Merge pull request #24444 from veblush/tidy-readability-container-size-empty

[Clang-Tidy] Enable readability-container-size-empty

.clang-tidy

@@ -30,7 +30,7 @@ Checks: '-*,
   modernize-use-bool-literals,
   modernize-use-nullptr,
   -modernize-use-override,
-  -readability-container-size-empty,
+  readability-container-size-empty,
   readability-deleted-default,
   readability-function-size,
   -readability-inconsistent-declaration-parameter-name,

src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb.cc

@@ -941,7 +941,7 @@ void GrpcLb::BalancerCallState::SendClientLoadReportLocked() {
   if (num_calls_started == 0 && num_calls_finished == 0 &&
       num_calls_finished_with_client_failed_to_send == 0 &&
       num_calls_finished_known_received == 0 &&
-      (drop_token_counts == nullptr || drop_token_counts->size() == 0)) {
+      (drop_token_counts == nullptr || drop_token_counts->empty())) {
     if (last_client_load_report_counters_were_zero_) {
       ScheduleNextClientLoadReportLocked();
       return;

src/core/ext/filters/load_reporting/server_load_reporting_filter.cc

@@ -180,7 +180,7 @@ void ServerLoadReportingCallData::StoreClientIpAndLrToken(const char* lr_token,
       gpr_zalloc(client_ip_and_lr_token_len_ * sizeof(char)));
   char* cur_pos = client_ip_and_lr_token_;
   // Store the IP length prefix.
-  if (client_ip.size() == 0) {
+  if (client_ip.empty()) {
     strncpy(cur_pos, kEmptyAddressLengthString, kLengthPrefixSize);
   } else if (client_ip.size() == 8) {
     strncpy(cur_pos, kEncodedIpv4AddressLengthString, kLengthPrefixSize);

src/core/ext/xds/xds_api.cc

@@ -873,7 +873,7 @@ grpc_error* RoutePathMatchParse(const envoy_config_route_v3_RouteMatch* match,
     absl::string_view prefix =
         UpbStringToAbsl(envoy_config_route_v3_RouteMatch_prefix(match));
     // Empty prefix "" is accepted.
-    if (prefix.size() > 0) {
+    if (!prefix.empty()) {
       // Prefix "/" is accepted.
       if (prefix[0] != '/') {
         // Prefix which does not start with a / will never match anything, so
@@ -899,7 +899,7 @@ grpc_error* RoutePathMatchParse(const envoy_config_route_v3_RouteMatch* match,
   } else if (envoy_config_route_v3_RouteMatch_has_path(match)) {
     absl::string_view path =
         UpbStringToAbsl(envoy_config_route_v3_RouteMatch_path(match));
-    if (path.size() == 0) {
+    if (path.empty()) {
       // Path that is empty will never match anything, so ignore this route.
       *ignore_route = true;
       return GRPC_ERROR_NONE;
@@ -1068,7 +1068,7 @@ grpc_error* RouteActionParse(const envoy_config_route_v3_Route* route_msg,
   if (envoy_config_route_v3_RouteAction_has_cluster(route_action)) {
     route->cluster_name = UpbStringToStdString(
         envoy_config_route_v3_RouteAction_cluster(route_action));
-    if (route->cluster_name.size() == 0) {
+    if (route->cluster_name.empty()) {
       return GRPC_ERROR_CREATE_FROM_STATIC_STRING(
           "RouteAction cluster contains empty cluster name.");
     }
@@ -1650,7 +1650,7 @@ grpc_error* DropParseAndAppend(
   std::string category = UpbStringToStdString(
       envoy_config_endpoint_v3_ClusterLoadAssignment_Policy_DropOverload_category(
           drop_overload));
-  if (category.size() == 0) {
+  if (category.empty()) {
     return GRPC_ERROR_CREATE_FROM_STATIC_STRING("Empty drop category name");
   }
   // Get the drop rate (per million).

