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glib/gio/glocaldirectorymonitor.c
Ryan Lortie 33762a4173 glocalfile: add private worker monitor APIs 
Add a convenient and race-free method of watching local files from the
GLib worker thread.

Without this, the race-free way to create a monitor that dispatches
events to the worker thread looked something like this:

 - dispatch an idle to the worker thread
 - from the idle, create the monitor and connect signals
 - from the original thread, wait (on a cond?) until the worker thread
   has finished setting up the monitor
 - read the file that you were monitoring

which is just ridiculously complicated...

To use the new API:

  monitor = g_local_file_monitor_new_in_worker ("/path/to/some/file",
                                                G_FILE_MONITOR_NONE,
                                                &error);
  g_assert_no_error (error);

  g_signal_connect (monitor, "changed", G_CALLBACK (callback), NULL);

  g_local_file_monitor_start (monitor);

'callback' will run from the GLib worker thread.

This is the reason that the start() call was introduced in the previous
commit.  The backends that don't use the start() call will have a very
thin race between creating the monitor and connecting the signal, but
hopefully they will be fixed soon.

These new APIs will be used (at least) from gdesktopappinfo to watch for
changes in the desktop file directories.

https://bugzilla.gnome.org/show_bug.cgi?id=704887
2013-10-03 10:37:47 -04:00

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/* GIO - GLib Input, Output and Streaming Library
*
* Copyright (C) 2006-2007 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General
* Public License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*
* Author: Alexander Larsson <alexl@redhat.com>
*/
#include "config.h"
#include "glocaldirectorymonitor.h"
#include "gunixmounts.h"
#include "giomodule-priv.h"
#include "gfile.h"
#include "gioerror.h"
#include "glibintl.h"
#include <string.h>
enum
{
PROP_0,
PROP_DIRNAME,
PROP_FLAGS
};
static gboolean g_local_directory_monitor_cancel (GFileMonitor *monitor);
static void mounts_changed (GUnixMountMonitor *mount_monitor,
gpointer user_data);
G_DEFINE_ABSTRACT_TYPE (GLocalDirectoryMonitor, g_local_directory_monitor, G_TYPE_FILE_MONITOR)
static void
g_local_directory_monitor_finalize (GObject *object)
{
GLocalDirectoryMonitor *local_monitor;
local_monitor = G_LOCAL_DIRECTORY_MONITOR (object);
g_free (local_monitor->dirname);
if (local_monitor->mount_monitor)
{
g_signal_handlers_disconnect_by_func (local_monitor->mount_monitor, mounts_changed, local_monitor);
g_object_unref (local_monitor->mount_monitor);
local_monitor->mount_monitor = NULL;
}
G_OBJECT_CLASS (g_local_directory_monitor_parent_class)->finalize (object);
}
static void
g_local_directory_monitor_set_property (GObject *object,
guint property_id,
const GValue *value,
GParamSpec *pspec)
{
GLocalDirectoryMonitor *local_monitor = G_LOCAL_DIRECTORY_MONITOR (object);
switch (property_id)
{
case PROP_DIRNAME:
local_monitor->dirname = g_value_dup_string (value);
break;
case PROP_FLAGS:
local_monitor->flags = g_value_get_flags (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
break;
}
}
void
g_local_directory_monitor_start (GLocalDirectoryMonitor *local_monitor)
{
GLocalDirectoryMonitorClass *class;
class = G_LOCAL_DIRECTORY_MONITOR_GET_CLASS (local_monitor);
if (!class->mount_notify && (local_monitor->flags & G_FILE_MONITOR_WATCH_MOUNTS))
{
#ifdef G_OS_WIN32
/*claim everything was mounted */
local_monitor->was_mounted = TRUE;
#else
GUnixMountEntry *mount;
/* Emulate unmount detection */
