Archipelago » qemu

/*

 * 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 "vnc.h"

#include "vnc-jobs.h"

#include "qemu/sockets.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;

    Buffer buffer;

    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_malloc0(sizeof(VncJob));

    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_malloc0(sizeof(VncRectEntry));

    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;

}

bool vnc_has_job(VncState *vs)

{

    bool ret;

    vnc_lock_queue(queue);

    ret = vnc_has_job_locked(vs);

    vnc_unlock_queue(queue);

    return ret;

}

void vnc_jobs_clear(VncState *vs)

{

    VncJob *job, *tmp;

    vnc_lock_queue(queue);

    QTAILQ_FOREACH_SAFE(job, &queue->jobs, next, tmp) {

        if (job->vs == vs || !vs) {

            QTAILQ_REMOVE(&queue->jobs, job, next);

        }

    }

    vnc_unlock_queue(queue);

}

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) {

        vnc_write(vs, vs->jobs_buffer.buffer, vs->jobs_buffer.offset);

        buffer_reset(&vs->jobs_buffer);

    }

    flush = vs->csock != -1 && 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)

{

    local->vnc_encoding = orig->vnc_encoding;

    local->features = orig->features;

    local->ds = orig->ds;

    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->output =  queue->buffer;

    local->csock = -1; /* Don't do any network work on this thread */

    buffer_reset(&local->output);

}

static void vnc_async_encoding_end(VncState *orig, VncState *local)

{

    orig->tight = local->tight;

    orig->zlib = local->zlib;

    orig->hextile = local->hextile;

    orig->zrle = local->zrle;

    orig->lossy_rect = local->lossy_rect;

    queue->buffer = local->output;

}

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);

    if (queue->exit) {

        return -1;

    }

    vnc_lock_output(job->vs);

    if (job->vs->csock == -1 || job->vs->abort == true) {

        vnc_unlock_output(job->vs);

        goto disconnected;

    }

    vnc_unlock_output(job->vs);

    /* Make a local copy of vs and switch output buffers */

    vnc_async_encoding_start(job->vs, &vs);

    /* 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->csock == -1) {

            vnc_unlock_display(job->vs->vd);

            goto disconnected;

        }

        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);

    }

    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->csock != -1) {

        buffer_reserve(&job->vs->jobs_buffer, vs.output.offset);

        buffer_append(&job->vs->jobs_buffer, vs.output.buffer,

                      vs.output.offset);

        /* Copy persistent encoding data */

        vnc_async_encoding_end(job->vs, &vs);

        qemu_bh_schedule(job->vs->bh);

    }

    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);

    return 0;

}

static VncJobQueue *vnc_queue_init(void)

{

    VncJobQueue *queue = g_malloc0(sizeof(VncJobQueue));

    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);

    buffer_free(&queue->buffer);

    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_thread, q, QEMU_THREAD_DETACHED);

    queue = q; /* Set global queue */

}

void vnc_stop_worker_thread(void)

{

    if (!vnc_worker_thread_running())

        return ;

    /* Remove all jobs and wake up the thread */

    vnc_lock_queue(queue);

    queue->exit = true;

    vnc_unlock_queue(queue);

    vnc_jobs_clear(NULL);

    qemu_cond_broadcast(&queue->cond);

}