test/cpp/end2end/test_service_impl.cc - third_party/grpc - Git at Google

 /*
  *
  * Copyright 2016 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.
  *
  */

 #include "test/cpp/end2end/test_service_impl.h"

 #include <string>
 #include <thread>

 #include <grpc++/security/credentials.h>
 #include <grpc++/server_context.h>
 #include <grpc/support/log.h>

 #include "src/proto/grpc/testing/echo.grpc.pb.h"
 #include "test/cpp/util/string_ref_helper.h"

 #include <gtest/gtest.h>

 using std::chrono::system_clock;

 namespace grpc {
 namespace testing {
 namespace {

 // When echo_deadline is requested, deadline seen in the ServerContext is set in
 // the response in seconds.
 void MaybeEchoDeadline(ServerContext* context, const EchoRequest* request,
                        EchoResponse* response) {
   if (request->has_param() && request->param().echo_deadline()) {
     gpr_timespec deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
     if (context->deadline() != system_clock::time_point::max()) {
       Timepoint2Timespec(context->deadline(), &deadline);
     }
     response->mutable_param()->set_request_deadline(deadline.tv_sec);
   }
 }

 void CheckServerAuthContext(
     const ServerContext* context,
     const grpc::string& expected_transport_security_type,
     const grpc::string& expected_client_identity) {
   std::shared_ptr<const AuthContext> auth_ctx = context->auth_context();
   std::vector<grpc::string_ref> tst =
       auth_ctx->FindPropertyValues("transport_security_type");
   EXPECT_EQ(1u, tst.size());
   EXPECT_EQ(expected_transport_security_type, ToString(tst[0]));
   if (expected_client_identity.empty()) {
     EXPECT_TRUE(auth_ctx->GetPeerIdentityPropertyName().empty());
     EXPECT_TRUE(auth_ctx->GetPeerIdentity().empty());
     EXPECT_FALSE(auth_ctx->IsPeerAuthenticated());
   } else {
     auto identity = auth_ctx->GetPeerIdentity();
     EXPECT_TRUE(auth_ctx->IsPeerAuthenticated());
     EXPECT_EQ(1u, identity.size());
     EXPECT_EQ(expected_client_identity, identity[0]);
   }
 }
 }  // namespace

 Status TestServiceImpl::Echo(ServerContext* context, const EchoRequest* request,
                              EchoResponse* response) {
   if (request->has_param() && request->param().server_die()) {
     gpr_log(GPR_ERROR, "The request should not reach application handler.");
     GPR_ASSERT(0);
   }
   if (request->has_param() && request->param().has_expected_error()) {
     const auto& error = request->param().expected_error();
     return Status(static_cast<StatusCode>(error.code()), error.error_message(),
                   error.binary_error_details());
   }
   int server_try_cancel = GetIntValueFromMetadata(
       kServerTryCancelRequest, context->client_metadata(), DO_NOT_CANCEL);
   if (server_try_cancel > DO_NOT_CANCEL) {
     // Since this is a unary RPC, by the time this server handler is called,
     // the 'request' message is already read from the client. So the scenarios
     // in server_try_cancel don't make much sense. Just cancel the RPC as long
     // as server_try_cancel is not DO_NOT_CANCEL
     ServerTryCancel(context);
     return Status::CANCELLED;
   }

   response->set_message(request->message());
   MaybeEchoDeadline(context, request, response);
   if (host_) {
     response->mutable_param()->set_host(*host_);
   }
   if (request->has_param() && request->param().client_cancel_after_us()) {
     {
       std::unique_lock<std::mutex> lock(mu_);
       signal_client_ = true;
     }
     while (!context->IsCancelled()) {
       gpr_sleep_until(gpr_time_add(
           gpr_now(GPR_CLOCK_REALTIME),
           gpr_time_from_micros(request->param().client_cancel_after_us(),
                                GPR_TIMESPAN)));
     }
     return Status::CANCELLED;
   } else if (request->has_param() &&
              request->param().server_cancel_after_us()) {
     gpr_sleep_until(gpr_time_add(
         gpr_now(GPR_CLOCK_REALTIME),
         gpr_time_from_micros(request->param().server_cancel_after_us(),
                              GPR_TIMESPAN)));
     return Status::CANCELLED;
   } else if (!request->has_param() ||
              !request->param().skip_cancelled_check()) {
     EXPECT_FALSE(context->IsCancelled());
   }

