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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 or
/// invokes the user-provided function on expiry or cancellation.
#ifndef GRPCPP_ALARM_H
#define GRPCPP_ALARM_H
#include <functional>
#include <grpc/grpc.h>
#include <grpcpp/completion_queue.h>
#include <grpcpp/impl/completion_queue_tag.h>
#include <grpcpp/impl/grpc_library.h>
#include <grpcpp/support/time.h>
namespace grpc {
class Alarm : private grpc::internal::GrpcLibrary {
public:
/// Create an unset completion queue alarm
Alarm();
/// Destroy the given completion queue alarm, cancelling it in the process.
~Alarm() override;
/// DEPRECATED: Create and set a completion queue alarm instance associated to
/// \a cq.
/// This form is deprecated because it is inherently racy.
/// \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(grpc::CompletionQueue* cq, const T& deadline, void* tag) : Alarm() {
SetInternal(cq, grpc::TimePoint<T>(deadline).raw_time(), tag);
}
/// Trigger an alarm instance on completion queue \a cq at the specified time.
/// 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).
//
// USAGE NOTE: This is frequently used to inject arbitrary tags into \a cq by
// setting an immediate deadline. Such usage allows synchronizing an external
// event with an application's \a grpc::CompletionQueue::Next loop.
template <typename T>
void Set(grpc::CompletionQueue* cq, const T& deadline, void* tag) {
SetInternal(cq, grpc::TimePoint<T>(deadline).raw_time(), tag);
}
/// Alarms aren't copyable.
Alarm(const Alarm&) = delete;
Alarm& operator=(const Alarm&) = delete;
/// Alarms are movable.
Alarm(Alarm&& rhs) noexcept : alarm_(rhs.alarm_) { rhs.alarm_ = nullptr; }
Alarm& operator=(Alarm&& rhs) noexcept {
std::swap(alarm_, rhs.alarm_);
return *this;
}
/// Cancel a completion queue alarm. Calling this function over an alarm that
/// has already fired has no effect.
void Cancel();
/// Set an alarm to invoke callback \a f. The argument to the callback
/// states whether the alarm expired at \a deadline (true) or was cancelled
/// (false)
template <typename T>
void Set(const T& deadline, std::function<void(bool)> f) {
SetInternal(grpc::TimePoint<T>(deadline).raw_time(), std::move(f));
}
private:
void SetInternal(grpc::CompletionQueue* cq, gpr_timespec deadline, void* tag);
void SetInternal(gpr_timespec deadline, std::function<void(bool)> f);
grpc::internal::CompletionQueueTag* alarm_;
};
} // namespace grpc
#endif // GRPCPP_ALARM_H
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