avoid notification for non-existent delete objects (#11514)

Skip notifications on objects that might have had
an error during deletion, this also avoids unnecessary
replication attempt on such objects.

Refactor some places to make sure that we have notified
the client before we

- notify
- schedule for replication
- lifecycle etc.

cmd/object-handlers.go

@@ -2848,8 +2848,13 @@ func (api objectAPIHandlers) DeleteObjectHandler(w http.ResponseWriter, r *http.
 		return
 	}
 
+	deleteObject := objectAPI.DeleteObject
+	if api.CacheAPI() != nil {
+		deleteObject = api.CacheAPI().DeleteObject
+	}
+
 	// http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectDELETE.html
-	objInfo, err := deleteObject(ctx, objectAPI, api.CacheAPI(), bucket, object, w, r, opts)
+	objInfo, err := deleteObject(ctx, bucket, object, opts)
 	if err != nil {
 		switch err.(type) {
 		case BucketNotFound:
@@ -2857,9 +2862,32 @@ func (api objectAPIHandlers) DeleteObjectHandler(w http.ResponseWriter, r *http.
 			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
 			return
 		}
-		// Ignore delete object errors while replying to client, since we are suppposed to reply only 204.
 	}
 
+	if objInfo.Name == "" {
+		writeSuccessNoContent(w)
+		return
+	}
+
+	setPutObjHeaders(w, objInfo, true)
+	writeSuccessNoContent(w)
+
+	eventName := event.ObjectRemovedDelete
+	if objInfo.DeleteMarker {
+		eventName = event.ObjectRemovedDeleteMarkerCreated
+	}
+
+	// Notify object deleted event.
+	sendEvent(eventArgs{
+		EventName:    eventName,
+		BucketName:   bucket,
+		Object:       objInfo,
+		ReqParams:    extractReqParams(r),
+		RespElements: extractRespElements(w),
+		UserAgent:    r.UserAgent(),
+		Host:         handlers.GetSourceIP(r),
+	})
+
 	if replicateDel {
 		dmVersionID := ""
 		versionID := ""
@@ -2884,7 +2912,7 @@ func (api objectAPIHandlers) DeleteObjectHandler(w http.ResponseWriter, r *http.
 	}
 
 	if goi.TransitionStatus == lifecycle.TransitionComplete { // clean up transitioned tier
-		deleteTransitionedObject(ctx, newObjectLayerFn(), bucket, object, lifecycle.ObjectOpts{
+		deleteTransitionedObject(ctx, objectAPI, bucket, object, lifecycle.ObjectOpts{
 			Name:             object,
 			UserTags:         goi.UserTags,
 			VersionID:        goi.VersionID,
@@ -2893,9 +2921,6 @@ func (api objectAPIHandlers) DeleteObjectHandler(w http.ResponseWriter, r *http.
 			IsLatest:         goi.IsLatest,
 		}, false, true)
 	}
-
-	setPutObjHeaders(w, objInfo, true)
-	writeSuccessNoContent(w)
 }
 
 // PutObjectLegalHoldHandler - set legal hold configuration to object,