Prepare for using optimized conversion to map[string]interface{} in patch

pkg/genericapiserver/api/handlers/patch.go

@@ -0,0 +1,131 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package handlers
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/types"
+	"k8s.io/kubernetes/pkg/util/strategicpatch"
+
+	"github.com/evanphx/json-patch"
+)
+
+// patchObjectJSON patches the <originalObject> with <patchJS> and stores
+// the result in <objToUpdate>.
+// Currently it also returns the original and patched objects serialized to
+// JSONs (this may not be needed once we can apply patches at the
+// map[string]interface{} level).
+func patchObjectJSON(
+	patchType types.PatchType,
+	codec runtime.Codec,
+	originalObject runtime.Object,
+	patchJS []byte,
+	objToUpdate runtime.Object,
+	versionedObj runtime.Object,
+) (originalObjJS []byte, patchedObjJS []byte, retErr error) {
+	js, err := runtime.Encode(codec, originalObject)
+	if err != nil {
+		return nil, nil, err
+	}
+	originalObjJS = js
+
+	switch patchType {
+	case types.JSONPatchType:
+		patchObj, err := jsonpatch.DecodePatch(patchJS)
+		if err != nil {
+			return nil, nil, err
+		}
+		if patchedObjJS, err = patchObj.Apply(originalObjJS); err != nil {
+			return nil, nil, err
+		}
+	case types.MergePatchType:
+		if patchedObjJS, err = jsonpatch.MergePatch(originalObjJS, patchJS); err != nil {
+			return nil, nil, err
+		}
+	case types.StrategicMergePatchType:
+		if patchedObjJS, err = strategicpatch.StrategicMergePatch(originalObjJS, patchJS, versionedObj); err != nil {
+			return nil, nil, err
+		}
+	default:
+		// only here as a safety net - go-restful filters content-type
+		return nil, nil, fmt.Errorf("unknown Content-Type header for patch: %v", patchType)
+	}
+	if err := runtime.DecodeInto(codec, patchedObjJS, objToUpdate); err != nil {
+		return nil, nil, err
+	}
+	return
+}
+
+// strategicPatchObject applies a strategic merge patch of <patchJS> to
+// <originalObject> and stores the result in <objToUpdate>.
+// It additionally returns the map[string]interface{} representation of the
+// <originalObject> and <patchJS>.
+func strategicPatchObject(
+	codec runtime.Codec,
+	originalObject runtime.Object,
+	patchJS []byte,
+	objToUpdate runtime.Object,
+	versionedObj runtime.Object,
+) (originalObjMap map[string]interface{}, patchMap map[string]interface{}, retErr error) {
+	// TODO: This should be one-step conversion that doesn't require
+	// json marshaling and unmarshaling once #39017 is fixed.
+	data, err := runtime.Encode(codec, originalObject)
+	if err != nil {
+		return nil, nil, err
+	}
+	originalObjMap = make(map[string]interface{})
+	if err := json.Unmarshal(data, &originalObjMap); err != nil {
+		return nil, nil, err
+	}
+
+	patchMap = make(map[string]interface{})
+	if err := json.Unmarshal(patchJS, &patchMap); err != nil {
+		return nil, nil, err
+	}
+
+	if err := applyPatchToObject(codec, originalObjMap, patchMap, objToUpdate, versionedObj); err != nil {
+		return nil, nil, err
+	}
+	return
+}
+
+// applyPatchToObject applies a strategic merge patch of <patchMap> to
+// <originalMap> and stores the result in <objToUpdate>, though it operates
+// on versioned map[string]interface{} representations.
+func applyPatchToObject(
+	codec runtime.Codec,
+	originalMap map[string]interface{},
+	patchMap map[string]interface{},
+	objToUpdate runtime.Object,
+	versionedObj runtime.Object,
+) error {
+	patchedObjMap, err := strategicpatch.StrategicMergeMapPatch(originalMap, patchMap, versionedObj)
+	if err != nil {
+		return err
+	}
+
+	// TODO: This should be one-step conversion that doesn't require
+	// json marshaling and unmarshaling once #39017 is fixed.
+	data, err := json.Marshal(patchedObjMap)
+	if err != nil {
+		return err
+	}
+	return runtime.DecodeInto(codec, data, objToUpdate)
+}