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/* Support for thread stuff.
*
* JC & KM 9/5/94
* Modified:
* 28/11/94 JC
* - return(0) missing from tidy_thread_info()
* 4/8/99 RP JC
* - reorganised for POSIX
* 28/3/11
* - moved to vips_ namespace
*/
/*
This file is part of VIPS.
VIPS is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser 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
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
/*
#define DEBUG_IO
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <glib/gi18n-lib.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <errno.h>
#include <vips/vips.h>
#include <vips/thread.h>
#include <vips/internal.h>
void
vips_semaphore_init(VipsSemaphore *s, int v, char *name)
{
s->v = v;
s->name = name;
s->mutex = vips_g_mutex_new();
s->cond = vips_g_cond_new();
}
void
vips_semaphore_destroy(VipsSemaphore *s)
{
VIPS_FREEF(vips_g_mutex_free, s->mutex);
VIPS_FREEF(vips_g_cond_free, s->cond);
}
/* Add n to the semaphore and signal any threads that are blocked waiting
* a change.
*/
int
vips_semaphore_upn(VipsSemaphore *s, int n)
{
int value_after_op;
g_mutex_lock(s->mutex);
s->v += n;
value_after_op = s->v;
/* If we are only incrementing by one, we only need to wake a single
* thread. If we are incrementing by a lot, we must wake all threads.
*/
if (n == 1)
g_cond_signal(s->cond);
else
g_cond_broadcast(s->cond);
g_mutex_unlock(s->mutex);
#ifdef DEBUG_IO
printf("vips_semaphore_upn(\"%s\",%d) = %d\n",
s->name, n, value_after_op);
if (value_after_op > 1)
vips_error("vips_semaphore_upn", "up over 1!");
#endif /*DEBUG_IO*/
return value_after_op;
}
/* Increment the semaphore.
*/
int
vips_semaphore_up(VipsSemaphore *s)
{
return vips_semaphore_upn(s, 1);
}
/* Wait for sem > n, then subtract n.
* Returns -1 when the monotonic time in @end_time was passed.
*/
static int
vips__semaphore_downn_until(VipsSemaphore *s, int n, gint64 end_time)
{
int value_after_op;
VIPS_GATE_START("vips__semaphore_downn_until: wait");
g_mutex_lock(s->mutex);
while (s->v < n) {
if (end_time == -1)
vips__worker_cond_wait(s->cond, s->mutex);
else if (!g_cond_wait_until(s->cond, s->mutex, end_time)) {
/* timeout has passed.
*/
g_mutex_unlock(s->mutex);
VIPS_GATE_STOP("vips__semaphore_downn_until: wait");
return -1;
}
}
s->v -= n;
value_after_op = s->v;
g_mutex_unlock(s->mutex);
#ifdef DEBUG_IO
printf("vips__semaphore_downn_until(\"%s\",%d): %d\n",
s->name, n, value_after_op);
#endif /*DEBUG_IO*/
VIPS_GATE_STOP("vips__semaphore_downn_until: wait");
return value_after_op;
}
/* Wait for sem>n, then subtract n. n must be >= 0. Returns the new semaphore
* value.
*/
int
vips_semaphore_downn(VipsSemaphore *s, int n)
{
g_assert(n >= 0);
return vips__semaphore_downn_until(s, n, -1);
}
/* Wait for sem > 0, then decrement. Returns the new semaphore value.
*/
int
vips_semaphore_down(VipsSemaphore *s)
{
return vips__semaphore_downn_until(s, 1, -1);
}
/* Wait for sem > 0, then decrement.
* Returns -1 when @timeout (in microseconds) has passed, or the new
* semaphore value.
*/
int
vips_semaphore_down_timeout(VipsSemaphore *s, gint64 timeout)
{
gint64 end_time = g_get_monotonic_time() + timeout;
return vips__semaphore_downn_until(s, 1, end_time);
}
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