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/* $Id$ */
/***
This file is part of PulseAudio.
Copyright 2006 Lennart Poettering
PulseAudio 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 2.1 of the
License, or (at your option) any later version.
PulseAudio 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 PulseAudio; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
USA.
***/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <unistd.h>
#include <errno.h>
#include <pulsecore/atomic.h>
#include <pulsecore/log.h>
#include <pulsecore/thread.h>
#include <pulsecore/macro.h>
#include <pulsecore/core-util.h>
#include <pulse/xmalloc.h>
#include "fdsem.h"
struct pa_fdsem {
int fds[2];
pa_atomic_t waiting;
pa_atomic_t signalled;
pa_atomic_t in_pipe;
};
pa_fdsem *pa_fdsem_new(void) {
pa_fdsem *f;
f = pa_xnew(pa_fdsem, 1);
if (pipe(f->fds) < 0) {
pa_xfree(f);
return NULL;
}
pa_fd_set_cloexec(f->fds[0], 1);
pa_fd_set_cloexec(f->fds[1], 1);
pa_atomic_store(&f->waiting, 0);
pa_atomic_store(&f->signalled, 0);
pa_atomic_store(&f->in_pipe, 0);
return f;
}
void pa_fdsem_free(pa_fdsem *f) {
pa_assert(f);
close(f->fds[0]);
close(f->fds[1]);
pa_xfree(f);
}
static void flush(pa_fdsem *f) {
ssize_t r;
pa_assert(f);
if (pa_atomic_load(&f->in_pipe) <= 0)
return;
do {
char x[10];
if ((r = read(f->fds[0], &x, sizeof(x))) <= 0) {
pa_assert(r < 0 && errno == EINTR);
continue;
}
} while (pa_atomic_sub(&f->in_pipe, r) > r);
}
void pa_fdsem_post(pa_fdsem *f) {
pa_assert(f);
if (pa_atomic_cmpxchg(&f->signalled, 0, 1)) {
if (pa_atomic_load(&f->waiting)) {
ssize_t r;
char x = 'x';
pa_atomic_inc(&f->in_pipe);
for (;;) {
if ((r = write(f->fds[1], &x, 1)) != 1) {
pa_assert(r < 0 && errno == EINTR);
continue;
}
break;
}
}
}
}
void pa_fdsem_wait(pa_fdsem *f) {
pa_assert(f);
flush(f);
if (pa_atomic_cmpxchg(&f->signalled, 1, 0))
return;
pa_atomic_inc(&f->waiting);
while (!pa_atomic_cmpxchg(&f->signalled, 1, 0)) {
char x[10];
ssize_t r;
if ((r = read(f->fds[0], &x, sizeof(x))) <= 0) {
pa_assert(r < 0 && errno == EINTR);
continue;
}
pa_atomic_sub(&f->in_pipe, r);
}
pa_atomic_dec(&f->waiting);
}
int pa_fdsem_try(pa_fdsem *f) {
pa_assert(f);
flush(f);
if (pa_atomic_cmpxchg(&f->signalled, 1, 0))
return 1;
return 0;
}
int pa_fdsem_get(pa_fdsem *f) {
pa_assert(f);
return f->fds[0];
}
int pa_fdsem_before_poll(pa_fdsem *f) {
pa_assert(f);
flush(f);
if (pa_atomic_cmpxchg(&f->signalled, 1, 0))
return -1;
pa_atomic_inc(&f->waiting);
if (pa_atomic_cmpxchg(&f->signalled, 1, 0)) {
pa_assert_se(pa_atomic_dec(&f->waiting) >= 1);
return -1;
}
return 0;
}
int pa_fdsem_after_poll(pa_fdsem *f) {
pa_assert(f);
pa_assert_se(pa_atomic_dec(&f->waiting) >= 1);
flush(f);
if (pa_atomic_cmpxchg(&f->signalled, 1, 0))
return 1;
return 0;
}
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