src/linux/thread.c

   1 /*****************************************************************************
   2  * linux/thread.c: Linux specifics for threading
   3  *****************************************************************************
   4  * Copyright (C) 2016 Rémi Denis-Courmont
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU Lesser General Public License as published by
   8  * the Free Software Foundation; either version 2.1 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14  * GNU Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public License
  17  * along with this program; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
  19  *****************************************************************************/
  20
  21 #ifdef HAVE_CONFIG_H
  22 # include "config.h"
  23 #endif
  24
  25 #include <errno.h>
  26 #include <limits.h>
  27 #include <stdlib.h>
  28 #include <sys/types.h>
  29 #include <unistd.h>
  30 #include <sys/syscall.h>
  31 #include <linux/futex.h>
  32
  33 #ifndef FUTEX_PRIVATE_FLAG
  34 #define FUTEX_WAKE_PRIVATE FUTEX_WAKE
  35 #define FUTEX_WAIT_PRIVATE FUTEX_WAIT
  36 #endif
  37
  38 #include <vlc_common.h>
  39
  40 unsigned long vlc_thread_id(void)
  41 {
  42      static __thread pid_t tid = 0;
  43
  44      if (unlikely(tid == 0))
  45          tid = syscall(__NR_gettid);
  46
  47      return tid;
  48 }
  49
  50 static int sys_futex(void *addr, int op, unsigned val,
  51                      const struct timespec *to, void *addr2, int val3)
  52 {
  53     return syscall(__NR_futex, addr, op, val, to, addr2, val3);
  54 }
  55
  56 static int vlc_futex_wake(void *addr, int nr)
  57 {
  58     return sys_futex(addr, FUTEX_WAKE_PRIVATE, nr, NULL, NULL, 0);
  59 }
  60
  61 static int vlc_futex_wait(void *addr, unsigned val, const struct timespec *to)
  62 {
  63     return sys_futex(addr, FUTEX_WAIT_PRIVATE, val, to, NULL, 0);
  64 }
  65
  66 void vlc_addr_signal(void *addr)
  67 {
  68     vlc_futex_wake(addr, 1);
  69 }
  70
  71 void vlc_addr_broadcast(void *addr)
  72 {
  73     vlc_futex_wake(addr, INT_MAX);
  74 }
  75
  76 void vlc_addr_wait(void *addr, unsigned val)
  77 {
  78     vlc_futex_wait(addr, val, NULL);
  79 }
  80
  81 bool vlc_addr_timedwait(void *addr, unsigned val, mtime_t delay)
  82 {
  83     lldiv_t d = lldiv(delay, CLOCK_FREQ);
  84     struct timespec ts = { d.quot, d.rem * (1000000000 / CLOCK_FREQ) };
  85
  86     return (vlc_futex_wait(addr, val, &ts) == 0 || errno != ETIMEDOUT);
  87 }