VictoriaMetrics/lib/fs/fs.go

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package fs
import (
"fmt"
"io"
"net/http"
"net/url"
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"os"
"path/filepath"
"regexp"
"strings"
"sync"
"sync/atomic"
"time"
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"github.com/VictoriaMetrics/VictoriaMetrics/lib/fasttime"
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"github.com/VictoriaMetrics/VictoriaMetrics/lib/filestream"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
)
var tmpFileNum uint64
// MustSyncPath syncs contents of the given path.
func MustSyncPath(path string) {
mustSyncPath(path)
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}
// MustWriteSync writes data to the file at path and then calls fsync on the created file.
//
// The fsync guarantees that the written data survives hardware reset after successful call.
//
// This function may leave the file at the path in inconsistent state on app crash
// in the middle of the write.
// Use MustWriteAtomic if the file at the path must be either written in full
// or not written at all on app crash in the middle of the write.
func MustWriteSync(path string, data []byte) {
f := filestream.MustCreate(path, false)
if _, err := f.Write(data); err != nil {
f.MustClose()
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// Do not call MustRemoveAll(path), so the user could inspect
// the file contents during investigation of the issue.
logger.Panicf("FATAL: cannot write %d bytes to %q: %s", len(data), path, err)
}
// Sync and close the file.
f.MustClose()
}
// MustWriteAtomic atomically writes data to the given file path.
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//
// This function returns only after the file is fully written and synced
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// to the underlying storage.
//
// This function guarantees that the file at path either fully written or not written at all on app crash
// in the middle of the write.
//
// If the file at path already exists, then the file is overwritten atomically if canOverwrite is true.
// Otherwise error is returned.
func MustWriteAtomic(path string, data []byte, canOverwrite bool) {
// Check for the existing file. It is expected that
// the MustWriteAtomic function cannot be called concurrently
// with the same `path`.
if IsPathExist(path) && !canOverwrite {
logger.Panicf("FATAL: cannot create file %q, since it already exists", path)
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}
// Write data to a temporary file.
n := atomic.AddUint64(&tmpFileNum, 1)
tmpPath := fmt.Sprintf("%s.tmp.%d", path, n)
MustWriteSync(tmpPath, data)
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// Atomically move the temporary 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 investigation of the issue.
logger.Panicf("FATAL: cannot move temporary file %q to %q: %s", tmpPath, path, err)
}
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// 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 {
logger.Panicf("FATAL: cannot obtain absolute path to %q: %s", path, err)
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}
parentDirPath := filepath.Dir(absPath)
MustSyncPath(parentDirPath)
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}
// IsTemporaryFileName returns true if fn matches temporary file name pattern
// from MustWriteAtomic.
func IsTemporaryFileName(fn string) bool {
return tmpFileNameRe.MatchString(fn)
}
// tmpFileNameRe is regexp for temporary file name - see MustWriteAtomic for details.
var tmpFileNameRe = regexp.MustCompile(`\.tmp\.\d+$`)
// MustMkdirIfNotExist creates the given path dir if it isn't exist.
func MustMkdirIfNotExist(path string) {
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if IsPathExist(path) {
return
}
mustMkdirSync(path)
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}
// MustMkdirFailIfExist creates the given path dir if it isn't exist.
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//
// If the directory at the given path already exists, then the function logs the error and exits.
func MustMkdirFailIfExist(path string) {
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if IsPathExist(path) {
logger.Panicf("FATAL: the %q already exists", path)
}
mustMkdirSync(path)
}
func mustMkdirSync(path string) {
if err := os.MkdirAll(path, 0755); err != nil {
logger.Panicf("FATAL: cannot create directory: %s", err)
}
// Sync the parent directory, so the created directory becomes visible
// in the fs after power loss.
parentDirPath := filepath.Dir(path)
MustSyncPath(parentDirPath)
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}
// RemoveDirContents removes all the contents of the given dir if it exists.
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//
// 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: %s", err)
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}
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 := filepath.Join(dir, name)
MustRemoveAll(fullPath)
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}
MustSyncPath(dir)
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}
// 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())
}
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// 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)
}
// IsEmptyDir returns true if path points to empty directory.
func IsEmptyDir(path string) bool {
// See https://stackoverflow.com/a/30708914/274937
f, err := os.Open(path)
if err != nil {
logger.Panicf("FATAL: cannot open dir: %s", err)
}
_, err = f.Readdirnames(1)
MustClose(f)
if err != nil {
if err == io.EOF {
return true
}
logger.Panicf("FATAL: unexpected error when reading directory %q: %s", path, err)
}
return false
}
// MustRemoveDirAtomic removes the given dir atomically.
