4 * Copyright (c) 2003-2008 Fabrice Bellard
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
25 #include "qemu-common.h"
26 #include "block/aio.h"
27 #include "block/thread-pool.h"
28 #include "qemu/main-loop.h"
29 #include "qemu/atomic.h"
31 /***********************************************************/
32 /* bottom halves (can be seen as timers which expire ASAP) */
44 QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
47 bh = g_malloc0(sizeof(QEMUBH));
51 qemu_mutex_lock(&ctx->bh_lock);
52 bh->next = ctx->first_bh;
53 /* Make sure that the members are ready before putting bh into list */
56 qemu_mutex_unlock(&ctx->bh_lock);
60 /* Multiple occurrences of aio_bh_poll cannot be called concurrently */
61 int aio_bh_poll(AioContext *ctx)
63 QEMUBH *bh, **bhp, *next;
69 for (bh = ctx->first_bh; bh; bh = next) {
70 /* Make sure that fetching bh happens before accessing its members */
71 smp_read_barrier_depends();
73 if (!bh->deleted && bh->scheduled) {
75 /* Paired with write barrier in bh schedule to ensure reading for
76 * idle & callbacks coming after bh's scheduling.
88 /* remove deleted bhs */
89 if (!ctx->walking_bh) {
90 qemu_mutex_lock(&ctx->bh_lock);
101 qemu_mutex_unlock(&ctx->bh_lock);
107 void qemu_bh_schedule_idle(QEMUBH *bh)
112 /* Make sure that idle & any writes needed by the callback are done
113 * before the locations are read in the aio_bh_poll.
119 void qemu_bh_schedule(QEMUBH *bh)
128 * 1. idle & any writes needed by the callback are done before the
129 * locations are read in the aio_bh_poll.
130 * 2. ctx is loaded before scheduled is set and the callback has a chance
139 /* This func is async.
141 void qemu_bh_cancel(QEMUBH *bh)
146 /* This func is async.The bottom half will do the delete action at the finial
149 void qemu_bh_delete(QEMUBH *bh)
156 aio_compute_timeout(AioContext *ctx)
162 for (bh = ctx->first_bh; bh; bh = bh->next) {
163 if (!bh->deleted && bh->scheduled) {
165 /* idle bottom halves will be polled at least
169 /* non-idle bottom halves will be executed
176 deadline = timerlistgroup_deadline_ns(&ctx->tlg);
180 return qemu_soonest_timeout(timeout, deadline);
185 aio_ctx_prepare(GSource *source, gint *timeout)
187 AioContext *ctx = (AioContext *) source;
189 /* We assume there is no timeout already supplied */
190 *timeout = qemu_timeout_ns_to_ms(aio_compute_timeout(ctx));
191 return *timeout == 0;
195 aio_ctx_check(GSource *source)
197 AioContext *ctx = (AioContext *) source;
200 for (bh = ctx->first_bh; bh; bh = bh->next) {
201 if (!bh->deleted && bh->scheduled) {
205 return aio_pending(ctx) || (timerlistgroup_deadline_ns(&ctx->tlg) == 0);
209 aio_ctx_dispatch(GSource *source,
210 GSourceFunc callback,
213 AioContext *ctx = (AioContext *) source;
215 assert(callback == NULL);
216 aio_poll(ctx, false);
221 aio_ctx_finalize(GSource *source)
223 AioContext *ctx = (AioContext *) source;
225 thread_pool_free(ctx->thread_pool);
226 aio_set_event_notifier(ctx, &ctx->notifier, NULL);
227 event_notifier_cleanup(&ctx->notifier);
228 rfifolock_destroy(&ctx->lock);
229 qemu_mutex_destroy(&ctx->bh_lock);
230 g_array_free(ctx->pollfds, TRUE);
231 timerlistgroup_deinit(&ctx->tlg);
234 static GSourceFuncs aio_source_funcs = {
241 GSource *aio_get_g_source(AioContext *ctx)
243 g_source_ref(&ctx->source);
247 ThreadPool *aio_get_thread_pool(AioContext *ctx)
249 if (!ctx->thread_pool) {
250 ctx->thread_pool = thread_pool_new(ctx);
252 return ctx->thread_pool;
255 void aio_set_dispatching(AioContext *ctx, bool dispatching)
257 ctx->dispatching = dispatching;
259 /* Write ctx->dispatching before reading e.g. bh->scheduled.
260 * Optimization: this is only needed when we're entering the "unsafe"
261 * phase where other threads must call event_notifier_set.
267 void aio_notify(AioContext *ctx)
269 /* Write e.g. bh->scheduled before reading ctx->dispatching. */
271 if (!ctx->dispatching) {
272 event_notifier_set(&ctx->notifier);
276 static void aio_timerlist_notify(void *opaque)
281 static void aio_rfifolock_cb(void *opaque)
283 /* Kick owner thread in case they are blocked in aio_poll() */
287 AioContext *aio_context_new(void)
290 ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext));
291 ctx->pollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
292 ctx->thread_pool = NULL;
293 qemu_mutex_init(&ctx->bh_lock);
294 rfifolock_init(&ctx->lock, aio_rfifolock_cb, ctx);
295 event_notifier_init(&ctx->notifier, false);
296 aio_set_event_notifier(ctx, &ctx->notifier,
297 (EventNotifierHandler *)
298 event_notifier_test_and_clear);
299 timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
304 void aio_context_ref(AioContext *ctx)
306 g_source_ref(&ctx->source);
309 void aio_context_unref(AioContext *ctx)
311 g_source_unref(&ctx->source);
314 void aio_context_acquire(AioContext *ctx)
316 rfifolock_lock(&ctx->lock);
319 void aio_context_release(AioContext *ctx)
321 rfifolock_unlock(&ctx->lock);