1 /* 2 * 3 * Copyright 2017 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 #ifndef GRPC_CORE_LIB_IOMGR_LOCKFREE_EVENT_H 20 #define GRPC_CORE_LIB_IOMGR_LOCKFREE_EVENT_H 21 22 /* Lock free event notification for file descriptors */ 23 24 #include <grpc/support/port_platform.h> 25 26 #include <grpc/support/atm.h> 27 28 #include "src/core/lib/iomgr/closure.h" 29 30 namespace grpc_core { 31 32 class LockfreeEvent { 33 public: 34 LockfreeEvent(); 35 36 LockfreeEvent(const LockfreeEvent&) = delete; 37 LockfreeEvent& operator=(const LockfreeEvent&) = delete; 38 39 // These methods are used to initialize and destroy the internal state. These 40 // cannot be done in constructor and destructor because SetReady may be called 41 // when the event is destroyed and put in a freelist. 42 void InitEvent(); 43 void DestroyEvent(); 44 45 // Returns true if fd has been shutdown, false otherwise. IsShutdown()46 bool IsShutdown() const { 47 return (gpr_atm_no_barrier_load(&state_) & kShutdownBit) != 0; 48 } 49 50 // Schedules \a closure when the event is received (see SetReady()) or the 51 // shutdown state has been set. Note that the event may have already been 52 // received, in which case the closure would be scheduled immediately. 53 // If the shutdown state has already been set, then \a closure is scheduled 54 // with the shutdown error. 55 void NotifyOn(grpc_closure* closure); 56 57 // Sets the shutdown state. If a closure had been provided by NotifyOn and has 58 // not yet been scheduled, it will be scheduled with \a error. 59 bool SetShutdown(grpc_error* error); 60 61 // Signals that the event has been received. 62 void SetReady(); 63 64 private: 65 enum State { kClosureNotReady = 0, kClosureReady = 2, kShutdownBit = 1 }; 66 67 gpr_atm state_; 68 }; 69 70 } // namespace grpc_core 71 72 #endif /* GRPC_CORE_LIB_IOMGR_LOCKFREE_EVENT_H */ 73