ui/vnc-jobs.c

   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 "vnc.h"
  30 #include "vnc-jobs.h"
  31 #include "qemu/sockets.h"
  32 #include "qemu/main-loop.h"
  33 #include "block/aio.h"
  34
  35 /*
  36  * Locking:
  37  *
  38  * There are three levels of locking:
  39  * - jobs queue lock: for each operation on the queue (push, pop, isEmpty?)
  40  * - VncDisplay global lock: mainly used for framebuffer updates to avoid
  41  *                      screen corruption if the framebuffer is updated
  42  *                      while the worker is doing something.
  43  * - VncState::output lock: used to make sure the output buffer is not corrupted
  44  *                          if two threads try to write on it at the same time
  45  *
  46  * While the VNC worker thread is working, the VncDisplay global lock is held
  47  * to avoid screen corruption (this does not block vnc_refresh() because it
  48  * uses trylock()) but the output lock is not held because the thread works on
  49  * its own output buffer.
  50  * When the encoding job is done, the worker thread will hold the output lock
  51  * and copy its output buffer in vs->output.
  52  */
  53
  54 struct VncJobQueue {
  55     QemuCond cond;
  56     QemuMutex mutex;
  57     QemuThread thread;
  58     bool exit;
  59     QTAILQ_HEAD(, VncJob) jobs;
  60 };
  61
  62 typedef struct VncJobQueue VncJobQueue;
  63
  64 /*
  65  * We use a single global queue, but most of the functions are
  66  * already reentrant, so we can easily add more than one encoding thread
  67  */
  68 static VncJobQueue *queue;
  69
  70 static void vnc_lock_queue(VncJobQueue *queue)
  71 {
  72     qemu_mutex_lock(&queue->mutex);
  73 }
  74
  75 static void vnc_unlock_queue(VncJobQueue *queue)
  76 {
  77     qemu_mutex_unlock(&queue->mutex);
  78 }
  79
  80 VncJob *vnc_job_new(VncState *vs)
  81 {
  82     VncJob *job = g_new0(VncJob, 1);
  83
  84     job->vs = vs;
  85     vnc_lock_queue(queue);
  86     QLIST_INIT(&job->rectangles);
  87     vnc_unlock_queue(queue);
  88     return job;
  89 }
  90
  91 int vnc_job_add_rect(VncJob *job, int x, int y, int w, int h)
  92 {
  93     VncRectEntry *entry = g_new0(VncRectEntry, 1);
  94
  95     entry->rect.x = x;
  96     entry->rect.y = y;
  97     entry->rect.w = w;
  98     entry->rect.h = h;
  99
 100     vnc_lock_queue(queue);
 101     QLIST_INSERT_HEAD(&job->rectangles, entry, next);
 102     vnc_unlock_queue(queue);
 103     return 1;
 104 }
 105
 106 void vnc_job_push(VncJob *job)
 107 {
 108     vnc_lock_queue(queue);
 109     if (queue->exit || QLIST_EMPTY(&job->rectangles)) {
 110         g_free(job);
 111     } else {
 112         QTAILQ_INSERT_TAIL(&queue->jobs, job, next);
 113         qemu_cond_broadcast(&queue->cond);
 114     }
 115     vnc_unlock_queue(queue);
 116 }
 117
 118 static bool vnc_has_job_locked(VncState *vs)
 119 {
 120     VncJob *job;
 121
 122     QTAILQ_FOREACH(job, &queue->jobs, next) {
 123         if (job->vs == vs || !vs) {
 124             return true;
 125         }
 126     }
 127     return false;
 128 }
 129
 130 bool vnc_has_job(VncState *vs)
 131 {
 132     bool ret;
 133
 134     vnc_lock_queue(queue);
 135     ret = vnc_has_job_locked(vs);
 136     vnc_unlock_queue(queue);
 137     return ret;
 138 }
 139
 140 void vnc_jobs_clear(VncState *vs)
 141 {