//
// It uses the following algorithm:
//
// 1. Atomically rename the "<dir>" to "<dir>.must-remove.<XYZ>",
// where <XYZ> is an unique number.
// 2. Remove the "<dir>.must-remove.XYZ" in background.
//
// If the process crashes after the step 1, then the directory must be removed
// on the next process start by calling MustRemoveTemporaryDirs on the parent directory.
func MustRemoveDirAtomic(dir string) {
if !IsPathExist(dir) {
return
}
n := atomic.AddUint64(&atomicDirRemoveCounter, 1)
tmpDir := fmt.Sprintf("%s.must-remove.%d", dir, n)
if err := os.Rename(dir, tmpDir); err != nil {
logger.Panicf("FATAL: cannot move %s to %s: %s", dir, tmpDir, err)
}
MustRemoveAll(tmpDir)
parentDir := filepath.Dir(dir)
MustSyncPath(parentDir)
}
var atomicDirRemoveCounter = uint64(time.Now().UnixNano())
// MustReadDir reads directory entries at the given dir.
func MustReadDir(dir string) []os.DirEntry {
des, err := os.ReadDir(dir)
if err != nil {
logger.Panicf("FATAL: cannot read directory contents: %s", err)
}
return des
}
// MustRemoveTemporaryDirs removes all the subdirectories with ".must-remove.<XYZ>" suffix.
//
// Such directories may be left on unclean shutdown during MustRemoveDirAtomic call.
func MustRemoveTemporaryDirs(dir string) {
des := MustReadDir(dir)
for _, de := range des {
if !IsDirOrSymlink(de) {
// Skip non-directories
continue
}
dirName := de.Name()
if IsScheduledForRemoval(dirName) {
fullPath := filepath.Join(dir, dirName)
MustRemoveAll(fullPath)
}
}
MustSyncPath(dir)
}
// MustHardLinkFiles makes hard links for all the files from srcDir in dstDir.
func MustHardLinkFiles(srcDir, dstDir string) {
mustMkdirSync(dstDir)
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des := MustReadDir(srcDir)
for _, de := range des {
if IsDirOrSymlink(de) {
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// Skip directories.
continue
}
fn := de.Name()
srcPath := filepath.Join(srcDir, fn)
dstPath := filepath.Join(dstDir, fn)
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if err := os.Link(srcPath, dstPath); err != nil {
logger.Panicf("FATAL: cannot link files: %s", err)
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}
}
MustSyncPath(dstDir)
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}
// IsDirOrSymlink returns true if de is directory or symlink.
func IsDirOrSymlink(de os.DirEntry) bool {
return de.IsDir() || (de.Type()&os.ModeSymlink == os.ModeSymlink)
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}
// MustSymlinkRelative creates relative symlink for srcPath in dstPath.
func MustSymlinkRelative(srcPath, dstPath string) {
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baseDir := filepath.Dir(dstPath)
srcPathRel, err := filepath.Rel(baseDir, srcPath)
if err != nil {
logger.Panicf("FATAL: cannot make relative path for srcPath=%q: %s", srcPath, err)
}
if err := os.Symlink(srcPathRel, dstPath); err != nil {
logger.Panicf("FATAL: cannot make a symlink: %s", err)
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}
}
// MustCopyDirectory copies all the files in srcPath to dstPath.
func MustCopyDirectory(srcPath, dstPath string) {
des := MustReadDir(srcPath)
MustMkdirIfNotExist(dstPath)
for _, de := range des {
if !de.Type().IsRegular() {
// Skip non-files
continue
}
src := filepath.Join(srcPath, de.Name())
dst := filepath.Join(dstPath, de.Name())
MustCopyFile(src, dst)
}
MustSyncPath(dstPath)
}
// MustCopyFile copies the file from srcPath to dstPath.