   if (request->has_param() && request->param().echo_metadata()) {
     const std::multimap<grpc::string_ref, grpc::string_ref>& client_metadata =
         context->client_metadata();
     for (std::multimap<grpc::string_ref, grpc::string_ref>::const_iterator
              iter = client_metadata.begin();
          iter != client_metadata.end(); ++iter) {
       context->AddTrailingMetadata(ToString(iter->first),
                                    ToString(iter->second));
     }
     // Terminate rpc with error and debug info in trailer.
     if (request->param().debug_info().stack_entries_size() ||
         !request->param().debug_info().detail().empty()) {
       grpc::string serialized_debug_info =
           request->param().debug_info().SerializeAsString();
       context->AddTrailingMetadata(kDebugInfoTrailerKey, serialized_debug_info);
       return Status::CANCELLED;
     }
   }
   if (request->has_param() &&
       (request->param().expected_client_identity().length() > 0 ||
        request->param().check_auth_context())) {
     CheckServerAuthContext(context,
                            request->param().expected_transport_security_type(),
                            request->param().expected_client_identity());
   }
   if (request->has_param() && request->param().response_message_length() > 0) {
     response->set_message(
         grpc::string(request->param().response_message_length(), '\0'));
   }
   if (request->has_param() && request->param().echo_peer()) {
     response->mutable_param()->set_peer(context->peer());
   }
   return Status::OK;
 }

 // Unimplemented is left unimplemented to test the returned error.

 Status TestServiceImpl::RequestStream(ServerContext* context,
                                       ServerReader<EchoRequest>* reader,
                                       EchoResponse* response) {
   // If 'server_try_cancel' is set in the metadata, the RPC is cancelled by
   // the server by calling ServerContext::TryCancel() depending on the value:
   //   CANCEL_BEFORE_PROCESSING: The RPC is cancelled before the server reads
   //   any message from the client
   //   CANCEL_DURING_PROCESSING: The RPC is cancelled while the server is
   //   reading messages from the client
   //   CANCEL_AFTER_PROCESSING: The RPC is cancelled after the server reads
   //   all the messages from the client
   int server_try_cancel = GetIntValueFromMetadata(
       kServerTryCancelRequest, context->client_metadata(), DO_NOT_CANCEL);

   // If 'cancel_after_reads' is set in the metadata AND non-zero, the server
   // will cancel the RPC (by just returning Status::CANCELLED - doesn't call
   // ServerContext::TryCancel()) after reading the number of records specified
   // by the 'cancel_after_reads' value set in the metadata.
   int cancel_after_reads = GetIntValueFromMetadata(
       kServerCancelAfterReads, context->client_metadata(), 0);

   EchoRequest request;
   response->set_message("");

   if (server_try_cancel == CANCEL_BEFORE_PROCESSING) {
     ServerTryCancel(context);
     return Status::CANCELLED;
   }

   std::thread* server_try_cancel_thd = nullptr;
   if (server_try_cancel == CANCEL_DURING_PROCESSING) {
     server_try_cancel_thd =
         new std::thread(&TestServiceImpl::ServerTryCancel, this, context);
   }

   int num_msgs_read = 0;
   while (reader->Read(&request)) {
     if (cancel_after_reads == 1) {
       gpr_log(GPR_INFO, "return cancel status");
       return Status::CANCELLED;
     } else if (cancel_after_reads > 0) {
       cancel_after_reads--;
     }
     response->mutable_message()->append(request.message());
   }
   gpr_log(GPR_INFO, "Read: %d messages", num_msgs_read);

