1 // 2 // 3 // Copyright 2015 gRPC authors. 4 // 5 // Licensed under the Apache License, Version 2.0 (the "License"); 6 // you may not use this file except in compliance with the License. 7 // You may obtain a copy of the License at 8 // 9 // http://www.apache.org/licenses/LICENSE-2.0 10 // 11 // Unless required by applicable law or agreed to in writing, software 12 // distributed under the License is distributed on an "AS IS" BASIS, 13 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 // See the License for the specific language governing permissions and 15 // limitations under the License. 16 // 17 // 18 19 /// An Alarm posts the user-provided tag to its associated completion queue or 20 /// invokes the user-provided function on expiry or cancellation. 21 #ifndef GRPCPP_ALARM_H 22 #define GRPCPP_ALARM_H 23 24 #include <functional> 25 26 #include <grpc/grpc.h> 27 #include <grpcpp/completion_queue.h> 28 #include <grpcpp/impl/completion_queue_tag.h> 29 #include <grpcpp/impl/grpc_library.h> 30 #include <grpcpp/support/time.h> 31 32 namespace grpc { 33 34 class Alarm : private grpc::internal::GrpcLibrary { 35 public: 36 /// Create an unset completion queue alarm 37 Alarm(); 38 39 /// Destroy the given completion queue alarm, cancelling it in the process. 40 ~Alarm() override; 41 42 /// DEPRECATED: Create and set a completion queue alarm instance associated to 43 /// \a cq. 44 /// This form is deprecated because it is inherently racy. 45 /// \internal We rely on the presence of \a cq for grpc initialization. If \a 46 /// cq were ever to be removed, a reference to a static 47 /// internal::GrpcLibraryInitializer instance would need to be introduced 48 /// here. \endinternal. 49 template <typename T> Alarm(grpc::CompletionQueue * cq,const T & deadline,void * tag)50 Alarm(grpc::CompletionQueue* cq, const T& deadline, void* tag) : Alarm() { 51 SetInternal(cq, grpc::TimePoint<T>(deadline).raw_time(), tag); 52 } 53 54 /// Trigger an alarm instance on completion queue \a cq at the specified time. 55 /// Once the alarm expires (at \a deadline) or it's cancelled (see \a Cancel), 56 /// an event with tag \a tag will be added to \a cq. If the alarm expired, the 57 /// event's success bit will be true, false otherwise (ie, upon cancellation). 58 // 59 // USAGE NOTE: This is frequently used to inject arbitrary tags into \a cq by 60 // setting an immediate deadline. Such usage allows synchronizing an external 61 // event with an application's \a grpc::CompletionQueue::Next loop. 62 template <typename T> Set(grpc::CompletionQueue * cq,const T & deadline,void * tag)63 void Set(grpc::CompletionQueue* cq, const T& deadline, void* tag) { 64 SetInternal(cq, grpc::TimePoint<T>(deadline).raw_time(), tag); 65 } 66 67 /// Alarms aren't copyable. 68 Alarm(const Alarm&) = delete; 69 Alarm& operator=(const Alarm&) = delete; 70 71 /// Alarms are movable. Alarm(Alarm && rhs)72 Alarm(Alarm&& rhs) noexcept : alarm_(rhs.alarm_) { rhs.alarm_ = nullptr; } 73 Alarm& operator=(Alarm&& rhs) noexcept { 74 std::swap(alarm_, rhs.alarm_); 75 return *this; 76 } 77 78 /// Cancel a completion queue alarm. Calling this function over an alarm that 79 /// has already fired has no effect. 80 void Cancel(); 81 82 /// Set an alarm to invoke callback \a f. The argument to the callback 83 /// states whether the alarm expired at \a deadline (true) or was cancelled 84 /// (false) 85 template <typename T> Set(const T & deadline,std::function<void (bool)> f)86 void Set(const T& deadline, std::function<void(bool)> f) { 87 SetInternal(grpc::TimePoint<T>(deadline).raw_time(), std::move(f)); 88 } 89 90 private: 91 void SetInternal(grpc::CompletionQueue* cq, gpr_timespec deadline, void* tag); 92 void SetInternal(gpr_timespec deadline, std::function<void(bool)> f); 93 94 grpc::internal::CompletionQueueTag* alarm_; 95 }; 96 97 } // namespace grpc 98 99 #endif // GRPCPP_ALARM_H 100