ui/vnc-jobs-async.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
  32 /*
  33  * Locking:
  34  *
  35  * There is three levels of locking:
  36  * - jobs queue lock: for each operation on the queue (push, pop, isEmpty?)
  37  * - VncDisplay global lock: mainly used for framebuffer updates to avoid
  38  *                      screen corruption if the framebuffer is updated
  39  *                      while the worker is doing something.
  40  * - VncState::output lock: used to make sure the output buffer is not corrupted
  41  *                       if two threads try to write on it at the same time
  42  *
  43  * While the VNC worker thread is working, the VncDisplay global lock is hold
  44  * to avoid screen corruptions (this does not block vnc_refresh() because it
  45  * uses trylock()) but the output lock is not hold because the thread work on
  46  * its own output buffer.
  47  * When the encoding job is done, the worker thread will hold the output lock
  48  * and copy its output buffer in vs->output.
  49 */
  50
  51 struct VncJobQueue {
  52     QemuCond cond;
  53     QemuMutex mutex;
  54     QemuThread thread;
  55     Buffer buffer;
  56     bool exit;
  57     QTAILQ_HEAD(, VncJob) jobs;
  58 };
  59
  60 typedef struct VncJobQueue VncJobQueue;
  61
  62 /*
  63  * We use a single global queue, but most of the functions are
  64  * already reetrant, so we can easilly add more than one encoding thread
  65  */
  66 static VncJobQueue *queue;
  67
  68 static void vnc_lock_queue(VncJobQueue *queue)
  69 {
  70     qemu_mutex_lock(&queue->mutex);
  71 }
  72
  73 static void vnc_unlock_queue(VncJobQueue *queue)
  74 {
  75     qemu_mutex_unlock(&queue->mutex);
  76 }
  77
  78 VncJob *vnc_job_new(VncState *vs)
  79 {
  80     VncJob *job = qemu_mallocz(sizeof(VncJob));
  81
  82     job->vs = vs;
  83     vnc_lock_queue(queue);
  84     QLIST_INIT(&job->rectangles);
  85     vnc_unlock_queue(queue);
  86     return job;
  87 }
  88
  89 int vnc_job_add_rect(VncJob *job, int x, int y, int w, int h)
  90 {
  91     VncRectEntry *entry = qemu_mallocz(sizeof(VncRectEntry));
  92
  93     entry->rect.x = x;
  94     entry->rect.y = y;
  95     entry->rect.w = w;
  96     entry->rect.h = h;
  97
  98     vnc_lock_queue(queue);
  99     QLIST_INSERT_HEAD(&job->rectangles, entry, next);
 100     vnc_unlock_queue(queue);
 101     return 1;
 102 }
 103
 104 void vnc_job_push(VncJob *job)
 105 {
 106     vnc_lock_queue(queue);
 107     if (queue->exit || QLIST_EMPTY(&job->rectangles)) {
 108         qemu_free(job);
 109     } else {
 110         QTAILQ_INSERT_TAIL(&queue->jobs, job, next);
 111         qemu_cond_broadcast(&queue->cond);
 112     }
 113     vnc_unlock_queue(queue);
 114 }
 115
 116 static bool vnc_has_job_locked(VncState *vs)
 117 {
 118     VncJob *job;
 119
 120     QTAILQ_FOREACH(job, &queue->jobs, next) {
 121         if (job->vs == vs || !vs) {
 122             return true;
 123         }
 124     }
 125     return false;
 126 }
 127
 128 bool vnc_has_job(VncState *vs)
 129 {
 130     bool ret;
 131
 132     vnc_lock_queue(queue);
 133     ret = vnc_has_job_locked(vs);
 134     vnc_unlock_queue(queue);
 135     return ret;
 136 }
 137
 138 void vnc_jobs_clear(VncState *vs)
 139 {
 140     VncJob *job, *tmp;
 141
 142     vnc_lock_queue(queue);
 143     QTAILQ_FOREACH_SAFE(job, &queue->jobs, next, tmp) {
 144         if (job->vs == vs || !vs) {
 145             QTAILQ_REMOVE(&queue->jobs, job, next);
 146         }
 147     }
 148     vnc_unlock_queue(queue);
 149 }
 150
 151 void vnc_jobs_join(VncState *vs)
 152 {
 153     vnc_lock_queue(queue);
 154     while (vnc_has_job_locked(vs)) {
 155         qemu_cond_wait(&queue->cond, &queue->mutex);
 156     }
 157     vnc_unlock_queue(queue);
 158 }
 159
 160 /*
 161  * Copy data for local use
 162  */
 163 static void vnc_async_encoding_start(VncState *orig, VncState *local)
 164 {
 165     local->vnc_encoding = orig->vnc_encoding;
 166     local->features = orig->features;
 167     local->ds = orig->ds;
 168     local->vd = orig->vd;
 169     local->lossy_rect = orig->lossy_rect;
 170     local->write_pixels = orig->write_pixels;
 171     local->clientds = orig->clientds;
 172     local->tight = orig->tight;
 173     local->zlib = orig->zlib;
 174     local->hextile = orig->hextile;
 175     local->zrle = orig->zrle;
 176     local->output =  queue->buffer;
 177     local->csock = -1; /* Don't do any network work on this thread */
 178
 179     buffer_reset(&local->output);
 180 }
 181
 182 static void vnc_async_encoding_end(VncState *orig, VncState *local)
 183 {
