ui/vnc-jobs.c - third_party/qemu - Git at Google

 /*
  * QEMU VNC display driver
  *
  * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
  * Copyright (C) 2006 Fabrice Bellard
  * Copyright (C) 2009 Red Hat, Inc
  * Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */


 #include "qemu/osdep.h"
 #include "vnc.h"
 #include "vnc-jobs.h"
 #include "qemu/sockets.h"
 #include "qemu/main-loop.h"
 #include "block/aio.h"
 #include "trace.h"

 /*
  * Locking:
  *
  * There are three levels of locking:
  * - jobs queue lock: for each operation on the queue (push, pop, isEmpty?)
  * - VncDisplay global lock: mainly used for framebuffer updates to avoid
  *                      screen corruption if the framebuffer is updated
  *                      while the worker is doing something.
  * - VncState::output lock: used to make sure the output buffer is not corrupted
  *                          if two threads try to write on it at the same time
  *
  * While the VNC worker thread is working, the VncDisplay global lock is held
  * to avoid screen corruption (this does not block vnc_refresh() because it
  * uses trylock()) but the output lock is not held because the thread works on
  * its own output buffer.
  * When the encoding job is done, the worker thread will hold the output lock
  * and copy its output buffer in vs->output.
  */

 struct VncJobQueue {
     QemuCond cond;
     QemuMutex mutex;
     QemuThread thread;
     bool exit;
     QTAILQ_HEAD(, VncJob) jobs;
 };

 typedef struct VncJobQueue VncJobQueue;

 /*
  * We use a single global queue, but most of the functions are
  * already reentrant, so we can easily add more than one encoding thread
  */
 static VncJobQueue *queue;

 static void vnc_lock_queue(VncJobQueue *queue)
 {
     qemu_mutex_lock(&queue->mutex);
 }

 static void vnc_unlock_queue(VncJobQueue *queue)
 {
     qemu_mutex_unlock(&queue->mutex);
 }

 VncJob *vnc_job_new(VncState *vs)
 {
     VncJob *job = g_new0(VncJob, 1);

     assert(vs->magic == VNC_MAGIC);
     job->vs = vs;
     vnc_lock_queue(queue);
     QLIST_INIT(&job->rectangles);
     vnc_unlock_queue(queue);
     return job;
 }

 int vnc_job_add_rect(VncJob *job, int x, int y, int w, int h)
 {
     VncRectEntry *entry = g_new0(VncRectEntry, 1);

     trace_vnc_job_add_rect(job->vs, job, x, y, w, h);

     entry->rect.x = x;
     entry->rect.y = y;
     entry->rect.w = w;
     entry->rect.h = h;

     vnc_lock_queue(queue);
     QLIST_INSERT_HEAD(&job->rectangles, entry, next);
     vnc_unlock_queue(queue);
     return 1;
 }

 void vnc_job_push(VncJob *job)
 {
     vnc_lock_queue(queue);
     if (queue->exit || QLIST_EMPTY(&job->rectangles)) {
         g_free(job);
     } else {
         QTAILQ_INSERT_TAIL(&queue->jobs, job, next);
         qemu_cond_broadcast(&queue->cond);
     }
     vnc_unlock_queue(queue);
 }

 static bool vnc_has_job_locked(VncState *vs)
 {
     VncJob *job;

     QTAILQ_FOREACH(job, &queue->jobs, next) {
         if (job->vs == vs || !vs) {
             return true;
         }
     }
     return false;
 }

 void vnc_jobs_join(VncState *vs)
 {
     vnc_lock_queue(queue);
     while (vnc_has_job_locked(vs)) {
         qemu_cond_wait(&queue->cond, &queue->mutex);
     }
     vnc_unlock_queue(queue);
     vnc_jobs_consume_buffer(vs);
 }

 void vnc_jobs_consume_buffer(VncState *vs)
 {
     bool flush;

     vnc_lock_output(vs);
     if (vs->jobs_buffer.offset) {
         if (vs->ioc != NULL && buffer_empty(&vs->output)) {
             if (vs->ioc_tag) {
                 g_source_remove(vs->ioc_tag);
             }
             if (vs->disconnecting == FALSE) {
                 vs->ioc_tag = qio_channel_add_watch(
                     vs->ioc, G_IO_IN | G_IO_HUP | G_IO_ERR | G_IO_OUT,
                     vnc_client_io, vs, NULL);
             }
         }
         buffer_move(&vs->output, &vs->jobs_buffer);

