Monitoring directory changes with gnomevfs

[Damien Moore-3]

Hi List,

I'm trying to use the directory monitoring API in gnomevfs, but I'm having difficulty understanding how it is supposed to be used. The documentation at http://library.gnome.org/devel/gnome-vfs-2.0/unstable/gnome-vfs-20-gnome-vfs-monitor.html doesn't have any examples and I haven't been able to find a simple example on the web. The API seems simple enough, but I'm not sure I understand how the callback mechanism is supposed to work. (This probably reflects a deeper lack of understanding of glib, but I'll persist...)

For example, I gather this program won't work because there is no GMainLoop in place to generate the callback:

#include <libgnomevfs/gnome-vfs.h>

int exit=0;

static void MonitorCallback(GnomeVFSMonitorHandle *handle, const gchar *monitor_uri, const gchar *info_uri, GnomeVFSMonitorEventType event_type, gpointer user_data)
{
    exit=1;
}

int main()
{
    if(!gnome_vfs_initialized())
        gnome_vfs_init();
    GnomeVFSMonitorHandle *h;
    gnome_vfs_monitor_add(&h, "/home/myusername", GNOME_VFS_MONITOR_DIRECTORY, MonitorCallback, NULL);
    while(!exit);
    gnome_vfs_monitor_cancel(h);
    return 0;
}

but something like this should work correctly?

#include <glib.h>
#include <libgnomevfs/gnome-vfs.h>

static void MonitorCallback(GnomeVFSMonitorHandle *handle, const gchar *monitor_uri, const gchar *info_uri, GnomeVFSMonitorEventType event_type, gpointer user_data)
{
    g_print("Monitor event received, exiting...\n");
    g_main_loop_quit((GMainLoop*)user_data);
}

int main()
{
    if(!gnome_vfs_initialized())
        gnome_vfs_init();
    GMainLoop *loop;
    loop = g_main_loop_new(NULL, FALSE);
    GnomeVFSMonitorHandle *h;
    gnome_vfs_monitor_add(&h, "/home/myusername", GNOME_VFS_MONITOR_DIRECTORY, MonitorCallback, loop);
    g_main_loop_run(loop);
    gnome_vfs_monitor_cancel(h);
    return 0;
}

Can someone can give me an idea of whether the above should work or what I would need to do to that simple example to get it working? Looking at the above I don't really understand how glib would know how to attach the MonitorCallback to the GMainLoop, which isn't even running yet (if I created and started another main loop inside the outer loop, would it also generate callbacks?).

thanks,
D
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[Hans Petter Jansson]

On Thu, 2008-08-28 at 10:01 -0400, Damien Moore wrote:

> Can someone can give me an idea of whether the above should work or
> what I would need to do to that simple example to get it working?
> Looking at the above I don't really understand how glib would know how
> to attach the MonitorCallback to the GMainLoop, which isn't even
> running yet (if I created and started another main loop inside the
> outer loop, would it also generate callbacks?).

You're correct that you must spin the main loop for callbacks to work.
The default main loop is global, so gnome-vfs will be able to find it
and add the callback even if it's not running or passed in.

These days you should be using GIO/GVFS instead of gnome-vfs, though.
Take a look at the documentation here:

http://library.gnome.org/devel/gio/stable/

GIO is part of GLib. You can read more about main loops here:

http://library.gnome.org/devel/glib/stable/glib-The-Main-Event-Loop.html

--
Hans Petter

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[Mikael Hermansson]

You should use gvfs instead gnomevfs is deprecated

2008/8/28 Damien Moore <damien.moore@...>

Hi List,

I'm trying to use the directory monitoring API in gnomevfs, but I'm having difficulty understanding how it is supposed to be used. The documentation at http://library.gnome.org/devel/gnome-vfs-2.0/unstable/gnome-vfs-20-gnome-vfs-monitor.html doesn't have any examples and I haven't been able to find a simple example on the web. The API seems simple enough, but I'm not sure I understand how the callback mechanism is supposed to work. (This probably reflects a deeper lack of understanding of glib, but I'll persist...)

For example, I gather this program won't work because there is no GMainLoop in place to generate the callback:

#include <libgnomevfs/gnome-vfs.h>

int exit=0;

static void MonitorCallback(GnomeVFSMonitorHandle *handle, const gchar *monitor_uri, const gchar *info_uri, GnomeVFSMonitorEventType event_type, gpointer user_data)
{
    exit=1;
}

int main()
{
    if(!gnome_vfs_initialized())
        gnome_vfs_init();
    GnomeVFSMonitorHandle *h;
    gnome_vfs_monitor_add(&h, "/home/myusername", GNOME_VFS_MONITOR_DIRECTORY, MonitorCallback, NULL);
    while(!exit);
    gnome_vfs_monitor_cancel(h);
    return 0;
}

but something like this should work correctly?

#include <glib.h>
#include <libgnomevfs/gnome-vfs.h>

static void MonitorCallback(GnomeVFSMonitorHandle *handle, const gchar *monitor_uri, const gchar *info_uri, GnomeVFSMonitorEventType event_type, gpointer user_data)
{
    g_print("Monitor event received, exiting...\n");
    g_main_loop_quit((GMainLoop*)user_data);
}

int main()
{
    if(!gnome_vfs_initialized())
        gnome_vfs_init();
    GMainLoop *loop;
    loop = g_main_loop_new(NULL, FALSE);
    GnomeVFSMonitorHandle *h;
    gnome_vfs_monitor_add(&h, "/home/myusername", GNOME_VFS_MONITOR_DIRECTORY, MonitorCallback, loop);
    g_main_loop_run(loop);
    gnome_vfs_monitor_cancel(h);
    return 0;
}

Can someone can give me an idea of whether the above should work or what I would need to do to that simple example to get it working? Looking at the above I don't really understand how glib would know how to attach the MonitorCallback to the GMainLoop, which isn't even running yet (if I created and started another main loop inside the outer loop, would it also generate callbacks?).

thanks,
D
_______________________________________________
gnome-vfs-list mailing list
gnome-vfs-list@...
http://mail.gnome.org/mailman/listinfo/gnome-vfs-list

_______________________________________________
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gnome-vfs-list@...
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