExist(err) {
// There is no need to clean a nonexistent dir.
return nil
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}
versionsPerFile := make(map[string][]string)
dirTracker := make(emptyDirTracker)
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walkFn := func(path string, f fs.FileInfo, err error) error {
if err != nil {
return err
}
select {
case <-ctx.Done():
return ctx.Err()
default:
}
if f.IsDir() && !f.IsSymlink() {
dirTracker.addDir(path)
return nil
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}
// Regular file, or possibly a symlink.
dirTracker.addFile(path)
name, _ := UntagFilename(path)
if name == "" {
return nil
}
versionsPerFile[name] = append(versionsPerFile[name], path)
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return nil
}
if err := v.versionsFs.Walk(".", walkFn); err != nil {
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l.Warnln("Versioner: error scanning versions dir", err)
return err
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}
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for _, versionList := range versionsPerFile {
select {
case <-ctx.Done():
return ctx.Err()
default:
}
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v.expire(versionList)
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}
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dirTracker.deleteEmptyDirs(v.versionsFs)
l.Debugln("Cleaner: Finished cleaning", v.versionsFs)
return nil
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}
func (v *staggered) expire(versions []string) {
Implement facility based logger, debugging via REST API This implements a new debug/trace infrastructure based on a slightly hacked up logger. Instead of the traditional "if debug { ... }" I've rewritten the logger to have no-op Debugln and Debugf, unless debugging has been enabled for a given "facility". The "facility" is just a string, typically a package name. This will be slightly slower than before; but not that much as it's mostly a function call that returns immediately. For the cases where it matters (the Debugln takes a hex.Dump() of something for example, and it's not in a very occasional "if err != nil" branch) there is an l.ShouldDebug(facility) that is fast enough to be used like the old "if debug". The point of all this is that we can now toggle debugging for the various packages on and off at runtime. There's a new method /rest/system/debug that can be POSTed a set of facilities to enable and disable debug for, or GET from to get a list of facilities with descriptions and their current debug status. Similarly a /rest/system/log?since=... can grab the latest log entries, up to 250 of them (hardcoded constant in main.go) plus the initial few. Not implemented in this commit (but planned) is a simple debug GUI available on /debug that shows the current log in an easily pasteable format and has checkboxes to enable the various debug facilities. The debug instructions to a user then becomes "visit this URL, check these boxes, reproduce your problem, copy and paste the log". The actual log viewer on the hypothetical /debug URL can poll regularly for new log entries and this bypass the 250 line limit. The existing STTRACE=foo variable is still obeyed and just sets the start state of the system.
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l.Debugln("Versioner: Expiring versions", versions)
for _, file := range v.toRemove(versions, time.Now()) {
if fi, err := v.versionsFs.Lstat(file); err != nil {
l.Warnln("versioner:", err)
continue
} else if fi.IsDir() {
l.Infof("non-file %q is named like a file version", file)
continue
}
if err := v.versionsFs.Remove(file); err != nil {
l.Warnf("Versioner: can't remove %q: %v", file, err)
}
}
}
func (v *staggered) toRemove(versions []string, now time.Time) []string {
var prevAge int64
firstFile := true
var remove []string
// The list of versions may or may not be properly sorted.
sort.Strings(versions)
for _, version := range versions {
versionTime, err := time.ParseInLocation(TimeFormat, extractTag(version), time.Local)
if err != nil {
l.Debugf("Versioner: file name %q is invalid: %v", version, err)
continue
}
age := int64(now.Sub(versionTime).Seconds())
// If the file is older than the max age of the last interval, remove it
if lastIntv := v.interval[len(v.interval)-1]; lastIntv.end > 0 && age > lastIntv.end {
l.Debugln("Versioner: File over maximum age -> delete ", version)
remove = append(remove, version)
continue
}
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// If it's the first (oldest) file in the list we can skip the interval checks
if firstFile {
prevAge = age
firstFile = false
continue
}
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// Find the interval the file fits in
var usedInterval interval
for _, usedInterval = range v.interval {
if age < usedInterval.end {
break
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}
}
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if prevAge-age < usedInterval.step {
l.Debugln("too many files in step -> delete", version)
remove = append(remove, version)
continue
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}
prevAge = age
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}
return remove
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}
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// Archive moves the named file away to a version archive. If this function
// returns nil, the named file does not exist any more (has been archived).
func (v *staggered) Archive(filePath string) error {
if err := archiveFile(v.copyRangeMethod, v.folderFs, v.versionsFs, filePath, TagFilename); err != nil {
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return err
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}
v.expire(findAllVersions(v.versionsFs, filePath))
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return nil
}
func (v *staggered) GetVersions() (map[string][]FileVersion, error) {
return retrieveVersions(v.versionsFs)
}
func (v *staggered) Restore(filepath string, versionTime time.Time) error {
return restoreFile(v.copyRangeMethod, v.versionsFs, v.folderFs, filepath, versionTime, TagFilename)
}
func (v *staggered) String() string {
return fmt.Sprintf("Staggered/@%p", v)
}