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/*
* Copyright (C) 2021 The Android Open Source Project
*
* 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.
*/
#pragma once
#include <memory>
#include <android-base/result.h>
#include <android-base/unique_fd.h>
#include <utils/Errors.h>
#include <binder/RpcTransport.h>
namespace android {
/** This is not a pipe. */
class FdTrigger {
public:
/** Returns nullptr for error case */
static std::unique_ptr<FdTrigger> make();
/**
* Close the write end of the pipe so that the read end receives POLLHUP.
* Not threadsafe.
*/
void trigger();
/**
* Check whether this has been triggered by checking the write end. Note:
* this has no internal locking, and it is inherently racey, but this is
* okay, because if we accidentally return false when a trigger has already
* happened, we can imagine that instead, the scheduler actually executed
* the code which is polling isTriggered earlier.
*/
[[nodiscard]] bool isTriggered();
/**
* Poll for a read event.
*
* event - for pollfd
*
* Return:
* true - time to read!
* false - trigger happened
*/
[[nodiscard]] status_t triggerablePoll(const android::RpcTransportFd& transportFd,
int16_t event);
private:
#ifdef BINDER_RPC_SINGLE_THREADED
bool mTriggered = false;
#else
base::unique_fd mWrite;
base::unique_fd mRead;
#endif
};
} // namespace android
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