diff options
Diffstat (limited to 'src/pulsecore/asyncq.c')
| -rw-r--r-- | src/pulsecore/asyncq.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/src/pulsecore/asyncq.c b/src/pulsecore/asyncq.c new file mode 100644 index 00000000..75b15c0e --- /dev/null +++ b/src/pulsecore/asyncq.c @@ -0,0 +1,213 @@ +/* $Id$ */ + +/*** + 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); +} |