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 #include "trace.h"
  36
  37 /*
  38  * Locking:
  39  *
  40  * There are three levels of locking:
  41  * - jobs queue lock: for each operation on the queue (push, pop, isEmpty?)
  42  * - VncDisplay global lock: mainly used for framebuffer updates to avoid
  43  *                      screen corruption if the framebuffer is updated
  44  *                      while the worker is doing something.
  45  * - VncState::output lock: used to make sure the output buffer is not corrupted
  46  *                          if two threads try to write on it at the same time
  47  *
  48  * While the VNC worker thread is working, the VncDisplay global lock is held
  49  * to avoid screen corruption (this does not block vnc_refresh() because it
  50  * uses trylock()) but the output lock is not held because the thread works on
  51  * its own output buffer.
  52  * When the encoding job is done, the worker thread will hold the output lock
  53  * and copy its output buffer in vs->output.
  54  */
  55
  56 struct VncJobQueue {
  57     QemuCond cond;
  58     QemuMutex mutex;
  59     QemuThread thread;
  60     bool exit;
  61     QTAILQ_HEAD(, VncJob) jobs;
  62 };
  63
  64 typedef struct VncJobQueue VncJobQueue;
  65
  66 /*
  67  * We use a single global queue, but most of the functions are
  68  * already reentrant, so we can easily add more than one encoding thread
  69  */
  70 static VncJobQueue *queue;
  71
  72 static void vnc_lock_queue(VncJobQueue *queue)
  73 {
  74     qemu_mutex_lock(&queue->mutex);
  75 }
  76
  77 static void vnc_unlock_queue(VncJobQueue *queue)
  78 {
  79     qemu_mutex_unlock(&queue->mutex);
  80 }
  81
  82 VncJob *vnc_job_new(VncState *vs)
  83 {
  84     VncJob *job = g_new0(VncJob, 1);
  85
  86     assert(vs->magic == VNC_MAGIC);
  87     job->vs = vs;
  88     vnc_lock_queue(queue);
  89     QLIST_INIT(&job->rectangles);
  90     vnc_unlock_queue(queue);
  91     return job;
  92 }
  93
  94 int vnc_job_add_rect(VncJob *job, int x, int y, int w, int h)
  95 {
  96     VncRectEntry *entry = g_new0(VncRectEntry, 1);
  97
  98     trace_vnc_job_add_rect(job->vs, job, x, y, w, h);
  99
 100     entry->rect.x = x;
 101     entry->rect.y = y;
 102     entry->rect.w = w;
 103     entry->rect.h = h;
 104
 105     vnc_lock_queue(queue);
 106     QLIST_INSERT_HEAD(&job->rectangles, entry, next);
 107     vnc_unlock_queue(queue);
 108     return 1;
 109 }
 110
 111 void vnc_job_push(VncJob *job)
 112 {
 113     vnc_lock_queue(queue);
 114     if (queue->exit || QLIST_EMPTY(&job->rectangles)) {
 115         g_free(job);
 116     } else {
 117         QTAILQ_INSERT_TAIL(&queue->jobs, job, next);
 118         qemu_cond_broadcast(&queue->cond);
 119     }
 120     vnc_unlock_queue(queue);
 121 }
 122
 123 static bool vnc_has_job_locked(VncState *vs)
 124 {
 125     VncJob *job;
 126
 127     QTAILQ_FOREACH(job, &queue->jobs, next) {
 128         if (job->vs == vs || !vs) {
 129             return true;
 130         }
 131     }
 132     return false;
 133 }
 134
 135 void vnc_jobs_join(VncState *vs)
 136 {
 137     vnc_lock_queue(queue);
 138     while (vnc_has_job_locked(vs)) {
 139         qemu_cond_wait(&queue->cond, &queue->mutex);
 140     }
 141     vnc_unlock_queue(queue);
 142     vnc_jobs_consume_buffer(vs);
 143 }
 144
 145 void vnc_jobs_consume_buffer(VncState *vs)
 146 {
 147     bool flush;
 148
 149     vnc_lock_output(vs);
 150     if (vs->jobs_buffer.offset) {
 151         if (vs->ioc != NULL && buffer_empty(&vs->output)) {
