62 lines
1.8 KiB
C++
62 lines
1.8 KiB
C++
/*
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* Copyright (C) 2021 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <memory>
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#include <android-base/result.h>
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#include <android-base/unique_fd.h>
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#include <utils/Errors.h>
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namespace android {
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/** This is not a pipe. */
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class FdTrigger {
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public:
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/** Returns nullptr for error case */
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static std::unique_ptr<FdTrigger> make();
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/**
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* Close the write end of the pipe so that the read end receives POLLHUP.
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* Not threadsafe.
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*/
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void trigger();
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/**
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* Check whether this has been triggered by checking the write end. Note:
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* this has no internal locking, and it is inherently racey, but this is
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* okay, because if we accidentally return false when a trigger has already
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* happened, we can imagine that instead, the scheduler actually executed
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* the code which is polling isTriggered earlier.
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*/
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[[nodiscard]] bool isTriggered();
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/**
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* Poll for a read event.
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*
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* event - for pollfd
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*
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* Return:
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* true - time to read!
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* false - trigger happened
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*/
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[[nodiscard]] status_t triggerablePoll(base::borrowed_fd fd, int16_t event);
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private:
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base::unique_fd mWrite;
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base::unique_fd mRead;
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};
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} // namespace android
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