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/*
*
* Copyright 2015 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.
*
*/
/// An Alarm posts the user provided tag to its associated completion queue upon
/// expiry or cancellation.
#ifndef GRPCXX_ALARM_H
#define GRPCXX_ALARM_H
#include <grpc++/impl/codegen/completion_queue.h>
#include <grpc++/impl/codegen/completion_queue_tag.h>
#include <grpc++/impl/codegen/grpc_library.h>
#include <grpc++/impl/codegen/time.h>
#include <grpc++/impl/grpc_library.h>
#include <grpc/grpc.h>
struct grpc_alarm;
namespace grpc {
class CompletionQueue;
/// A thin wrapper around \a grpc_alarm (see / \a / src/core/surface/alarm.h).
class Alarm : private GrpcLibraryCodegen {
public:
/// Create a completion queue alarm instance associated to \a cq.
///
/// Once the alarm expires (at \a deadline) or it's cancelled (see \a Cancel),
/// an event with tag \a tag will be added to \a cq. If the alarm expired, the
/// event's success bit will be true, false otherwise (ie, upon cancellation).
/// \internal We rely on the presence of \a cq for grpc initialization. If \a
/// cq were ever to be removed, a reference to a static
/// internal::GrpcLibraryInitializer instance would need to be introduced
/// here. \endinternal.
template <typename T>
Alarm(CompletionQueue* cq, const T& deadline, void* tag)
: tag_(tag),
alarm_(grpc_alarm_create(cq->cq(), TimePoint<T>(deadline).raw_time(),
static_cast<void*>(&tag_))) {}
/// Alarms aren't copyable.
Alarm(const Alarm&) = delete;
Alarm& operator=(const Alarm&) = delete;
/// Alarms are movable.
Alarm(Alarm&& rhs) : tag_(rhs.tag_), alarm_(rhs.alarm_) {
rhs.alarm_ = nullptr;
}
Alarm& operator=(Alarm&& rhs) {
tag_ = rhs.tag_;
alarm_ = rhs.alarm_;
rhs.alarm_ = nullptr;
return *this;
}
/// Destroy the given completion queue alarm, cancelling it in the process.
~Alarm() {
if (alarm_ != nullptr) grpc_alarm_destroy(alarm_);
}
/// Cancel a completion queue alarm. Calling this function over an alarm that
/// has already fired has no effect.
void Cancel() { grpc_alarm_cancel(alarm_); }
private:
class AlarmEntry : public CompletionQueueTag {
public:
AlarmEntry(void* tag) : tag_(tag) {}
bool FinalizeResult(void** tag, bool* status) override {
*tag = tag_;
return true;
}
private:
void* tag_;
};
AlarmEntry tag_;
grpc_alarm* alarm_; // owned
};
} // namespace grpc
#endif // GRPCXX_ALARM_H
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