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//
//
// Copyright 2015 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.
//
//
#ifndef GRPCPP_IMPL_CLIENT_UNARY_CALL_H
#define GRPCPP_IMPL_CLIENT_UNARY_CALL_H
#include <grpcpp/impl/call.h>
#include <grpcpp/impl/call_op_set.h>
#include <grpcpp/impl/channel_interface.h>
#include <grpcpp/support/config.h>
#include <grpcpp/support/status.h>
namespace grpc {
class ClientContext;
namespace internal {
class RpcMethod;
/// Wrapper that performs a blocking unary call. May optionally specify the base
/// class of the Request and Response so that the internal calls and structures
/// below this may be based on those base classes and thus achieve code reuse
/// across different RPCs (e.g., for protobuf, MessageLite would be a base
/// class).
template <class InputMessage, class OutputMessage,
class BaseInputMessage = InputMessage,
class BaseOutputMessage = OutputMessage>
Status BlockingUnaryCall(ChannelInterface* channel, const RpcMethod& method,
grpc::ClientContext* context,
const InputMessage& request, OutputMessage* result) {
static_assert(std::is_base_of<BaseInputMessage, InputMessage>::value,
"Invalid input message specification");
static_assert(std::is_base_of<BaseOutputMessage, OutputMessage>::value,
"Invalid output message specification");
return BlockingUnaryCallImpl<BaseInputMessage, BaseOutputMessage>(
channel, method, context, request, result)
.status();
}
template <class InputMessage, class OutputMessage>
class BlockingUnaryCallImpl {
public:
BlockingUnaryCallImpl(ChannelInterface* channel, const RpcMethod& method,
grpc::ClientContext* context,
const InputMessage& request, OutputMessage* result) {
grpc::CompletionQueue cq(grpc_completion_queue_attributes{
GRPC_CQ_CURRENT_VERSION, GRPC_CQ_PLUCK, GRPC_CQ_DEFAULT_POLLING,
nullptr}); // Pluckable completion queue
grpc::internal::Call call(channel->CreateCall(method, context, &cq));
CallOpSet<CallOpSendInitialMetadata, CallOpSendMessage,
CallOpRecvInitialMetadata, CallOpRecvMessage<OutputMessage>,
CallOpClientSendClose, CallOpClientRecvStatus>
ops;
status_ = ops.SendMessagePtr(&request);
if (!status_.ok()) {
return;
}
ops.SendInitialMetadata(&context->send_initial_metadata_,
context->initial_metadata_flags());
ops.RecvInitialMetadata(context);
ops.RecvMessage(result);
ops.AllowNoMessage();
ops.ClientSendClose();
ops.ClientRecvStatus(context, &status_);
call.PerformOps(&ops);
cq.Pluck(&ops);
// Some of the ops might fail. If the ops fail in the core layer, status
// would reflect the error. But, if the ops fail in the C++ layer, the
// status would still be the same as the one returned by gRPC Core. This can
// happen if deserialization of the message fails.
// TODO(yashykt): If deserialization fails, but the status received is OK,
// then it might be a good idea to change the status to something better
// than StatusCode::UNIMPLEMENTED to reflect this.
if (!ops.got_message && status_.ok()) {
status_ = Status(StatusCode::UNIMPLEMENTED,
"No message returned for unary request");
}
}
Status status() { return status_; }
private:
Status status_;
};
} // namespace internal
} // namespace grpc
#endif // GRPCPP_IMPL_CLIENT_UNARY_CALL_H
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