         if (vs->job_update == VNC_STATE_UPDATE_FORCE) {
             vs->force_update_offset = vs->output.offset;
         }
         vs->job_update = VNC_STATE_UPDATE_NONE;
     }
     flush = vs->ioc != NULL && vs->abort != true;
     vnc_unlock_output(vs);

     if (flush) {
       vnc_flush(vs);
     }
 }

 /*
  * Copy data for local use
  */
 static void vnc_async_encoding_start(VncState *orig, VncState *local)
 {
     buffer_init(&local->output, "vnc-worker-output");
     local->sioc = NULL; /* Don't do any network work on this thread */
     local->ioc = NULL; /* Don't do any network work on this thread */

     local->vnc_encoding = orig->vnc_encoding;
     local->features = orig->features;
     local->vd = orig->vd;
     local->lossy_rect = orig->lossy_rect;
     local->write_pixels = orig->write_pixels;
     local->client_pf = orig->client_pf;
     local->client_be = orig->client_be;
     local->tight = orig->tight;
     local->zlib = orig->zlib;
     local->hextile = orig->hextile;
     local->zrle = orig->zrle;
     local->client_width = orig->client_width;
     local->client_height = orig->client_height;
 }

 static void vnc_async_encoding_end(VncState *orig, VncState *local)
 {
     buffer_free(&local->output);
     orig->tight = local->tight;
     orig->zlib = local->zlib;
     orig->hextile = local->hextile;
     orig->zrle = local->zrle;
     orig->lossy_rect = local->lossy_rect;
 }

 static bool vnc_worker_clamp_rect(VncState *vs, VncJob *job, VncRect *rect)
 {
     trace_vnc_job_clamp_rect(vs, job, rect->x, rect->y, rect->w, rect->h);

     if (rect->x >= vs->client_width) {
         goto discard;
     }
     rect->w = MIN(vs->client_width - rect->x, rect->w);
     if (rect->w == 0) {
         goto discard;
     }

     if (rect->y >= vs->client_height) {
         goto discard;
     }
     rect->h = MIN(vs->client_height - rect->y, rect->h);
     if (rect->h == 0) {
         goto discard;
     }

     trace_vnc_job_clamped_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
     return true;

  discard:
     trace_vnc_job_discard_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
     return false;
 }

 static int vnc_worker_thread_loop(VncJobQueue *queue)
 {
     VncJob *job;
     VncRectEntry *entry, *tmp;
     VncState vs = {};
     int n_rectangles;
     int saved_offset;

     vnc_lock_queue(queue);
     while (QTAILQ_EMPTY(&queue->jobs) && !queue->exit) {
         qemu_cond_wait(&queue->cond, &queue->mutex);
     }
     /* Here job can only be NULL if queue->exit is true */
     job = QTAILQ_FIRST(&queue->jobs);
     vnc_unlock_queue(queue);
     assert(job->vs->magic == VNC_MAGIC);

     if (queue->exit) {
         return -1;
     }

     vnc_lock_output(job->vs);
     if (job->vs->ioc == NULL || job->vs->abort == true) {
         vnc_unlock_output(job->vs);
         goto disconnected;
     }
     if (buffer_empty(&job->vs->output)) {
         /*
          * Looks like a NOP as it obviously moves no data.  But it
          * moves the empty buffer, so we don't have to malloc a new
          * one for vs.output
          */
         buffer_move_empty(&vs.output, &job->vs->output);
     }
     vnc_unlock_output(job->vs);

     /* Make a local copy of vs and switch output buffers */
     vnc_async_encoding_start(job->vs, &vs);
     vs.magic = VNC_MAGIC;

     /* Start sending rectangles */
     n_rectangles = 0;
     vnc_write_u8(&vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
     vnc_write_u8(&vs, 0);
     saved_offset = vs.output.offset;
     vnc_write_u16(&vs, 0);

     vnc_lock_display(job->vs->vd);
     QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
         int n;

         if (job->vs->ioc == NULL) {
             vnc_unlock_display(job->vs->vd);
             /* Copy persistent encoding data */
             vnc_async_encoding_end(job->vs, &vs);
             goto disconnected;
         }

         if (vnc_worker_clamp_rect(&vs, job, &entry->rect)) {
             n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
                                             entry->rect.w, entry->rect.h);

             if (n >= 0) {
                 n_rectangles += n;
             }
         }
         g_free(entry);
     }
     trace_vnc_job_nrects(&vs, job, n_rectangles);
     vnc_unlock_display(job->vs->vd);

