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gRPC callbackService support added (#8666)

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* grpc callbackService support added

Signed-off-by: shankeleven <shashanksati11@gmail.com>

* tests: regenerate C++ gRPC golden with --grpc-callback-api (CallbackService & async_ reactor APIs); update formatting and method placement

---------

Signed-off-by: shankeleven <shashanksati11@gmail.com>
Co-authored-by: Wouter van Oortmerssen <aardappel@gmail.com>
This commit is contained in:
Shashank
2025-08-29 04:19:27 +05:30
committed by GitHub
parent b87d04af8c
commit deb3d93454
21 changed files with 617 additions and 51 deletions
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63
grpc/README.md
View File

@@ -1,5 +1,4 @@
GRPC implementation and test
============================
NOTE: files in `src/` are shared with the GRPC project, and maintained there
(any changes should be submitted to GRPC instead). These files are copied
@@ -39,4 +38,64 @@ For Bazel users:
```shell
$bazel test tests/...
```
```
## C++ Callback API Generation
FlatBuffers gRPC C++ code generation now optionally supports the modern gRPC Callback API.
To enable generation of a `CallbackService` skeleton alongside the existing `Service` and async mixins, invoke `flatc` with both `--grpc` and `--grpc-callback-api`:
```shell
flatc --cpp --grpc --grpc-callback-api your_service.fbs
```
This adds (guarded by `#if defined(GRPC_CALLBACK_API_NONEXPERIMENTAL)`) a class:
```cpp
class YourService::CallbackService : public ::grpc::Service { /* reactor virtuals */ };
```
Each RPC shape maps to the appropriate reactor return type:
- Unary -> `::grpc::ServerUnaryReactor*` Method(...)
- Client streaming -> `::grpc::ServerReadReactor<Request>*`
- Server streaming -> `::grpc::ServerWriteReactor<Response>*`
- Bidi streaming -> `::grpc::ServerBidiReactor<Request, Response>*`
Default generated implementations return `nullptr`; override in your derived class and return a reactor instance you manage (see gRPC docs for lifecycle patterns).
If your gRPC library predates the stable callback API macro, the code inside the guard will be skipped (no breaking changes). Ensure you build against a recent gRPC (1.38+; verify current minimum in grpc repo) to use this feature.
### Client Callback Stubs
When `--grpc-callback-api` is supplied, the generated C++ client stub gains native callback / reactor based async methods in addition to the existing synchronous / generic async flavors, guarded by the same macro. For each RPC named `Foo`:
Unary:
```
void async_Foo(::grpc::ClientContext*, const Request&, Response*, std::function<void(::grpc::Status)>);
void async_Foo(::grpc::ClientContext*, const Request&, Response*, ::grpc::ClientUnaryReactor*);
```
Client streaming:
```
::grpc::ClientWriteReactor<Request>* async_Foo(::grpc::ClientContext*, Response*, ::grpc::ClientWriteReactor<Request>*);
```
Server streaming:
```
::grpc::ClientReadReactor<Response>* async_Foo(::grpc::ClientContext*, const Request&, ::grpc::ClientReadReactor<Response>*);
```
Bidirectional streaming:
```
::grpc::ClientBidiReactor<Request, Response>* async_Foo(::grpc::ClientContext*, ::grpc::ClientBidiReactor<Request, Response>*);
```
These map directly onto the native gRPC callback API factories (e.g. `CallbackUnaryCall`, `ClientCallbackWriterFactory::Create`, etc.) and do not spawn threads. Override the appropriate reactor callbacks per gRPC's documentation to drive I/O.
If your build uses an older gRPC lacking the non-experimental macro, these symbols will not be emitted, preserving backwards compatibility.

