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     assert(vs->magic == VNC_MAGIC);
  86     job->vs = vs;
  87     vnc_lock_queue(queue);
  88     QLIST_INIT(&job->rectangles);
  89     vnc_unlock_queue(queue);
  90     return job;
  91 }
  92
  93 int vnc_job_add_rect(VncJob *job, int x, int y, int w, int h)
  94 {
  95     VncRectEntry *entry = g_new0(VncRectEntry, 1);
  96
  97     entry->rect.x = x;
  98     entry->rect.y = y;
  99     entry->rect.w = w;
 100     entry->rect.h = h;
 101
 102     vnc_lock_queue(queue);
 103     QLIST_INSERT_HEAD(&job->rectangles, entry, next);
 104     vnc_unlock_queue(queue);
 105     return 1;
 106 }
 107
 108 void vnc_job_push(VncJob *job)
 109 {
 110     vnc_lock_queue(queue);
 111     if (queue->exit || QLIST_EMPTY(&job->rectangles)) {
 112         g_free(job);
 113     } else {
 114         QTAILQ_INSERT_TAIL(&queue->jobs, job, next);
 115         qemu_cond_broadcast(&queue->cond);
 116     }
 117     vnc_unlock_queue(queue);
 118 }
 119
 120 static bool vnc_has_job_locked(VncState *vs)
 121 {
 122     VncJob *job;
 123
 124     QTAILQ_FOREACH(job, &queue->jobs, next) {
 125         if (job->vs == vs || !vs) {
 126             return true;
 127         }
 128     }
 129     return false;
 130 }
 131
 132 void vnc_jobs_join(VncState *vs)
 133 {
 134     vnc_lock_queue(queue);
 135     while (vnc_has_job_locked(vs)) {
 136         qemu_cond_wait(&queue->cond, &queue->mutex);
 137     }
 138     vnc_unlock_queue(queue);
 139     vnc_jobs_consume_buffer(vs);
 140 }
 141
 142 void vnc_jobs_consume_buffer(VncState *vs)
 143 {
 144     bool flush;
 145
 146     vnc_lock_output(vs);
 147     if (vs->jobs_buffer.offset) {
 148         if (vs->ioc != NULL && buffer_empty(&vs->output)) {
 149             if (vs->ioc_tag) {
 150                 g_source_remove(vs->ioc_tag);
 151             }
 152             if (vs->disconnecting == FALSE) {
 153                 vs->ioc_tag = qio_channel_add_watch(
 154                     vs->ioc, G_IO_IN | G_IO_OUT, vnc_client_io, vs, NULL);
 155             }
 156         }
 157         buffer_move(&vs->output, &vs->jobs_buffer);
 158
 159         if (vs->job_update == VNC_STATE_UPDATE_FORCE) {
 160             vs->force_update_offset = vs->output.offset;
 161         }
 162         vs->job_update = VNC_STATE_UPDATE_NONE;
 163     }
 164     flush = vs->ioc != NULL && vs->abort != true;
 165     vnc_unlock_output(vs);
 166
 167     if (flush) {
 168       vnc_flush(vs);
 169     }
 170 }
 171
 172 /*
 173  * Copy data for local use
 174  */
 175 static void vnc_async_encoding_start(VncState *orig, VncState *local)
 176 {
 177     buffer_init(&local->output, "vnc-worker-output");
 178     local->sioc = NULL; /* Don't do any network work on this thread */
 179     local->ioc = NULL; /* Don't do any network work on this thread */
 180
 181     local->vnc_encoding = orig->vnc_encoding;
 182     local->features = orig->features;
 183     local->vd = orig->vd;
 184     local->lossy_rect = orig->lossy_rect;
 185     local->write_pixels = orig->write_pixels;
 186     local->client_pf = orig->client_pf;
 187     local->client_be = orig->client_be;
 188     local->tight = orig->tight;
 189     local->zlib = orig->zlib;
 190     local->hextile = orig->hextile;
 191     local->zrle = orig->zrle;
 192 }
 193
 194 static void vnc_async_encoding_end(VncState *orig, VncState *local)
 195 {
 196     buffer_free(&local->output);
 197     orig->tight = local->tight;
