xref: /openbmc/qemu/ui/vnc-jobs.c (revision fee5b753)
1 /*
2  * QEMU VNC display driver
3  *
4  * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
5  * Copyright (C) 2006 Fabrice Bellard
6  * Copyright (C) 2009 Red Hat, Inc
7  * Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>
8  *
9  * Permission is hereby granted, free of charge, to any person obtaining a copy
10  * of this software and associated documentation files (the "Software"), to deal
11  * in the Software without restriction, including without limitation the rights
12  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13  * copies of the Software, and to permit persons to whom the Software is
14  * furnished to do so, subject to the following conditions:
15  *
16  * The above copyright notice and this permission notice shall be included in
17  * all copies or substantial portions of the Software.
18  *
19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
22  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
24  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
25  * THE SOFTWARE.
26  */
27 
28 
29 #include "qemu/osdep.h"
30 #include "vnc.h"
31 #include "vnc-jobs.h"
32 #include "qemu/sockets.h"
33 #include "qemu/main-loop.h"
34 #include "block/aio.h"
35 
36 /*
37  * Locking:
38  *
39  * There are three levels of locking:
40  * - jobs queue lock: for each operation on the queue (push, pop, isEmpty?)
41  * - VncDisplay global lock: mainly used for framebuffer updates to avoid
42  *                      screen corruption if the framebuffer is updated
43  *                      while the worker is doing something.
44  * - VncState::output lock: used to make sure the output buffer is not corrupted
45  *                          if two threads try to write on it at the same time
46  *
47  * While the VNC worker thread is working, the VncDisplay global lock is held
48  * to avoid screen corruption (this does not block vnc_refresh() because it
49  * uses trylock()) but the output lock is not held because the thread works on
50  * its own output buffer.
51  * When the encoding job is done, the worker thread will hold the output lock
52  * and copy its output buffer in vs->output.
53  */
54 
55 struct VncJobQueue {
56     QemuCond cond;
57     QemuMutex mutex;
58     QemuThread thread;
59     bool exit;
60     QTAILQ_HEAD(, VncJob) jobs;
61 };
62 
63 typedef struct VncJobQueue VncJobQueue;
64 
65 /*
66  * We use a single global queue, but most of the functions are
67  * already reentrant, so we can easily add more than one encoding thread
68  */
69 static VncJobQueue *queue;
70 
71 static void vnc_lock_queue(VncJobQueue *queue)
72 {
73     qemu_mutex_lock(&queue->mutex);
74 }
75 
76 static void vnc_unlock_queue(VncJobQueue *queue)
77 {
78     qemu_mutex_unlock(&queue->mutex);
79 }
80 
81 VncJob *vnc_job_new(VncState *vs)
82 {
83     VncJob *job = g_new0(VncJob, 1);
84 
85     job->vs = vs;
86     vnc_lock_queue(queue);
87     QLIST_INIT(&job->rectangles);
88     vnc_unlock_queue(queue);
89     return job;
90 }
91 
92 int vnc_job_add_rect(VncJob *job, int x, int y, int w, int h)
93 {
94     VncRectEntry *entry = g_new0(VncRectEntry, 1);
95 
96     entry->rect.x = x;
97     entry->rect.y = y;
98     entry->rect.w = w;
99     entry->rect.h = h;
100 
101     vnc_lock_queue(queue);
102     QLIST_INSERT_HEAD(&job->rectangles, entry, next);
103     vnc_unlock_queue(queue);
104     return 1;
105 }
106 
107 void vnc_job_push(VncJob *job)
108 {
109     vnc_lock_queue(queue);
110     if (queue->exit || QLIST_EMPTY(&job->rectangles)) {
111         g_free(job);
112     } else {
