[ObjC] default GRPC_IOS_EVENT_ENGINE_CLIENT to 1 (#36785)

It's still possible to define GRPC_IOS_EVENT_ENGINE_CLIENT=0 to disable event engine for iOS.

Closes #36785

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/36785 from HannahShiSFB:default-to-event-engine-in-ios 441fe552a6
PiperOrigin-RevId: 640716651

include/grpc/support/port_platform.h

@@ -272,6 +272,9 @@
 #define GPR_PLATFORM_STRING "ios"
 #define GPR_CPU_IPHONE 1
 #define GRPC_CFSTREAM 1
+#ifndef GRPC_IOS_EVENT_ENGINE_CLIENT
+#define GRPC_IOS_EVENT_ENGINE_CLIENT 1
+#endif /* GRPC_IOS_EVENT_ENGINE_CLIENT */
 /* the c-ares resolver isn't safe to enable on iOS */
 #define GRPC_ARES 0
 #else /* TARGET_OS_IPHONE */

src/core/lib/event_engine/shim.cc

@@ -30,7 +30,7 @@ bool UseEventEngineClient() {
   return grpc_core::IsEventEngineClientEnabled();
 #elif defined(GPR_WINDOWS) && !defined(GRPC_DO_NOT_INSTANTIATE_POSIX_POLLER)
   return grpc_core::IsEventEngineClientEnabled();
-#elif defined(GRPC_IOS_EVENT_ENGINE_CLIENT)
+#elif GRPC_IOS_EVENT_ENGINE_CLIENT
   return true;
 #else
   return false;

src/core/resolver/dns/dns_resolver_plugin.cc

@@ -32,7 +32,7 @@
 namespace grpc_core {
 
 void RegisterDnsResolver(CoreConfiguration::Builder* builder) {
-#ifdef GRPC_IOS_EVENT_ENGINE_CLIENT
+#if GRPC_IOS_EVENT_ENGINE_CLIENT
   VLOG(2) << "Using EventEngine dns resolver";
   builder->resolver_registry()->RegisterResolverFactory(
       std::make_unique<EventEngineClientChannelDNSResolverFactory>());

src/objective-c/tests/BUILD

@@ -336,7 +336,6 @@ grpc_objc_ios_unit_test(
 grpc_objc_testing_library(
     name = "EventEngineClientTests-lib",
     srcs = ["EventEngineTests/CFEventEngineClientTests.mm"],
-    # defines = ["GRPC_IOS_EVENT_ENGINE_CLIENT=1"],
     deps = [
         "//src/core:cf_event_engine",
         "//test/core/event_engine/test_suite/posix:oracle_event_engine_posix",
@@ -347,7 +346,6 @@ grpc_objc_testing_library(
 grpc_objc_testing_library(
     name = "EventEngineUnitTests-lib",
     srcs = ["EventEngineTests/CFEventEngineUnitTests.mm"],
-    defines = ["GRPC_IOS_EVENT_ENGINE_CLIENT=1"],
     deps = [
         "//src/core:cf_event_engine",
         "//test/core/event_engine/cf:cf_engine_unit_test_lib",

test/core/event_engine/test_suite/BUILD

@@ -118,7 +118,6 @@ grpc_cc_test(
 grpc_cc_test(
     name = "cf_event_engine_test",
     srcs = ["cf_event_engine_test.cc"],
-    copts = ["-DGRPC_IOS_EVENT_ENGINE_CLIENT=1"],
     tags = [
         "no_linux",
         "no_windows",

test/core/event_engine/test_suite/tests/dns_test.cc

@@ -111,7 +111,7 @@ MATCHER(StatusCodeEq, "") {
 class EventEngineDNSTest : public EventEngineTest {
  protected:
   static void SetUpTestSuite() {
-#ifndef GRPC_IOS_EVENT_ENGINE_CLIENT
+#if !GRPC_IOS_EVENT_ENGINE_CLIENT
     std::string test_records_path = kDNSTestRecordGroupsYamlPath;
     std::string dns_server_path = kDNSServerRelPath;
     std::string dns_resolver_path = kDNSResolverRelPath;
@@ -182,7 +182,7 @@ class EventEngineDNSTest : public EventEngineTest {
   }
 
