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 void vnc_jobs_join(VncState *vs)
 132 {
 133     vnc_lock_queue(queue);
 134     while (vnc_has_job_locked(vs)) {
 135         qemu_cond_wait(&queue->cond, &queue->mutex);
 136     }
 137     vnc_unlock_queue(queue);
 138     vnc_jobs_consume_buffer(vs);
 139 }
 140
 141 void vnc_jobs_consume_buffer(VncState *vs)
 142 {
 143     bool flush;
 144
 145     vnc_lock_output(vs);
 146     if (vs->jobs_buffer.offset) {
 147         if (vs->ioc != NULL && buffer_empty(&vs->output)) {
 148             if (vs->ioc_tag) {
 149                 g_source_remove(vs->ioc_tag);
 150             }
 151             vs->ioc_tag = qio_channel_add_watch(
 152                 vs->ioc, G_IO_IN | G_IO_OUT, vnc_client_io, vs, NULL);
 153         }
 154         buffer_move(&vs->output, &vs->jobs_buffer);
 155     }
 156     flush = vs->ioc != NULL && vs->abort != true;
 157     vnc_unlock_output(vs);
 158
 159     if (flush) {
 160       vnc_flush(vs);
 161     }
 162 }
 163
 164 /*
 165  * Copy data for local use
 166  */
 167 static void vnc_async_encoding_start(VncState *orig, VncState *local)
 168 {
 169     buffer_init(&local->output, "vnc-worker-output");
 170     local->sioc = NULL; /* Don't do any network work on this thread */
 171     local->ioc = NULL; /* Don't do any network work on this thread */
 172
 173     local->vnc_encoding = orig->vnc_encoding;
 174     local->features = orig->features;
 175     local->vd = orig->vd;
 176     local->lossy_rect = orig->lossy_rect;
 177     local->write_pixels = orig->write_pixels;
 178     local->client_pf = orig->client_pf;
 179     local->client_be = orig->client_be;
 180     local->tight = orig->tight;
 181     local->zlib = orig->zlib;
 182     local->hextile = orig->hextile;
 183     local->zrle = orig->zrle;
 184 }
 185
 186 static void vnc_async_encoding_end(VncState *orig, VncState *local)
 187 {
 188     orig->tight = local->tight;
 189     orig->zlib = local->zlib;
 190     orig->hextile = local->hextile;
 191     orig->zrle = local->zrle;
 192     orig->lossy_rect = local->lossy_rect;
 193 }
 194
 195 static int vnc_worker_thread_loop(VncJobQueue *queue)
 196 {
 197     VncJob *job;
 198     VncRectEntry *entry, *tmp;
 199     VncState vs = {};
 200     int n_rectangles;
 201     int saved_offset;
 202
 203     vnc_lock_queue(queue);
 204     while (QTAILQ_EMPTY(&queue->jobs) && !queue->exit) {
 205         qemu_cond_wait(&queue->cond, &queue->mutex);
 206     }
 207     /* Here job can only be NULL if queue->exit is true */
 208     job = QTAILQ_FIRST(&queue->jobs);
 209     vnc_unlock_queue(queue);
 210
 211     if (queue->exit) {
 212         return -1;
 213     }
 214
 215     vnc_lock_output(job->vs);
 216     if (job->vs->ioc == NULL || job->vs->abort == true) {
 217         vnc_unlock_output(job->vs);
 218         goto disconnected;
 219     }
 220     if (buffer_empty(&job->vs->output)) {
 221         /*
 222          * Looks like a NOP as it obviously moves no data.  But it
 223          * moves the empty buffer, so we don't have to malloc a new
 224          * one for vs.output
 225          */
 226         buffer_move_empty(&vs.output, &job->vs->output);
 227     }
 228     vnc_unlock_output(job->vs);
 229
 230     /* Make a local copy of vs and switch output buffers */
 231     vnc_async_encoding_start(job->vs, &vs);
 232
 233     /* Start sending rectangles */
 234     n_rectangles = 0;
 235     vnc_write_u8(&vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
 236     vnc_write_u8(&vs, 0);
 237     saved_offset = vs.output.offset;
 238     vnc_write_u16(&vs, 0);
 239
 240     vnc_lock_display(job->vs->vd);
 241     QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
 242         int n;
 243
 244         if (job->vs->ioc == NULL) {
 245             vnc_unlock_display(job->vs->vd);
 246             /* Copy persistent encoding data */
 247             vnc_async_encoding_end(job->vs, &vs);
 248             goto disconnected;
 249         }
 250
 251         n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
 252                                         entry->rect.w, entry->rect.h);
 253
 254         if (n >= 0) {
 255             n_rectangles += n;
 256         }
 257         g_free(entry);
 258     }
 259     vnc_unlock_display(job->vs->vd);
 260
 261     /* Put n_rectangles at the beginning of the message */
 262     vs.output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
 263     vs.output.buffer[saved_offset + 1] = n_rectangles & 0xFF;
 264
 265     vnc_lock_output(job->vs);
 266     if (job->vs->ioc != NULL) {
 267         buffer_move(&job->vs->jobs_buffer, &vs.output);
 268         /* Copy persistent encoding data */
 269         vnc_async_encoding_end(job->vs, &vs);
 270
 271         qemu_bh_schedule(job->vs->bh);
 272     }  else {
 273         buffer_reset(&vs.output);
 274         /* Copy persistent encoding data */
 275         vnc_async_encoding_end(job->vs, &vs);
 276     }
 277     vnc_unlock_output(job->vs);
 278
 279 disconnected:
 280     vnc_lock_queue(queue);
 281     QTAILQ_REMOVE(&queue->jobs, job, next);
 282     vnc_unlock_queue(queue);
 283     qemu_cond_broadcast(&queue->cond);
 284     g_free(job);
 285     return 0;
 286 }
 287
 288 static VncJobQueue *vnc_queue_init(void)
 289 {
 290     VncJobQueue *queue = g_new0(VncJobQueue, 1);
 291
 292     qemu_cond_init(&queue->cond);
 293     qemu_mutex_init(&queue->mutex);
 294     QTAILQ_INIT(&queue->jobs);
 295     return queue;
 296 }
 297
 298 static void vnc_queue_clear(VncJobQueue *q)
 299 {
 300     qemu_cond_destroy(&queue->cond);
 301     qemu_mutex_destroy(&queue->mutex);
 302     g_free(q);
 303     queue = NULL; /* Unset global queue */
 304 }
 305
 306 static void *vnc_worker_thread(void *arg)
 307 {
 308     VncJobQueue *queue = arg;
 309
 310     qemu_thread_get_self(&queue->thread);
 311
 312     while (!vnc_worker_thread_loop(queue)) ;
 313     vnc_queue_clear(queue);
 314     return NULL;
 315 }
 316
 317 static bool vnc_worker_thread_running(void)
 318 {
 319     return queue; /* Check global queue */
 320 }
 321
 322 void vnc_start_worker_thread(void)
 323 {
 324     VncJobQueue *q;
 325
 326     if (vnc_worker_thread_running())
 327         return ;
 328
 329     q = vnc_queue_init();
 330     qemu_thread_create(&q->thread, "vnc_worker", vnc_worker_thread, q,
 331                        QEMU_THREAD_DETACHED);
 332     queue = q; /* Set global queue */
 333 }