objects.c

VLC Player Source Code

{
    vlc_mutex_lock( &(vlc_internals(obj)->lock) );
}

void __vlc_object_unlock( vlc_object_t *obj )
{
    vlc_assert_locked( &(vlc_internals(obj)->lock) );
    vlc_mutex_unlock( &(vlc_internals(obj)->lock) );
}

#ifdef WIN32
# include <winsock2.h>
# include <ws2tcpip.h>

/**
 * select()-able pipes emulated using Winsock
 */
static int pipe (int fd[2])
{
    SOCKADDR_IN addr;
    int addrlen = sizeof (addr);

    SOCKET l = socket (PF_INET, SOCK_STREAM, IPPROTO_TCP), a,
           c = socket (PF_INET, SOCK_STREAM, IPPROTO_TCP);
    if ((l == INVALID_SOCKET) || (c == INVALID_SOCKET))
        goto error;

    memset (&addr, 0, sizeof (addr));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl (INADDR_LOOPBACK);
    if (bind (l, (PSOCKADDR)&addr, sizeof (addr))
     || getsockname (l, (PSOCKADDR)&addr, &addrlen)
     || listen (l, 1)
     || connect (c, (PSOCKADDR)&addr, addrlen))
        goto error;

    a = accept (l, NULL, NULL);
    if (a == INVALID_SOCKET)
        goto error;

    closesocket (l);
    //shutdown (a, 0);
    //shutdown (c, 1);
    fd[0] = c;
    fd[1] = a;
    return 0;

error:
    if (l != INVALID_SOCKET)
        closesocket (l);
    if (c != INVALID_SOCKET)
        closesocket (c);
    return -1;
}

#undef  read
#define read( a, b, c )  recv (a, b, c, 0)
#undef  write
#define write( a, b, c ) send (a, b, c, 0)
#undef  close
#define close( a )       closesocket (a)
#endif /* WIN32 */

/**
 * Returns the readable end of a pipe that becomes readable once termination
 * of the object is requested (vlc_object_kill()).
 * This can be used to wake-up out of a select() or poll() event loop, such
 * typically when doing network I/O.
 *
 * Note that the pipe will remain the same for the lifetime of the object.
 * DO NOT read the pipe nor close it yourself. Ever.
 *
 * @param obj object that would be "killed"
 * @return a readable pipe descriptor, or -1 on error.
 */
int __vlc_object_waitpipe( vlc_object_t *obj )
{
    int pfd[2] = { -1, -1 };
    vlc_object_internals_t *internals = vlc_internals( obj );
    bool killed = false;

    vlc_spin_lock (&internals->spin);
    if (internals->pipes[0] == -1)
    {
        /* This can only ever happen if someone killed us without locking: */
        assert (internals->pipes[1] == -1);
        vlc_spin_unlock (&internals->spin);

        if (pipe (pfd))
            return -1;

        vlc_spin_lock (&internals->spin);
        if (internals->pipes[0] == -1)
        {
            internals->pipes[0] = pfd[0];
            internals->pipes[1] = pfd[1];
            pfd[0] = pfd[1] = -1;
        }
        killed = obj->b_die;
    }
    vlc_spin_unlock (&internals->spin);

    if (killed)
    {
        /* Race condition: vlc_object_kill() already invoked! */
        int fd;

        vlc_spin_lock (&internals->spin);
        fd = internals->pipes[1];
        internals->pipes[1] = -1;
        vlc_spin_unlock (&internals->spin);

        msg_Dbg (obj, "waitpipe: object already dying");
        if (fd != -1)
            close (fd);
    }

    /* Race condition: two threads call pipe() - unlikely */
    if (pfd[0] != -1)
        close (pfd[0]);
    if (pfd[1] != -1)
        close (pfd[1]);

    return internals->pipes[0];
}


/**
 * Waits for the object to be signaled (using vlc_object_signal()).
 * It is assumed that the caller has locked the object. This function will
 * unlock the object, and lock it again before returning.
 * If the object was signaled before the caller locked the object, it is
 * undefined whether the signal will be lost or will wake the process.
 *
 * @return true if the object is dying and should terminate.
 */
void __vlc_object_wait( vlc_object_t *obj )
{
    vlc_object_internals_t *priv = vlc_internals( obj );
    vlc_assert_locked( &priv->lock);
    vlc_cond_wait( &priv->wait, &priv->lock );
}


