package main import ( "bufio" "context" "flag" "fmt" "io" "io/ioutil" "log" "os" "path/filepath" "regexp" "strconv" "strings" "sync" "syscall" "time" ) type unixVolumeAdder struct { *Config } // String implements flag.Value func (s *unixVolumeAdder) String() string { return "-" } func (vs *unixVolumeAdder) Set(path string) error { if dirs := strings.Split(path, ","); len(dirs) > 1 { log.Print("DEPRECATED: using comma-separated volume list.") for _, dir := range dirs { if err := vs.Set(dir); err != nil { return err } } return nil } vs.Config.Volumes = append(vs.Config.Volumes, &UnixVolume{ Root: path, ReadOnly: deprecated.flagReadonly, Serialize: deprecated.flagSerializeIO, }) return nil } func init() { VolumeTypes = append(VolumeTypes, func() VolumeWithExamples { return &UnixVolume{} }) flag.Var(&unixVolumeAdder{theConfig}, "volumes", "see Volumes configuration") flag.Var(&unixVolumeAdder{theConfig}, "volume", "see Volumes configuration") } // Discover adds a UnixVolume for every directory named "keep" that is // located at the top level of a device- or tmpfs-backed mount point // other than "/". It returns the number of volumes added. func (vs *unixVolumeAdder) Discover() int { added := 0 f, err := os.Open(ProcMounts) if err != nil { log.Fatalf("opening %s: %s", ProcMounts, err) } scanner := bufio.NewScanner(f) for scanner.Scan() { args := strings.Fields(scanner.Text()) if err := scanner.Err(); err != nil { log.Fatalf("reading %s: %s", ProcMounts, err) } dev, mount := args[0], args[1] if mount == "/" { continue } if dev != "tmpfs" && !strings.HasPrefix(dev, "/dev/") { continue } keepdir := mount + "/keep" if st, err := os.Stat(keepdir); err != nil || !st.IsDir() { continue } // Set the -readonly flag (but only for this volume) // if the filesystem is mounted readonly. flagReadonlyWas := deprecated.flagReadonly for _, fsopt := range strings.Split(args[3], ",") { if fsopt == "ro" { deprecated.flagReadonly = true break } if fsopt == "rw" { break } } if err := vs.Set(keepdir); err != nil { log.Printf("adding %q: %s", keepdir, err) } else { added++ } deprecated.flagReadonly = flagReadonlyWas } return added } // A UnixVolume stores and retrieves blocks in a local directory. type UnixVolume struct { Root string // path to the volume's root directory ReadOnly bool Serialize bool DirectoryReplication int // something to lock during IO, typically a sync.Mutex (or nil // to skip locking) locker sync.Locker } // Examples implements VolumeWithExamples. func (*UnixVolume) Examples() []Volume { return []Volume{ &UnixVolume{ Root: "/mnt/local-disk", Serialize: true, DirectoryReplication: 1, }, &UnixVolume{ Root: "/mnt/network-disk", Serialize: false, DirectoryReplication: 2, }, } } // Type implements Volume func (v *UnixVolume) Type() string { return "Directory" } // Start implements Volume func (v *UnixVolume) Start() error { if v.Serialize { v.locker = &sync.Mutex{} } if !strings.HasPrefix(v.Root, "/") { return fmt.Errorf("volume root does not start with '/': %q", v.Root) } if v.DirectoryReplication == 0 { v.DirectoryReplication = 1 } _, err := os.Stat(v.Root) return err } // Touch sets the timestamp for the given locator to the current time func (v *UnixVolume) Touch(loc string) error { if v.ReadOnly { return MethodDisabledError } p := v.blockPath(loc) f, err := os.OpenFile(p, os.O_RDWR|os.O_APPEND, 0644) if err != nil { return err } defer f.Close() if v.locker != nil { v.locker.Lock() defer v.locker.Unlock() } if e := lockfile(f); e != nil { return e } defer unlockfile(f) ts := syscall.NsecToTimespec(time.Now().UnixNano()) return syscall.UtimesNano(p, []syscall.Timespec{ts, ts}) } // Mtime returns the stored timestamp for the given locator. func (v *UnixVolume) Mtime(loc string) (time.Time, error) { p := v.blockPath(loc) fi, err := os.Stat(p) if err != nil { return