client/context_middleware.go

/*
 * Copyright 2022 CloudWeGo 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 client

import (
	"context"

	"github.com/cloudwego/kitex/pkg/endpoint"
)

type ctxMWChainKey struct{}

// WithContextMiddlewares add middlewares into current ctx
// Every client receive this ctx will execute the middlewares.
// Note that ContextMiddleware is prior to the ClientMiddleware.
func WithContextMiddlewares(ctx context.Context, mws ...endpoint.Middleware) context.Context {
	if len(mws) == 0 {
		return ctx
	}
	mw := getContextMiddleware(ctx)
	if mw != nil {
		mws = append([]endpoint.Middleware{mw}, mws...)
	}
	mw = endpoint.Chain(mws...)
	return context.WithValue(ctx, ctxMWChainKey{}, mw)
}

func getContextMiddleware(ctx context.Context) endpoint.Middleware {
	mws, _ := ctx.Value(ctxMWChainKey{}).(endpoint.Middleware)
	return mws
}

// contextMW execute the ContextMiddlewares in ctx
func contextMW(next endpoint.Endpoint) endpoint.Endpoint {
	return func(ctx context.Context, req, resp interface{}) (err error) {
		mw := getContextMiddleware(ctx)
		if mw != nil {
			return mw(next)(ctx, req, resp)
		}
		return next(ctx, req, resp)
	}
}