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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 "asyncq.h"
#include "fdsem.h"
#define ASYNCQ_SIZE 128
/* For debugging purposes we can define _Y to put and extra thread
* yield between each operation. */
/* #define PROFILE */
#ifdef PROFILE
#define _Y pa_thread_yield()
#else
#define _Y do { } while(0)
#endif
struct pa_asyncq {
unsigned size;
unsigned read_idx;
unsigned write_idx;
pa_fdsem *read_fdsem, *write_fdsem;
};
#define PA_ASYNCQ_CELLS(x) ((pa_atomic_ptr_t*) ((uint8_t*) (x) + PA_ALIGN(sizeof(struct pa_asyncq))))
static int is_power_of_two(unsigned size) {
return !(size & (size - 1));
}
static int reduce(pa_asyncq *l, int value) {
return value & (unsigned) (l->size - 1);
}
pa_asyncq *pa_asyncq_new(unsigned size) {
pa_asyncq *l;
if (!size)
size = ASYNCQ_SIZE;
pa_assert(is_power_of_two(size));
l = pa_xmalloc0(PA_ALIGN(sizeof(pa_asyncq)) + (sizeof(pa_atomic_ptr_t) * size));
l->size = size;
if (!(l->read_fdsem = pa_fdsem_new())) {
pa_xfree(l);
return NULL;
}
if (!(l->write_fdsem = pa_fdsem_new())) {
pa_fdsem_free(l->read_fdsem);
pa_xfree(l);
return NULL;
}
return l;
}
void pa_asyncq_free(pa_asyncq *l, pa_free_cb_t free_cb) {
pa_assert(l);
if (free_cb) {
void *p;
while ((p = pa_asyncq_pop(l, 0)))
free_cb(p);
}
pa_fdsem_free(l->read_fdsem);
pa_fdsem_free(l->write_fdsem);
pa_xfree(l);
}
int pa_asyncq_push(pa_asyncq*l, void *p, int wait) {
int idx;
pa_atomic_ptr_t *cells;
pa_assert(l);
pa_assert(p);
cells = PA_ASYNCQ_CELLS(l);
_Y;
idx = reduce(l, l->write_idx);
if (!pa_atomic_ptr_cmpxchg(&cells[idx], NULL, p)) {
if (!wait)
return -1;
/* pa_log("sleeping on push"); */
do {
pa_fdsem_wait(l->read_fdsem);
} while (!pa_atomic_ptr_cmpxchg(&cells[idx], NULL, p));
}
_Y;
l->write_idx++;
pa_fdsem_post(l->write_fdsem);
return 0;
}
void* pa_asyncq_pop(pa_asyncq*l, int wait) {
int idx;
void *ret;
pa_atomic_ptr_t *cells;
pa_assert(l);
cells = PA_ASYNCQ_CELLS(l);
_Y;
idx = reduce(l, l->read_idx);
if (!(ret = pa_atomic_ptr_load(&cells[idx]))) {
if (!wait)
return NULL;
/* pa_log("sleeping on pop"); */
do {
pa_fdsem_wait(l->write_fdsem);
} while (!(ret = pa_atomic_ptr_load(&cells[idx])));
}
pa_assert(ret);
/* Guaranteed to succeed if we only have a single reader */
pa_assert_se(pa_atomic_ptr_cmpxchg(&cells[idx], ret, NULL));
_Y;
l->read_idx++;
pa_fdsem_post(l->read_fdsem);
return ret;
}
int pa_asyncq_get_fd(pa_asyncq *q) {
pa_assert(q);
return pa_fdsem_get(q->write_fdsem);
}
int pa_asyncq_before_poll(pa_asyncq *l) {
int idx;
pa_atomic_ptr_t *cells;
pa_assert(l);
cells = PA_ASYNCQ_CELLS(l);
_Y;
idx = reduce(l, l->read_idx);
for (;;) {
if (pa_atomic_ptr_load(&cells[idx]))
return -1;
if (pa_fdsem_before_poll(l->write_fdsem) >= 0)
return 0;
}
return 0;
}
void pa_asyncq_after_poll(pa_asyncq *l) {
pa_assert(l);
pa_fdsem_after_poll(l->write_fdsem);
}
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