334
grpc/src/compiler/cpp_generator.cc
View File

@@ -8,8 +8,7 @@
namespace grpc_cpp_generator {
namespace {
template<class T>
static grpc::string as_string(T x) {
template<class T> static grpc::string as_string(T x) {
std::ostringstream out;
out << x;
return out.str();
@@ -39,12 +38,13 @@ static grpc::string FilenameIdentifier(const grpc::string &filename) {
return result;
}
template<class T, size_t N>
static T *array_end(T (&array)[N]) { return array + N; }
template<class T, size_t N> static T *array_end(T (&array)[N]) {
return array + N;
}
static void PrintIncludes(grpc_generator::Printer *printer,
const std::vector<grpc::string> &headers,
const Parameters &params) {
const std::vector<grpc::string> &headers,
const Parameters &params) {
std::map<grpc::string, grpc::string> vars;
vars["l"] = params.use_system_headers ? '<' : '"';
@@ -60,6 +60,18 @@ static void PrintIncludes(grpc_generator::Printer *printer,
vars["h"] = *i;
printer->Print(vars, "#include $l$$h$$r$\n");
}
if (params.generate_callback_api) {
// Callback API headers (guarded later by feature macro in emitted code).
static const char *cb_headers[] = {
"grpcpp/impl/codegen/callback_common.h",
"grpcpp/impl/codegen/server_callback_handlers.h",
"grpcpp/support/client_callback.h"
};
for (auto &h : cb_headers) {
vars["h"] = h;
printer->Print(vars, "#include $l$$h$$r$\n");
}
}
}
} // namespace
@@ -138,7 +150,6 @@ grpc::string GetHeaderIncludes(grpc_generator::File *file,
return output;
}
namespace {
static void PrintHeaderClientMethodInterfaces(
@@ -355,12 +366,10 @@ static void PrintHeaderClientMethodInterfaces(
}
}
static void PrintHeaderClientMethod(grpc_generator::Printer *printer,
const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars,
bool is_public) {
const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars,
bool is_public) {
(*vars)["Method"] = method->name();
(*vars)["Request"] = method->input_type_name();
(*vars)["Response"] = method->output_type_name();
@@ -377,6 +386,22 @@ static void PrintHeaderClientMethod(grpc_generator::Printer *printer,
*vars,
"::grpc::Status $Method$(::grpc::ClientContext* context, "
"const $Request$& request, $Response$* response) override;\n");
if ((*vars)["generate_callback_api"] == "1") {
// Native gRPC callback unary wrappers (function callback & reactor
// variants).
printer->Print(*vars,
"// Callback unary (function form). Request/response "
"must outlive callback.\n");
printer->Print(*vars,
"void async_$Method$(::grpc::ClientContext* context, "
"const $Request$& request, $Response$* response, "
"std::function<void(::grpc::Status)> on_done);\n");
printer->Print(*vars, "// Callback unary (reactor form).\n");
printer->Print(*vars,
"void async_$Method$(::grpc::ClientContext* context, "
"const $Request$& request, $Response$* response, "
"::grpc::ClientUnaryReactor* reactor);\n");
}
for (size_t i = 0; i < sizeof(async_prefixes) / sizeof(async_prefixes[0]);
i++) {
auto &async_prefix = async_prefixes[i];
@@ -407,6 +432,12 @@ static void PrintHeaderClientMethod(grpc_generator::Printer *printer,
"($Method$Raw(context, response));\n");
printer->Outdent();
printer->Print("}\n");
if ((*vars)["generate_callback_api"] == "1") {
printer->Print(*vars, "// Client streaming callback reactor entry.\n");
printer->Print(
*vars,
"void async_$Method$(::grpc::ClientContext* context, $Response$* response, ::grpc::ClientWriteReactor< $Request$ >* reactor);\n");
}
for (size_t i = 0; i < sizeof(async_prefixes) / sizeof(async_prefixes[0]);
i++) {
auto &async_prefix = async_prefixes[i];