 142     VncJob *job, *tmp;
 143
 144     vnc_lock_queue(queue);
 145     QTAILQ_FOREACH_SAFE(job, &queue->jobs, next, tmp) {
 146         if (job->vs == vs || !vs) {
 147             QTAILQ_REMOVE(&queue->jobs, job, next);
 148         }
 149     }
 150     vnc_unlock_queue(queue);
 151 }
 152
 153 void vnc_jobs_join(VncState *vs)
 154 {
 155     vnc_lock_queue(queue);
 156     while (vnc_has_job_locked(vs)) {
 157         qemu_cond_wait(&queue->cond, &queue->mutex);
 158     }
 159     vnc_unlock_queue(queue);
 160     vnc_jobs_consume_buffer(vs);
 161 }
 162
 163 void vnc_jobs_consume_buffer(VncState *vs)
 164 {
 165     bool flush;
 166
 167     vnc_lock_output(vs);
 168     if (vs->jobs_buffer.offset) {
 169         if (vs->ioc != NULL && buffer_empty(&vs->output)) {
 170             if (vs->ioc_tag) {
 171                 g_source_remove(vs->ioc_tag);
 172             }
 173             vs->ioc_tag = qio_channel_add_watch(
 174                 vs->ioc, G_IO_IN | G_IO_OUT, vnc_client_io, vs, NULL);
 175         }
 176         buffer_move(&vs->output, &vs->jobs_buffer);
 177     }
 178     flush = vs->ioc != NULL && vs->abort != true;
 179     vnc_unlock_output(vs);
 180
 181     if (flush) {
 182       vnc_flush(vs);
 183     }
 184 }
 185
 186 /*
 187  * Copy data for local use
 188  */
 189 static void vnc_async_encoding_start(VncState *orig, VncState *local)
 190 {
 191     buffer_init(&local->output, "vnc-worker-output");
 192     local->sioc = NULL; /* Don't do any network work on this thread */
 193     local->ioc = NULL; /* Don't do any network work on this thread */
 194
 195     local->vnc_encoding = orig->vnc_encoding;
 196     local->features = orig->features;
 197     local->vd = orig->vd;
 198     local->lossy_rect = orig->lossy_rect;
 199     local->write_pixels = orig->write_pixels;
 200     local->client_pf = orig->client_pf;
 201     local->client_be = orig->client_be;
 202     local->tight = orig->tight;
 203     local->zlib = orig->zlib;
 204     local->hextile = orig->hextile;
 205     local->zrle = orig->zrle;
 206 }
 207
 208 static void vnc_async_encoding_end(VncState *orig, VncState *local)
 209 {
 210     orig->tight = local->tight;
 211     orig->zlib = local->zlib;
 212     orig->hextile = local->hextile;
 213     orig->zrle = local->zrle;
 214     orig->lossy_rect = local->lossy_rect;
 215 }
 216
 217 static int vnc_worker_thread_loop(VncJobQueue *queue)
 218 {
 219     VncJob *job;
 220     VncRectEntry *entry, *tmp;
 221     VncState vs = {};
 222     int n_rectangles;
 223     int saved_offset;
 224
 225     vnc_lock_queue(queue);
 226     while (QTAILQ_EMPTY(&queue->jobs) && !queue->exit) {
 227         qemu_cond_wait(&queue->cond, &queue->mutex);
 228     }
 229     /* Here job can only be NULL if queue->exit is true */
 230     job = QTAILQ_FIRST(&queue->jobs);
 231     vnc_unlock_queue(queue);
 232
 233     if (queue->exit) {
 234         return -1;
 235     }
 236
 237     vnc_lock_output(job->vs);
 238     if (job->vs->ioc == NULL || job->vs->abort == true) {
 239         vnc_unlock_output(job->vs);
 240         goto disconnected;
 241     }
 242     if (buffer_empty(&job->vs->output)) {
 243         /*
 244          * Looks like a NOP as it obviously moves no data.  But it
 245          * moves the empty buffer, so we don't have to malloc a new
 246          * one for vs.output
