60 lines
2.7 KiB
C++
60 lines
2.7 KiB
C++
|
/*
|
||
|
|
* Copyright (C) 2017 The Android Open Source Project
|
||
|
|
* All rights reserved.
|
||
|
|
*
|
||
|
|
* Redistribution and use in source and binary forms, with or without
|
||
|
|
* modification, are permitted provided that the following conditions
|
||
|
|
* are met:
|
||
|
|
* * Redistributions of source code must retain the above copyright
|
||
|
|
* notice, this list of conditions and the following disclaimer.
|
||
|
|
* * Redistributions in binary form must reproduce the above copyright
|
||
|
|
* notice, this list of conditions and the following disclaimer in
|
||
|
|
* the documentation and/or other materials provided with the
|
||
|
|
* distribution.
|
||
|
|
*
|
||
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
||
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
||
|
|
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
||
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
||
|
|
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
|
||
|
|
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
||
|
|
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
|
||
|
|
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
|
||
|
|
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
||
|
|
* SUCH DAMAGE.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include "private/bionic_futex.h"
|
||
|
|
|
||
|
|
#include <time.h>
|
||
|
|
|
||
|
|
#include "private/bionic_time_conversions.h"
|
||
|
|
|
||
|
|
int __futex_wait_ex(volatile void* ftx, bool shared, int value, bool use_realtime_clock,
|
||
|
|
const timespec* abs_timeout) {
|
||
|
|
const timespec* futex_abs_timeout = abs_timeout;
|
||
|
|
// pthread's and semaphore's default behavior is to use CLOCK_REALTIME, however this behavior is
|
||
|
|
// essentially never intended, as that clock is prone to change discontinuously.
|
||
|
|
//
|
||
|
|
// What users really intend is to use CLOCK_MONOTONIC, however only pthread_cond_timedwait()
|
||
|
|
// provides this as an option and even there, a large amount of existing code does not opt into
|
||
|
|
// CLOCK_MONOTONIC.
|
||
|
|
//
|
||
|
|
// We have seen numerous bugs directly attributable to this difference. Therefore, we provide
|
||
|
|
// this general workaround to always use CLOCK_MONOTONIC for waiting, regardless of what the input
|
||
|
|
// timespec is.
|
||
|
|
timespec converted_monotonic_abs_timeout;
|
||
|
|
if (abs_timeout && use_realtime_clock) {
|
||
|
|
monotonic_time_from_realtime_time(converted_monotonic_abs_timeout, *abs_timeout);
|
||
|
|
if (converted_monotonic_abs_timeout.tv_sec < 0) {
|
||
|
|
return -ETIMEDOUT;
|
||
|
|
}
|
||
|
|
futex_abs_timeout = &converted_monotonic_abs_timeout;
|
||
|
|
}
|
||
|
|
|
||
|
|
return __futex(ftx, (shared ? FUTEX_WAIT_BITSET : FUTEX_WAIT_BITSET_PRIVATE), value,
|
||
|
|
futex_abs_timeout, FUTEX_BITSET_MATCH_ANY);
|
||
|
|
}
|