@@ -440,6 +471,11 @@ static void PrintHeaderClientMethod(grpc_generator::Printer *printer,
"($Method$Raw(context, request));\n");
printer->Outdent();
printer->Print("}\n");
if ((*vars)["generate_callback_api"] == "1") {
printer->Print(*vars, "// Server streaming callback reactor entry.\n");
printer->Print(*vars,
"void async_$Method$(::grpc::ClientContext* context, const $Request$& request, ::grpc::ClientReadReactor< $Response$ >* reactor);\n");
}
for (size_t i = 0; i < sizeof(async_prefixes) / sizeof(async_prefixes[0]);
i++) {
auto &async_prefix = async_prefixes[i];
@@ -472,6 +508,12 @@ static void PrintHeaderClientMethod(grpc_generator::Printer *printer,
"$Method$Raw(context));\n");
printer->Outdent();
printer->Print("}\n");
if ((*vars)["generate_callback_api"] == "1") {
printer->Print(*vars, "// Bidirectional streaming callback reactor entry.\n");
printer->Print(
*vars,
"void async_$Method$(::grpc::ClientContext* context, ::grpc::ClientBidiReactor< $Request$, $Response$ >* reactor);\n");
}
for (size_t i = 0; i < sizeof(async_prefixes) / sizeof(async_prefixes[0]);
i++) {
auto &async_prefix = async_prefixes[i];
@@ -506,6 +548,10 @@ static void PrintHeaderClientMethod(grpc_generator::Printer *printer,
"const $Request$& request, "
"::grpc::CompletionQueue* cq) override;\n");
}
if ((*vars)["generate_callback_api"] == "1") {
// Native callback unary forms declared earlier (no private sync helper
// needed).
}
} else if (ClientOnlyStreaming(method)) {
printer->Print(*vars,
"::grpc::ClientWriter< $Request$>* $Method$Raw("
@@ -560,17 +606,17 @@ static void PrintHeaderClientMethod(grpc_generator::Printer *printer,
}
}
static void PrintHeaderClientMethodData(grpc_generator::Printer *printer,
const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars) {
static void PrintHeaderClientMethodData(
grpc_generator::Printer *printer, const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars) {
(*vars)["Method"] = method->name();
printer->Print(*vars,
"const ::grpc::internal::RpcMethod rpcmethod_$Method$_;\n");
}
static void PrintHeaderServerMethodSync(grpc_generator::Printer *printer,
const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars) {
static void PrintHeaderServerMethodSync(
grpc_generator::Printer *printer, const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars) {
(*vars)["Method"] = method->name();
(*vars)["Request"] = method->input_type_name();
(*vars)["Response"] = method->output_type_name();
@@ -602,9 +648,9 @@ static void PrintHeaderServerMethodSync(grpc_generator::Printer *printer,
printer->Print(method->GetTrailingComments("//").c_str());
}
static void PrintHeaderServerMethodAsync(grpc_generator::Printer *printer,
const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars) {
static void PrintHeaderServerMethodAsync(
grpc_generator::Printer *printer, const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars) {
(*vars)["Method"] = method->name();
(*vars)["Request"] = method->input_type_name();
(*vars)["Response"] = method->output_type_name();
@@ -894,8 +940,8 @@ static void PrintHeaderServerMethodGeneric(
}
static void PrintHeaderService(grpc_generator::Printer *printer,
const grpc_generator::Service *service,
std::map<grpc::string, grpc::string> *vars) {
const grpc_generator::Service *service,
std::map<grpc::string, grpc::string> *vars) {
(*vars)["Service"] = service->name();
printer->Print(service->GetLeadingComments("//").c_str());
@@ -930,6 +976,10 @@ static void PrintHeaderService(grpc_generator::Printer *printer,
false);
}
printer->Outdent();
// Forward declaration of nested CallbackService if callback API enabled.