 184     orig->tight = local->tight;
 185     orig->zlib = local->zlib;
 186     orig->hextile = local->hextile;
 187     orig->zrle = local->zrle;
 188     orig->lossy_rect = local->lossy_rect;
 189
 190     queue->buffer = local->output;
 191 }
 192
 193 static int vnc_worker_thread_loop(VncJobQueue *queue)
 194 {
 195     VncJob *job;
 196     VncRectEntry *entry, *tmp;
 197     VncState vs;
 198     int n_rectangles;
 199     int saved_offset;
 200     bool flush;
 201
 202     vnc_lock_queue(queue);
 203     while (QTAILQ_EMPTY(&queue->jobs) && !queue->exit) {
 204         qemu_cond_wait(&queue->cond, &queue->mutex);
 205     }
 206     /* Here job can only be NULL if queue->exit is true */
 207     job = QTAILQ_FIRST(&queue->jobs);
 208     vnc_unlock_queue(queue);
 209
 210     if (queue->exit) {
 211         return -1;
 212     }
 213
 214     vnc_lock_output(job->vs);
 215     if (job->vs->csock == -1 || job->vs->abort == true) {
 216         goto disconnected;
 217     }
 218     vnc_unlock_output(job->vs);
 219
 220     /* Make a local copy of vs and switch output buffers */
 221     vnc_async_encoding_start(job->vs, &vs);
 222
 223     /* Start sending rectangles */
 224     n_rectangles = 0;
 225     vnc_write_u8(&vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
 226     vnc_write_u8(&vs, 0);
 227     saved_offset = vs.output.offset;
 228     vnc_write_u16(&vs, 0);
 229
 230     vnc_lock_display(job->vs->vd);
 231     QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
 232         int n;
 233
 234         if (job->vs->csock == -1) {
 235             vnc_unlock_display(job->vs->vd);
 236             /* output mutex must be locked before going to
 237              * disconnected:
 238              */
 239             vnc_lock_output(job->vs);
 240             goto disconnected;
 241         }
 242
 243         n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
 244                                         entry->rect.w, entry->rect.h);
 245
 246         if (n >= 0) {
 247             n_rectangles += n;
 248         }
 249         qemu_free(entry);
 250     }
 251     vnc_unlock_display(job->vs->vd);
 252
 253     /* Put n_rectangles at the beginning of the message */
 254     vs.output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
 255     vs.output.buffer[saved_offset + 1] = n_rectangles & 0xFF;
 256
 257     /* Switch back buffers */
 258     vnc_lock_output(job->vs);
 259     if (job->vs->csock == -1) {
 260         goto disconnected;
 261     }
 262
 263     vnc_write(job->vs, vs.output.buffer, vs.output.offset);
 264
 265 disconnected:
 266     /* Copy persistent encoding data */
 267     vnc_async_encoding_end(job->vs, &vs);
 268     flush = (job->vs->csock != -1 && job->vs->abort != true);
 269     vnc_unlock_output(job->vs);
 270
 271     if (flush) {
 272         vnc_flush(job->vs);
 273     }
 274
 275     vnc_lock_queue(queue);
 276     QTAILQ_REMOVE(&queue->jobs, job, next);
 277     vnc_unlock_queue(queue);
 278     qemu_cond_broadcast(&queue->cond);
 279     qemu_free(job);
 280     return 0;
 281 }
 282
 283 static VncJobQueue *vnc_queue_init(void)
 284 {
 285     VncJobQueue *queue = qemu_mallocz(sizeof(VncJobQueue));
 286
 287     qemu_cond_init(&queue->cond);
 288     qemu_mutex_init(&queue->mutex);
 289     QTAILQ_INIT(&queue->jobs);
 290     return queue;
 291 }
 292
 293 static void vnc_queue_clear(VncJobQueue *q)
 294 {
 295     qemu_cond_destroy(&queue->cond);
 296     qemu_mutex_destroy(&queue->mutex);
 297     buffer_free(&queue->buffer);
 298     qemu_free(q);
 299     queue = NULL; /* Unset global queue */
 300 }
 301
 302 static void *vnc_worker_thread(void *arg)
 303 {
 304     VncJobQueue *queue = arg;
 305
 306     qemu_thread_get_self(&queue->thread);
 307
 308     while (!vnc_worker_thread_loop(queue)) ;
 309     vnc_queue_clear(queue);
 310     return NULL;
 311 }
 312
 313 void vnc_start_worker_thread(void)
 314 {
 315     VncJobQueue *q;
 316
 317     if (vnc_worker_thread_running())
 318         return ;
 319
 320     q = vnc_queue_init();
 321     qemu_thread_create(&q->thread, vnc_worker_thread, q);
 322     queue = q; /* Set global queue */
 323 }
 324
 325 bool vnc_worker_thread_running(void)
 326 {
 327     return queue; /* Check global queue */
 328 }
 329
 330 void vnc_stop_worker_thread(void)
 331 {
 332     if (!vnc_worker_thread_running())
 333         return ;
 334
 335     /* Remove all jobs and wake up the thread */
 336     vnc_lock_queue(queue);
 337     queue->exit = true;
 338     vnc_unlock_queue(queue);
 339     vnc_jobs_clear(NULL);
 340     qemu_cond_broadcast(&queue->cond);
 341 }