-// A UnixVolume is a Volume backed by a locally mounted disk.
-//
package main
import (
+ "bufio"
+ "errors"
+ "flag"
"fmt"
"io"
"io/ioutil"
"log"
"os"
"path/filepath"
+ "regexp"
"strconv"
"strings"
"sync"
"time"
)
+type unixVolumeAdder struct {
+ *volumeSet
+}
+
+func (vs *unixVolumeAdder) Set(value string) error {
+ if dirs := strings.Split(value, ","); 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
+ }
+ if len(value) == 0 || value[0] != '/' {
+ return errors.New("Invalid volume: must begin with '/'.")
+ }
+ if _, err := os.Stat(value); err != nil {
+ return err
+ }
+ var locker sync.Locker
+ if flagSerializeIO {
+ locker = &sync.Mutex{}
+ }
+ *vs.volumeSet = append(*vs.volumeSet, &UnixVolume{
+ root: value,
+ locker: locker,
+ readonly: flagReadonly,
+ })
+ return nil
+}
+
+func init() {
+ flag.Var(
+ &unixVolumeAdder{&volumes},
+ "volumes",
+ "Deprecated synonym for -volume.")
+ flag.Var(
+ &unixVolumeAdder{&volumes},
+ "volume",
+ "Local storage directory. Can be given more than once to add multiple directories. If none are supplied, the default is to use all directories named \"keep\" that exist in the top level directory of a mount point at startup time. Can be a comma-separated list, but this is deprecated: use multiple -volume arguments instead.")
+}
+
+// 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 := flagReadonly
+ for _, fsopt := range strings.Split(args[3], ",") {
+ if fsopt == "ro" {
+ flagReadonly = true
+ break
+ }
+ if fsopt == "rw" {
+ break
+ }
+ }
+ if err := vs.Set(keepdir); err != nil {
+ log.Printf("adding %q: %s", keepdir, err)
+ } else {
+ added++
+ }
+ 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
- serialize bool
- readonly bool
- mutex sync.Mutex
+ // path to the volume's root directory
+ root string
+ // something to lock during IO, typically a sync.Mutex (or nil
+ // to skip locking)
+ locker sync.Locker
+ readonly bool
}
+// Touch sets the timestamp for the given locator to the current time
func (v *UnixVolume) Touch(loc string) error {
if v.readonly {
return MethodDisabledError
return err
}
defer f.Close()
- if v.serialize {
- v.mutex.Lock()
- defer v.mutex.Unlock()
+ if v.locker != nil {
+ v.locker.Lock()
+ defer v.locker.Unlock()
}
if e := lockfile(f); e != nil {
return e
return syscall.Utime(p, &utime)
}
+// Mtime returns the stored timestamp for the given locator.
func (v *UnixVolume) Mtime(loc string) (time.Time, error) {
p := v.blockPath(loc)
- if fi, err := os.Stat(p); err != nil {
+ fi, err := os.Stat(p)
+ if err != nil {
return time.Time{}, err
- } else {
- return fi.ModTime(), nil
}
+ 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(path string, fn func(io.Reader) error) error {
+ if v.locker != nil {
+ v.locker.Lock()
+ defer v.locker.Unlock()
+ }
+ 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 identified by the locator string "loc", and
// returns its contents as a byte slice.
//
-// If the block could not be found, opened, or read, Get returns a nil
-// slice and whatever non-nil error was returned by Stat or ReadFile.
+// Get returns a nil buffer IFF it returns a non-nil error.
