// // // Copyright 2018 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_SUPPORT_CALLBACK_COMMON_H #define GRPCPP_SUPPORT_CALLBACK_COMMON_H #include #include "absl/log/absl_check.h" #include #include #include #include #include #include #include #include namespace grpc { namespace internal { /// An exception-safe way of invoking a user-specified callback function // TODO(vjpai): decide whether it is better for this to take a const lvalue // parameter or an rvalue parameter, or if it even matters template void CatchingCallback(Func&& func, Args&&... args) { #if GRPC_ALLOW_EXCEPTIONS try { func(std::forward(args)...); } catch (...) { // nothing to return or change here, just don't crash the library } #else // GRPC_ALLOW_EXCEPTIONS func(std::forward(args)...); #endif // GRPC_ALLOW_EXCEPTIONS } template Reactor* CatchingReactorGetter(Func&& func, Args&&... args) { #if GRPC_ALLOW_EXCEPTIONS try { return func(std::forward(args)...); } catch (...) { // fail the RPC, don't crash the library return nullptr; } #else // GRPC_ALLOW_EXCEPTIONS return func(std::forward(args)...); #endif // GRPC_ALLOW_EXCEPTIONS } // The contract on these tags is that they are single-shot. They must be // constructed and then fired at exactly one point. There is no expectation // that they can be reused without reconstruction. class CallbackWithStatusTag : public grpc_completion_queue_functor { public: // always allocated against a call arena, no memory free required static void operator delete(void* /*ptr*/, std::size_t size) { ABSL_CHECK_EQ(size, sizeof(CallbackWithStatusTag)); } // This operator should never be called as the memory should be freed as part // of the arena destruction. It only exists to provide a matching operator // delete to the operator new so that some compilers will not complain (see // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this // there are no tests catching the compiler warning. static void operator delete(void*, void*) { ABSL_CHECK(false); } CallbackWithStatusTag(grpc_call* call, std::function f, CompletionQueueTag* ops) : call_(call), func_(std::move(f)), ops_(ops) { grpc_call_ref(call); functor_run = &CallbackWithStatusTag::StaticRun; // A client-side callback should never be run inline since they will always // have work to do from the user application. So, set the parent's // inlineable field to false inlineable = false; } ~CallbackWithStatusTag() {} Status* status_ptr() { return &status_; } // force_run can not be performed on a tag if operations using this tag // have been sent to PerformOpsOnCall. It is intended for error conditions // that are detected before the operations are internally processed. void force_run(Status s) { status_ = std::move(s); Run(true); } private: grpc_call* call_; std::function func_; CompletionQueueTag* ops_; Status status_; static void StaticRun(grpc_completion_queue_functor* cb, int ok) { static_cast(cb)->Run(static_cast(ok)); } void Run(bool ok) { void* ignored = ops_; if (!ops_->FinalizeResult(&ignored, &ok)) { // The tag was swallowed return; } ABSL_CHECK(ignored == ops_); // Last use of func_ or status_, so ok to move them out auto func = std::move(func_); auto status = std::move(status_); func_ = nullptr; // reset to clear this out for sure status_ = Status(); // reset to clear this out for sure CatchingCallback(std::move(func), std::move(status)); grpc_call_unref(call_); } }; /// CallbackWithSuccessTag can be reused multiple times, and will be used in /// this fashion for streaming operations. As a result, it shouldn't clear /// anything up until its destructor class CallbackWithSuccessTag : public grpc_completion_queue_functor { public: // always allocated against a call arena, no memory free required static void operator delete(void* /*ptr*/, std::size_t size) { ABSL_CHECK_EQ(size, sizeof(CallbackWithSuccessTag)); } // This operator should never be called as the memory should be freed as part // of the arena destruction. It only exists to provide a matching operator // delete to the operator new so that some compilers will not complain (see // https://github.com/grpc/grpc/issues/11301) Note at the time of adding this // there are no tests catching the compiler warning. static void operator delete(void*, void*) { ABSL_CHECK(false); } CallbackWithSuccessTag() : call_(nullptr) {} CallbackWithSuccessTag(const CallbackWithSuccessTag&) = delete; CallbackWithSuccessTag& operator=(const CallbackWithSuccessTag&) = delete; ~CallbackWithSuccessTag() { Clear(); } // Set can only be called on a default-constructed or Clear'ed tag. // It should never be called on a tag that was constructed with arguments // or on a tag that has been Set before unless the tag has been cleared. // can_inline indicates that this particular callback can be executed inline // (without needing a thread hop) and is only used for library-provided server // callbacks. void Set(grpc_call* call, std::function f, CompletionQueueTag* ops, bool can_inline) { ABSL_CHECK_EQ(call_, nullptr); grpc_call_ref(call); call_ = call; func_ = std::move(f); ops_ = ops; functor_run = &CallbackWithSuccessTag::StaticRun; inlineable = can_inline; } void Clear() { if (call_ != nullptr) { grpc_call* call = call_; call_ = nullptr; func_ = nullptr; grpc_call_unref(call); } } CompletionQueueTag* ops() { return ops_; } // force_run can not be performed on a tag if operations using this tag // have been sent to PerformOpsOnCall. It is intended for error conditions // that are detected before the operations are internally processed. void force_run(bool ok) { Run(ok); } /// check if this tag is currently set // NOLINTNEXTLINE(google-explicit-constructor) operator bool() const { return call_ != nullptr; } private: grpc_call* call_; std::function func_; CompletionQueueTag* ops_; static void StaticRun(grpc_completion_queue_functor* cb, int ok) { static_cast(cb)->Run(static_cast(ok)); } void Run(bool ok) { void* ignored = ops_; // Allow a "false" return value from FinalizeResult to silence the // callback, just as it silences a CQ tag in the async cases #ifndef NDEBUG auto* ops = ops_; #endif bool do_callback = ops_->FinalizeResult(&ignored, &ok); #ifndef NDEBUG ABSL_DCHECK(ignored == ops); #endif if (do_callback) { CatchingCallback(func_, ok); } } }; } // namespace internal } // namespace grpc #endif // GRPCPP_SUPPORT_CALLBACK_COMMON_H