Removing readAllMeta from xl-v1-healing.go and placing it in xl-v1-utils.go (#2296)

xl-v1-utils.go

@@ -20,6 +20,7 @@ import (
 	"encoding/json"
 	"hash/crc32"
 	"path"
+	"sync"
 )
 
 // Returns number of errors that occurred the most (incl. nil) and the
@@ -112,6 +113,38 @@ func readXLMeta(disk StorageAPI, bucket string, object string) (xlMeta xlMetaV1,
 	return xlMeta, nil
 }
 
+// Reads all `xl.json` metadata as a xlMetaV1 slice.
+// Returns error slice indicating the failed metadata reads.
+func readAllXLMetadata(disks []StorageAPI, bucket, object string) ([]xlMetaV1, []error) {
+	errs := make([]error, len(disks))
+	metadataArray := make([]xlMetaV1, len(disks))
+	var wg = &sync.WaitGroup{}
+	// Read `xl.json` parallelly across disks.
+	for index, disk := range disks {
+		if disk == nil {
+			errs[index] = errDiskNotFound
+			continue
+		}
+		wg.Add(1)
+		// Read `xl.json` in routine.
+		go func(index int, disk StorageAPI) {
+			defer wg.Done()
+			var err error
+			metadataArray[index], err = readXLMeta(disk, bucket, object)
+			if err != nil {
+				errs[index] = err
+				return
+			}
+		}(index, disk)
+	}
+
+	// Wait for all the routines to finish.
+	wg.Wait()
+
+	// Return all the metadata.
+	return metadataArray, errs
+}
+
 // Return ordered partsMetadata depeinding on distribution.
 func getOrderedPartsMetadata(distribution []int, partsMetadata []xlMetaV1) (orderedPartsMetadata []xlMetaV1) {
 	orderedPartsMetadata = make([]xlMetaV1, len(partsMetadata))