113         QTAILQ_INSERT_TAIL(&queue->jobs, job, next);
114         qemu_cond_broadcast(&queue->cond);
115     }
116     vnc_unlock_queue(queue);
117 }
118 
119 static bool vnc_has_job_locked(VncState *vs)
120 {
121     VncJob *job;
122 
123     QTAILQ_FOREACH(job, &queue->jobs, next) {
124         if (job->vs == vs || !vs) {
125             return true;
126         }
127     }
128     return false;
129 }
130 
131 bool vnc_has_job(VncState *vs)
132 {
133     bool ret;
134 
135     vnc_lock_queue(queue);
136     ret = vnc_has_job_locked(vs);
137     vnc_unlock_queue(queue);
138     return ret;
139 }
140 
141 void vnc_jobs_clear(VncState *vs)
142 {
143     VncJob *job, *tmp;
144 
145     vnc_lock_queue(queue);
146     QTAILQ_FOREACH_SAFE(job, &queue->jobs, next, tmp) {
147         if (job->vs == vs || !vs) {
148             QTAILQ_REMOVE(&queue->jobs, job, next);
149         }
150     }
151     vnc_unlock_queue(queue);
152 }
153 
154 void vnc_jobs_join(VncState *vs)
155 {
156     vnc_lock_queue(queue);
157     while (vnc_has_job_locked(vs)) {
158         qemu_cond_wait(&queue->cond, &queue->mutex);
159     }
160     vnc_unlock_queue(queue);
161     vnc_jobs_consume_buffer(vs);
162 }
163 
164 void vnc_jobs_consume_buffer(VncState *vs)
165 {
166     bool flush;
167 
168     vnc_lock_output(vs);
169     if (vs->jobs_buffer.offset) {
170         if (vs->ioc != NULL && buffer_empty(&vs->output)) {
171             if (vs->ioc_tag) {
172                 g_source_remove(vs->ioc_tag);
173             }
174             vs->ioc_tag = qio_channel_add_watch(
175                 vs->ioc, G_IO_IN | G_IO_OUT, vnc_client_io, vs, NULL);
176         }
177         buffer_move(&vs->output, &vs->jobs_buffer);
178     }
179     flush = vs->ioc != NULL && vs->abort != true;
180     vnc_unlock_output(vs);
181 
182     if (flush) {
183       vnc_flush(vs);
184     }
185 }
186 
187 /*
188  * Copy data for local use
189  */
190 static void vnc_async_encoding_start(VncState *orig, VncState *local)
191 {
192     buffer_init(&local->output, "vnc-worker-output");
193     local->sioc = NULL; /* Don't do any network work on this thread */
194     local->ioc = NULL; /* Don't do any network work on this thread */
195 
196     local->vnc_encoding = orig->vnc_encoding;
197     local->features = orig->features;
198     local->vd = orig->vd;
199     local->lossy_rect = orig->lossy_rect;
200     local->write_pixels = orig->write_pixels;
201     local->client_pf = orig->client_pf;
202     local->client_be = orig->client_be;
203     local->tight = orig->tight;
204     local->zlib = orig->zlib;
205     local->hextile = orig->hextile;
206     local->zrle = orig->zrle;
207 }
208 
209 static void vnc_async_encoding_end(VncState *orig, VncState *local)
210 {
211     orig->tight = local->tight;
212     orig->zlib = local->zlib;
213     orig->hextile = local->hextile;
214     orig->zrle = local->zrle;
215     orig->lossy_rect = local->lossy_rect;
216 }
217 
218 static int vnc_worker_thread_loop(VncJobQueue *queue)
219 {
220     VncJob *job;
221     VncRectEntry *entry, *tmp;
222     VncState vs = {};
223     int n_rectangles;
224     int saved_offset;
225 
226     vnc_lock_queue(queue);
227     while (QTAILQ_EMPTY(&queue->jobs) && !queue->exit) {
228         qemu_cond_wait(&queue->cond, &queue->mutex);
229     }
230     /* Here job can only be NULL if queue->exit is true */
231     job = QTAILQ_FIRST(&queue->jobs);
232     vnc_unlock_queue(queue);
233 
234     if (queue->exit) {
235         return -1;
236     }
237 
238     vnc_lock_output(job->vs);
239     if (job->vs->ioc == NULL || job->vs->abort == true) {
