121 lines
3.9 KiB
C++
121 lines
3.9 KiB
C++
// futex -*- C++ -*-
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// Copyright (C) 2015-2017 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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#include <bits/atomic_futex.h>
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#if defined(_GLIBCXX_HAS_GTHREADS) && defined(_GLIBCXX_USE_C99_STDINT_TR1)
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#if defined(_GLIBCXX_HAVE_LINUX_FUTEX) && ATOMIC_INT_LOCK_FREE > 1
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#include <chrono>
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#include <climits>
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#if ! (defined (__e2k__) && defined (__ptr128__))
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# include <syscall.h>
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# include <unistd.h>
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#else /* (defined (__e2k__) && defined (__ptr128__)) */
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# include <e2k128/futex.h>
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#endif /* (defined (__e2k__) && defined (__ptr128__)) */
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#include <sys/time.h>
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#include <errno.h>
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#include <debug/debug.h>
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// Constants for the wait/wake futex syscall operations
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const unsigned futex_wait_op = 0;
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const unsigned futex_wake_op = 1;
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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bool
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__atomic_futex_unsigned_base::_M_futex_wait_until(unsigned *__addr,
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unsigned __val,
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bool __has_timeout, chrono::seconds __s, chrono::nanoseconds __ns)
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{
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if (!__has_timeout)
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{
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// Ignore whether we actually succeeded to block because at worst,
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// we will fall back to spin-waiting. The only thing we could do
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// here on errors is abort.
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int ret __attribute__((unused));
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ret =
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# if !(defined (__e2k__) && defined (__ptr128__))
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syscall (SYS_futex,
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# else /* (defined (__e2k__) && defined (__ptr128__)) */
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futex (
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# endif /* (defined (__e2k__) && defined (__ptr128__)) */
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__addr, futex_wait_op, __val, nullptr);
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_GLIBCXX_DEBUG_ASSERT(ret == 0 || errno == EINTR || errno == EAGAIN);
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return true;
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}
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else
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{
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struct timeval tv;
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gettimeofday (&tv, NULL);
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// Convert the absolute timeout value to a relative timeout
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struct timespec rt;
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rt.tv_sec = __s.count() - tv.tv_sec;
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rt.tv_nsec = __ns.count() - tv.tv_usec * 1000;
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if (rt.tv_nsec < 0)
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{
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rt.tv_nsec += 1000000000;
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--rt.tv_sec;
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}
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// Did we already time out?
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if (rt.tv_sec < 0)
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return false;
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if (
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# if !(defined (__e2k__) && defined (__ptr128__))
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syscall (SYS_futex,
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# else /* (defined (__e2k__) && defined (__ptr128__)) */
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futex (
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# endif /* (defined (__e2k__) && defined (__ptr128__)) */
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__addr, futex_wait_op, __val, &rt) == -1)
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{
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_GLIBCXX_DEBUG_ASSERT(errno == EINTR || errno == EAGAIN
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|| errno == ETIMEDOUT);
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if (errno == ETIMEDOUT)
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return false;
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}
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return true;
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}
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}
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void
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__atomic_futex_unsigned_base::_M_futex_notify_all(unsigned* __addr)
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{
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// This syscall can fail for various reasons, including in situations
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// in which there is no real error. Thus, we don't bother checking
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// the error codes. See the futex documentation and glibc for background.
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# if !(defined (__e2k__) && defined (__ptr128__))
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syscall (SYS_futex,
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# else /* (defined (__e2k__) && defined (__ptr128__)) */
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futex (
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# endif /* (defined (__e2k__) && defined (__ptr128__)) */
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__addr, futex_wake_op, INT_MAX);
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}
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_GLIBCXX_END_NAMESPACE_VERSION
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}
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#endif
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#endif
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