/**
 * Waits for the object to be signaled (using vlc_object_signal()), or for
 * a timer to expire. It is asserted that the caller holds the object lock.
 *
 * @return 0 if the object was signaled before the timer expiration, or
 * ETIMEDOUT if the timer expired without any signal.
 */
int __vlc_object_timedwait( vlc_object_t *obj, mtime_t deadline )
{
    vlc_object_internals_t *priv = vlc_internals( obj );
    vlc_assert_locked( &priv->lock);
    return vlc_cond_timedwait( &priv->wait, &priv->lock, deadline );
}


/**
 * Signals an object for which the lock is held.
 * At least one thread currently sleeping in vlc_object_wait() or
 * vlc_object_timedwait() will wake up, assuming that there is at least one
 * such thread in the first place. Otherwise, it is undefined whether the
 * signal will be lost or will wake up one or more thread later.
 */
void __vlc_object_signal_unlocked( vlc_object_t *obj )
{
    vlc_assert_locked (&(vlc_internals(obj)->lock));
    vlc_cond_signal( &(vlc_internals(obj)->wait) );
}


/**
 * Requests termination of an object.
 * If the object is LibVLC, also request to terminate all its children.
 */
void __vlc_object_kill( vlc_object_t *p_this )
{
    vlc_object_internals_t *priv = vlc_internals( p_this );
    int fd;

    vlc_object_lock( p_this );
    p_this->b_die = true;

    vlc_spin_lock (&priv->spin);
    fd = priv->pipes[1];
    priv->pipes[1] = -1;
    vlc_spin_unlock (&priv->spin);

    if( fd != -1 )
    {
        msg_Dbg (p_this, "waitpipe: object killed");
        close (fd);
    }

    vlc_object_signal_unlocked( p_this );
    /* This also serves as a memory barrier toward vlc_object_alive(): */
    vlc_object_unlock( p_this );
}


/**
 * Find an object given its ID.
 *
 * This function looks for the object whose i_object_id field is i_id.
 * This function is slow, and often used to hide bugs. Do not use it.
 * If you need to retain reference to an object, yield the object pointer with
 * vlc_object_yield(), use the pointer as your reference, and call
 * vlc_object_release() when you're done.
 */
void * vlc_object_get( int i_id )
{
    libvlc_global_data_t *p_libvlc_global = vlc_global();
    vlc_object_t *obj = NULL;
#ifndef NDEBUG
    vlc_object_t *caller = vlc_threadobj ();

    if (caller)
        msg_Dbg (caller, "uses deprecated vlc_object_get(%d)", i_id);
    else
        fprintf (stderr, "main thread uses deprecated vlc_object_get(%d)\n",
                 i_id);
#endif
    vlc_mutex_lock( &structure_lock );

    for( obj = vlc_internals (p_libvlc_global)->next;
         obj != VLC_OBJECT (p_libvlc_global);
         obj = vlc_internals (obj)->next )
    {
        if( obj->i_object_id == i_id )
        {
            vlc_object_yield( obj );
            goto out;
        }
    }
    obj = NULL;
#ifndef NDEBUG
    if (caller)
        msg_Warn (caller, "wants non-existing object %d", i_id);
    else
        fprintf (stderr, "main thread wants non-existing object %d\n", i_id);
#endif
out:
    vlc_mutex_unlock( &structure_lock );
    return obj;
}

/**
 ****************************************************************************
 * find a typed object and increment its refcount
 *****************************************************************************
 * This function recursively looks for a given object type. i_mode can be one
 * of FIND_PARENT, FIND_CHILD or FIND_ANYWHERE.
 *****************************************************************************/
void * __vlc_object_find( vlc_object_t *p_this, int i_type, int i_mode )
{
    vlc_object_t *p_found;

    /* If we are of the requested type ourselves, don't look further */
    if( !(i_mode & FIND_STRICT) && p_this->i_object_type == i_type )
    {
        vlc_object_yield( p_this );
        return p_this;
    }