func MustCopyFile(srcPath, dstPath string) {
src, err := os.Open(srcPath)
if err != nil {
logger.Panicf("FATAL: cannot open srcPath: %s", err)
}
defer MustClose(src)
dst, err := os.Create(dstPath)
if err != nil {
logger.Panicf("FATAL: cannot create dstPath: %s", err)
}
defer MustClose(dst)
if _, err := io.Copy(dst, src); err != nil {
logger.Panicf("FATAL: cannot copy %q to %q: %s", srcPath, dstPath, err)
}
MustSyncPath(dstPath)
}
// MustReadData reads len(data) bytes from r.
func MustReadData(r filestream.ReadCloser, data []byte) {
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n, err := io.ReadFull(r, data)
if err != nil {
if err == io.EOF {
return
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}
logger.Panicf("FATAL: cannot read %d bytes from %s; read only %d bytes; error: %s", len(data), r.Path(), n, err)
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}
if n != len(data) {
logger.Panicf("BUG: io.ReadFull read only %d bytes from %s; must read %d bytes", n, r.Path(), len(data))
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}
}
// MustWriteData writes data to w.
func MustWriteData(w filestream.WriteCloser, data []byte) {
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if len(data) == 0 {
return
}
n, err := w.Write(data)
if err != nil {
logger.Panicf("FATAL: cannot write %d bytes to %s: %s", len(data), w.Path(), err)
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}
if n != len(data) {
logger.Panicf("BUG: writer wrote %d bytes instead of %d bytes to %s", n, len(data), w.Path())
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}
}
// MustCreateFlockFile creates FlockFilename file in the directory dir
// and returns the handler to the file.
func MustCreateFlockFile(dir string) *os.File {
flockFilepath := filepath.Join(dir, FlockFilename)
f, err := createFlockFile(flockFilepath)
if err != nil {
logger.Panicf("FATAL: cannot create lock file: %s; make sure a single process has exclusive access to %q", err, dir)
}
return f
}
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// FlockFilename is the filename for the file created by MustCreateFlockFile().
const FlockFilename = "flock.lock"
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// MustGetFreeSpace returns free space for the given directory path.
func MustGetFreeSpace(path string) uint64 {
// Try obtaining cached value at first.
freeSpaceMapLock.Lock()
defer freeSpaceMapLock.Unlock()
e, ok := freeSpaceMap[path]
if ok && fasttime.UnixTimestamp()-e.updateTime < 2 {
// Fast path - the entry is fresh.
return e.freeSpace
}
// Slow path.
// Determine the amount of free space at path.
e.freeSpace = mustGetFreeSpace(path)
e.updateTime = fasttime.UnixTimestamp()
freeSpaceMap[path] = e
return e.freeSpace
}
var (
freeSpaceMap = make(map[string]freeSpaceEntry)
freeSpaceMapLock sync.Mutex
)
type freeSpaceEntry struct {
updateTime uint64
freeSpace uint64
}
// ReadFileOrHTTP reads path either from local filesystem or from http if path starts with http or https.
func ReadFileOrHTTP(path string) ([]byte, error) {
if isHTTPURL(path) {
// reads remote file via http or https, if url is given
resp, err := http.Get(path)
if err != nil {
return nil, fmt.Errorf("cannot fetch %q: %w", path, err)
}
data, err := io.ReadAll(resp.Body)
_ = resp.Body.Close()
if resp.StatusCode != http.StatusOK {
if len(data) > 4*1024 {
data = data[:4*1024]
}
return nil, fmt.Errorf("unexpected status code when fetching %q: %d, expecting %d; response: %q", path, resp.StatusCode, http.StatusOK, data)
}
if err != nil {
return nil, fmt.Errorf("cannot read %q: %s", path, err)
}
return data, nil
}
data, err := os.ReadFile(path)
if err != nil {
return nil, fmt.Errorf("cannot read %q: %w", path, err)
}
return data, nil
}
// GetFilepath returns full path to file for the given baseDir and path.
func GetFilepath(baseDir, path string) string {
if filepath.IsAbs(path) || isHTTPURL(path) {
return path
}
return filepath.Join(baseDir, path)
}
// isHTTPURL checks if a given targetURL is valid and contains a valid http scheme
func isHTTPURL(targetURL string) bool {
parsed, err := url.Parse(targetURL)
return err == nil && (parsed.Scheme == "http" || parsed.Scheme == "https") && parsed.Host != ""
}
// IsScheduledForRemoval returns true if the filename contains .must-remove. substring
func IsScheduledForRemoval(filename string) bool {
return strings.Contains(filename, ".must-remove.")
}