 152             if (vs->ioc_tag) {
 153                 g_source_remove(vs->ioc_tag);
 154             }
 155             if (vs->disconnecting == FALSE) {
 156                 vs->ioc_tag = qio_channel_add_watch(
 157                     vs->ioc, G_IO_IN | G_IO_HUP | G_IO_ERR | G_IO_OUT,
 158                     vnc_client_io, vs, NULL);
 159             }
 160         }
 161         buffer_move(&vs->output, &vs->jobs_buffer);
 162
 163         if (vs->job_update == VNC_STATE_UPDATE_FORCE) {
 164             vs->force_update_offset = vs->output.offset;
 165         }
 166         vs->job_update = VNC_STATE_UPDATE_NONE;
 167     }
 168     flush = vs->ioc != NULL && vs->abort != true;
 169     vnc_unlock_output(vs);
 170
 171     if (flush) {
 172       vnc_flush(vs);
 173     }
 174 }
 175
 176 /*
 177  * Copy data for local use
 178  */
 179 static void vnc_async_encoding_start(VncState *orig, VncState *local)
 180 {
 181     buffer_init(&local->output, "vnc-worker-output");
 182     local->sioc = NULL; /* Don't do any network work on this thread */
 183     local->ioc = NULL; /* Don't do any network work on this thread */
 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->client_width = orig->client_width;
 197     local->client_height = orig->client_height;
 198 }
 199
 200 static void vnc_async_encoding_end(VncState *orig, VncState *local)
 201 {
 202     buffer_free(&local->output);
 203     orig->tight = local->tight;
 204     orig->zlib = local->zlib;
 205     orig->hextile = local->hextile;
 206     orig->zrle = local->zrle;
 207     orig->lossy_rect = local->lossy_rect;
 208 }
 209
 210 static bool vnc_worker_clamp_rect(VncState *vs, VncJob *job, VncRect *rect)
 211 {
 212     trace_vnc_job_clamp_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
 213
 214     if (rect->x >= vs->client_width) {
 215         goto discard;
 216     }
 217     rect->w = MIN(vs->client_width - rect->x, rect->w);
 218     if (rect->w == 0) {
 219         goto discard;
 220     }
 221
 222     if (rect->y >= vs->client_height) {
 223         goto discard;
 224     }
 225     rect->h = MIN(vs->client_height - rect->y, rect->h);
 226     if (rect->h == 0) {
 227         goto discard;
 228     }
 229
 230     trace_vnc_job_clamped_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
 231     return true;
 232
 233  discard:
 234     trace_vnc_job_discard_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
 235     return false;
 236 }
 237
 238 static int vnc_worker_thread_loop(VncJobQueue *queue)
 239 {
 240     VncJob *job;
 241     VncRectEntry *entry, *tmp;
 242     VncState vs = {};
 243     int n_rectangles;
 244     int saved_offset;
 245
 246     vnc_lock_queue(queue);
 247     while (QTAILQ_EMPTY(&queue->jobs) && !queue->exit) {
 248         qemu_cond_wait(&queue->cond, &queue->mutex);
 249     }
 250     /* Here job can only be NULL if queue->exit is true */
 251     job = QTAILQ_FIRST(&queue->jobs);
 252     vnc_unlock_queue(queue);
 253
 254     if (queue->exit) {
 255         return -1;
 256     }
 257
 258     assert(job->vs->magic == VNC_MAGIC);
 259
 260     vnc_lock_output(job->vs);
 261     if (job->vs->ioc == NULL || job->vs->abort == true) {
 262         vnc_unlock_output(job->vs);
 263         goto disconnected;
 264     }
 265     if (buffer_empty(&job->vs->output)) {
 266         /*
 267          * Looks like a NOP as it obviously moves no data.  But it
 268          * moves the empty buffer, so we don't have to malloc a new
 269          * one for vs.output