   static void TearDownTestSuite() {
-#ifndef GRPC_IOS_EVENT_ENGINE_CLIENT
+#if !GRPC_IOS_EVENT_ENGINE_CLIENT
     dns_server_.server_process->Interrupt();
     dns_server_.server_process->Join();
     delete dns_server_.server_process;
@@ -233,7 +233,7 @@ class EventEngineDNSTest : public EventEngineTest {
 EventEngineDNSTest::DNSServer EventEngineDNSTest::dns_server_;
 
 // TODO(hork): implement XFAIL for resolvers that don't support TXT or SRV
-#ifndef GRPC_IOS_EVENT_ENGINE_CLIENT
+#if !GRPC_IOS_EVENT_ENGINE_CLIENT
 
 TEST_F(EventEngineDNSTest, QueryNXHostname) {
   SKIP_TEST_FOR_NATIVE_DNS_RESOLVER();
@@ -434,7 +434,7 @@ TEST_F(EventEngineDNSTest, LocalHost) {
   auto dns_resolver = CreateDNSResolverWithoutSpecifyingServer();
   dns_resolver->LookupHostname(
       [this](auto result) {
-#ifdef GRPC_IOS_EVENT_ENGINE_CLIENT
+#if GRPC_IOS_EVENT_ENGINE_CLIENT
         EXPECT_SUCCESS();
 #else
         EXPECT_TRUE(result.ok());

test/core/iomgr/ios/CFStreamTests/Podfile

@@ -29,6 +29,7 @@ post_install do |installer|
         config.build_settings['GCC_WARN_ABOUT_RETURN_TYPE'] = 'NO'
         # Abseil isn't free from the following warning
         config.build_settings['GCC_WARN_64_TO_32_BIT_CONVERSION'] = 'NO'
+        config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] = '$(inherited) GRPC_IOS_EVENT_ENGINE_CLIENT=0'
       end
     end
   end

test/core/iomgr/ios/CFStreamTests/build_and_run_tests.sh

@@ -25,6 +25,7 @@ XCODEBUILD_FILTER_OUTPUT_SCRIPT="../../../../../src/objective-c/tests/xcodebuild
 
 XCODEBUILD_FLAGS="
   IPHONEOS_DEPLOYMENT_TARGET=10
+  GCC_PREPROCESSOR_DEFINITIONS='DGRPC_IOS_EVENT_ENGINE_CLIENT=0'
 "
 
 XCODEBUILD_DESTINATION="platform=iOS Simulator,name=iPhone 11"

tools/internal_ci/macos/grpc_objc_bazel_test.sh

@@ -116,6 +116,7 @@ objc_bazel_tests/bazel_wrapper \
   --google_credentials="${KOKORO_GFILE_DIR}/GrpcTesting-d0eeee2db331.json" \
   "${BAZEL_REMOTE_CACHE_ARGS[@]}" \
   $BAZEL_FLAGS \
+  --cxxopt=-DGRPC_IOS_EVENT_ENGINE_CLIENT=0 \
   "${OBJC_TEST_ENV_ARGS[@]}" \
   -- \
   "${EXAMPLE_TARGETS[@]}" \
@@ -141,7 +142,6 @@ objc_event_engine_bazel_tests/bazel_wrapper \
   --google_credentials="${KOKORO_GFILE_DIR}/GrpcTesting-d0eeee2db331.json" \
   "${BAZEL_REMOTE_CACHE_ARGS[@]}" \
   $BAZEL_FLAGS \
-  --cxxopt=-DGRPC_IOS_EVENT_ENGINE_CLIENT=1 \
   --test_env=GRPC_EXPERIMENTS=event_engine_client \
   --test_env=GRPC_VERBOSITY=debug --test_env=GRPC_TRACE=event_engine,api \
   "${OBJC_TEST_ENV_ARGS[@]}" \