VictoriaMetrics/lib/fs/fs.go
2019-08-28 01:46:09 +03:00

420 lines
11 KiB
Go

package fs
import (
"fmt"
"io"
"os"
"path/filepath"
"regexp"
"strings"
"sync/atomic"
"time"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/filestream"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
"github.com/VictoriaMetrics/metrics"
"golang.org/x/sys/unix"
)
// ReadAtCloser is rand-access read interface.
type ReadAtCloser interface {
// ReadAt must read len(p) bytes from offset off to p.
ReadAt(p []byte, off int64)
// MustClose must close the reader.
MustClose()
}
// ReaderAt implements rand-access read.
type ReaderAt struct {
f *os.File
}
// ReadAt reads len(p) bytes from off to p.
func (ra *ReaderAt) ReadAt(p []byte, off int64) {
if len(p) == 0 {
return
}
n, err := ra.f.ReadAt(p, off)
if err != nil {
logger.Panicf("FATAL: cannot read %d bytes at offset %d of file %q: %s", len(p), off, ra.f.Name(), err)
}
if n != len(p) {
logger.Panicf("FATAL: unexpected number of bytes read; got %d; want %d", n, len(p))
}
readCalls.Inc()
readBytes.Add(len(p))
}
// MustClose closes ra.
func (ra *ReaderAt) MustClose() {
if err := ra.f.Close(); err != nil {
logger.Panicf("FATAL: cannot close file %q: %s", ra.f.Name(), err)
}
readersCount.Dec()
}
// OpenReaderAt opens a file on the given path for random-read access.
//
// The file must be closed with MustClose when no longer needed.
func OpenReaderAt(path string) (*ReaderAt, error) {
f, err := os.Open(path)
if err != nil {
return nil, err
}
readersCount.Inc()
ra := &ReaderAt{
f: f,
}
return ra, nil
}
var (
readCalls = metrics.NewCounter(`vm_fs_read_calls_total`)
readBytes = metrics.NewCounter(`vm_fs_read_bytes_total`)
readersCount = metrics.NewCounter(`vm_fs_readers`)
)
// MustSyncPath syncs contents of the given path.
func MustSyncPath(path string) {
d, err := os.Open(path)
if err != nil {
logger.Panicf("FATAL: cannot open %q: %s", path, err)
}
if err := d.Sync(); err != nil {
_ = d.Close()
logger.Panicf("FATAL: cannot flush %q to storage: %s", path, err)
}
if err := d.Close(); err != nil {
logger.Panicf("FATAL: cannot close %q: %s", path, err)
}
}
var tmpFileNum uint64
// WriteFileAtomically atomically writes data to the given file path.
//
// WriteFile returns only after the file is fully written and synced
// to the underlying storage.
func WriteFileAtomically(path string, data []byte) error {
// Check for the existing file. It is expected that
// the WriteFileAtomically function cannot be called concurrently
// with the same `path`.
if IsPathExist(path) {
return fmt.Errorf("cannot create file %q, since it already exists", path)
}
n := atomic.AddUint64(&tmpFileNum, 1)
tmpPath := fmt.Sprintf("%s.tmp.%d", path, n)
f, err := filestream.Create(tmpPath, false)
if err != nil {
return fmt.Errorf("cannot create file %q: %s", tmpPath, err)
}
if _, err := f.Write(data); err != nil {
f.MustClose()
MustRemoveAll(tmpPath)
return fmt.Errorf("cannot write %d bytes to file %q: %s", len(data), tmpPath, err)
}
// Sync and close the file.
f.MustClose()
// Atomically move the file from tmpPath to path.
if err := os.Rename(tmpPath, path); err != nil {
// do not call MustRemoveAll(tmpPath) here, so the user could inspect
// the file contents during investigating the issue.
return fmt.Errorf("cannot move %q to %q: %s", tmpPath, path, err)
}
// Sync the containing directory, so the file is guaranteed to appear in the directory.
