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/*
*
* Copyright 2017 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 GRPC_CORE_LIB_IOMGR_LOCKFREE_EVENT_H
#define GRPC_CORE_LIB_IOMGR_LOCKFREE_EVENT_H
/* Lock free event notification for file descriptors */
#include <grpc/support/port_platform.h>
#include <grpc/support/atm.h>
#include "src/core/lib/iomgr/closure.h"
namespace grpc_core {
class LockfreeEvent {
public:
LockfreeEvent();
LockfreeEvent(const LockfreeEvent&) = delete;
LockfreeEvent& operator=(const LockfreeEvent&) = delete;
// These methods are used to initialize and destroy the internal state. These
// cannot be done in constructor and destructor because SetReady may be called
// when the event is destroyed and put in a freelist.
void InitEvent();
void DestroyEvent();
// Returns true if fd has been shutdown, false otherwise.
bool IsShutdown() const {
return (gpr_atm_no_barrier_load(&state_) & kShutdownBit) != 0;
}
// Schedules \a closure when the event is received (see SetReady()) or the
// shutdown state has been set. Note that the event may have already been
// received, in which case the closure would be scheduled immediately.
// If the shutdown state has already been set, then \a closure is scheduled
// with the shutdown error.
void NotifyOn(grpc_closure* closure);
// Sets the shutdown state. If a closure had been provided by NotifyOn and has
// not yet been scheduled, it will be scheduled with \a error.
bool SetShutdown(grpc_error* error);
// Signals that the event has been received.
void SetReady();
private:
enum State { kClosureNotReady = 0, kClosureReady = 2, kShutdownBit = 1 };
gpr_atm state_;
};
} // namespace grpc_core
#endif /* GRPC_CORE_LIB_IOMGR_LOCKFREE_EVENT_H */
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