xl: code refactor, cleanup ReadFile and CreateFile.

xl-v1-utils.go

@@ -0,0 +1,76 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	slashpath "path"
+	"path/filepath"
+)
+
+// Get parts.json metadata as a map slice.
+// Returns error slice indicating the failed metadata reads.
+func (xl XL) getPartsMetadata(volume, path string) ([]map[string]string, []error) {
+	errs := make([]error, len(xl.storageDisks))
+	metadataArray := make([]map[string]string, len(xl.storageDisks))
+	metadataFilePath := slashpath.Join(path, metadataFile)
+	for index, disk := range xl.storageDisks {
+		metadata := make(map[string]string)
+		offset := int64(0)
+		metadataReader, err := disk.ReadFile(volume, metadataFilePath, offset)
+		if err != nil {
+			errs[index] = err
+			continue
+		}
+		defer metadataReader.Close()
+
+		decoder := json.NewDecoder(metadataReader)
+		if err = decoder.Decode(&metadata); err != nil {
+			// Unable to parse parts.json, set error.
+			errs[index] = err
+			continue
+		}
+		metadataArray[index] = metadata
+	}
+	return metadataArray, errs
+}
+
+// Writes/Updates `parts.json` for given file. updateParts carries
+// index of disks where `parts.json` needs to be updated.
+//
+// Returns collection of errors, indexed in accordance with input
+// updateParts order.
+func (xl XL) setPartsMetadata(volume, path string, metadata map[string]string, updateParts []bool) []error {
+	metadataFilePath := filepath.Join(path, metadataFile)
+	errs := make([]error, len(xl.storageDisks))
+
+	for index := range updateParts {
+		errs[index] = errors.New("metadata not updated")
+	}
+
+	metadataBytes, err := json.Marshal(metadata)
+	if err != nil {
+		for index := range updateParts {
+			errs[index] = err
+		}
+		return errs
+	}
+
+	for index, shouldUpdate := range updateParts {
+		if !shouldUpdate {
+			continue
+		}
+		writer, err := xl.storageDisks[index].CreateFile(volume, metadataFilePath)
+		errs[index] = err
+		if err != nil {
+			continue
+		}
+		_, err = writer.Write(metadataBytes)
+		if err != nil {
+			errs[index] = err
+			safeCloseAndRemove(writer)
+			continue
+		}
+		writer.Close()
+	}
+	return errs
+}