mount = g_unix_mount_at (local_monitor->dirname, NULL);
local_monitor->was_mounted = mount != NULL;
if (mount)
g_unix_mount_free (mount);
local_monitor->mount_monitor = g_unix_mount_monitor_new ();
g_signal_connect_object (local_monitor->mount_monitor, "mounts-changed",
G_CALLBACK (mounts_changed), local_monitor, 0);
#endif
}
if (class->start)
class->start (local_monitor);
}
static void
g_local_directory_monitor_class_init (GLocalDirectoryMonitorClass* klass)
{
GObjectClass* gobject_class = G_OBJECT_CLASS (klass);
GFileMonitorClass *file_monitor_class = G_FILE_MONITOR_CLASS (klass);
gobject_class->finalize = g_local_directory_monitor_finalize;
gobject_class->set_property = g_local_directory_monitor_set_property;
file_monitor_class->cancel = g_local_directory_monitor_cancel;
g_object_class_install_property (gobject_class,
PROP_DIRNAME,
g_param_spec_string ("dirname",
P_("Directory name"),
P_("Directory to monitor"),
NULL,
G_PARAM_CONSTRUCT_ONLY|
G_PARAM_WRITABLE|
G_PARAM_STATIC_NAME|G_PARAM_STATIC_NICK|G_PARAM_STATIC_BLURB));
g_object_class_install_property (gobject_class,
PROP_FLAGS,
g_param_spec_flags ("flags",
P_("Monitor flags"),
P_("Monitor flags"),
G_TYPE_FILE_MONITOR_FLAGS,
0,
G_PARAM_CONSTRUCT_ONLY|
G_PARAM_WRITABLE|
G_PARAM_STATIC_NAME|G_PARAM_STATIC_NICK|G_PARAM_STATIC_BLURB));
klass->mount_notify = FALSE;
}
static void
g_local_directory_monitor_init (GLocalDirectoryMonitor *local_monitor)
{
}
static void
mounts_changed (GUnixMountMonitor *mount_monitor,
gpointer user_data)
{
GLocalDirectoryMonitor *local_monitor = user_data;
#ifdef G_OS_UNIX
GUnixMountEntry *mount;
#endif
gboolean is_mounted;
GFile *file;
/* Emulate unmount detection */
#ifdef G_OS_UNIX
mount = g_unix_mount_at (local_monitor->dirname, NULL);
is_mounted = mount != NULL;
if (mount)
g_unix_mount_free (mount);
#else
/*claim everything was mounted */
is_mounted = TRUE;
#endif
if (local_monitor->was_mounted != is_mounted)
{
if (local_monitor->was_mounted && !is_mounted)
{
file = g_file_new_for_path (local_monitor->dirname);
g_file_monitor_emit_event (G_FILE_MONITOR (local_monitor),
file, NULL,
G_FILE_MONITOR_EVENT_UNMOUNTED);
g_object_unref (file);
}
local_monitor->was_mounted = is_mounted;
}
}
GFileMonitor*
_g_local_directory_monitor_new (const char *dirname,
GFileMonitorFlags flags,
GMainContext *context,
gboolean is_remote_fs,
gboolean do_start,
GError **error)
{
GFileMonitor *monitor = NULL;
GType type = G_TYPE_INVALID;
if (is_remote_fs)
type = _g_io_module_get_default_type (G_NFS_DIRECTORY_MONITOR_EXTENSION_POINT_NAME,
"GIO_USE_FILE_MONITOR",
G_STRUCT_OFFSET (GLocalDirectoryMonitorClass, is_supported));
if (type == G_TYPE_INVALID)
type = _g_io_module_get_default_type (G_LOCAL_DIRECTORY_MONITOR_EXTENSION_POINT_NAME,
"GIO_USE_FILE_MONITOR",
G_STRUCT_OFFSET (GLocalDirectoryMonitorClass, is_supported));
if (type != G_TYPE_INVALID)
monitor = G_FILE_MONITOR (g_object_new (type, "dirname", dirname, "flags", flags, "context", context, NULL));
else
g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
_("Unable to find default local directory monitor type"));
if (monitor && do_start)
g_local_directory_monitor_start (G_LOCAL_DIRECTORY_MONITOR (monitor));
return monitor;
}
static gboolean
g_local_directory_monitor_cancel (GFileMonitor *monitor)
{
GLocalDirectoryMonitor *local_monitor = G_LOCAL_DIRECTORY_MONITOR (monitor);
if (local_monitor->mount_monitor)
{
g_signal_handlers_disconnect_by_func (local_monitor->mount_monitor, mounts_changed, local_monitor);
g_object_unref (local_monitor->mount_monitor);
local_monitor->mount_monitor = NULL;
}
return TRUE;
}
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