 247          */
 248         buffer_move_empty(&vs.output, &job->vs->output);
 249     }
 250     vnc_unlock_output(job->vs);
 251
 252     /* Make a local copy of vs and switch output buffers */
 253     vnc_async_encoding_start(job->vs, &vs);
 254
 255     /* Start sending rectangles */
 256     n_rectangles = 0;
 257     vnc_write_u8(&vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
 258     vnc_write_u8(&vs, 0);
 259     saved_offset = vs.output.offset;
 260     vnc_write_u16(&vs, 0);
 261
 262     vnc_lock_display(job->vs->vd);
 263     QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
 264         int n;
 265
 266         if (job->vs->ioc == NULL) {
 267             vnc_unlock_display(job->vs->vd);
 268             /* Copy persistent encoding data */
 269             vnc_async_encoding_end(job->vs, &vs);
 270             goto disconnected;
 271         }
 272
 273         n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
 274                                         entry->rect.w, entry->rect.h);
 275
 276         if (n >= 0) {
 277             n_rectangles += n;
 278         }
 279         g_free(entry);
 280     }
 281     vnc_unlock_display(job->vs->vd);
 282
 283     /* Put n_rectangles at the beginning of the message */
 284     vs.output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
 285     vs.output.buffer[saved_offset + 1] = n_rectangles & 0xFF;
 286
 287     vnc_lock_output(job->vs);
 288     if (job->vs->ioc != NULL) {
 289         buffer_move(&job->vs->jobs_buffer, &vs.output);
 290         /* Copy persistent encoding data */
 291         vnc_async_encoding_end(job->vs, &vs);
 292
 293         qemu_bh_schedule(job->vs->bh);
 294     }  else {
 295         buffer_reset(&vs.output);
 296         /* Copy persistent encoding data */
 297         vnc_async_encoding_end(job->vs, &vs);
 298     }
 299     vnc_unlock_output(job->vs);
 300
 301 disconnected:
 302     vnc_lock_queue(queue);
 303     QTAILQ_REMOVE(&queue->jobs, job, next);
 304     vnc_unlock_queue(queue);
 305     qemu_cond_broadcast(&queue->cond);
 306     g_free(job);
 307     return 0;
 308 }
 309
 310 static VncJobQueue *vnc_queue_init(void)
 311 {
 312     VncJobQueue *queue = g_new0(VncJobQueue, 1);
 313
 314     qemu_cond_init(&queue->cond);
 315     qemu_mutex_init(&queue->mutex);
 316     QTAILQ_INIT(&queue->jobs);
 317     return queue;
 318 }
 319
 320 static void vnc_queue_clear(VncJobQueue *q)
 321 {
 322     qemu_cond_destroy(&queue->cond);
 323     qemu_mutex_destroy(&queue->mutex);
 324     g_free(q);
 325     queue = NULL; /* Unset global queue */
 326 }
 327
 328 static void *vnc_worker_thread(void *arg)
 329 {
 330     VncJobQueue *queue = arg;
 331
 332     qemu_thread_get_self(&queue->thread);
 333
 334     while (!vnc_worker_thread_loop(queue)) ;
 335     vnc_queue_clear(queue);
 336     return NULL;
 337 }
 338
 339 static bool vnc_worker_thread_running(void)
 340 {
 341     return queue; /* Check global queue */
 342 }
 343
 344 void vnc_start_worker_thread(void)
 345 {
 346     VncJobQueue *q;
 347
 348     if (vnc_worker_thread_running())
 349         return ;
 350
 351     q = vnc_queue_init();
 352     qemu_thread_create(&q->thread, "vnc_worker", vnc_worker_thread, q,
 353                        QEMU_THREAD_DETACHED);
 354     queue = q; /* Set global queue */
 355 }