if ((*vars)["generate_callback_api"] == "1") {
printer->Print("class CallbackService;\n");
}
printer->Print("};\n");
printer->Print(
"class Stub final : public StubInterface"
@@ -1062,9 +1112,51 @@ static void PrintHeaderService(grpc_generator::Printer *printer,
printer->Outdent();
printer->Print("};\n");
printer->Print(service->GetTrailingComments("//").c_str());
// Optional CallbackService (modern async API)
if ((*vars)["generate_callback_api"] == "1") {
(*vars)["Service"] = service->name();
printer->Print("\n#if defined(GRPC_CALLBACK_API_NONEXPERIMENTAL)\n");
printer->Print(*vars,
"class $Service$::CallbackService : public ::grpc::Service "
"{\n public:\n CallbackService();\n virtual "
"~CallbackService();\n");
printer->Indent();
for (int i = 0; i < service->method_count(); ++i) {
auto m = service->method(i);
(*vars)["Method"] = m->name();
(*vars)["Request"] = m->input_type_name();
(*vars)["Response"] = m->output_type_name();
if (m->NoStreaming()) {
printer->Print(*vars,
"virtual ::grpc::ServerUnaryReactor* "
"$Method$(::grpc::CallbackServerContext* context, const "
"$Request$* request, $Response$* response);\n");
} else if (ClientOnlyStreaming(m.get())) {
printer->Print(*vars,
"virtual ::grpc::ServerReadReactor<$Request$>* "
"$Method$(::grpc::CallbackServerContext* context, "
"$Response$* response);\n");
} else if (ServerOnlyStreaming(m.get())) {
printer->Print(*vars,
"virtual ::grpc::ServerWriteReactor<$Response$>* "
"$Method$(::grpc::CallbackServerContext* context, const "
"$Request$* request);\n");
} else if (m->BidiStreaming()) {
printer->Print(
*vars,
"virtual ::grpc::ServerBidiReactor<$Request$, $Response$>* "
"$Method$(::grpc::CallbackServerContext* context);\n");
}
}
printer->Outdent();
printer->Print(
"};\n#else\n// Callback API requested but not available in this gRPC "
"version.\n#endif // GRPC_CALLBACK_API_NONEXPERIMENTAL\n");
}
}
} // namespace
} // namespace
grpc::string GetHeaderServices(grpc_generator::File *file,
const Parameters &params) {
@@ -1084,9 +1176,14 @@ grpc::string GetHeaderServices(grpc_generator::File *file,
}
for (int i = 0; i < file->service_count(); ++i) {
vars["generate_callback_api"] = params.generate_callback_api ? "1" : "0";
PrintHeaderService(printer.get(), file->service(i).get(), &vars);
printer->Print("\n");
}
if (params.generate_callback_api) {
printer->Print("// FlatBuffers: Callback API code generated.\n");
printer->Print("#define FLATBUFFERS_GENERATED_GRPC_CALLBACK_API 1\n\n");
}
if (!params.services_namespace.empty()) {
printer->Print(vars, "} // namespace $services_namespace$\n\n");
@@ -1139,7 +1236,8 @@ grpc::string GetSourcePrologue(grpc_generator::File *file,
printer->Print(vars, "// Generated by the gRPC C++ plugin.\n");
printer->Print(vars,
"// If you make any local change, they will be lost.\n");
"// FlatBuffers modified generator: native gRPC callback "
"client API enabled when --grpc-callback-api.\n");
printer->Print(vars, "// source: $filename$\n\n");
printer->Print(vars, "#include \"$filename_base$$message_header_ext$\"\n");
@@ -1184,12 +1282,11 @@ grpc::string GetSourceIncludes(grpc_generator::File *file,
return output;
}
namespace {
static void PrintSourceClientMethod(grpc_generator::Printer *printer,
const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars) {
static void PrintSourceClientMethod(
grpc_generator::Printer *printer, const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars) {
