dbus/dbus-sysdeps-pthread.c

/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* dbus-sysdeps-pthread.c Implements threads using pthreads (internal to libdbus)
 * 
 * Copyright (C) 2002, 2003, 2006  Red Hat, Inc.
 *
 * Licensed under the Academic Free License version 2.1
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include <config.h>
#include "dbus-internals.h"
#include "dbus-sysdeps.h"
#include "dbus-threads.h"

#include <sys/time.h>
#include <pthread.h>
#include <stdio.h>
#include <string.h>

#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif

#include <config.h>

#ifdef HAVE_MONOTONIC_CLOCK
/* Whether we have a "monotonic" clock; i.e. a clock not affected by
 * changes in system time.
 * This is initialized once in check_monotonic_clock below.
 * https://bugs.freedesktop.org/show_bug.cgi?id=18121
 */
static dbus_bool_t have_monotonic_clock = 0;
#endif

struct DBusRMutex {
  pthread_mutex_t lock; /**< the lock */
};

struct DBusCMutex {
  pthread_mutex_t lock; /**< the lock */
};

struct DBusCondVar {
  pthread_cond_t cond; /**< the condition */
};

#define DBUS_MUTEX(m)         ((DBusMutex*) m)
#define DBUS_MUTEX_PTHREAD(m) ((DBusMutexPThread*) m)

#define DBUS_COND_VAR(c)         ((DBusCondVar*) c)
#define DBUS_COND_VAR_PTHREAD(c) ((DBusCondVarPThread*) c)


#ifdef DBUS_DISABLE_ASSERT
/* (tmp != 0) is a no-op usage to silence compiler */
#define PTHREAD_CHECK(func_name, result_or_call)    \
    do { int tmp = (result_or_call); if (tmp != 0) {;} } while (0)
#else
#define PTHREAD_CHECK(func_name, result_or_call) do {                                  \
    int tmp = (result_or_call);                                                        \
    if (tmp != 0) {                                                                    \
      _dbus_warn_check_failed ("pthread function %s failed with %d %s in %s",          \
                               func_name, tmp, strerror(tmp), _DBUS_FUNCTION_NAME);    \
    }                                                                                  \
} while (0)
#endif /* !DBUS_DISABLE_ASSERT */

DBusCMutex *
_dbus_platform_cmutex_new (void)
{
  DBusCMutex *pmutex;
  int result;

  pmutex = dbus_new (DBusCMutex, 1);
  if (pmutex == NULL)
    return NULL;

  result = pthread_mutex_init (&pmutex->lock, NULL);

  if (result == ENOMEM || result == EAGAIN)
    {
      dbus_free (pmutex);
      return NULL;
    }
  else
    {
      PTHREAD_CHECK ("pthread_mutex_init", result);
    }

  return pmutex;
}

DBusRMutex *
_dbus_platform_rmutex_new (void)
{
  DBusRMutex *pmutex;
  pthread_mutexattr_t mutexattr;
  int result;

  pmutex = dbus_new (DBusRMutex, 1);
  if (pmutex == NULL)
    return NULL;

  pthread_mutexattr_init (&mutexattr);
  pthread_mutexattr_settype (&mutexattr, PTHREAD_MUTEX_RECURSIVE);
  result = pthread_mutex_init (&pmutex->lock, &mutexattr);
  pthread_mutexattr_destroy (&mutexattr);

  if (result == ENOMEM || result == EAGAIN)
    {
      dbus_free (pmutex);
      return NULL;
    }
  else
    {
      PTHREAD_CHECK ("pthread_mutex_init", result);
    }

  return pmutex;
}

void
_dbus_platform_cmutex_free (DBusCMutex *mutex)
{
  PTHREAD_CHECK ("pthread_mutex_destroy", pthread_mutex_destroy (&mutex->lock));
  dbus_free (mutex);
}

void
_dbus_platform_rmutex_free (DBusRMutex *mutex)
{
  PTHREAD_CHECK ("pthread_mutex_destroy", pthread_mutex_destroy (&mutex->lock));
  dbus_free (mutex);
}

void
_dbus_platform_cmutex_lock (DBusCMutex *mutex)
{
  PTHREAD_CHECK ("pthread_mutex_lock", pthread_mutex_lock (&mutex->lock));
}

void
_dbus_platform_rmutex_lock (DBusRMutex *mutex)
{
  PTHREAD_CHECK ("pthread_mutex_lock", pthread_mutex_lock (&mutex->lock));
}

void
_dbus_platform_cmutex_unlock (DBusCMutex *mutex)
{
  PTHREAD_CHECK ("pthread_mutex_unlock", pthread_mutex_unlock (&mutex->lock));
}

void
_dbus_platform_rmutex_unlock (DBusRMutex *mutex)
{
  PTHREAD_CHECK ("pthread_mutex_unlock", pthread_mutex_unlock (&mutex->lock));
}