     /* Put n_rectangles at the beginning of the message */
     vs.output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
     vs.output.buffer[saved_offset + 1] = n_rectangles & 0xFF;

     vnc_lock_output(job->vs);
     if (job->vs->ioc != NULL) {
         buffer_move(&job->vs->jobs_buffer, &vs.output);
         /* Copy persistent encoding data */
         vnc_async_encoding_end(job->vs, &vs);

         qemu_bh_schedule(job->vs->bh);
     }  else {
         buffer_reset(&vs.output);
         /* Copy persistent encoding data */
         vnc_async_encoding_end(job->vs, &vs);
     }
     vnc_unlock_output(job->vs);

 disconnected:
     vnc_lock_queue(queue);
     QTAILQ_REMOVE(&queue->jobs, job, next);
     vnc_unlock_queue(queue);
     qemu_cond_broadcast(&queue->cond);
     g_free(job);
     vs.magic = 0;
     return 0;
 }

 static VncJobQueue *vnc_queue_init(void)
 {
     VncJobQueue *queue = g_new0(VncJobQueue, 1);

     qemu_cond_init(&queue->cond);
     qemu_mutex_init(&queue->mutex);
     QTAILQ_INIT(&queue->jobs);
     return queue;
 }

 static void vnc_queue_clear(VncJobQueue *q)
 {
     qemu_cond_destroy(&queue->cond);
     qemu_mutex_destroy(&queue->mutex);
     g_free(q);
     queue = NULL; /* Unset global queue */
 }

 static void *vnc_worker_thread(void *arg)
 {
     VncJobQueue *queue = arg;

     qemu_thread_get_self(&queue->thread);

     while (!vnc_worker_thread_loop(queue)) ;
     vnc_queue_clear(queue);
     return NULL;
 }

 static bool vnc_worker_thread_running(void)
 {
     return queue; /* Check global queue */
 }

 void vnc_start_worker_thread(void)
 {
     VncJobQueue *q;

     if (vnc_worker_thread_running())
         return ;

     q = vnc_queue_init();
     qemu_thread_create(&q->thread, "vnc_worker", vnc_worker_thread, q,
                        QEMU_THREAD_DETACHED);
     queue = q; /* Set global queue */
 }
	/*
	* QEMU VNC display driver
	*
	* Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
	* Copyright (C) 2006 Fabrice Bellard
	* Copyright (C) 2009 Red Hat, Inc
	* Copyright (C) 2010 Corentin Chary <corentin.chary@gmail.com>
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*/


	#include "qemu/osdep.h"
	#include "vnc.h"
	#include "vnc-jobs.h"
	#include "qemu/sockets.h"
	#include "qemu/main-loop.h"
	#include "block/aio.h"
	#include "trace.h"

	/*
	* Locking:
	*
	* There are three levels of locking:
	* - jobs queue lock: for each operation on the queue (push, pop, isEmpty?)
	* - VncDisplay global lock: mainly used for framebuffer updates to avoid
	* screen corruption if the framebuffer is updated
	* while the worker is doing something.
	* - VncState::output lock: used to make sure the output buffer is not corrupted
	* if two threads try to write on it at the same time
	*
	* While the VNC worker thread is working, the VncDisplay global lock is held
	* to avoid screen corruption (this does not block vnc_refresh() because it
	* uses trylock()) but the output lock is not held because the thread works on
	* its own output buffer.
	* When the encoding job is done, the worker thread will hold the output lock
	* and copy its output buffer in vs->output.
	*/

	struct VncJobQueue {
	QemuCond cond;
	QemuMutex mutex;
	QemuThread thread;
	bool exit;
	QTAILQ_HEAD(, VncJob) jobs;
	};

	typedef struct VncJobQueue VncJobQueue;

	/*
	* We use a single global queue, but most of the functions are
	* already reentrant, so we can easily add more than one encoding thread
	*/
	static VncJobQueue *queue;

	static void vnc_lock_queue(VncJobQueue *queue)
	{
	qemu_mutex_lock(&queue->mutex);
	}

	static void vnc_unlock_queue(VncJobQueue *queue)
	{
	qemu_mutex_unlock(&queue->mutex);
	}

