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 "block/aio.h"
  33
  34 /*
  35  * Locking:
  36  *
  37  * There are three levels of locking:
  38  * - jobs queue lock: for each operation on the queue (push, pop, isEmpty?)
  39  * - VncDisplay global lock: mainly used for framebuffer updates to avoid
  40  *                      screen corruption if the framebuffer is updated
  41  *                      while the worker is doing something.
  42  * - VncState::output lock: used to make sure the output buffer is not corrupted
  43  *                          if two threads try to write on it at the same time
  44  *
  45  * While the VNC worker thread is working, the VncDisplay global lock is held
  46  * to avoid screen corruption (this does not block vnc_refresh() because it
  47  * uses trylock()) but the output lock is not held because the thread works on
  48  * its own output buffer.
  49  * When the encoding job is done, the worker thread will hold the output lock
  50  * and copy its output buffer in vs->output.
  51  */
  52
  53 struct VncJobQueue {
  54     QemuCond cond;
  55     QemuMutex mutex;
  56     QemuThread thread;
  57     Buffer buffer;
  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         vnc_write(vs, vs->jobs_buffer.buffer, vs->jobs_buffer.offset);
 170         buffer_reset(&vs->jobs_buffer);
 171     }
 172     flush = vs->csock != -1 && vs->abort != true;
 173     vnc_unlock_output(vs);
 174
 175     if (flush) {
 176       vnc_flush(vs);
 177     }
 178 }
 179
 180 /*
 181  * Copy data for local use
 182  */
 183 static void vnc_async_encoding_start(VncState *orig, VncState *local)
 184 {
 185     local->vnc_encoding = orig->vnc_encoding;
 186     local->features = orig->features;
 187     local->vd = orig->vd;
 188     local->lossy_rect = orig->lossy_rect;
 189     local->write_pixels = orig->write_pixels;
 190     local->client_pf = orig->client_pf;
 191     local->client_be = orig->client_be;
 192     local->tight = orig->tight;
 193     local->zlib = orig->zlib;
 194     local->hextile = orig->hextile;
 195     local->zrle = orig->zrle;
 196     local->output =  queue->buffer;
 197     local->csock = -1; /* Don't do any network work on this thread */
 198
 199     buffer_reset(&local->output);
 200 }
 201
 202 static void vnc_async_encoding_end(VncState *orig, VncState *local)
 203 {
 204     orig->tight = local->tight;
 205     orig->zlib = local->zlib;
 206     orig->hextile = local->hextile;
 207     orig->zrle = local->zrle;
 208     orig->lossy_rect = local->lossy_rect;
 209
 210     queue->buffer = local->output;
 211 }
 212
 213 static int vnc_worker_thread_loop(VncJobQueue *queue)
 214 {
 215     VncJob *job;
 216     VncRectEntry *entry, *tmp;
 217     VncState vs;
 218     int n_rectangles;
 219     int saved_offset;
 220
 221     vnc_lock_queue(queue);
 222     while (QTAILQ_EMPTY(&queue->jobs) && !queue->exit) {
 223         qemu_cond_wait(&queue->cond, &queue->mutex);
 224     }
 225     /* Here job can only be NULL if queue->exit is true */
 226     job = QTAILQ_FIRST(&queue->jobs);
 227     vnc_unlock_queue(queue);
 228
 229     if (queue->exit) {
 230         return -1;
 231     }
 232
 233     vnc_lock_output(job->vs);
 234     if (job->vs->csock == -1 || job->vs->abort == true) {
 235         vnc_unlock_output(job->vs);
 236         goto disconnected;
 237     }
 238     vnc_unlock_output(job->vs);
 239
 240     /* Make a local copy of vs and switch output buffers */
 241     vnc_async_encoding_start(job->vs, &vs);
 242
 243     /* Start sending rectangles */
 244     n_rectangles = 0;
 245     vnc_write_u8(&vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
 246     vnc_write_u8(&vs, 0);
 247     saved_offset = vs.output.offset;
 248     vnc_write_u16(&vs, 0);
 249
 250     vnc_lock_display(job->vs->vd);
 251     QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
 252         int n;
 253
 254         if (job->vs->csock == -1) {
 255             vnc_unlock_display(job->vs->vd);
 256             /* Copy persistent encoding data */
 257             vnc_async_encoding_end(job->vs, &vs);
 258             goto disconnected;
 259         }
 260
 261         n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
 262                                         entry->rect.w, entry->rect.h);
 263
 264         if (n >= 0) {
 265             n_rectangles += n;
 266         }
 267         g_free(entry);
 268     }
 269     vnc_unlock_display(job->vs->vd);
 270
 271     /* Put n_rectangles at the beginning of the message */
 272     vs.output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
 273     vs.output.buffer[saved_offset + 1] = n_rectangles & 0xFF;
 274
 275     vnc_lock_output(job->vs);
 276     if (job->vs->csock != -1) {
 277         buffer_reserve(&job->vs->jobs_buffer, vs.output.offset);
 278         buffer_append(&job->vs->jobs_buffer, vs.output.buffer,
 279                       vs.output.offset);
 280         /* Copy persistent encoding data */
 281         vnc_async_encoding_end(job->vs, &vs);
 282
 283         qemu_bh_schedule(job->vs->bh);
 284     }  else {
 285         /* Copy persistent encoding data */
 286         vnc_async_encoding_end(job->vs, &vs);
 287     }
 288     vnc_unlock_output(job->vs);
 289
 290 disconnected:
 291     vnc_lock_queue(queue);
 292     QTAILQ_REMOVE(&queue->jobs, job, next);
 293     vnc_unlock_queue(queue);
 294     qemu_cond_broadcast(&queue->cond);
 295     g_free(job);
 296     return 0;
 297 }
 298
 299 static VncJobQueue *vnc_queue_init(void)
 300 {
 301     VncJobQueue *queue = g_new0(VncJobQueue, 1);
 302
 303     qemu_cond_init(&queue->cond);
 304     qemu_mutex_init(&queue->mutex);
 305     QTAILQ_INIT(&queue->jobs);
 306     return queue;
 307 }
 308
 309 static void vnc_queue_clear(VncJobQueue *q)
 310 {
 311     qemu_cond_destroy(&queue->cond);
 312     qemu_mutex_destroy(&queue->mutex);
 313     buffer_free(&queue->buffer);
 314     g_free(q);
 315     queue = NULL; /* Unset global queue */
 316 }
 317
 318 static void *vnc_worker_thread(void *arg)
 319 {
 320     VncJobQueue *queue = arg;
 321
 322     qemu_thread_get_self(&queue->thread);
 323
 324     while (!vnc_worker_thread_loop(queue)) ;
 325     vnc_queue_clear(queue);
 326     return NULL;
 327 }
 328
 329 static bool vnc_worker_thread_running(void)
 330 {
 331     return queue; /* Check global queue */
 332 }
 333
 334 void vnc_start_worker_thread(void)
 335 {
 336     VncJobQueue *q;
 337
 338     if (vnc_worker_thread_running())
 339         return ;
 340
 341     q = vnc_queue_init();
 342     qemu_thread_create(&q->thread, "vnc_worker", vnc_worker_thread, q,
 343                        QEMU_THREAD_DETACHED);
 344     queue = q; /* Set global queue */
 345 }