time.Time{}, err } return fi.ModTime(), nil } // Lock the locker (if one is in use), open the file for reading, and // call the given function if and when the file is ready to read. func (v *UnixVolume) getFunc(ctx context.Context, path string, fn func(io.Reader) error) error { if v.locker != nil { v.locker.Lock() defer v.locker.Unlock() } if ctx.Err() != nil { return ctx.Err() } f, err := os.Open(path) if err != nil { return err } defer f.Close() return fn(f) } // stat is os.Stat() with some extra sanity checks. func (v *UnixVolume) stat(path string) (os.FileInfo, error) { stat, err := os.Stat(path) if err == nil { if stat.Size() < 0 { err = os.ErrInvalid } else if stat.Size() > BlockSize { err = TooLongError } } return stat, err } // Get retrieves a block, copies it to the given slice, and returns // the number of bytes copied. func (v *UnixVolume) Get(ctx context.Context, loc string, buf []byte) (int, error) { path := v.blockPath(loc) stat, err := v.stat(path) if err != nil { return 0, v.translateError(err) } if stat.Size() > int64(len(buf)) { return 0, TooLongError } var read int size := int(stat.Size()) err = v.getFunc(ctx, path, func(rdr io.Reader) error { read, err = io.ReadFull(rdr, buf[:size]) return err }) return read, err } // Compare returns nil if Get(loc) would return the same content as // expect. It is functionally equivalent to Get() followed by // bytes.Compare(), but uses less memory. func (v *UnixVolume) Compare(ctx context.Context, loc string, expect []byte) error { path := v.blockPath(loc) if _, err := v.stat(path); err != nil { return v.translateError(err) } return v.getFunc(ctx, path, func(rdr io.Reader) error { return compareReaderWithBuf(ctx, rdr, expect, loc[:32]) }) } // Put stores a block of data identified by the locator string // "loc". It returns nil on success. If the volume is full, it // returns a FullError. If the write fails due to some other error, // that error is returned. func (v *UnixVolume) Put(ctx context.Context, loc string, block []byte) error { if v.ReadOnly { return MethodDisabledError } if v.IsFull() { return FullError } bdir := v.blockDir(loc) if err := os.MkdirAll(bdir, 0755); err != nil { log.Printf("%s: could not create directory %s: %s", loc, bdir, err) return err } tmpfile, tmperr := ioutil.TempFile(bdir, "tmp"+loc) if tmperr != nil { log.Printf("ioutil.TempFile(%s, tmp%s): %s", bdir, loc, tmperr) return tmperr } bpath := v.blockPath(loc) if v.locker != nil { v.locker.Lock() defer v.locker.Unlock() } select { case <-ctx.Done(): return ctx.Err() default: } if _, err := tmpfile.Write(block); err != nil { log.Printf("%s: writing to %s: %s\n", v, bpath, err) tmpfile.Close() os.Remove(tmpfile.Name()) return err } if err := tmpfile.Close(); err != nil { log.Printf("closing %s: %s\n", tmpfile.Name(), err) os.Remove(tmpfile.Name()) return err } if err := os.Rename(tmpfile.Name(), bpath); err != nil { log.Printf("rename %s %s: %s\n", tmpfile.Name(), bpath, err) os.Remove(tmpfile.Name()) return err } return nil } // Status returns a VolumeStatus struct describing the volume's // current state, or nil if an error occurs. // func (v *UnixVolume) Status() *VolumeStatus { var fs syscall.Statfs_t var devnum uint64 if fi, err := os.Stat(v.Root); err == nil { devnum = fi.Sys().