   if (server_try_cancel_thd != nullptr) {
     server_try_cancel_thd->join();
     delete server_try_cancel_thd;
     return Status::CANCELLED;
   }

   if (server_try_cancel == CANCEL_AFTER_PROCESSING) {
     ServerTryCancel(context);
     return Status::CANCELLED;
   }

   return Status::OK;
 }

 // Return 'kNumResponseStreamMsgs' messages.
 // TODO(yangg) make it generic by adding a parameter into EchoRequest
 Status TestServiceImpl::ResponseStream(ServerContext* context,
                                        const EchoRequest* request,
                                        ServerWriter<EchoResponse>* writer) {
   // If server_try_cancel is set in the metadata, the RPC is cancelled by the
   // server by calling ServerContext::TryCancel() depending on the value:
   //   CANCEL_BEFORE_PROCESSING: The RPC is cancelled before the server writes
   //   any messages to the client
   //   CANCEL_DURING_PROCESSING: The RPC is cancelled while the server is
   //   writing messages to the client
   //   CANCEL_AFTER_PROCESSING: The RPC is cancelled after the server writes
   //   all the messages to the client
   int server_try_cancel = GetIntValueFromMetadata(
       kServerTryCancelRequest, context->client_metadata(), DO_NOT_CANCEL);

   int server_coalescing_api = GetIntValueFromMetadata(
       kServerUseCoalescingApi, context->client_metadata(), 0);

   int server_responses_to_send = GetIntValueFromMetadata(
       kServerResponseStreamsToSend, context->client_metadata(),
       kServerDefaultResponseStreamsToSend);

   if (server_try_cancel == CANCEL_BEFORE_PROCESSING) {
     ServerTryCancel(context);
     return Status::CANCELLED;
   }

   EchoResponse response;
   std::thread* server_try_cancel_thd = nullptr;
   if (server_try_cancel == CANCEL_DURING_PROCESSING) {
     server_try_cancel_thd =
         new std::thread(&TestServiceImpl::ServerTryCancel, this, context);
   }

   for (int i = 0; i < server_responses_to_send; i++) {
     response.set_message(request->message() + grpc::to_string(i));
     if (i == server_responses_to_send - 1 && server_coalescing_api != 0) {
       writer->WriteLast(response, WriteOptions());
     } else {
       writer->Write(response);
     }
   }

   if (server_try_cancel_thd != nullptr) {
     server_try_cancel_thd->join();
     delete server_try_cancel_thd;
     return Status::CANCELLED;
   }

   if (server_try_cancel == CANCEL_AFTER_PROCESSING) {
     ServerTryCancel(context);
     return Status::CANCELLED;
   }

   return Status::OK;
 }

 Status TestServiceImpl::BidiStream(
     ServerContext* context,
     ServerReaderWriter<EchoResponse, EchoRequest>* stream) {
   // If server_try_cancel is set in the metadata, the RPC is cancelled by the
   // server by calling ServerContext::TryCancel() depending on the value:
   //   CANCEL_BEFORE_PROCESSING: The RPC is cancelled before the server reads/
   //   writes any messages from/to the client
   //   CANCEL_DURING_PROCESSING: The RPC is cancelled while the server is
   //   reading/writing messages from/to the client
   //   CANCEL_AFTER_PROCESSING: The RPC is cancelled after the server
   //   reads/writes all messages from/to the client
   int server_try_cancel = GetIntValueFromMetadata(
       kServerTryCancelRequest, context->client_metadata(), DO_NOT_CANCEL);

   EchoRequest request;
   EchoResponse response;

   if (server_try_cancel == CANCEL_BEFORE_PROCESSING) {
     ServerTryCancel(context);
     return Status::CANCELLED;
   }

   std::thread* server_try_cancel_thd = nullptr;
   if (server_try_cancel == CANCEL_DURING_PROCESSING) {
     server_try_cancel_thd =
         new std::thread(&TestServiceImpl::ServerTryCancel, this, context);
   }