src/cpp/server/load_reporter/load_data_store.cc

@@ -43,7 +43,7 @@ bool UnorderedMapOfSetEraseKeyValue(std::unordered_map<K, std::set<V>>& map,
   auto it = map.find(key);
   if (it != map.end()) {
     size_t erased = it->second.erase(value);
-    if (it->second.size() == 0) {
+    if (it->second.empty()) {
       map.erase(it);
     }
     return erased;

src/cpp/server/load_reporter/load_reporter.cc

@@ -431,7 +431,7 @@ void LoadReporter::ProcessViewDataCallEnd(
       // This is due to a bug reported internally of Java server load reporting
       // implementation.
       // TODO(juanlishen): Check whether this situation happens in OSS C++.
-      if (client_ip_and_token.size() == 0) {
+      if (client_ip_and_token.empty()) {
         gpr_log(GPR_DEBUG,
                 "Skipping processing Opencensus record with empty "
                 "client_ip_and_token tag.");

test/cpp/end2end/client_lb_end2end_test.cc

@@ -290,7 +290,7 @@ class ClientLbEnd2endTest : public ::testing::Test {
       const std::string& lb_policy_name,
       const FakeResolverResponseGeneratorWrapper& response_generator,
       ChannelArguments args = ChannelArguments()) {
-    if (lb_policy_name.size() > 0) {
+    if (!lb_policy_name.empty()) {
       args.SetLoadBalancingPolicyName(lb_policy_name);
     }  // else, default to pick first
     args.SetPointer(GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR,

test/cpp/end2end/flaky_network_test.cc

@@ -193,7 +193,7 @@ class FlakyNetworkTest : public ::testing::TestWithParam<TestScenario> {
   std::shared_ptr<Channel> BuildChannel(
       const std::string& lb_policy_name,
       ChannelArguments args = ChannelArguments()) {
-    if (lb_policy_name.size() > 0) {
+    if (!lb_policy_name.empty()) {
       args.SetLoadBalancingPolicyName(lb_policy_name);
     }  // else, default to pick first
     auto channel_creds = GetCredentialsProvider()->GetChannelCredentials(

test/cpp/end2end/mock_test.cc

@@ -299,11 +299,11 @@ class TestServiceImpl : public EchoTestService::Service {
         buff += n;
         continue;
       }
-      if (buff == "") continue;
+      if (buff.empty()) continue;
       result.push_back(buff);
       buff = "";
     }
-    if (buff != "") result.push_back(buff);
+    if (!buff.empty()) result.push_back(buff);
 
     return result;
   }

test/cpp/end2end/proto_server_reflection_test.cc

@@ -133,7 +133,7 @@ TEST_F(ProtoServerReflectionTest, CheckResponseWithLocalDescriptorPool) {
   std::vector<std::string> services;
   desc_db_->GetServices(&services);
   // The service list has at least one service (reflection servcie).
-  EXPECT_TRUE(services.size() > 0);
+  EXPECT_TRUE(!services.empty());
 
   for (auto it = services.begin(); it != services.end(); ++it) {
     CompareService(*it);

test/cpp/interop/client.cc

@@ -179,7 +179,7 @@ int main(int argc, char** argv) {
 
   grpc::testing::ChannelCreationFunc channel_creation_func;
   std::string test_case = FLAGS_test_case;
-  if (FLAGS_additional_metadata == "") {
+  if (FLAGS_additional_metadata.empty()) {
     channel_creation_func = [test_case]() {
       return CreateChannelForTestCase(test_case);
     };

test/cpp/microbenchmarks/bm_call_create.cc

@@ -508,13 +508,13 @@ static void BM_IsolatedFilter(benchmark::State& state) {
 
   grpc_core::ExecCtx exec_ctx;
   size_t channel_size = grpc_channel_stack_size(
-      filters.size() == 0 ? nullptr : &filters[0], filters.size());
+      filters.empty() ? nullptr : &filters[0], filters.size());
   grpc_channel_stack* channel_stack =
       static_cast<grpc_channel_stack*>(gpr_zalloc(channel_size));
   GPR_ASSERT(GRPC_LOG_IF_ERROR(
       "channel_stack_init",
       grpc_channel_stack_init(1, FilterDestroy, channel_stack,
-                              filters.size() == 0 ? nullptr : &filters[0],
+                              filters.empty() ? nullptr : &filters[0],
                               filters.size(), &channel_args,
                               fixture.flags & REQUIRES_TRANSPORT
                                   ? &dummy_transport::dummy_transport

