XL: Bring in some modularity into format verification and healing. (#1832)

xl-v1-utils.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"io"
 	"math/rand"
+	"path"
 	"time"
 )
 
@@ -38,14 +39,40 @@ func randInts(count int) []int {
 	return ints
 }
 
-// readAll reads from bucket, object until an error or returns the data it read until io.EOF.
-func readAll(disk StorageAPI, bucket, object string) ([]byte, error) {
+// readAll - returns contents from volume/path as byte array.
+func readAll(disk StorageAPI, volume string, path string) ([]byte, error) {
 	var writer = new(bytes.Buffer)
 	startOffset := int64(0)
+
+	// Allocate 10MiB buffer.
+	buf := make([]byte, blockSizeV1)
+
 	// Read until io.EOF.
 	for {
-		buf := make([]byte, blockSizeV1)
-		n, err := disk.ReadFile(bucket, object, startOffset, buf)
+		n, err := disk.ReadFile(volume, path, startOffset, buf)
+		if err == io.EOF {
+			break
+		}
+		if err != nil && err != io.EOF {
+			return nil, err
+		}
+		writer.Write(buf[:n])
+		startOffset += n
+	}
+	return writer.Bytes(), nil
+}
+
+// readXLMeta reads `xl.json` returns contents as byte array.
+func readXLMeta(disk StorageAPI, bucket string, object string) ([]byte, error) {
+	var writer = new(bytes.Buffer)
+	startOffset := int64(0)
+
+	// Allocate 2MiB buffer, this is sufficient for the most of `xl.json`.
+	buf := make([]byte, 2*1024*1024)
+
+	// Read until io.EOF.
+	for {
+		n, err := disk.ReadFile(bucket, path.Join(object, xlMetaJSONFile), startOffset, buf)
 		if err == io.EOF {
 			break
 		}