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4eb984d3ab
This patch combines BUSY_WAIT_NOP and atomic_delay into a new atomic_spin_nop function and adjusts all clients. The new function is put into atomic.h because what is best done in a spin loop is architecture-specific, and atomics must be used for spinning. The function name is meant to tell users that this has no effect on synchronization semantics but is a performance aid for spinning.
62 lines
1.9 KiB
C
62 lines
1.9 KiB
C
/* Timed waiting for thread death. NaCl version.
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Copyright (C) 2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C 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 GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <assert.h>
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#include <atomic.h>
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#include <errno.h>
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#include <lowlevellock.h>
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#include <sys/time.h>
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int
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__lll_timedwait_tid (int *tidp, const struct timespec *abstime)
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{
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/* Reject invalid timeouts. */
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if (__glibc_unlikely (abstime->tv_nsec < 0)
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|| __glibc_unlikely (abstime->tv_nsec >= 1000000000))
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return EINVAL;
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/* Repeat until thread terminated. */
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int tid;
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while ((tid = atomic_load_relaxed (tidp)) != 0)
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{
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/* See exit-thread.h for details. */
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if (tid == NACL_EXITING_TID)
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/* The thread should now be in the process of exiting, so it will
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finish quick enough that the timeout doesn't matter. If any
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thread ever stays in this state for long, there is something
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catastrophically wrong. */
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atomic_spin_nop ();
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else
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{
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assert (tid > 0);
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/* If *FUTEX == TID, wait until woken or timeout. */
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int err = __nacl_irt_futex.futex_wait_abs ((volatile int *) tidp,
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tid, abstime);
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if (err != 0)
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{
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if (__glibc_likely (err == ETIMEDOUT))
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return err;
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assert (err == EAGAIN);
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}
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}
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}
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return 0;
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}
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