fix: various performance improvements to tiering (#12965)

- deletes should always Sweep() for tiering at the
  end and does not need an extra getObjectInfo() call
- puts, copy and multipart writes should conditionally
  do getObjectInfo() when tiering targets are configured
- introduce 'TransitionedObject' struct for ease of usage
  and understanding.
- multiple-pools optimization deletes don't need to hold
  read locks verifying objects across namespace and pools.

cmd/bucket-handlers.go

@@ -450,6 +450,7 @@ func (api objectAPIHandlers) DeleteMultipleObjectsHandler(w http.ResponseWriter,
 	if api.CacheAPI() != nil {
 		getObjectInfoFn = api.CacheAPI().GetObjectInfo
 	}
+
 	var (
 		hasLockEnabled, replicateSync bool
 		goi                           ObjectInfo
@@ -460,6 +461,9 @@ func (api objectAPIHandlers) DeleteMultipleObjectsHandler(w http.ResponseWriter,
 		hasLockEnabled = true
 	}
 
+	versioned := globalBucketVersioningSys.Enabled(bucket)
+	suspended := globalBucketVersioningSys.Suspended(bucket)
+
 	dErrs := make([]DeleteError, len(deleteObjects.Objects))
 	oss := make([]*objSweeper, len(deleteObjects.Objects))
 	for index, object := range deleteObjects.Objects {
@@ -491,16 +495,24 @@ func (api objectAPIHandlers) DeleteMultipleObjectsHandler(w http.ResponseWriter,
 			}
 		}
 
-		oss[index] = newObjSweeper(bucket, object.ObjectName).WithVersion(multiDelete(object))
-		// Mutations of objects on versioning suspended buckets
-		// affect its null version. Through opts below we select
-		// the null version's remote object to delete if
-		// transitioned.
-		opts := oss[index].GetOpts()
-		goi, gerr = getObjectInfoFn(ctx, bucket, object.ObjectName, opts)
-		if gerr == nil {
-			oss[index].SetTransitionState(goi)
+		opts := ObjectOptions{
+			VersionID:        object.VersionID,
+			Versioned:        versioned,
+			VersionSuspended: suspended,
 		}
+
+		if replicateDeletes || object.VersionID != "" && hasLockEnabled || !globalTierConfigMgr.Empty() {
+			if !globalTierConfigMgr.Empty() && object.VersionID == "" && opts.VersionSuspended {
+				opts.VersionID = nullVersionID
+			}
+			goi, gerr = getObjectInfoFn(ctx, bucket, object.ObjectName, opts)
+		}
+
+		if !globalTierConfigMgr.Empty() {
+			oss[index] = newObjSweeper(bucket, object.ObjectName).WithVersion(opts.VersionID).WithVersioning(versioned, suspended)
+			oss[index].SetTransitionState(goi.TransitionedObject)
+		}
+
 		if replicateDeletes {
 			replicate, repsync := checkReplicateDelete(ctx, bucket, ObjectToDelete{
 				ObjectName: object.ObjectName,
@@ -522,18 +534,16 @@ func (api objectAPIHandlers) DeleteMultipleObjectsHandler(w http.ResponseWriter,
 				}
 			}
 		}
-		if object.VersionID != "" {
-			if hasLockEnabled {
-				if apiErrCode := enforceRetentionBypassForDelete(ctx, r, bucket, object, goi, gerr); apiErrCode != ErrNone {
-					apiErr := errorCodes.ToAPIErr(apiErrCode)
-					dErrs[index] = DeleteError{
-						Code:      apiErr.Code,
-						Message:   apiErr.Description,
-						Key:       object.ObjectName,
-						VersionID: object.VersionID,
-					}
-					continue
+		if object.VersionID != "" && hasLockEnabled {
+			if apiErrCode := enforceRetentionBypassForDelete(ctx, r, bucket, object, goi, gerr); apiErrCode != ErrNone {
+				apiErr := errorCodes.ToAPIErr(apiErrCode)
+				dErrs[index] = DeleteError{
+					Code:      apiErr.Code,
+					Message:   apiErr.Description,
+					Key:       object.ObjectName,
+					VersionID: object.VersionID,
 				}
+				continue
 			}
 		}
 
@@ -555,8 +565,8 @@ func (api objectAPIHandlers) DeleteMultipleObjectsHandler(w http.ResponseWriter,
 
 	deleteList := toNames(objectsToDelete)
 	dObjects, errs := deleteObjectsFn(ctx, bucket, deleteList, ObjectOptions{
-		Versioned:        globalBucketVersioningSys.Enabled(bucket),
-		VersionSuspended: globalBucketVersioningSys.Suspended(bucket),
+		Versioned:        versioned,
+		VersionSuspended: suspended,
 	})
 	deletedObjects := make([]DeletedObject, len(deleteObjects.Objects))
 	for i := range errs {
@@ -620,6 +630,10 @@ func (api objectAPIHandlers) DeleteMultipleObjectsHandler(w http.ResponseWriter,
 
 	// Notify deleted event for objects.
 	for _, dobj := range deletedObjects {
+		if dobj.ObjectName == "" {
+			continue
+		}
+
 		eventName := event.ObjectRemovedDelete
 		objInfo := ObjectInfo{
 			Name:         dobj.ObjectName,