GRPC C++  1.26.0
lockfree_event.h
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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
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14  * See the License for the specific language governing permissions and
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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 
25 
26 #include <grpc/support/atm.h>
27 
29 
30 namespace grpc_core {
31 
33  public:
35 
36  LockfreeEvent(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.
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 */
Definition: lockfree_event.h:32
bool IsShutdown() const
Definition: lockfree_event.h:46
LockfreeEvent & operator=(const LockfreeEvent &)=delete
bool SetShutdown(grpc_error *error)
void NotifyOn(grpc_closure *closure)
LockfreeEvent(const LockfreeEvent &)=delete
intptr_t gpr_atm
Definition: atm_gcc_atomic.h:30
#define gpr_atm_no_barrier_load(p)
Definition: atm_gcc_atomic.h:51
Internal thread interface.
Definition: backoff.h:26
A closure over a grpc_iomgr_cb_func.
Definition: closure.h:56
Definition: error_internal.h:39