	VncJob vnc_job_new(VncState vs)
	{
	VncJob *job = g_new0(VncJob, 1);

	assert(vs->magic == VNC_MAGIC);
	job->vs = vs;
	vnc_lock_queue(queue);
	QLIST_INIT(&job->rectangles);
	vnc_unlock_queue(queue);
	return job;
	}

	int vnc_job_add_rect(VncJob *job, int x, int y, int w, int h)
	{
	VncRectEntry *entry = g_new0(VncRectEntry, 1);

	trace_vnc_job_add_rect(job->vs, job, x, y, w, h);

	entry->rect.x = x;
	entry->rect.y = y;
	entry->rect.w = w;
	entry->rect.h = h;

	vnc_lock_queue(queue);
	QLIST_INSERT_HEAD(&job->rectangles, entry, next);
	vnc_unlock_queue(queue);
	return 1;
	}

	void vnc_job_push(VncJob *job)
	{
	vnc_lock_queue(queue);
	if (queue->exit \|\| QLIST_EMPTY(&job->rectangles)) {
	g_free(job);
	} else {
	QTAILQ_INSERT_TAIL(&queue->jobs, job, next);
	qemu_cond_broadcast(&queue->cond);
	}
	vnc_unlock_queue(queue);
	}

	static bool vnc_has_job_locked(VncState *vs)
	{
	VncJob *job;

	QTAILQ_FOREACH(job, &queue->jobs, next) {
	if (job->vs == vs \|\| !vs) {
	return true;
	}
	}
	return false;
	}

	void vnc_jobs_join(VncState *vs)
	{
	vnc_lock_queue(queue);
	while (vnc_has_job_locked(vs)) {
	qemu_cond_wait(&queue->cond, &queue->mutex);
	}
	vnc_unlock_queue(queue);
	vnc_jobs_consume_buffer(vs);
	}

	void vnc_jobs_consume_buffer(VncState *vs)
	{
	bool flush;

	vnc_lock_output(vs);
	if (vs->jobs_buffer.offset) {
	if (vs->ioc != NULL && buffer_empty(&vs->output)) {
	if (vs->ioc_tag) {
	g_source_remove(vs->ioc_tag);
	}
	if (vs->disconnecting == FALSE) {
	vs->ioc_tag = qio_channel_add_watch(
	vs->ioc, G_IO_IN \| G_IO_HUP \| G_IO_ERR \| G_IO_OUT,
	vnc_client_io, vs, NULL);
	}
	}
	buffer_move(&vs->output, &vs->jobs_buffer);

	if (vs->job_update == VNC_STATE_UPDATE_FORCE) {
	vs->force_update_offset = vs->output.offset;
	}
	vs->job_update = VNC_STATE_UPDATE_NONE;
	}
	flush = vs->ioc != NULL && vs->abort != true;
	vnc_unlock_output(vs);

	if (flush) {
	vnc_flush(vs);
	}
	}

	/*
	* Copy data for local use
	*/
	static void vnc_async_encoding_start(VncState orig, VncState local)
	{
	buffer_init(&local->output, "vnc-worker-output");
	local->sioc = NULL; /* Don't do any network work on this thread */
	local->ioc = NULL; /* Don't do any network work on this thread */

	local->vnc_encoding = orig->vnc_encoding;
	local->features = orig->features;
	local->vd = orig->vd;
	local->lossy_rect = orig->lossy_rect;
	local->write_pixels = orig->write_pixels;
	local->client_pf = orig->client_pf;
	local->client_be = orig->client_be;
	local->tight = orig->tight;
	local->zlib = orig->zlib;
	local->hextile = orig->hextile;
	local->zrle = orig->zrle;
	local->client_width = orig->client_width;
	local->client_height = orig->client_height;
	}

	static void vnc_async_encoding_end(VncState orig, VncState local)
	{
	buffer_free(&local->output);
	orig->tight = local->tight;
	orig->zlib = local->zlib;
	orig->hextile = local->hextile;
	orig->zrle = local->zrle;
	orig->lossy_rect = local->lossy_rect;
	}

	static bool vnc_worker_clamp_rect(VncState vs, VncJob job, VncRect *rect)
	{
	trace_vnc_job_clamp_rect(vs, job, rect->x, rect->y, rect->w, rect->h);

	if (rect->x >= vs->client_width) {
	goto discard;
	}
	rect->w = MIN(vs->client_width - rect->x, rect->w);
	if (rect->w == 0) {
	goto discard;
	}

	if (rect->y >= vs->client_height) {
	goto discard;
	}
	rect->h = MIN(vs->client_height - rect->y, rect->h);
	if (rect->h == 0) {
	goto discard;
	}

	trace_vnc_job_clamped_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
	return true;

	discard:
	trace_vnc_job_discard_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
	return false;
	}