   // kServerFinishAfterNReads suggests after how many reads, the server should
   // write the last message and send status (coalesced using WriteLast)
   int server_write_last = GetIntValueFromMetadata(
       kServerFinishAfterNReads, context->client_metadata(), 0);

   int read_counts = 0;
   while (stream->Read(&request)) {
     read_counts++;
     gpr_log(GPR_INFO, "recv msg %s", request.message().c_str());
     response.set_message(request.message());
     if (read_counts == server_write_last) {
       stream->WriteLast(response, WriteOptions());
     } else {
       stream->Write(response);
     }
   }

   if (server_try_cancel_thd != nullptr) {
     server_try_cancel_thd->join();
     delete server_try_cancel_thd;
     return Status::CANCELLED;
   }

   if (server_try_cancel == CANCEL_AFTER_PROCESSING) {
     ServerTryCancel(context);
     return Status::CANCELLED;
   }

   return Status::OK;
 }

 int TestServiceImpl::GetIntValueFromMetadata(
     const char* key,
     const std::multimap<grpc::string_ref, grpc::string_ref>& metadata,
     int default_value) {
   if (metadata.find(key) != metadata.end()) {
     std::istringstream iss(ToString(metadata.find(key)->second));
     iss >> default_value;
     gpr_log(GPR_INFO, "%s : %d", key, default_value);
   }

   return default_value;
 }

 void TestServiceImpl::ServerTryCancel(ServerContext* context) {
   EXPECT_FALSE(context->IsCancelled());
   context->TryCancel();
   gpr_log(GPR_INFO, "Server called TryCancel() to cancel the request");
   // Now wait until it's really canceled
   while (!context->IsCancelled()) {
     gpr_sleep_until(gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
                                  gpr_time_from_micros(1000, GPR_TIMESPAN)));
   }
 }

 }  // namespace testing
 }  // namespace grpc
	/*
	*
	* Copyright 2016 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.
	*
	*/

	#include "test/cpp/end2end/test_service_impl.h"

	#include <string>
	#include <thread>

	#include <grpc++/security/credentials.h>
	#include <grpc++/server_context.h>
	#include <grpc/support/log.h>

	#include "src/proto/grpc/testing/echo.grpc.pb.h"
	#include "test/cpp/util/string_ref_helper.h"

	#include <gtest/gtest.h>

	using std::chrono::system_clock;

	namespace grpc {
	namespace testing {
	namespace {

	// When echo_deadline is requested, deadline seen in the ServerContext is set in
	// the response in seconds.
	void MaybeEchoDeadline(ServerContext* context, const EchoRequest* request,
	EchoResponse* response) {
	if (request->has_param() && request->param().echo_deadline()) {
	gpr_timespec deadline = gpr_inf_future(GPR_CLOCK_REALTIME);
	if (context->deadline() != system_clock::time_point::max()) {
	Timepoint2Timespec(context->deadline(), &deadline);
	}
	response->mutable_param()->set_request_deadline(deadline.tv_sec);
	}
	}

	void CheckServerAuthContext(
	const ServerContext* context,
	const grpc::string& expected_transport_security_type,
	const grpc::string& expected_client_identity) {
	std::shared_ptr<const AuthContext> auth_ctx = context->auth_context();
	std::vector<grpc::string_ref> tst =
	auth_ctx->FindPropertyValues("transport_security_type");
	EXPECT_EQ(1u, tst.size());
	EXPECT_EQ(expected_transport_security_type, ToString(tst[0]));
	if (expected_client_identity.empty()) {
	EXPECT_TRUE(auth_ctx->GetPeerIdentityPropertyName().empty());
	EXPECT_TRUE(auth_ctx->GetPeerIdentity().empty());
	EXPECT_FALSE(auth_ctx->IsPeerAuthenticated());
	} else {
	auto identity = auth_ctx->GetPeerIdentity();
	EXPECT_TRUE(auth_ctx->IsPeerAuthenticated());
	EXPECT_EQ(1u, identity.size());
	EXPECT_EQ(expected_client_identity, identity[0]);
	}
	}
	} // namespace