    /* Otherwise, recursively look for the object */
    if ((i_mode & 0x000f) == FIND_ANYWHERE)
    {
#ifndef NDEBUG
        if (i_type == VLC_OBJECT_PLAYLIST)
	    msg_Err (p_this, "using vlc_object_find(VLC_OBJECT_PLAYLIST) "
                     "instead of pl_Yield()");
#endif
        return vlc_object_find (p_this->p_libvlc, i_type,
                                (i_mode & ~0x000f)|FIND_CHILD);
    }

    vlc_mutex_lock( &structure_lock );
    p_found = FindObject( p_this, i_type, i_mode );
    vlc_mutex_unlock( &structure_lock );
    return p_found;
}

/**
 ****************************************************************************
 * find a named object and increment its refcount
 *****************************************************************************
 * This function recursively looks for a given object name. i_mode can be one
 * of FIND_PARENT, FIND_CHILD or FIND_ANYWHERE.
 *****************************************************************************/
void * __vlc_object_find_name( vlc_object_t *p_this, const char *psz_name,
                               int i_mode )
{
    vlc_object_t *p_found;

    /* If have the requested name ourselves, don't look further */
    if( !(i_mode & FIND_STRICT)
        && p_this->psz_object_name
        && !strcmp( p_this->psz_object_name, psz_name ) )
    {
        vlc_object_yield( p_this );
        return p_this;
    }

    vlc_mutex_lock( &structure_lock );

    /* Otherwise, recursively look for the object */
    if( (i_mode & 0x000f) == FIND_ANYWHERE )
    {
        vlc_object_t *p_root = p_this;

        /* Find the root */
        while( p_root->p_parent != NULL &&
               p_root != VLC_OBJECT( p_this->p_libvlc ) )
        {
            p_root = p_root->p_parent;
        }

        p_found = FindObjectName( p_root, psz_name,
                                 (i_mode & ~0x000f)|FIND_CHILD );
        if( p_found == NULL && p_root != VLC_OBJECT( p_this->p_libvlc ) )
        {
            p_found = FindObjectName( VLC_OBJECT( p_this->p_libvlc ),
                                      psz_name, (i_mode & ~0x000f)|FIND_CHILD );
        }
    }
    else
    {
        p_found = FindObjectName( p_this, psz_name, i_mode );
    }

    vlc_mutex_unlock( &structure_lock );

    return p_found;
}

/**
 * Increment an object reference counter.
 */
void __vlc_object_yield( vlc_object_t *p_this )
{
    vlc_object_internals_t *internals = vlc_internals( p_this );

    vlc_spin_lock( &internals->ref_spin );
    /* Avoid obvious freed object uses */
    assert( internals->i_refcount > 0 );
    /* Increment the counter */
    internals->i_refcount++;
    vlc_spin_unlock( &internals->ref_spin );
#ifdef LIBVLC_REFCHECK
    /* Update the list of referenced objects */
    /* Using TLS, so no need to lock */
    /* The following line may leak memory if a thread leaks objects. */
    held_list_t *newhead = malloc (sizeof (*newhead));
    held_list_t *oldhead = vlc_threadvar_get (&held_objects);
    newhead->next = oldhead;
    newhead->obj = p_this;
    vlc_threadvar_set (&held_objects, newhead);
#endif
}

/*****************************************************************************
 * decrement an object refcount
 * And destroy the object if its refcount reach zero.
 *****************************************************************************/
void __vlc_object_release( vlc_object_t *p_this )
{
    vlc_object_internals_t *internals = vlc_internals( p_this );
    bool b_should_destroy;

#ifdef LIBVLC_REFCHECK
    /* Update the list of referenced objects */
    /* Using TLS, so no need to lock */
    for (held_list_t *hlcur = vlc_threadvar_get (&held_objects),
                     *hlprev = NULL;
         hlcur != NULL;
         hlprev = hlcur, hlcur = hlcur->next)
    {
        if (hlcur->obj == p_this)
        {
            if (hlprev == NULL)
                vlc_threadvar_set (&held_objects, hlcur->next);
            else
                hlprev->next = hlcur->next;
            free (hlcur);
            break;
        }
    }
    /* TODO: what if releasing without references? */