	static int vnc_worker_thread_loop(VncJobQueue *queue)
	{
	VncJob *job;
	VncRectEntry entry, tmp;
	VncState vs = {};
	int n_rectangles;
	int saved_offset;

	vnc_lock_queue(queue);
	while (QTAILQ_EMPTY(&queue->jobs) && !queue->exit) {
	qemu_cond_wait(&queue->cond, &queue->mutex);
	}
	/* Here job can only be NULL if queue->exit is true */
	job = QTAILQ_FIRST(&queue->jobs);
	vnc_unlock_queue(queue);
	assert(job->vs->magic == VNC_MAGIC);

	if (queue->exit) {
	return -1;
	}

	vnc_lock_output(job->vs);
	if (job->vs->ioc == NULL \|\| job->vs->abort == true) {
	vnc_unlock_output(job->vs);
	goto disconnected;
	}
	if (buffer_empty(&job->vs->output)) {
	/*
	* Looks like a NOP as it obviously moves no data. But it
	* moves the empty buffer, so we don't have to malloc a new
	* one for vs.output
	*/
	buffer_move_empty(&vs.output, &job->vs->output);
	}
	vnc_unlock_output(job->vs);

	/* Make a local copy of vs and switch output buffers */
	vnc_async_encoding_start(job->vs, &vs);
	vs.magic = VNC_MAGIC;

	/* Start sending rectangles */
	n_rectangles = 0;
	vnc_write_u8(&vs, VNC_MSG_SERVER_FRAMEBUFFER_UPDATE);
	vnc_write_u8(&vs, 0);
	saved_offset = vs.output.offset;
	vnc_write_u16(&vs, 0);

	vnc_lock_display(job->vs->vd);
	QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
	int n;

	if (job->vs->ioc == NULL) {
	vnc_unlock_display(job->vs->vd);
	/* Copy persistent encoding data */
	vnc_async_encoding_end(job->vs, &vs);
	goto disconnected;
	}

	if (vnc_worker_clamp_rect(&vs, job, &entry->rect)) {
	n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
	entry->rect.w, entry->rect.h);

	if (n >= 0) {
	n_rectangles += n;
	}
	}
	g_free(entry);
	}
	trace_vnc_job_nrects(&vs, job, n_rectangles);
	vnc_unlock_display(job->vs->vd);

	/* Put n_rectangles at the beginning of the message */
	vs.output.buffer[saved_offset] = (n_rectangles >> 8) & 0xFF;
	vs.output.buffer[saved_offset + 1] = n_rectangles & 0xFF;

	vnc_lock_output(job->vs);
	if (job->vs->ioc != NULL) {
	buffer_move(&job->vs->jobs_buffer, &vs.output);
	/* Copy persistent encoding data */
	vnc_async_encoding_end(job->vs, &vs);

	qemu_bh_schedule(job->vs->bh);
	} else {
	buffer_reset(&vs.output);
	/* Copy persistent encoding data */
	vnc_async_encoding_end(job->vs, &vs);
	}
	vnc_unlock_output(job->vs);

	disconnected:
	vnc_lock_queue(queue);
	QTAILQ_REMOVE(&queue->jobs, job, next);
	vnc_unlock_queue(queue);
	qemu_cond_broadcast(&queue->cond);
	g_free(job);
	vs.magic = 0;
	return 0;
	}

	static VncJobQueue *vnc_queue_init(void)
	{
	VncJobQueue *queue = g_new0(VncJobQueue, 1);

	qemu_cond_init(&queue->cond);
	qemu_mutex_init(&queue->mutex);
	QTAILQ_INIT(&queue->jobs);
	return queue;
	}

	static void vnc_queue_clear(VncJobQueue *q)
	{
	qemu_cond_destroy(&queue->cond);
	qemu_mutex_destroy(&queue->mutex);
	g_free(q);
	queue = NULL; /* Unset global queue */
	}

	static void vnc_worker_thread(void arg)
	{
	VncJobQueue *queue = arg;

	qemu_thread_get_self(&queue->thread);

	while (!vnc_worker_thread_loop(queue)) ;
	vnc_queue_clear(queue);
	return NULL;
	}

	static bool vnc_worker_thread_running(void)
	{
	return queue; /* Check global queue */
	}

	void vnc_start_worker_thread(void)
	{
	VncJobQueue *q;

	if (vnc_worker_thread_running())
	return ;

	q = vnc_queue_init();
	qemu_thread_create(&q->thread, "vnc_worker", vnc_worker_thread, q,
	QEMU_THREAD_DETACHED);
	queue = q; /* Set global queue */
	}