From 045c1d602dcba57868845ba3270510593c39480f Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Thu, 15 May 2008 23:34:41 +0000 Subject: merge glitch-free branch back into trunk git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@2445 fefdeb5f-60dc-0310-8127-8f9354f1896f --- src/pulsecore/shmasyncq.c | 222 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 222 insertions(+) create mode 100644 src/pulsecore/shmasyncq.c (limited to 'src/pulsecore/shmasyncq.c') diff --git a/src/pulsecore/shmasyncq.c b/src/pulsecore/shmasyncq.c new file mode 100644 index 00000000..7af2985c --- /dev/null +++ b/src/pulsecore/shmasyncq.c @@ -0,0 +1,222 @@ +/* $Id$ */ + +/*** + 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 +#endif + +#include +#include + +#include +#include +#include +#include +#include +#include + +#include "fdsem.h" + +/* 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_shmasyncq { + pa_fdsem *read_fdsem, *write_fdsem; + pa_shmasyncq_data *data; +}; + +static int is_power_of_two(unsigned size) { + return !(size & (size - 1)); +} + +static int reduce(pa_shmasyncq *l, int value) { + return value & (unsigned) (l->n_elements - 1); +} + +static pa_atomic_t* get_cell(pa_shmasyncq *l, unsigned i) { + pa_assert(i < l->data->n_elements); + + return (pa_atomic_t*) ((uint8*t) l->data + PA_ALIGN(sizeof(pa_shmasyncq_data)) + i * (PA_ALIGN(sizeof(pa_atomic_t)) + PA_ALIGN(element_size))) +} + +static void *get_cell_data(pa_atomic_t *a) { + return (uint8_t*) a + PA_ALIGN(sizeof(atomic_t)); +} + +pa_shmasyncq *pa_shmasyncq_new(unsigned n_elements, size_t element_size, void *data, int fd[2]) { + pa_shmasyncq *l; + + pa_assert(n_elements > 0); + pa_assert(is_power_of_two(n_elements)); + pa_assert(element_size > 0); + pa_assert(data); + pa_assert(fd); + + l = pa_xnew(pa_shmasyncq, 1); + + l->data = data; + memset(data, 0, PA_SHMASYNCQ_SIZE(n_elements, element_size)); + + l->data->n_elements = n_elements; + l->data->element_size = element_size; + + if (!(l->read_fdsem = pa_fdsem_new_shm(&d->read_fdsem_data, &fd[0]))) { + pa_xfree(l); + return NULL; + } + + if (!(l->write_fdsem = pa_fdsem_new(&d->write_fdsem_data, &fd[1]))) { + pa_fdsem_free(l->read_fdsem); + pa_xfree(l); + return NULL; + } + + return l; +} + +void pa_shmasyncq_free(pa_shmasyncq *l, pa_free_cb_t free_cb) { + pa_assert(l); + + if (free_cb) { + void *p; + + while ((p = pa_shmasyncq_pop(l, 0))) + free_cb(p); + } + + pa_fdsem_free(l->read_fdsem); + pa_fdsem_free(l->write_fdsem); + pa_xfree(l); +} + +int pa_shmasyncq_push(pa_shmasyncq*l, void *p, int wait) { + int idx; + pa_atomic_ptr_t *cells; + + pa_assert(l); + pa_assert(p); + + cells = PA_SHMASYNCQ_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_shmasyncq_pop(pa_shmasyncq*l, int wait) { + int idx; + void *ret; + pa_atomic_ptr_t *cells; + + pa_assert(l); + + cells = PA_SHMASYNCQ_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_shmasyncq_get_fd(pa_shmasyncq *q) { + pa_assert(q); + + return pa_fdsem_get(q->write_fdsem); +} + +int pa_shmasyncq_before_poll(pa_shmasyncq *l) { + int idx; + pa_atomic_ptr_t *cells; + + pa_assert(l); + + cells = PA_SHMASYNCQ_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_shmasyncq_after_poll(pa_shmasyncq *l) { + pa_assert(l); + + pa_fdsem_after_poll(l->write_fdsem); +} -- cgit