DBusCondVar *
_dbus_platform_condvar_new (void)
{
  DBusCondVar *pcond;
  pthread_condattr_t attr;
  int result;
  
  pcond = dbus_new (DBusCondVar, 1);
  if (pcond == NULL)
    return NULL;

  pthread_condattr_init (&attr);
#ifdef HAVE_MONOTONIC_CLOCK
  if (have_monotonic_clock)
    pthread_condattr_setclock (&attr, CLOCK_MONOTONIC);
#endif

  result = pthread_cond_init (&pcond->cond, &attr);
  pthread_condattr_destroy (&attr);

  if (result == EAGAIN || result == ENOMEM)
    {
      dbus_free (pcond);
      return NULL;
    }
  else
    {
      PTHREAD_CHECK ("pthread_cond_init", result);
    }
  
  return pcond;
}

void
_dbus_platform_condvar_free (DBusCondVar *cond)
{
  PTHREAD_CHECK ("pthread_cond_destroy", pthread_cond_destroy (&cond->cond));
  dbus_free (cond);
}

void
_dbus_platform_condvar_wait (DBusCondVar *cond,
                             DBusCMutex  *mutex)
{
  PTHREAD_CHECK ("pthread_cond_wait", pthread_cond_wait (&cond->cond, &mutex->lock));
}

dbus_bool_t
_dbus_platform_condvar_wait_timeout (DBusCondVar               *cond,
                                     DBusCMutex                *mutex,
                                     int                        timeout_milliseconds)
{
  struct timeval time_now;
  struct timespec end_time;
  int result;

#ifdef HAVE_MONOTONIC_CLOCK
  if (have_monotonic_clock)
    {
      struct timespec monotonic_timer;
      clock_gettime (CLOCK_MONOTONIC,&monotonic_timer);
      time_now.tv_sec = monotonic_timer.tv_sec;
      time_now.tv_usec = monotonic_timer.tv_nsec / 1000;
    }
  else
    /* This else falls through to gettimeofday */
#endif
  gettimeofday (&time_now, NULL);
  
  end_time.tv_sec = time_now.tv_sec + timeout_milliseconds / 1000;
  end_time.tv_nsec = (time_now.tv_usec + (timeout_milliseconds % 1000) * 1000) * 1000;
  if (end_time.tv_nsec > 1000*1000*1000)
    {
      end_time.tv_sec += 1;
      end_time.tv_nsec -= 1000*1000*1000;
    }

  result = pthread_cond_timedwait (&cond->cond, &mutex->lock, &end_time);
  
  if (result != ETIMEDOUT)
    {
      PTHREAD_CHECK ("pthread_cond_timedwait", result);
    }

  /* return true if we did not time out */
  return result != ETIMEDOUT;
}

void
_dbus_platform_condvar_wake_one (DBusCondVar *cond)
{
  PTHREAD_CHECK ("pthread_cond_signal", pthread_cond_signal (&cond->cond));
}

static void
check_monotonic_clock (void)
{
#ifdef HAVE_MONOTONIC_CLOCK
  struct timespec dummy;
  if (clock_getres (CLOCK_MONOTONIC, &dummy) == 0)
    have_monotonic_clock = TRUE;
#endif
}

dbus_bool_t
_dbus_threads_init_platform_specific (void)
{
  /* These have static variables, and we need to handle both the case
   * where dbus_threads_init() has been called and when it hasn't;
   * so initialize them before any threads are allowed to enter.
   */
  check_monotonic_clock ();
  (void) _dbus_check_setuid ();

  return TRUE;
}

static pthread_mutex_t init_mutex = PTHREAD_MUTEX_INITIALIZER;

void
_dbus_threads_lock_platform_specific (void)
{
  pthread_mutex_lock (&init_mutex);
}

void
_dbus_threads_unlock_platform_specific (void)
{
  pthread_mutex_unlock (&init_mutex);
}

#ifdef DBUS_ENABLE_VERBOSE_MODE
/*
 * If we can identify the current process and/or thread, print them to stderr followed by a colon.
 */
void
_dbus_print_thread (void)
{
#ifdef __linux__
  /* we know a pthread_t is numeric on Linux */
  fprintf (stderr, "%lu: 0x%lx: ", _dbus_pid_for_log (), (unsigned long) pthread_self ());
#else
  /* in principle pthread_t isn't required to be printable */
  fprintf (stderr, "%lu: ", _dbus_pid_for_log ());
#endif
}
#endif