func (v *UnixVolume) Get(loc string) ([]byte, error) {
path := v.blockPath(loc)
- stat, err := os.Stat(path)
+ stat, err := v.stat(path)
if err != nil {
return nil, err
}
- if stat.Size() < 0 {
- return nil, os.ErrInvalid
- } else if stat.Size() == 0 {
- return bufs.Get(0), nil
- } else if stat.Size() > BLOCKSIZE {
- return nil, TooLongError
- }
- f, err := os.Open(path)
- if err != nil {
- return nil, err
- }
- defer f.Close()
buf := bufs.Get(int(stat.Size()))
- if v.serialize {
- v.mutex.Lock()
- defer v.mutex.Unlock()
- }
- _, err = io.ReadFull(f, buf)
+ err = v.getFunc(path, func(rdr io.Reader) error {
+ _, err = io.ReadFull(rdr, buf)
+ return err
+ })
if err != nil {
bufs.Put(buf)
return nil, err
return buf, nil
}
+// 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(loc string, expect []byte) error {
+ path := v.blockPath(loc)
+ if _, err := v.stat(path); err != nil {
+ return err
+ }
+ return v.getFunc(path, func(rdr io.Reader) error {
+ return compareReaderWithBuf(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,
}
bpath := v.blockPath(loc)
- if v.serialize {
- v.mutex.Lock()
- defer v.mutex.Unlock()
+ if v.locker != nil {
+ v.locker.Lock()
+ defer v.locker.Unlock()
}
if _, err := tmpfile.Write(block); err != nil {
log.Printf("%s: writing to %s: %s\n", v, bpath, err)
}
// Status returns a VolumeStatus struct describing the volume's
-// current state.
+// current state, or nil if an error occurs.
//
func (v *UnixVolume) Status() *VolumeStatus {
var fs syscall.Statfs_t
return &VolumeStatus{v.root, devnum, free, used}
}
+var blockDirRe = regexp.MustCompile(`^[0-9a-f]+$`)
+
// 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.
// e4de7a2810f5554cd39b36d8ddb132ff+67108864 1388701136
//
func (v *UnixVolume) IndexTo(prefix string, w io.Writer) error {
- return filepath.Walk(v.root,
- func(path string, info os.FileInfo, err error) error {
- if err != nil {
- log.Printf("%s: IndexTo Walk error at %s: %s",
- v, path, err)
- return nil
- }
- basename := filepath.Base(path)
- if info.IsDir() &&
- !strings.HasPrefix(basename, prefix) &&
- !strings.HasPrefix(prefix, basename) {
- // Skip directories that do not match
- // prefix. We know there is nothing
- // interesting inside.
- return filepath.SkipDir
+ var lastErr error = nil
+ 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
}
- if info.IsDir() ||
- !IsValidLocator(basename) ||
- !strings.HasPrefix(basename, prefix) {
- return nil
+ name := fileInfo[0].Name()
+ if !strings.HasPrefix(name, prefix) {
+ continue
}
- _, err = fmt.Fprintf(w, "%s+%d %d\n",
- basename, info.Size(), info.ModTime().Unix())
- return err
- })
+ _, err = fmt.Fprint(w,
+ name,
+ "+", fileInfo[0].Size(),
+ " ", fileInfo[0].ModTime().Unix(),
+ "\n")
+ }
+ blockdir.Close()
+ }
}
+// Delete deletes the block data from the unix storage
func (v *UnixVolume) Delete(loc string) error {
// Touch() must be called before calling Write() on a block. Touch()
// also uses lockfile(). This avoids a race condition between Write()
if v.readonly {
return MethodDisabledError
}
- if v.serialize {
- v.mutex.Lock()
- defer v.mutex.Unlock()
+ 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)
}
defer unlockfile(f)
- // If the block has been PUT in the last blob_signature_ttl
+ // 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
if fi, err := os.Stat(p); err != nil {
return err
} else {
- if time.Since(fi.ModTime()) < blob_signature_ttl {
+ if time.Since(fi.ModTime()) < blobSignatureTTL {
return nil
}
}
}
// IsFull returns true if the free space on the volume is less than
-// MIN_FREE_KILOBYTES.
+// MinFreeKilobytes.
//
func (v *UnixVolume) IsFull() (isFull bool) {
fullSymlink := v.root + "/full"
}
if avail, err := v.FreeDiskSpace(); err == nil {
- isFull = avail < MIN_FREE_KILOBYTES
+ isFull = avail < MinFreeKilobytes
} else {
log.Printf("%s: FreeDiskSpace: %s\n", v, err)
isFull = false
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
}
+func (v *UnixVolume) Replication() int {
+ return 1
+}
+
// 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)
projects / arvados.git / blobdiff