lib/fs: add canOverwrite arg to WriteFileAtomically when it is allowed to overwrite the file atomically if it already exists

app/vmselect/promql/rollup_result_cache.go

@@ -387,8 +387,7 @@ func mustLoadRollupResultCacheKeyPrefix(path string) {
 func mustSaveRollupResultCacheKeyPrefix(path string) {
 	path = path + ".key.prefix"
 	data := encoding.MarshalUint64(nil, rollupResultCacheKeyPrefix)
-	fs.MustRemoveAll(path)
+	if err := fs.WriteFileAtomically(path, data, true); err != nil {
-	if err := fs.WriteFileAtomically(path, data); err != nil {
 		logger.Fatalf("cannot store rollupResult cache key prefix to %q: %s", path, err)
 	}
 }

lib/fs/fs.go

@@ -29,11 +29,14 @@ func MustSyncPath(path string) {
 //
 // WriteFileAtomically returns only after the file is fully written and synced
 // to the underlying storage.
-func WriteFileAtomically(path string, data []byte) error {
+//
+// If the file at path already exists, then the file is overwritten atomically if canOverwrite is true.
+// Otherwise error is returned.
+func WriteFileAtomically(path string, data []byte, canOverwrite bool) error {
 	// Check for the existing file. It is expected that
 	// the WriteFileAtomically function cannot be called concurrently
 	// with the same `path`.
-	if IsPathExist(path) {
+	if IsPathExist(path) && !canOverwrite {
 		return fmt.Errorf("cannot create file %q, since it already exists", path)
 	}
 

lib/mergeset/part_header.go

@@ -163,7 +163,7 @@ func (ph *partHeader) WriteMetadata(partPath string) error {
 		return fmt.Errorf("cannot marshal metadata: %w", err)
 	}
 	metadataPath := partPath + "/metadata.json"
-	if err := fs.WriteFileAtomically(metadataPath, metadata); err != nil {
+	if err := fs.WriteFileAtomically(metadataPath, metadata, false); err != nil {
 		return fmt.Errorf("cannot create %q: %w", metadataPath, err)
 	}
 	return nil

lib/mergeset/table.go

@@ -580,7 +580,7 @@ func (tb *Table) convertToV1280() {
 		logger.Infof("finished round 2 of background conversion of %q to v1.28.0 format in %.3f seconds", tb.path, time.Since(startTime).Seconds())
 	}
 
-	if err := fs.WriteFileAtomically(flagFilePath, []byte("ok")); err != nil {
+	if err := fs.WriteFileAtomically(flagFilePath, []byte("ok"), false); err != nil {
 		logger.Panicf("FATAL: cannot create %q: %s", flagFilePath, err)
 	}
 }
@@ -975,7 +975,7 @@ func (tb *Table) mergeParts(pws []*partWrapper, stopCh <-chan struct{}, isOuterP
 	dstPartPath := ph.Path(tb.path, mergeIdx)
 	fmt.Fprintf(&bb, "%s -> %s\n", tmpPartPath, dstPartPath)
 	txnPath := fmt.Sprintf("%s/txn/%016X", tb.path, mergeIdx)
-	if err := fs.WriteFileAtomically(txnPath, bb.B); err != nil {
+	if err := fs.WriteFileAtomically(txnPath, bb.B, false); err != nil {
 		return fmt.Errorf("cannot create transaction file %q: %w", txnPath, err)
 	}
 

lib/persistentqueue/persistentqueue.go

@@ -211,7 +211,7 @@ func tryOpeningQueue(path, name string, chunkFileSize, maxBlockSize, maxPendingB
 
 		// Create initial chunk file.
 		filepath := q.chunkFilePath(0)
-		if err := fs.WriteFileAtomically(filepath, nil); err != nil {
+		if err := fs.WriteFileAtomically(filepath, nil, false); err != nil {
 			return nil, fmt.Errorf("cannot create %q: %w", filepath, err)
 		}
 	}

lib/storage/part_header.go

@@ -151,7 +151,7 @@ func (ph *partHeader) writeMinDedupInterval(partPath string) error {
 	filePath := partPath + "/min_dedup_interval"
 	dedupInterval := time.Duration(ph.MinDedupInterval) * time.Millisecond
 	data := dedupInterval.String()
-	if err := fs.WriteFileAtomically(filePath, []byte(data)); err != nil {
+	if err := fs.WriteFileAtomically(filePath, []byte(data), false); err != nil {
 		return fmt.Errorf("cannot create %q: %w", filePath, err)
 	}
 	return nil

lib/storage/partition.go

@@ -1246,7 +1246,7 @@ func (pt *partition) mergeParts(pws []*partWrapper, stopCh <-chan struct{}) erro
 	}
 	fmt.Fprintf(&bb, "%s -> %s\n", tmpPartPath, dstPartPath)
 	txnPath := fmt.Sprintf("%s/txn/%016X", ptPath, mergeIdx)
-	if err := fs.WriteFileAtomically(txnPath, bb.B); err != nil {
+	if err := fs.WriteFileAtomically(txnPath, bb.B, false); err != nil {
 		return fmt.Errorf("cannot create transaction file %q: %w", txnPath, err)
 	}
 

lib/storage/storage.go

@@ -1076,10 +1076,7 @@ func mustGetMinTimestampForCompositeIndex(metadataDir string, isEmptyDB bool) in
 	}
 	minTimestamp = date * msecPerDay
 	dateBuf := encoding.MarshalInt64(nil, minTimestamp)
-	if err := os.RemoveAll(path); err != nil {
+	if err := fs.WriteFileAtomically(path, dateBuf, true); err != nil {
-		logger.Fatalf("cannot remove a file with minTimestampForCompositeIndex: %s", err)
-	}
-	if err := fs.WriteFileAtomically(path, dateBuf); err != nil {
 		logger.Fatalf("cannot store minTimestampForCompositeIndex: %s", err)
 	}
 	return minTimestamp