(*vars)["Method"] = method->name();
(*vars)["Request"] = method->input_type_name();
(*vars)["Response"] = method->output_type_name();
@@ -1209,6 +1306,27 @@ static void PrintSourceClientMethod(grpc_generator::Printer *printer,
" return ::grpc::internal::BlockingUnaryCall"
"(channel_.get(), rpcmethod_$Method$_, "
"context, request, response);\n}\n\n");
if ((*vars)["generate_callback_api"] == "1") {
printer->Print(
*vars,
"void $ns$$Service$::Stub::async_$Method$(::grpc::ClientContext* "
"context, const $Request$& request, $Response$* response, "
"std::function<void(::grpc::Status)> on_done) {\n");
printer->Print(*vars,
" ::grpc::internal::CallbackUnaryCall(channel_.get(), "
"rpcmethod_$Method$_, context, &request, response, "
"std::move(on_done));\n}\n\n");
printer->Print(
*vars,
"void $ns$$Service$::Stub::async_$Method$(::grpc::ClientContext* "
"context, const $Request$& request, $Response$* response, "
"::grpc::ClientUnaryReactor* reactor) {\n");
printer->Print(
*vars,
" "
"::grpc::internal::ClientCallbackUnaryFactory::Create(channel_.get(),"
" rpcmethod_$Method$_, context, &request, response, reactor);\n}\n\n");
}
for (size_t i = 0; i < sizeof(async_prefixes) / sizeof(async_prefixes[0]);
i++) {
auto &async_prefix = async_prefixes[i];
@@ -1241,6 +1359,17 @@ static void PrintSourceClientMethod(grpc_generator::Printer *printer,
"rpcmethod_$Method$_, "
"context, response);\n"
"}\n\n");
if ((*vars)["generate_callback_api"] == "1") {
printer->Print(
*vars,
"void $ns$$Service$::Stub::async_$Method$(::grpc::ClientContext* "
"context, $Response$* response, ::grpc::ClientWriteReactor< "
"$Request$ >* reactor) {\n");
printer->Print(*vars,
" ::grpc::internal::ClientCallbackWriterFactory< "
"$Request$ >::Create(channel_.get(), rpcmethod_$Method$_, "
"context, response, reactor);\n}\n\n");
}
for (size_t i = 0; i < sizeof(async_prefixes) / sizeof(async_prefixes[0]);
i++) {
auto &async_prefix = async_prefixes[i];
@@ -1274,6 +1403,17 @@ static void PrintSourceClientMethod(grpc_generator::Printer *printer,
"rpcmethod_$Method$_, "
"context, request);\n"
"}\n\n");
if ((*vars)["generate_callback_api"] == "1") {
printer->Print(
*vars,
"void $ns$$Service$::Stub::async_$Method$(::grpc::ClientContext* "
"context, const $Request$& request, ::grpc::ClientReadReactor< "
"$Response$ >* reactor) {\n");
printer->Print(*vars,
" ::grpc::internal::ClientCallbackReaderFactory< "
"$Response$ >::Create(channel_.get(), "
"rpcmethod_$Method$_, context, &request, reactor);\n}\n\n");
}
for (size_t i = 0; i < sizeof(async_prefixes) / sizeof(async_prefixes[0]);
i++) {
auto &async_prefix = async_prefixes[i];
@@ -1307,6 +1447,17 @@ static void PrintSourceClientMethod(grpc_generator::Printer *printer,
"rpcmethod_$Method$_, "
"context);\n"
"}\n\n");
if ((*vars)["generate_callback_api"] == "1") {
printer->Print(
*vars,
"void $ns$$Service$::Stub::async_$Method$(::grpc::ClientContext* "
"context, ::grpc::ClientBidiReactor< $Request$, $Response$ >* "
"reactor) {\n");
printer->Print(*vars,
" ::grpc::internal::ClientCallbackReaderWriterFactory< "
"$Request$, $Response$ >::Create(channel_.get(), "
"rpcmethod_$Method$_, context, reactor);\n}\n\n");
}
for (size_t i = 0; i < sizeof(async_prefixes) / sizeof(async_prefixes[0]);
i++) {
auto &async_prefix = async_prefixes[i];
@@ -1331,9 +1482,9 @@ static void PrintSourceClientMethod(grpc_generator::Printer *printer,
