1 /*
2 *
3 * Copyright 2015 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19 #ifndef GRPCPP_IMPL_CODEGEN_CLIENT_UNARY_CALL_H
20 #define GRPCPP_IMPL_CODEGEN_CLIENT_UNARY_CALL_H
21
22 #include <grpcpp/impl/codegen/call.h>
23 #include <grpcpp/impl/codegen/channel_interface.h>
24 #include <grpcpp/impl/codegen/config.h>
25 #include <grpcpp/impl/codegen/core_codegen_interface.h>
26 #include <grpcpp/impl/codegen/status.h>
27
28 namespace grpc_impl {
29
30 class ClientContext;
31 } // namespace grpc_impl
32 namespace grpc {
33
34 namespace internal {
35 class RpcMethod;
36 /// Wrapper that performs a blocking unary call
37 template <class InputMessage, class OutputMessage>
BlockingUnaryCall(ChannelInterface * channel,const RpcMethod & method,grpc_impl::ClientContext * context,const InputMessage & request,OutputMessage * result)38 Status BlockingUnaryCall(ChannelInterface* channel, const RpcMethod& method,
39 grpc_impl::ClientContext* context,
40 const InputMessage& request, OutputMessage* result) {
41 return BlockingUnaryCallImpl<InputMessage, OutputMessage>(
42 channel, method, context, request, result)
43 .status();
44 }
45
46 template <class InputMessage, class OutputMessage>
47 class BlockingUnaryCallImpl {
48 public:
BlockingUnaryCallImpl(ChannelInterface * channel,const RpcMethod & method,grpc_impl::ClientContext * context,const InputMessage & request,OutputMessage * result)49 BlockingUnaryCallImpl(ChannelInterface* channel, const RpcMethod& method,
50 grpc_impl::ClientContext* context,
51 const InputMessage& request, OutputMessage* result) {
52 ::grpc_impl::CompletionQueue cq(grpc_completion_queue_attributes{
53 GRPC_CQ_CURRENT_VERSION, GRPC_CQ_PLUCK, GRPC_CQ_DEFAULT_POLLING,
54 nullptr}); // Pluckable completion queue
55 ::grpc::internal::Call call(channel->CreateCall(method, context, &cq));
56 CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
57 CallOpRecvInitialMetadata, CallOpRecvMessage<OutputMessage>,
58 CallOpClientSendClose, CallOpClientRecvStatus>
59 ops;
60 status_ = ops.SendMessagePtr(&request);
61 if (!status_.ok()) {
62 return;
63 }
64 ops.SendInitialMetadata(&context->send_initial_metadata_,
65 context->initial_metadata_flags());
66 ops.RecvInitialMetadata(context);
67 ops.RecvMessage(result);
68 ops.AllowNoMessage();
69 ops.ClientSendClose();
70 ops.ClientRecvStatus(context, &status_);
71 call.PerformOps(&ops);
72 cq.Pluck(&ops);
73 // Some of the ops might fail. If the ops fail in the core layer, status
74 // would reflect the error. But, if the ops fail in the C++ layer, the
75 // status would still be the same as the one returned by gRPC Core. This can
76 // happen if deserialization of the message fails.
77 // TODO(yashykt): If deserialization fails, but the status received is OK,
78 // then it might be a good idea to change the status to something better
79 // than StatusCode::UNIMPLEMENTED to reflect this.
80 if (!ops.got_message && status_.ok()) {
81 status_ = Status(StatusCode::UNIMPLEMENTED,
82 "No message returned for unary request");
83 }
84 }
status()85 Status status() { return status_; }
86
87 private:
88 Status status_;
89 };
90
91 } // namespace internal
92 } // namespace grpc
93
94 #endif // GRPCPP_IMPL_CODEGEN_CLIENT_UNARY_CALL_H
95