Source: call.go in package google.golang.org/grpc

* * Copyright 2014 gRPC 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 grpc

import (
	"context"
)

Invoke sends the RPC request on the wire and returns after response is received. This is typically called by generated code. All errors returned by Invoke are compatible with the status package.

allow interceptor to see all applicable call options, which means those configured as defaults from dial option as well as per-call options

	opts = combine(cc.dopts.callOptions, opts)

	if cc.dopts.unaryInt != nil {
		return cc.dopts.unaryInt(ctx, method, args, reply, cc, invoke, opts...)
	}
	return invoke(ctx, method, args, reply, cc, opts...)
}

we don't use append because o1 could have extra capacity whose elements would be overwritten, which could cause inadvertent sharing (and race conditions) between concurrent calls

	if len(o1) == 0 {
		return o2
	} else if len(o2) == 0 {
		return o1
	}
	ret := make([]CallOption, len(o1)+len(o2))
	copy(ret, o1)
	copy(ret[len(o1):], o2)
	return ret
}

Invoke sends the RPC request on the wire and returns after response is received. This is typically called by generated code. DEPRECATED: Use ClientConn.Invoke instead.

func Invoke(ctx context.Context, method string, args, reply interface{}, cc *ClientConn, opts ...CallOption) error {
	return cc.Invoke(ctx, method, args, reply, opts...)
}

var unaryStreamDesc = &StreamDesc{ServerStreams: false, ClientStreams: false}

func invoke(ctx context.Context, method string, req, reply interface{}, cc *ClientConn, opts ...CallOption) error {
	cs, err := newClientStream(ctx, unaryStreamDesc, cc, method, opts...)
	if err != nil {
		return err
	}
	if err := cs.SendMsg(req); err != nil {
		return err
	}
	return cs.RecvMsg(reply)