	Status TestServiceImpl::Echo(ServerContext* context, const EchoRequest* request,
	EchoResponse* response) {
	if (request->has_param() && request->param().server_die()) {
	gpr_log(GPR_ERROR, "The request should not reach application handler.");
	GPR_ASSERT(0);
	}
	if (request->has_param() && request->param().has_expected_error()) {
	const auto& error = request->param().expected_error();
	return Status(static_cast<StatusCode>(error.code()), error.error_message(),
	error.binary_error_details());
	}
	int server_try_cancel = GetIntValueFromMetadata(
	kServerTryCancelRequest, context->client_metadata(), DO_NOT_CANCEL);
	if (server_try_cancel > DO_NOT_CANCEL) {
	// Since this is a unary RPC, by the time this server handler is called,
	// the 'request' message is already read from the client. So the scenarios
	// in server_try_cancel don't make much sense. Just cancel the RPC as long
	// as server_try_cancel is not DO_NOT_CANCEL
	ServerTryCancel(context);
	return Status::CANCELLED;
	}

	response->set_message(request->message());
	MaybeEchoDeadline(context, request, response);
	if (host_) {
	response->mutable_param()->set_host(*host_);
	}
	if (request->has_param() && request->param().client_cancel_after_us()) {
	{
	std::unique_lock<std::mutex> lock(mu_);
	signal_client_ = true;
	}
	while (!context->IsCancelled()) {
	gpr_sleep_until(gpr_time_add(
	gpr_now(GPR_CLOCK_REALTIME),
	gpr_time_from_micros(request->param().client_cancel_after_us(),
	GPR_TIMESPAN)));
	}
	return Status::CANCELLED;
	} else if (request->has_param() &&
	request->param().server_cancel_after_us()) {
	gpr_sleep_until(gpr_time_add(
	gpr_now(GPR_CLOCK_REALTIME),
	gpr_time_from_micros(request->param().server_cancel_after_us(),
	GPR_TIMESPAN)));
	return Status::CANCELLED;
	} else if (!request->has_param() \|\|
	!request->param().skip_cancelled_check()) {
	EXPECT_FALSE(context->IsCancelled());
	}

	if (request->has_param() && request->param().echo_metadata()) {
	const std::multimap<grpc::string_ref, grpc::string_ref>& client_metadata =
	context->client_metadata();
	for (std::multimap<grpc::string_ref, grpc::string_ref>::const_iterator
	iter = client_metadata.begin();
	iter != client_metadata.end(); ++iter) {
	context->AddTrailingMetadata(ToString(iter->first),
	ToString(iter->second));
	}
	// Terminate rpc with error and debug info in trailer.
	if (request->param().debug_info().stack_entries_size() \|\|
	!request->param().debug_info().detail().empty()) {
	grpc::string serialized_debug_info =
	request->param().debug_info().SerializeAsString();
	context->AddTrailingMetadata(kDebugInfoTrailerKey, serialized_debug_info);
	return Status::CANCELLED;
	}
	}
	if (request->has_param() &&
	(request->param().expected_client_identity().length() > 0 \|\|
	request->param().check_auth_context())) {
	CheckServerAuthContext(context,
	request->param().expected_transport_security_type(),
	request->param().expected_client_identity());
	}
	if (request->has_param() && request->param().response_message_length() > 0) {
	response->set_message(
	grpc::string(request->param().response_message_length(), '\0'));
	}
	if (request->has_param() && request->param().echo_peer()) {
	response->mutable_param()->set_peer(context->peer());
	}
	return Status::OK;
	}

	// Unimplemented is left unimplemented to test the returned error.