test/cpp/naming/resolver_component_test.cc

@@ -161,7 +161,7 @@ class GrpcLBAddress final {
 
 vector<GrpcLBAddress> ParseExpectedAddrs(std::string expected_addrs) {
   std::vector<GrpcLBAddress> out;
-  while (expected_addrs.size() != 0) {
+  while (!expected_addrs.empty()) {
     // get the next <ip>,<port> (v4 or v6)
     size_t next_comma = expected_addrs.find(',');
     if (next_comma == std::string::npos) {
@@ -185,7 +185,7 @@ vector<GrpcLBAddress> ParseExpectedAddrs(std::string expected_addrs) {
     expected_addrs =
         expected_addrs.substr(next_semicolon + 1, std::string::npos);
   }
-  if (out.size() == 0) {
+  if (out.empty()) {
     gpr_log(GPR_ERROR,
             "expected_addrs arg should be a semicolon-separated list of "
             "<ip-port>,<bool> pairs");
@@ -275,11 +275,11 @@ void PollPollsetUntilRequestDone(ArgsStruct* args) {
 void CheckServiceConfigResultLocked(const char* service_config_json,
                                     grpc_error* service_config_error,
                                     ArgsStruct* args) {
-  if (args->expected_service_config_string != "") {
+  if (!args->expected_service_config_string.empty()) {
     GPR_ASSERT(service_config_json != nullptr);
     EXPECT_EQ(service_config_json, args->expected_service_config_string);
   }
-  if (args->expected_service_config_error == "") {
+  if (args->expected_service_config_error.empty()) {
     EXPECT_EQ(service_config_error, GRPC_ERROR_NONE);
   } else {
     EXPECT_THAT(grpc_error_string(service_config_error),
@@ -292,7 +292,7 @@ void CheckLBPolicyResultLocked(const grpc_channel_args* channel_args,
                                ArgsStruct* args) {
   const grpc_arg* lb_policy_arg =
       grpc_channel_args_find(channel_args, GRPC_ARG_LB_POLICY_NAME);
-  if (args->expected_lb_policy != "") {
+  if (!args->expected_lb_policy.empty()) {
     GPR_ASSERT(lb_policy_arg != nullptr);
     GPR_ASSERT(lb_policy_arg->type == GRPC_ARG_STRING);
     EXPECT_EQ(lb_policy_arg->value.string, args->expected_lb_policy);
@@ -513,7 +513,7 @@ class CheckingResultHandler : public ResultHandler {
             : result.service_config->json_string().c_str();
     CheckServiceConfigResultLocked(
         service_config_json, GRPC_ERROR_REF(result.service_config_error), args);
-    if (args->expected_service_config_string == "") {
+    if (args->expected_service_config_string.empty()) {
       CheckLBPolicyResultLocked(result.args, args);
     }
   }
@@ -678,7 +678,7 @@ int main(int argc, char** argv) {
   grpc::testing::TestEnvironment env(argc, argv);
   ::testing::InitGoogleTest(&argc, argv);
   grpc::testing::InitTest(&argc, &argv, true);
-  if (FLAGS_target_name == "") {
+  if (FLAGS_target_name.empty()) {
     gpr_log(GPR_ERROR, "Missing target_name param.");
     abort();
   }

test/cpp/naming/resolver_component_tests_runner_invoker.cc

@@ -164,10 +164,10 @@ int main(int argc, char** argv) {
   grpc::testing::TestEnvironment env(argc, argv);
   grpc::testing::InitTest(&argc, &argv, true);
   grpc_init();
-  GPR_ASSERT(FLAGS_test_bin_name != "");
+  GPR_ASSERT(!FLAGS_test_bin_name.empty());
   std::string my_bin = argv[0];
   if (FLAGS_running_under_bazel) {
-    GPR_ASSERT(FLAGS_grpc_test_directory_relative_to_test_srcdir != "");
+    GPR_ASSERT(!FLAGS_grpc_test_directory_relative_to_test_srcdir.empty());
     // Use bazel's TEST_SRCDIR environment variable to locate the "test data"
     // binaries.
     char* test_srcdir = gpr_getenv("TEST_SRCDIR");

