Rework metadata helper with genny

Signed-off-by: Vladimir Popov <vladimir.popov@xored.com>

.golangci.yml

@@ -176,6 +176,11 @@ issues:
       linters:
         - dupl
         - golint
+        - goheader
+    - path: .*\.template\.go
+      linters:
+        - dupl
+        - deadcode
     - path: .*registry.*.go
       linters:
         - dupl

go.mod

@@ -5,6 +5,7 @@ go 1.15
 require (
 	github.com/HdrHistogram/hdrhistogram-go v1.0.0 // indirect
 	github.com/RoaringBitmap/roaring v0.4.23
+	github.com/cheekybits/genny v1.0.0
 	github.com/dgrijalva/jwt-go v3.2.0+incompatible
 	github.com/edwarnicke/exechelper v1.0.2
 	github.com/edwarnicke/grpcfd v0.0.0-20200920223154-d5b6e1f19bd0

go.sum

@@ -49,6 +49,8 @@ github.com/bombsimon/wsl/v3 v3.1.0/go.mod h1:st10JtZYLE4D5sC7b8xV4zTKZwAQjCH/Hy2
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/cespare/xxhash v1.1.0 h1:a6HrQnmkObjyL+Gs60czilIUGqrzKutQD6XZog3p+ko=
 github.com/cespare/xxhash v1.1.0/go.mod h1:XrSqR1VqqWfGrhpAt58auRo0WTKS1nRRg3ghfAqPWnc=
+github.com/cheekybits/genny v1.0.0 h1:uGGa4nei+j20rOSeDeP5Of12XVm7TGUd4dJA9RDitfE=
+github.com/cheekybits/genny v1.0.0/go.mod h1:+tQajlRqAUrPI7DOSpB0XAqZYtQakVtB7wXkRAgjxjQ=
 github.com/circonus-labs/circonus-gometrics v2.3.1+incompatible/go.mod h1:nmEj6Dob7S7YxXgwXpfOuvO54S+tGdZdw9fuRZt25Ag=
 github.com/circonus-labs/circonusllhist v0.1.3/go.mod h1:kMXHVDlOchFAehlya5ePtbp5jckzBHf4XRpQvBOLI+I=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=

pkg/networkservice/utils/metadata/helper/README.md

@@ -0,0 +1,69 @@
+# Metadata helper
+
+Metadata helper is a [genny](https://github.com/cheekybits/genny) template to generate a helper class for the metadata
+usage. Temlate parameters are:
+* prefix - prefix for the metadata type and constructor;
+* valueType - stored type.
+Generated helpers can both be exported (**P**refix) and unexported (**p**refix).
+
+gen.go:
+```go
+package connect
+
+//go:generate genny -in=../../utils/metadata/helper/meta_data.template.go -out=client_meta_data.gen.go -pkg=connect gen "prefix=client valueType=networkservice.NetworkServiceClient"
+```
+client_meta_data.gen.go:
+```go
+// This file was automatically generated by genny.
+// Any changes will be lost if this file is regenerated.
+// see https://github.com/cheekybits/genny
+
+package connect
+
+import (
+	"context"
+	"sync"
+
+	"github.com/networkservicemesh/api/pkg/api/networkservice"
+	"github.com/networkservicemesh/sdk/pkg/networkservice/utils/metadata"
+)
+
+type _ClientKeyType struct{}
+
+type clientMetadataHelper struct {
+	m *sync.Map
+}
+
+func clientMetadata(ctx context.Context, isClient bool) *clientMetadataHelper {
+	return &clientMetadataHelper{
+		m: metadata.Map(ctx, isClient),
+	}
+}
+
+func (h *clientMetadataHelper) Store(value networkservice.NetworkServiceClient) {
+	h.m.Store(_ClientKeyType{}, value)
+}
+
+func (h *clientMetadataHelper) LoadOrStore(value networkservice.NetworkServiceClient) (networkservice.NetworkServiceClient, bool) {
+	raw, ok := h.m.LoadOrStore(_ClientKeyType{}, value)
+	return raw.(networkservice.NetworkServiceClient), ok
+}
+
+func (h *clientMetadataHelper) Load() (networkservice.NetworkServiceClient, bool) {
+	if raw, ok := h.m.Load(_ClientKeyType{}); ok {
+		return raw.(networkservice.NetworkServiceClient), true
+	}
+	return func() (v networkservice.NetworkServiceClient) { return }(), false
+}
+
+func (h *clientMetadataHelper) LoadAndDelete() (networkservice.NetworkServiceClient, bool) {
+	if raw, ok := h.m.LoadAndDelete(_ClientKeyType{}); ok {
+		return raw.(networkservice.NetworkServiceClient), true
+	}
+	return func() (v networkservice.NetworkServiceClient) { return }(), false
+}
+
+func (h *clientMetadataHelper) Delete() {
+	h.m.Delete(_ClientKeyType{})
+}
+```

pkg/networkservice/utils/metadata/helper/doc.go

@@ -0,0 +1,18 @@
+// Copyright (c) 2020 Doc.ai and/or its affiliates.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// 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 helper provides template for generating metadata helpers.
+package helper

pkg/networkservice/utils/metadata/helper/gen.go

@@ -0,0 +1,19 @@
+// Copyright (c) 2020 Doc.ai and/or its affiliates.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// 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 helper
+
+//go:generate genny -in=meta_data.template.go -out=int_meta_data.gen.go gen "prefix=Int valueType=int"