// See https://www.quora.com/When-should-you-fsync-the-containing-directory-in-addition-to-the-file-itself
absPath, err := filepath.Abs(path)
if err != nil {
return fmt.Errorf("cannot obtain absolute path to %q: %s", path, err)
}
parentDirPath := filepath.Dir(absPath)
MustSyncPath(parentDirPath)
return nil
}
// IsTemporaryFileName returns true if fn matches temporary file name pattern
// from WriteFileAtomically.
func IsTemporaryFileName(fn string) bool {
return tmpFileNameRe.MatchString(fn)
}
// tmpFileNameRe is regexp for temporary file name - see WriteFileAtomically for details.
var tmpFileNameRe = regexp.MustCompile(`\.tmp\.\d+$`)
// MkdirAllIfNotExist creates the given path dir if it isn't exist.
func MkdirAllIfNotExist(path string) error {
if IsPathExist(path) {
return nil
}
return mkdirSync(path)
}
// MkdirAllFailIfExist creates the given path dir if it isn't exist.
//
// Returns error if path already exists.
func MkdirAllFailIfExist(path string) error {
if IsPathExist(path) {
return fmt.Errorf("the %q already exists", path)
}
return mkdirSync(path)
}
func mkdirSync(path string) error {
if err := os.MkdirAll(path, 0755); err != nil {
return err
}
// Sync the parent directory, so the created directory becomes visible
// in the fs after power loss.
parentDirPath := filepath.Dir(path)
MustSyncPath(parentDirPath)
return nil
}
// RemoveDirContents removes all the contents of the given dir it it exists.
//
// It doesn't remove the dir itself, so the dir may be mounted
// to a separate partition.
func RemoveDirContents(dir string) {
if !IsPathExist(dir) {
// The path doesn't exist, so nothing to remove.
return
}
d, err := os.Open(dir)
if err != nil {
logger.Panicf("FATAL: cannot open dir %q: %s", dir, err)
}
defer MustClose(d)
names, err := d.Readdirnames(-1)
if err != nil {
logger.Panicf("FATAL: cannot read contents of the dir %q: %s", dir, err)
}
for _, name := range names {
if name == "." || name == ".." || name == "lost+found" {
// Skip special dirs.
continue
}
fullPath := dir + "/" + name
MustRemoveAll(fullPath)
}
MustSyncPath(dir)
}
// MustClose must close the given file f.
func MustClose(f *os.File) {
fname := f.Name()
if err := f.Close(); err != nil {
logger.Panicf("FATAL: cannot close %q: %s", fname, err)
}
}
// MustFileSize returns file size for the given path.
func MustFileSize(path string) uint64 {
fi, err := os.Stat(path)
if err != nil {
logger.Panicf("FATAL: cannot stat %q: %s", path, err)
}
if fi.IsDir() {
logger.Panicf("FATAL: %q must be a file, not a directory", path)
}
return uint64(fi.Size())
}
// IsPathExist returns whether the given path exists.
func IsPathExist(path string) bool {
if _, err := os.Stat(path); err != nil {
if os.IsNotExist(err) {
return false
}
logger.Panicf("FATAL: cannot stat %q: %s", path, err)
}
return true
}
func mustSyncParentDirIfExists(path string) {
parentDirPath := filepath.Dir(path)
if !IsPathExist(parentDirPath) {
return
}
MustSyncPath(parentDirPath)
}
// MustRemoveAll removes path with all the contents.
//
// It properly handles NFS issue https://github.com/VictoriaMetrics/VictoriaMetrics/issues/61 .
func MustRemoveAll(path string) {
err := os.RemoveAll(path)
if err == nil {
// Make sure the parent directory doesn't contain references
// to the current directory.
mustSyncParentDirIfExists(path)
return
}
if !isTemporaryNFSError(err) {
logger.Panicf("FATAL: cannot remove %q: %s", path, err)
}
// NFS prevents from removing directories with open files.
// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/61 .
// Schedule for later directory removal.
select {
case removeDirCh <- path:
default:
logger.Panicf("FATAL: cannot schedule %s for removal, since the removal queue is full (%d entries)", path, cap(removeDirCh))
}
}
var removeDirCh = make(chan string, 1024)
func dirRemover() {
for path := range removeDirCh {
attempts := 0
for {
err := os.RemoveAll(path)
if err == nil {
break
}
if !isTemporaryNFSError(err) {
logger.Panicf("FATAL: cannot remove %q: %s", path, err)
}
// NFS prevents from removing directories with open files.
// Sleep for a while and try again in the hope open files will be closed.
// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/61 .
attempts++
if attempts > 10 {
logger.Panicf("FATAL: cannot remove %q in %d attempts: %s", path, attempts, err)
}
time.Sleep(100 * time.Millisecond)
}
// Make sure the parent directory doesn't contain references
// to the current directory.
mustSyncParentDirIfExists(path)
}
}
func isTemporaryNFSError(err error) bool {
// See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/61 for details.
errStr := err.Error()
return strings.Contains(errStr, "directory not empty") || strings.Contains(errStr, "device or resource busy")
}
func init() {
go dirRemover()
}
// HardLinkFiles makes hard links for all the files from srcDir in dstDir.
func HardLinkFiles(srcDir, dstDir string) error {
if err := mkdirSync(dstDir); err != nil {
return fmt.Errorf("cannot create dstDir=%q: %s", dstDir, err)
}
d, err := os.Open(srcDir)
if err != nil {
return fmt.Errorf("cannot open srcDir=%q: %s", srcDir, err)
}
defer func() {
if err := d.Close(); err != nil {
logger.Panicf("FATAL: cannot close %q: %s", srcDir, err)
}
}()
fis, err := d.Readdir(-1)
if err != nil {
return fmt.Errorf("cannot read files in scrDir=%q: %s", srcDir, err)
}
for _, fi := range fis {
if IsDirOrSymlink(fi) {
// Skip directories.
continue
}
fn := fi.Name()
srcPath := srcDir + "/" + fn
dstPath := dstDir + "/" + fn
if err := os.Link(srcPath, dstPath); err != nil {
return err
}
}
MustSyncPath(dstDir)
return nil
}
// IsDirOrSymlink returns true if fi is directory or symlink.
func IsDirOrSymlink(fi os.FileInfo) bool {
return fi.IsDir() || (fi.Mode()&os.ModeSymlink == os.ModeSymlink)
}
// SymlinkRelative creates relative symlink for srcPath in dstPath.
func SymlinkRelative(srcPath, dstPath string) error {
baseDir := filepath.Dir(dstPath)
srcPathRel, err := filepath.Rel(baseDir, srcPath)
if err != nil {
return fmt.Errorf("cannot make relative path for srcPath=%q: %s", srcPath, err)
}
return os.Symlink(srcPathRel, dstPath)
}
// ReadFullData reads len(data) bytes from r.
func ReadFullData(r io.Reader, data []byte) error {
n, err := io.ReadFull(r, data)
if err != nil {
if err == io.EOF {
return io.EOF
}
return fmt.Errorf("cannot read %d bytes; read only %d bytes; error: %s", len(data), n, err)
}
if n != len(data) {
logger.Panicf("BUG: io.ReadFull read only %d bytes; must read %d bytes", n, len(data))
}
return nil
}
// MustWriteData writes data to w.
func MustWriteData(w io.Writer, data []byte) {
if len(data) == 0 {
return
}
n, err := w.Write(data)
if err != nil {
logger.Panicf("FATAL: cannot write %d bytes: %s", len(data), err)
}
if n != len(data) {
logger.Panicf("BUG: writer wrote %d bytes instead of %d bytes", n, len(data))
}
}
// CreateFlockFile creates flock.lock file in the directory dir
// and returns the handler to the file.
func CreateFlockFile(dir string) (*os.File, error) {
flockFile := dir + "/flock.lock"
flockF, err := os.Create(flockFile)
if err != nil {
return nil, fmt.Errorf("cannot create lock file %q: %s", flockFile, err)
}
if err := unix.Flock(int(flockF.Fd()), unix.LOCK_EX|unix.LOCK_NB); err != nil {
return nil, fmt.Errorf("cannot acquire lock on file %q: %s", flockFile, err)
}
return flockF, nil
}
// MustGetFreeSpace returns free space for the given directory path.
func MustGetFreeSpace(path string) uint64 {
d, err := os.Open(path)
if err != nil {
logger.Panicf("FATAL: cannot determine free disk space on %q: %s", path, err)
}
defer MustClose(d)
fd := d.Fd()
var stat unix.Statfs_t
if err := unix.Fstatfs(int(fd), &stat); err != nil {
logger.Panicf("FATAL: cannot determine free disk space on %q: %s", path, err)
}
freeSpace := uint64(stat.Bavail) * uint64(stat.Bsize)
return freeSpace
}