}
}
static void PrintSourceServerMethod(grpc_generator::Printer *printer,
const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars) {
static void PrintSourceServerMethod(
grpc_generator::Printer *printer, const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars) {
(*vars)["Method"] = method->name();
(*vars)["Request"] = method->input_type_name();
(*vars)["Response"] = method->output_type_name();
@@ -1381,8 +1532,8 @@ static void PrintSourceServerMethod(grpc_generator::Printer *printer,
}
static void PrintSourceService(grpc_generator::Printer *printer,
const grpc_generator::Service *service,
std::map<grpc::string, grpc::string> *vars) {
const grpc_generator::Service *service,
std::map<grpc::string, grpc::string> *vars) {
(*vars)["Service"] = service->name();
if (service->method_count() > 0) {
@@ -1495,9 +1646,110 @@ static void PrintSourceService(grpc_generator::Printer *printer,
(*vars)["Idx"] = as_string(i);
PrintSourceServerMethod(printer, service->method(i).get(), vars);
}
// CallbackService implementation (if enabled)
if ((*vars)["generate_callback_api"] == "1") {
(*vars)["Service"] = service->name();
printer->Print("#if defined(GRPC_CALLBACK_API_NONEXPERIMENTAL)\n");
printer->Print(*vars,
"$ns$$Service$::CallbackService::CallbackService() {\n");
printer->Indent();
for (int i = 0; i < service->method_count(); ++i) {
auto method = service->method(i);
(*vars)["Idx"] = as_string(i);
(*vars)["Method"] = method->name();
(*vars)["Request"] = method->input_type_name();
(*vars)["Response"] = method->output_type_name();
if (method->NoStreaming()) {
printer->Print(
*vars,
"AddMethod(new ::grpc::internal::RpcServiceMethod(\n"
" $prefix$$Service$_method_names[$Idx$],\n"
" ::grpc::internal::RpcMethod::NORMAL_RPC,\n"
" new ::grpc::internal::CallbackUnaryHandler<$Request$, $Response$>(\n"
" [this](::grpc::CallbackServerContext* ctx, const $Request$* req, $Response$* resp) {\n"
" return this->$Method$(ctx, req, resp);\n"
" })));\n");
} else if (ClientOnlyStreaming(method.get())) {
printer->Print(
*vars,
"AddMethod(new ::grpc::internal::RpcServiceMethod(\n"
" $prefix$$Service$_method_names[$Idx$],\n"
" ::grpc::internal::RpcMethod::CLIENT_STREAMING,\n"
" new ::grpc::internal::CallbackClientStreamingHandler<$Request$, $Response$>(\n"
" [this](::grpc::CallbackServerContext* ctx, $Response$* resp) {\n"
" return this->$Method$(ctx, resp);\n"
" })));\n");
} else if (ServerOnlyStreaming(method.get())) {
printer->Print(
*vars,
"AddMethod(new ::grpc::internal::RpcServiceMethod(\n"
" $prefix$$Service$_method_names[$Idx$],\n"
" ::grpc::internal::RpcMethod::SERVER_STREAMING,\n"
" new ::grpc::internal::CallbackServerStreamingHandler<$Request$, $Response$>(\n"
" [this](::grpc::CallbackServerContext* ctx, const $Request$* req) {\n"
" return this->$Method$(ctx, req);\n"
" })));\n");
} else if (method->BidiStreaming()) {
printer->Print(
*vars,
"AddMethod(new ::grpc::internal::RpcServiceMethod(\n"
" $prefix$$Service$_method_names[$Idx$],\n"
" ::grpc::internal::RpcMethod::BIDI_STREAMING,\n"
" new ::grpc::internal::CallbackBidiHandler<$Request$, $Response$>(\n"
" [this](::grpc::CallbackServerContext* ctx) {\n"
" return this->$Method$(ctx);\n"
" })));\n");
}
}
printer->Outdent();
printer->Print("}\n\n");
printer->Print(*vars,
"$ns$$Service$::CallbackService::~CallbackService() {}\n\n");
// Default method bodies returning UNIMPLEMENTED reactors.