(*syscall.Stat_t).Dev } else { log.Printf("%s: os.Stat: %s\n", v, err) return nil } err := syscall.Statfs(v.Root, &fs) if err != nil { log.Printf("%s: statfs: %s\n", v, err) return nil } // These calculations match the way df calculates disk usage: // "free" space is measured by fs.Bavail, but "used" space // uses fs.Blocks - fs.Bfree. free := fs.Bavail * uint64(fs.Bsize) used := (fs.Blocks - fs.Bfree) * uint64(fs.Bsize) return &VolumeStatus{ MountPoint: v.Root, DeviceNum: devnum, BytesFree: free, BytesUsed: used, } } var blockDirRe = regexp.MustCompile(`^[0-9a-f]+$`) var blockFileRe = regexp.MustCompile(`^[0-9a-f]{32}$`) // IndexTo writes (to the given Writer) a list of blocks found on this // volume which begin with the specified prefix. If the prefix is an // empty string, IndexTo writes a complete list of blocks. // // Each block is given in the format // // locator+size modification-time {newline} // // e.g.: // // e4df392f86be161ca6ed3773a962b8f3+67108864 1388894303 // e4d41e6fd68460e0e3fc18cc746959d2+67108864 1377796043 // e4de7a2810f5554cd39b36d8ddb132ff+67108864 1388701136 // func (v *UnixVolume) IndexTo(prefix string, w io.Writer) error { var lastErr error rootdir, err := os.Open(v.Root) if err != nil { return err } defer rootdir.Close() for { names, err := rootdir.Readdirnames(1) if err == io.EOF { return lastErr } else if err != nil { return err } if !strings.HasPrefix(names[0], prefix) && !strings.HasPrefix(prefix, names[0]) { // prefix excludes all blocks stored in this dir continue } if !blockDirRe.MatchString(names[0]) { continue } blockdirpath := filepath.Join(v.Root, names[0]) blockdir, err := os.Open(blockdirpath) if err != nil { log.Print("Error reading ", blockdirpath, ": ", err) lastErr = err continue } for { fileInfo, err := blockdir.Readdir(1) if err == io.EOF { break } else if err != nil { log.Print("Error reading ", blockdirpath, ": ", err) lastErr = err break } name := fileInfo[0].Name() if !strings.HasPrefix(name, prefix) { continue } if !blockFileRe.MatchString(name) { continue } _, err = fmt.Fprint(w, name, "+", fileInfo[0].Size(), " ", fileInfo[0].ModTime().UnixNano(), "\n") } blockdir.Close() } } // Trash trashes the block data from the unix storage // If TrashLifetime == 0, the block is deleted // Else, the block is renamed as path/{loc}.trash.{deadline}, // where deadline = now + TrashLifetime func (v *UnixVolume) Trash(loc string) error { // Touch() must be called before calling Write() on a block. Touch() // also uses lockfile(). This avoids a race condition between Write() // and Trash() because either (a) the file will be trashed and Touch() // will signal to the caller that the file is not present (and needs to // be re-written), or (b) Touch() will update the file's timestamp and // Trash() will read the correct up-to-date timestamp and choose not to // trash the file. if v.ReadOnly { return MethodDisabledError } if v.locker != nil { v.locker.Lock() defer v.locker.Unlock() } p := v.blockPath(loc) f, err := os.OpenFile(p, os.O_RDWR|os.O_APPEND, 0644) if err != nil { return err } defer f.Close() if e := lockfile(f); e != nil { return e } defer unlockfile(f) // If the block has been PUT in the last blobSignatureTTL // seconds, return success without removing the block. This // protects data from garbage collection until it is no longer // possible for clients to retrieve the unreferenced blocks // anyway (because the permission signatures have expired). if fi, err := os.Stat(p); err != nil { return err } else if time.Since(fi.ModTime()) < time.Duration(theConfig.BlobSignatureTTL) { return nil } if theConfig.TrashLifetime == 0 { return os.Remove(p) } return os.Rename(p, fmt.Sprintf("%v.trash.%d", p, time.Now().Add(theConfig.TrashLifetime.Duration()).Unix())) } // Untrash moves block from trash back into store // Look for path/{loc}.trash.