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 "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 }