for (int i = 0; i < service->method_count(); ++i) {
auto method = service->method(i);
(*vars)["Method"] = method->name();
(*vars)["Request"] = method->input_type_name();
(*vars)["Response"] = method->output_type_name();
if (method->NoStreaming()) {
printer->Print(*vars,
"::grpc::ServerUnaryReactor* "
"$ns$$Service$::CallbackService::$Method$(::grpc::"
"CallbackServerContext* /*context*/, const $Request$* "
"/*request*/, $Response$* /*response*/) {\n"
" return nullptr; // user must override\n"
"}\n\n");
} else if (ClientOnlyStreaming(method.get())) {
printer->Print(
*vars,
"::grpc::ServerReadReactor<$Request$>* "
"$ns$$Service$::CallbackService::$Method$(::grpc::"
"CallbackServerContext* /*context*/, $Response$* /*response*/) {\n"
" return nullptr; // user must override\n"
"}\n\n");
} else if (ServerOnlyStreaming(method.get())) {
printer->Print(*vars,
"::grpc::ServerWriteReactor<$Response$>* "
"$ns$$Service$::CallbackService::$Method$(::grpc::"
"CallbackServerContext* /*context*/, const $Request$* "
"/*request*/) {\n"
" return nullptr; // user must override\n"
"}\n\n");
} else if (method->BidiStreaming()) {
printer->Print(*vars,
"::grpc::ServerBidiReactor<$Request$, $Response$>* "
"$ns$$Service$::CallbackService::$Method$(::grpc::"
"CallbackServerContext* /*context*/) {\n"
" return nullptr; // user must override\n"
"}\n\n");
}
}
printer->Print("#endif // GRPC_CALLBACK_API_NONEXPERIMENTAL\n");
}
}
} // namespace
} // namespace
grpc::string GetSourceServices(grpc_generator::File *file,
const Parameters &params) {
@@ -1519,6 +1771,7 @@ grpc::string GetSourceServices(grpc_generator::File *file,
}
for (int i = 0; i < file->service_count(); ++i) {
vars["generate_callback_api"] = params.generate_callback_api ? "1" : "0";
PrintSourceService(printer.get(), file->service(i).get(), &vars);
printer->Print("\n");
}
@@ -1601,12 +1854,11 @@ grpc::string GetMockIncludes(grpc_generator::File *file,
return output;
}
namespace {
static void PrintMockClientMethods(grpc_generator::Printer *printer,
const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars) {
const grpc_generator::Method *method,
std::map<grpc::string, grpc::string> *vars) {
(*vars)["Method"] = method->name();
(*vars)["Request"] = method->input_type_name();
(*vars)["Response"] = method->output_type_name();
@@ -1697,8 +1949,8 @@ static void PrintMockClientMethods(grpc_generator::Printer *printer,
}
static void PrintMockService(grpc_generator::Printer *printer,
const grpc_generator::Service *service,
std::map<grpc::string, grpc::string> *vars) {
const grpc_generator::Service *service,
std::map<grpc::string, grpc::string> *vars) {
(*vars)["Service"] = service->name();
printer->Print(*vars,
@@ -1712,7 +1964,7 @@ static void PrintMockService(grpc_generator::Printer *printer,
printer->Print("};\n");
}
} // namespace
} // namespace
grpc::string GetMockServices(grpc_generator::File *file,
const Parameters &params) {

2
grpc/src/compiler/cpp_generator.h
View File

@@ -37,6 +37,8 @@ struct Parameters {
std::string message_header_extension;
// Default: ".grpc.fb.h"
std::string service_header_extension;
// Generate modern callback-based async API service code (CallbackService)
bool generate_callback_api = false;
};
// Return the prologue of the generated header file.

24
grpc/tests/BUILD
View File

@@ -17,3 +17,27 @@ cc_test(
"@com_github_grpc_grpc//:grpc++",
],
)
cc_test(
name = "grpc_callback_compile_test",
srcs = ["grpctest_callback_compile.cpp"],
copts = ["-Itests"],
linkstatic = 1,
deps = [
"//tests:monster_test_cc_fbs",
"//tests:monster_test_grpc",
"@com_github_grpc_grpc//:grpc++",
],
)
cc_test(
name = "grpc_callback_client_compile_test",
srcs = ["grpctest_callback_client_compile.cpp"],
copts = ["-Itests"],
linkstatic = 1,
deps = [
"//tests:monster_test_cc_fbs",
"//tests:monster_test_grpc",
"@com_github_grpc_grpc//:grpc++",
],
)

61
grpc/tests/grpctest_callback_client_compile.cpp Normal file
View File

@@ -0,0 +1,61 @@
// Verifies that the generated gRPC callback client stub methods are present.