{deadline} in storage, // and rename the first such file as path/{loc} func (v *UnixVolume) Untrash(loc string) (err error) { if v.ReadOnly { return MethodDisabledError } files, err := ioutil.ReadDir(v.blockDir(loc)) if err != nil { return err } if len(files) == 0 { return os.ErrNotExist } foundTrash := false prefix := fmt.Sprintf("%v.trash.", loc) for _, f := range files { if strings.HasPrefix(f.Name(), prefix) { foundTrash = true err = os.Rename(v.blockPath(f.Name()), v.blockPath(loc)) if err == nil { break } } } if foundTrash == false { return os.ErrNotExist } return } // blockDir returns the fully qualified directory name for the directory // where loc is (or would be) stored on this volume. func (v *UnixVolume) blockDir(loc string) string { return filepath.Join(v.Root, loc[0:3]) } // blockPath returns the fully qualified pathname for the path to loc // on this volume. func (v *UnixVolume) blockPath(loc string) string { return filepath.Join(v.blockDir(loc), loc) } // IsFull returns true if the free space on the volume is less than // MinFreeKilobytes. // func (v *UnixVolume) IsFull() (isFull bool) { fullSymlink := v.Root + "/full" // Check if the volume has been marked as full in the last hour. if link, err := os.Readlink(fullSymlink); err == nil { if ts, err := strconv.Atoi(link); err == nil { fulltime := time.Unix(int64(ts), 0) if time.Since(fulltime).Hours() < 1.0 { return true } } } if avail, err := v.FreeDiskSpace(); err == nil { isFull = avail < MinFreeKilobytes } else { log.Printf("%s: FreeDiskSpace: %s\n", v, err) isFull = false } // If the volume is full, timestamp it. if isFull { now := fmt.Sprintf("%d", time.Now().Unix()) os.Symlink(now, fullSymlink) } return } // FreeDiskSpace returns the number of unused 1k blocks available on // the volume. // func (v *UnixVolume) FreeDiskSpace() (free uint64, err error) { var fs syscall.Statfs_t err = syscall.Statfs(v.Root, &fs) if err == nil { // Statfs output is not guaranteed to measure free // space in terms of 1K blocks. free = fs.Bavail * uint64(fs.Bsize) / 1024 } return } func (v *UnixVolume) String() string { return fmt.Sprintf("[UnixVolume %s]", v.Root) } // Writable returns false if all future Put, Mtime, and Delete calls // are expected to fail. func (v *UnixVolume) Writable() bool { return !v.ReadOnly } // Replication returns the number of replicas promised by the // underlying device (as specified in configuration). func (v *UnixVolume) Replication() int { return v.DirectoryReplication } // lockfile and unlockfile use flock(2) to manage kernel file locks. func lockfile(f *os.File) error { return syscall.Flock(int(f.Fd()), syscall.LOCK_EX) } func unlockfile(f *os.File) error { return syscall.Flock(int(f.Fd()), syscall.LOCK_UN) } // Where appropriate, translate a more specific filesystem error to an // error recognized by handlers, like os.ErrNotExist. func (v *UnixVolume) translateError(err error) error { switch err.(type) { case *os.PathError: // stat() returns a PathError if the parent directory // (not just the file itself) is missing return os.ErrNotExist default: return err } } var unixTrashLocRegexp = regexp.MustCompile(`/([0-9a-f]{32})\.trash\.(\d+)$`) // EmptyTrash walks hierarchy looking for {hash}.trash.* // and deletes those with deadline < now. func (v *UnixVolume) EmptyTrash() { var bytesDeleted, bytesInTrash int64 var blocksDeleted, blocksInTrash int err := filepath.Walk(v.Root, func(path string, info os.FileInfo, err error) error { if err != nil { log.Printf("EmptyTrash: filepath.Walk: %v: %v", path, err) return nil } if info.Mode().IsDir() { return nil } matches := unixTrashLocRegexp.FindStringSubmatch(path) if len(matches) != 3 { return nil } deadline, err := strconv.ParseInt(matches[2], 10, 64) if err != nil { log.Printf("EmptyTrash: %v: ParseInt(%v): %v", path, matches[2], err) return nil } bytesInTrash += info.Size() blocksInTrash++ if deadline > time.Now().Unix() { return nil } err = os.Remove(path) if err != nil { log.Printf("EmptyTrash: Remove %v: %v", path, err) return nil } bytesDeleted += info.Size() blocksDeleted++ return nil }) if err != nil { log.Printf("EmptyTrash error for %v: %v", v.String(), err) } log.Printf("EmptyTrash stats for %v: Deleted %v bytes in %v blocks. Remaining in trash: %v bytes in %v blocks.", v.String(), bytesDeleted, blocksDeleted, bytesInTrash-bytesDeleted, blocksInTrash-blocksDeleted) }