 198     orig->zlib = local->zlib;
 199     orig->hextile = local->hextile;
 200     orig->zrle = local->zrle;
 201     orig->lossy_rect = local->lossy_rect;
 202 }
 203
 204 static int vnc_worker_thread_loop(VncJobQueue *queue)
 205 {
 206     VncJob *job;
 207     VncRectEntry *entry, *tmp;
 208     VncState vs = {};
 209     int n_rectangles;
 210     int saved_offset;
 211
 212     vnc_lock_queue(queue);
 213     while (QTAILQ_EMPTY(&queue->jobs) && !queue->exit) {
 214         qemu_cond_wait(&queue->cond, &queue->mutex);
 215     }
 216     /* Here job can only be NULL if queue->exit is true */
 217     job = QTAILQ_FIRST(&queue->jobs);
 218     vnc_unlock_queue(queue);
 219     assert(job->vs->magic == VNC_MAGIC);
 220
 221     if (queue->exit) {
 222         return -1;
 223     }
 224
 225     vnc_lock_output(job->vs);
 226     if (job->vs->ioc == NULL || job->vs->abort == true) {
 227         vnc_unlock_output(job->vs);
 228         goto disconnected;
 229     }
 230     if (buffer_empty(&job->vs->output)) {
 231         /*
 232          * Looks like a NOP as it obviously moves no data.  But it
 233          * moves the empty buffer, so we don't have to malloc a new
 234          * one for vs.output
 235          */
 236         buffer_move_empty(&vs.output, &job->vs->output);
 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     vs.magic = VNC_MAGIC;
 243
 244     /* Start sending rectangles */
 245     n_rectangles = 0;
 246     vnc_write_u8(&vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
 247     vnc_write_u8(&vs, 0);
 248     saved_offset = vs.output.offset;
 249     vnc_write_u16(&vs, 0);
 250
 251     vnc_lock_display(job->vs->vd);
 252     QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
 253         int n;
 254
 255         if (job->vs->ioc == NULL) {
 256             vnc_unlock_display(job->vs->vd);
 257             /* Copy persistent encoding data */
 258             vnc_async_encoding_end(job->vs, &vs);
 259             goto disconnected;
 260         }
 261
 262         n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
 263                                         entry->rect.w, entry->rect.h);
 264
 265         if (n >= 0) {
 266             n_rectangles += n;
 267         }
 268         g_free(entry);
 269     }
 270     vnc_unlock_display(job->vs->vd);
 271
 272     /* Put n_rectangles at the beginning of the message */
 273     vs.output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
 274     vs.output.buffer[saved_offset + 1] = n_rectangles & 0xFF;
 275
 276     vnc_lock_output(job->vs);
 277     if (job->vs->ioc != NULL) {
 278         buffer_move(&job->vs->jobs_buffer, &vs.output);
 279         /* Copy persistent encoding data */
 280         vnc_async_encoding_end(job->vs, &vs);
 281
 282         qemu_bh_schedule(job->vs->bh);
 283     }  else {
 284         buffer_reset(&vs.output);
 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     vs.magic = 0;
 297     return 0;
 298 }
 299
 300 static VncJobQueue *vnc_queue_init(void)
 301 {
 302     VncJobQueue *queue = g_new0(VncJobQueue, 1);
 303
 304     qemu_cond_init(&queue->cond);
 305     qemu_mutex_init(&queue->mutex);
 306     QTAILQ_INIT(&queue->jobs);
 307     return queue;
 308 }
 309
 310 static void vnc_queue_clear(VncJobQueue *q)
 311 {
 312     qemu_cond_destroy(&queue->cond);
 313     qemu_mutex_destroy(&queue->mutex);
 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 }