	Status TestServiceImpl::RequestStream(ServerContext* context,
	ServerReader<EchoRequest>* reader,
	EchoResponse* response) {
	// If 'server_try_cancel' is set in the metadata, the RPC is cancelled by
	// the server by calling ServerContext::TryCancel() depending on the value:
	// CANCEL_BEFORE_PROCESSING: The RPC is cancelled before the server reads
	// any message from the client
	// CANCEL_DURING_PROCESSING: The RPC is cancelled while the server is
	// reading messages from the client
	// CANCEL_AFTER_PROCESSING: The RPC is cancelled after the server reads
	// all the messages from the client
	int server_try_cancel = GetIntValueFromMetadata(
	kServerTryCancelRequest, context->client_metadata(), DO_NOT_CANCEL);

	// If 'cancel_after_reads' is set in the metadata AND non-zero, the server
	// will cancel the RPC (by just returning Status::CANCELLED - doesn't call
	// ServerContext::TryCancel()) after reading the number of records specified
	// by the 'cancel_after_reads' value set in the metadata.
	int cancel_after_reads = GetIntValueFromMetadata(
	kServerCancelAfterReads, context->client_metadata(), 0);

	EchoRequest request;
	response->set_message("");

	if (server_try_cancel == CANCEL_BEFORE_PROCESSING) {
	ServerTryCancel(context);
	return Status::CANCELLED;
	}

	std::thread* server_try_cancel_thd = nullptr;
	if (server_try_cancel == CANCEL_DURING_PROCESSING) {
	server_try_cancel_thd =
	new std::thread(&TestServiceImpl::ServerTryCancel, this, context);
	}

	int num_msgs_read = 0;
	while (reader->Read(&request)) {
	if (cancel_after_reads == 1) {
	gpr_log(GPR_INFO, "return cancel status");
	return Status::CANCELLED;
	} else if (cancel_after_reads > 0) {
	cancel_after_reads--;
	}
	response->mutable_message()->append(request.message());
	}
	gpr_log(GPR_INFO, "Read: %d messages", num_msgs_read);

	if (server_try_cancel_thd != nullptr) {
	server_try_cancel_thd->join();
	delete server_try_cancel_thd;
	return Status::CANCELLED;
	}

	if (server_try_cancel == CANCEL_AFTER_PROCESSING) {
	ServerTryCancel(context);
	return Status::CANCELLED;
	}

	return Status::OK;
	}

	// Return 'kNumResponseStreamMsgs' messages.
	// TODO(yangg) make it generic by adding a parameter into EchoRequest
	Status TestServiceImpl::ResponseStream(ServerContext* context,
	const EchoRequest* request,
	ServerWriter<EchoResponse>* writer) {
	// If server_try_cancel is set in the metadata, the RPC is cancelled by the
	// server by calling ServerContext::TryCancel() depending on the value:
	// CANCEL_BEFORE_PROCESSING: The RPC is cancelled before the server writes
	// any messages to the client
	// CANCEL_DURING_PROCESSING: The RPC is cancelled while the server is
	// writing messages to the client
	// CANCEL_AFTER_PROCESSING: The RPC is cancelled after the server writes
	// all the messages to the client
	int server_try_cancel = GetIntValueFromMetadata(
	kServerTryCancelRequest, context->client_metadata(), DO_NOT_CANCEL);

	int server_coalescing_api = GetIntValueFromMetadata(
	kServerUseCoalescingApi, context->client_metadata(), 0);

	int server_responses_to_send = GetIntValueFromMetadata(
	kServerResponseStreamsToSend, context->client_metadata(),
	kServerDefaultResponseStreamsToSend);

	if (server_try_cancel == CANCEL_BEFORE_PROCESSING) {
	ServerTryCancel(context);
	return Status::CANCELLED;
	}