 270          */
 271         buffer_move_empty(&vs.output, &job->vs->output);
 272     }
 273     vnc_unlock_output(job->vs);
 274
 275     /* Make a local copy of vs and switch output buffers */
 276     vnc_async_encoding_start(job->vs, &vs);
 277     vs.magic = VNC_MAGIC;
 278
 279     /* Start sending rectangles */
 280     n_rectangles = 0;
 281     vnc_write_u8(&vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
 282     vnc_write_u8(&vs, 0);
 283     saved_offset = vs.output.offset;
 284     vnc_write_u16(&vs, 0);
 285
 286     vnc_lock_display(job->vs->vd);
 287     QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
 288         int n;
 289
 290         if (job->vs->ioc == NULL) {
 291             vnc_unlock_display(job->vs->vd);
 292             /* Copy persistent encoding data */
 293             vnc_async_encoding_end(job->vs, &vs);
 294             goto disconnected;
 295         }
 296
 297         if (vnc_worker_clamp_rect(&vs, job, &entry->rect)) {
 298             n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
 299                                             entry->rect.w, entry->rect.h);
 300
 301             if (n >= 0) {
 302                 n_rectangles += n;
 303             }
 304         }
 305         g_free(entry);
 306     }
 307     trace_vnc_job_nrects(&vs, job, n_rectangles);
 308     vnc_unlock_display(job->vs->vd);
 309
 310     /* Put n_rectangles at the beginning of the message */
 311     vs.output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
 312     vs.output.buffer[saved_offset + 1] = n_rectangles & 0xFF;
 313
 314     vnc_lock_output(job->vs);
 315     if (job->vs->ioc != NULL) {
 316         buffer_move(&job->vs->jobs_buffer, &vs.output);
 317         /* Copy persistent encoding data */
 318         vnc_async_encoding_end(job->vs, &vs);
 319
 320         qemu_bh_schedule(job->vs->bh);
 321     }  else {
 322         buffer_reset(&vs.output);
 323         /* Copy persistent encoding data */
 324         vnc_async_encoding_end(job->vs, &vs);
 325     }
 326     vnc_unlock_output(job->vs);
 327
 328 disconnected:
 329     vnc_lock_queue(queue);
 330     QTAILQ_REMOVE(&queue->jobs, job, next);
 331     vnc_unlock_queue(queue);
 332     qemu_cond_broadcast(&queue->cond);
 333     g_free(job);
 334     vs.magic = 0;
 335     return 0;
 336 }
 337
 338 static VncJobQueue *vnc_queue_init(void)
 339 {
 340     VncJobQueue *queue = g_new0(VncJobQueue, 1);
 341
 342     qemu_cond_init(&queue->cond);
 343     qemu_mutex_init(&queue->mutex);
 344     QTAILQ_INIT(&queue->jobs);
 345     return queue;
 346 }
 347
 348 static void vnc_queue_clear(VncJobQueue *q)
 349 {
 350     qemu_cond_destroy(&queue->cond);
 351     qemu_mutex_destroy(&queue->mutex);
 352     g_free(q);
 353     queue = NULL; /* Unset global queue */
 354 }
 355
 356 static void *vnc_worker_thread(void *arg)
 357 {
 358     VncJobQueue *queue = arg;
 359
 360     qemu_thread_get_self(&queue->thread);
 361
 362     while (!vnc_worker_thread_loop(queue)) ;
 363     vnc_queue_clear(queue);
 364     return NULL;
 365 }
 366
 367 static bool vnc_worker_thread_running(void)
 368 {
 369     return queue; /* Check global queue */
 370 }
 371
 372 void vnc_start_worker_thread(void)
 373 {
 374     VncJobQueue *q;
 375
 376     if (vnc_worker_thread_running())
 377         return;
 378
 379     q = vnc_queue_init();
 380     qemu_thread_create(&q->thread, "vnc_worker", vnc_worker_thread, q,
 381                        QEMU_THREAD_DETACHED);
 382     queue = q; /* Set global queue */
 383 }