qemu/ui/vnc-jobs.c
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   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
  56struct VncJobQueue {
  57    QemuCond cond;
  58    QemuMutex mutex;
  59    QemuThread thread;
  60    bool exit;
  61    QTAILQ_HEAD(, VncJob) jobs;
  62};
  63
  64typedef 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 */
  70static VncJobQueue *queue;
  71
  72static void vnc_lock_queue(VncJobQueue *queue)
  73{
  74    qemu_mutex_lock(&queue->mutex);
  75}
  76
  77static void vnc_unlock_queue(VncJobQueue *queue)
  78{
  79    qemu_mutex_unlock(&queue->mutex);
  80}
  81
  82VncJob *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
  94int 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
 111void 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
 123static 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
 135void 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
 145void 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 */
 179static 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
 200static 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
 210static 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
 238static 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
 328disconnected:
 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
 338static 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
 348static 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
 356static 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
 367static bool vnc_worker_thread_running(void)
 368{
 369    return queue; /* Check global queue */
 370}
 371
 372void 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}
 384