240         vnc_unlock_output(job->vs);
241         goto disconnected;
242     }
243     if (buffer_empty(&job->vs->output)) {
244         /*
245          * Looks like a NOP as it obviously moves no data.  But it
246          * moves the empty buffer, so we don't have to malloc a new
247          * one for vs.output
248          */
249         buffer_move_empty(&vs.output, &job->vs->output);
250     }
251     vnc_unlock_output(job->vs);
252 
253     /* Make a local copy of vs and switch output buffers */
254     vnc_async_encoding_start(job->vs, &vs);
255 
256     /* Start sending rectangles */
257     n_rectangles = 0;
258     vnc_write_u8(&vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
259     vnc_write_u8(&vs, 0);
260     saved_offset = vs.output.offset;
261     vnc_write_u16(&vs, 0);
262 
263     vnc_lock_display(job->vs->vd);
264     QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
265         int n;
266 
267         if (job->vs->ioc == NULL) {
268             vnc_unlock_display(job->vs->vd);
269             /* Copy persistent encoding data */
270             vnc_async_encoding_end(job->vs, &vs);
271             goto disconnected;
272         }
273 
274         n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
275                                         entry->rect.w, entry->rect.h);
276 
277         if (n >= 0) {
278             n_rectangles += n;
279         }
280         g_free(entry);
281     }
282     vnc_unlock_display(job->vs->vd);
283 
284     /* Put n_rectangles at the beginning of the message */
285     vs.output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
286     vs.output.buffer[saved_offset + 1] = n_rectangles & 0xFF;
287 
288     vnc_lock_output(job->vs);
289     if (job->vs->ioc != NULL) {
290         buffer_move(&job->vs->jobs_buffer, &vs.output);
291         /* Copy persistent encoding data */
292         vnc_async_encoding_end(job->vs, &vs);
293 
294 	qemu_bh_schedule(job->vs->bh);
295     }  else {
296         buffer_reset(&vs.output);
297         /* Copy persistent encoding data */
298         vnc_async_encoding_end(job->vs, &vs);
299     }
300     vnc_unlock_output(job->vs);
301 
302 disconnected:
303     vnc_lock_queue(queue);
304     QTAILQ_REMOVE(&queue->jobs, job, next);
305     vnc_unlock_queue(queue);
306     qemu_cond_broadcast(&queue->cond);
307     g_free(job);
308     return 0;
309 }
310 
311 static VncJobQueue *vnc_queue_init(void)
312 {
313     VncJobQueue *queue = g_new0(VncJobQueue, 1);
314 
315     qemu_cond_init(&queue->cond);
316     qemu_mutex_init(&queue->mutex);
317     QTAILQ_INIT(&queue->jobs);
318     return queue;
319 }
320 
321 static void vnc_queue_clear(VncJobQueue *q)
322 {
323     qemu_cond_destroy(&queue->cond);
324     qemu_mutex_destroy(&queue->mutex);
325     g_free(q);
326     queue = NULL; /* Unset global queue */
327 }
328 
329 static void *vnc_worker_thread(void *arg)
330 {
331     VncJobQueue *queue = arg;
332 
333     qemu_thread_get_self(&queue->thread);
334 
335     while (!vnc_worker_thread_loop(queue)) ;
336     vnc_queue_clear(queue);
337     return NULL;
338 }
339 
340 static bool vnc_worker_thread_running(void)
341 {
342     return queue; /* Check global queue */
343 }
344 
345 void vnc_start_worker_thread(void)
346 {
347     VncJobQueue *q;
348 
349     if (vnc_worker_thread_running())
350         return ;
351 
352     q = vnc_queue_init();
353     qemu_thread_create(&q->thread, "vnc_worker", vnc_worker_thread, q,
354                        QEMU_THREAD_DETACHED);
355     queue = q; /* Set global queue */
356 }
357