	EchoResponse response;
	std::thread* server_try_cancel_thd = nullptr;
	if (server_try_cancel == CANCEL_DURING_PROCESSING) {
	server_try_cancel_thd =
	new std::thread(&TestServiceImpl::ServerTryCancel, this, context);
	}

	for (int i = 0; i < server_responses_to_send; i++) {
	response.set_message(request->message() + grpc::to_string(i));
	if (i == server_responses_to_send - 1 && server_coalescing_api != 0) {
	writer->WriteLast(response, WriteOptions());
	} else {
	writer->Write(response);
	}
	}

	if (server_try_cancel_thd != nullptr) {
	server_try_cancel_thd->join();
	delete server_try_cancel_thd;
	return Status::CANCELLED;
	}

	if (server_try_cancel == CANCEL_AFTER_PROCESSING) {
	ServerTryCancel(context);
	return Status::CANCELLED;
	}

	return Status::OK;
	}

	Status TestServiceImpl::BidiStream(
	ServerContext* context,
	ServerReaderWriter<EchoResponse, EchoRequest>* stream) {
	// If server_try_cancel is set in the metadata, the RPC is cancelled by the
	// server by calling ServerContext::TryCancel() depending on the value:
	// CANCEL_BEFORE_PROCESSING: The RPC is cancelled before the server reads/
	// writes any messages from/to the client
	// CANCEL_DURING_PROCESSING: The RPC is cancelled while the server is
	// reading/writing messages from/to the client
	// CANCEL_AFTER_PROCESSING: The RPC is cancelled after the server
	// reads/writes all messages from/to the client
	int server_try_cancel = GetIntValueFromMetadata(
	kServerTryCancelRequest, context->client_metadata(), DO_NOT_CANCEL);

	EchoRequest request;
	EchoResponse response;

	if (server_try_cancel == CANCEL_BEFORE_PROCESSING) {
	ServerTryCancel(context);
	return Status::CANCELLED;
	}

	std::thread* server_try_cancel_thd = nullptr;
	if (server_try_cancel == CANCEL_DURING_PROCESSING) {
	server_try_cancel_thd =
	new std::thread(&TestServiceImpl::ServerTryCancel, this, context);
	}

	// kServerFinishAfterNReads suggests after how many reads, the server should
	// write the last message and send status (coalesced using WriteLast)
	int server_write_last = GetIntValueFromMetadata(
	kServerFinishAfterNReads, context->client_metadata(), 0);

	int read_counts = 0;
	while (stream->Read(&request)) {
	read_counts++;
	gpr_log(GPR_INFO, "recv msg %s", request.message().c_str());
	response.set_message(request.message());
	if (read_counts == server_write_last) {
	stream->WriteLast(response, WriteOptions());
	} else {
	stream->Write(response);
	}
	}

	if (server_try_cancel_thd != nullptr) {
	server_try_cancel_thd->join();
	delete server_try_cancel_thd;
	return Status::CANCELLED;
	}

	if (server_try_cancel == CANCEL_AFTER_PROCESSING) {
	ServerTryCancel(context);
	return Status::CANCELLED;
	}

	return Status::OK;
	}

	int TestServiceImpl::GetIntValueFromMetadata(
	const char* key,
	const std::multimap<grpc::string_ref, grpc::string_ref>& metadata,
	int default_value) {
	if (metadata.find(key) != metadata.end()) {
	std::istringstream iss(ToString(metadata.find(key)->second));
	iss >> default_value;
	gpr_log(GPR_INFO, "%s : %d", key, default_value);
	}

	return default_value;
	}

	void TestServiceImpl::ServerTryCancel(ServerContext* context) {
	EXPECT_FALSE(context->IsCancelled());
	context->TryCancel();
	gpr_log(GPR_INFO, "Server called TryCancel() to cancel the request");
	// Now wait until it's really canceled
	while (!context->IsCancelled()) {
	gpr_sleep_until(gpr_time_add(gpr_now(GPR_CLOCK_REALTIME),
	gpr_time_from_micros(1000, GPR_TIMESPAN)));
	}
	}

	} // namespace testing
	} // namespace grpc