// This is a compile-time only test: it never performs an actual RPC.
// It supplements grpctest_callback_compile.cpp (server side) by checking
// client-side async_ / reactor entry points.
#include <type_traits>
#include "monster_test.grpc.fb.h"
#if defined(FLATBUFFERS_GENERATED_GRPC_CALLBACK_API) && \
defined(GRPC_CALLBACK_API_NONEXPERIMENTAL)
using Stub = MyGame::Example::MonsterStorage::Stub;
using namespace MyGame::Example; // NOLINT
// Unary async overloads
static_assert(std::is_member_function_pointer<
decltype(static_cast<void (Stub::*)(
::grpc::ClientContext *,
const flatbuffers::grpc::Message<Monster> &,
flatbuffers::grpc::Message<Stat> *,
std::function<void(::grpc::Status)>)>(
&Stub::async_Store))>::value,
"Function-form unary async_Store missing");
static_assert(std::is_member_function_pointer<
decltype(static_cast<void (Stub::*)(
::grpc::ClientContext *,
const flatbuffers::grpc::Message<Monster> &,
flatbuffers::grpc::Message<Stat> *,
::grpc::ClientUnaryReactor *)>(
&Stub::async_Store))>::value,
"Reactor-form unary async_Store missing");
// Streaming reactor entry points
static_assert(
std::is_member_function_pointer<
decltype(static_cast<void (Stub::*)(
::grpc::ClientContext *,
const flatbuffers::grpc::Message<Stat> &,
::grpc::ClientReadReactor<flatbuffers::grpc::Message<
Monster> > *)>(&Stub::async_Retrieve))>::value,
"Server streaming reactor async_Retrieve missing");
static_assert(
std::is_member_function_pointer<
decltype(static_cast<void (Stub::*)(
::grpc::ClientContext *,
flatbuffers::grpc::Message<Stat> *,
::grpc::ClientWriteReactor<flatbuffers::grpc::Message<
Monster> > *)>(&Stub::async_GetMaxHitPoint))>::value,
"Client streaming reactor async_GetMaxHitPoint missing");
static_assert(std::is_member_function_pointer<
decltype(static_cast<void (Stub::*)(
::grpc::ClientContext *,
::grpc::ClientBidiReactor<
flatbuffers::grpc::Message<Monster>,
flatbuffers::grpc::Message<Stat> > *)>(
&Stub::async_GetMinMaxHitPoints))>::value,
"Bidi streaming reactor async_GetMinMaxHitPoints missing");
#endif // FLATBUFFERS_GENERATED_GRPC_CALLBACK_API &&
// GRPC_CALLBACK_API_NONEXPERIMENTAL
int main() { return 0; }

22
grpc/tests/grpctest_callback_compile.cpp Normal file
View File

@@ -0,0 +1,22 @@
#include "monster_test.grpc.fb.h"
// This test only verifies that the generated CallbackService compiles when the
// callback API is available. It does not run any RPCs.
#if defined(FLATBUFFERS_GENERATED_GRPC_CALLBACK_API) && \
defined(GRPC_CALLBACK_API_NONEXPERIMENTAL)
class CallbackServiceImpl
: public MyGame::Example::MonsterStorage::CallbackService {
public:
// For brevity we don't override methods; user code will provide reactors.
};
#endif
int main() {
#if defined(FLATBUFFERS_GENERATED_GRPC_CALLBACK_API) && \
defined(GRPC_CALLBACK_API_NONEXPERIMENTAL)
CallbackServiceImpl svc;
(void)svc; // suppress unused
#endif
return 0;
}