test/cpp/qps/benchmark_config.cc

@@ -66,7 +66,7 @@ static std::shared_ptr<Reporter> InitBenchmarkReporters() {
     composite_reporter->add(
         std::unique_ptr<Reporter>(new GprLogReporter("LogReporter")));
   }
-  if (FLAGS_scenario_result_file != "") {
+  if (!FLAGS_scenario_result_file.empty()) {
     composite_reporter->add(std::unique_ptr<Reporter>(
         new JsonReporter("JsonReporter", FLAGS_scenario_result_file)));
   }

test/cpp/qps/driver.cc

@@ -77,7 +77,7 @@ static deque<string> get_workers(const string& env_name) {
       }
     }
   }
-  if (out.size() == 0) {
+  if (out.empty()) {
     gpr_log(GPR_ERROR,
             "Environment variable \"%s\" does not contain a list of QPS "
             "workers to use. Set it to a comma-separated list of "
@@ -410,7 +410,7 @@ std::unique_ptr<ScenarioResult> RunScenario(
       workers.push_back(addr);
     }
   }
-  GPR_ASSERT(workers.size() != 0);
+  GPR_ASSERT(!workers.empty());
 
   // if num_clients is set to <=0, do dynamic sizing: all workers
   // except for servers are clients
@@ -656,7 +656,7 @@ bool RunQuit(
   // Get client, server lists
   bool result = true;
   auto workers = get_workers("QPS_WORKERS");
-  if (workers.size() == 0) {
+  if (workers.empty()) {
     return false;
   }
 

test/cpp/qps/qps_json_driver.cc

@@ -153,7 +153,7 @@ static std::unique_ptr<ScenarioResult> RunAndReport(
     *success = result->server_success(i);
   }
 
-  if (FLAGS_json_file_out != "") {
+  if (!FLAGS_json_file_out.empty()) {
     std::ofstream json_outfile;
     json_outfile.open(FLAGS_json_file_out);
     json_outfile << "{\"qps\": " << result->summary().qps() << "}\n";
@@ -229,8 +229,8 @@ static double SearchOfferedLoad(
 static bool QpsDriver() {
   std::string json;
 
-  bool scfile = (FLAGS_scenarios_file != "");
+  bool scfile = (!FLAGS_scenarios_file.empty());
-  bool scjson = (FLAGS_scenarios_json != "");
+  bool scjson = (!FLAGS_scenarios_json.empty());
   if ((!scfile && !scjson && !FLAGS_quit) ||
       (scfile && (scjson || FLAGS_quit)) || (scjson && FLAGS_quit)) {
     gpr_log(GPR_ERROR,
@@ -267,7 +267,7 @@ static bool QpsDriver() {
   GPR_ASSERT(scenarios.scenarios_size() > 0);
 
   for (int i = 0; i < scenarios.scenarios_size(); i++) {
-    if (FLAGS_search_param == "") {
+    if (FLAGS_search_param.empty()) {
       const Scenario& scenario = scenarios.scenarios(i);
       RunAndReport(scenario, per_worker_credential_types, &success);
     } else {

test/cpp/util/create_test_channel.cc

@@ -59,7 +59,7 @@ void AddProdSslType() {
 }
 
 void MaybeSetCustomChannelArgs(grpc::ChannelArguments* args) {
-  if (FLAGS_grpc_test_use_grpclb_with_child_policy.size() > 0) {
+  if (!FLAGS_grpc_test_use_grpclb_with_child_policy.empty()) {
     args->SetString("grpc.service_config",
                     "{\"loadBalancingConfig\":[{\"grpclb\":{\"childPolicy\":[{"
                     "\"" +