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-rw-r--r--src/pulsecore/asyncq.c320
1 files changed, 320 insertions, 0 deletions
diff --git a/src/pulsecore/asyncq.c b/src/pulsecore/asyncq.c
new file mode 100644
index 0000000..53bfe4f
--- /dev/null
+++ b/src/pulsecore/asyncq.c
@@ -0,0 +1,320 @@
+/***
+ This file is part of PulseAudio.
+
+ Copyright 2006-2008 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, see <http://www.gnu.org/licenses/>.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <unistd.h>
+#include <errno.h>
+
+#include <pulse/xmalloc.h>
+
+#include <pulsecore/atomic.h>
+#include <pulsecore/log.h>
+#include <pulsecore/thread.h>
+#include <pulsecore/macro.h>
+#include <pulsecore/core-util.h>
+#include <pulsecore/llist.h>
+#include <pulsecore/flist.h>
+#include <pulsecore/fdsem.h>
+
+#include "asyncq.h"
+
+#define ASYNCQ_SIZE 256
+
+/* For debugging purposes we can define _Y to put an extra thread
+ * yield between each operation. */
+
+/* #define PROFILE */
+
+#ifdef PROFILE
+#define _Y pa_thread_yield()
+#else
+#define _Y do { } while(0)
+#endif
+
+struct localq {
+ void *data;
+ PA_LLIST_FIELDS(struct localq);
+};
+
+struct pa_asyncq {
+ unsigned size;
+ unsigned read_idx;
+ unsigned write_idx;
+ pa_fdsem *read_fdsem, *write_fdsem;
+
+ PA_LLIST_HEAD(struct localq, localq);
+ struct localq *last_localq;
+ bool waiting_for_post;
+};
+
+PA_STATIC_FLIST_DECLARE(localq, 0, pa_xfree);
+
+#define PA_ASYNCQ_CELLS(x) ((pa_atomic_ptr_t*) ((uint8_t*) (x) + PA_ALIGN(sizeof(struct pa_asyncq))))
+
+static unsigned reduce(pa_asyncq *l, unsigned value) {
+ return value & (unsigned) (l->size - 1);
+}
+
+pa_asyncq *pa_asyncq_new(unsigned size) {
+ pa_asyncq *l;
+
+ if (!size)
+ size = ASYNCQ_SIZE;
+
+ pa_assert(pa_is_power_of_two(size));
+
+ l = pa_xmalloc0(PA_ALIGN(sizeof(pa_asyncq)) + (sizeof(pa_atomic_ptr_t) * size));
+
+ l->size = size;
+
+ PA_LLIST_HEAD_INIT(struct localq, l->localq);
+ l->last_localq = NULL;
+ l->waiting_for_post = false;
+
+ 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) {
+ struct localq *q;
+ pa_assert(l);
+
+ if (free_cb) {
+ void *p;
+
+ while ((p = pa_asyncq_pop(l, 0)))
+ free_cb(p);
+ }
+
+ while ((q = l->localq)) {
+ if (free_cb)
+ free_cb(q->data);
+
+ PA_LLIST_REMOVE(struct localq, l->localq, q);
+
+ if (pa_flist_push(PA_STATIC_FLIST_GET(localq), q) < 0)
+ pa_xfree(q);
+ }
+
+ pa_fdsem_free(l->read_fdsem);
+ pa_fdsem_free(l->write_fdsem);
+ pa_xfree(l);
+}
+
+static int push(pa_asyncq*l, void *p, bool wait_op) {
+ unsigned 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_op)
+ 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;
+}
+
+static bool flush_postq(pa_asyncq *l, bool wait_op) {
+ struct localq *q;
+
+ pa_assert(l);
+
+ while ((q = l->last_localq)) {
+
+ if (push(l, q->data, wait_op) < 0)
+ return false;
+
+ l->last_localq = q->prev;
+
+ PA_LLIST_REMOVE(struct localq, l->localq, q);
+
+ if (pa_flist_push(PA_STATIC_FLIST_GET(localq), q) < 0)
+ pa_xfree(q);
+ }
+
+ return true;
+}
+
+int pa_asyncq_push(pa_asyncq*l, void *p, bool wait_op) {
+ pa_assert(l);
+
+ if (!flush_postq(l, wait_op))
+ return -1;
+
+ return push(l, p, wait_op);
+}
+
+void pa_asyncq_post(pa_asyncq*l, void *p) {
+ struct localq *q;
+
+ pa_assert(l);
+ pa_assert(p);
+
+ if (flush_postq(l, false))
+ if (pa_asyncq_push(l, p, false) >= 0)
+ return;
+
+ /* OK, we couldn't push anything in the queue. So let's queue it
+ * locally and push it later */
+
+ if (pa_log_ratelimit(PA_LOG_WARN))
+ pa_log_warn("q overrun, queuing locally");
+
+ if (!(q = pa_flist_pop(PA_STATIC_FLIST_GET(localq))))
+ q = pa_xnew(struct localq, 1);
+
+ q->data = p;
+ PA_LLIST_PREPEND(struct localq, l->localq, q);
+
+ if (!l->last_localq)
+ l->last_localq = q;
+
+ return;
+}
+
+void* pa_asyncq_pop(pa_asyncq*l, bool wait_op) {
+ unsigned 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_op)
+ 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_read_fd(pa_asyncq *q) {
+ pa_assert(q);
+
+ return pa_fdsem_get(q->write_fdsem);
+}
+
+int pa_asyncq_read_before_poll(pa_asyncq *l) {
+ unsigned 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;
+ }
+}
+
+void pa_asyncq_read_after_poll(pa_asyncq *l) {
+ pa_assert(l);
+
+ pa_fdsem_after_poll(l->write_fdsem);
+}
+
+int pa_asyncq_write_fd(pa_asyncq *q) {
+ pa_assert(q);
+
+ return pa_fdsem_get(q->read_fdsem);
+}
+
+void pa_asyncq_write_before_poll(pa_asyncq *l) {
+ pa_assert(l);
+
+ for (;;) {
+
+ if (flush_postq(l, false))
+ break;
+
+ if (pa_fdsem_before_poll(l->read_fdsem) >= 0) {
+ l->waiting_for_post = true;
+ break;
+ }
+ }
+}
+
+void pa_asyncq_write_after_poll(pa_asyncq *l) {
+ pa_assert(l);
+
+ if (l->waiting_for_post) {
+ pa_fdsem_after_poll(l->read_fdsem);
+ l->waiting_for_post = false;
+ }
+}
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