[gnome-music/wip/mschraal/file-exists-async: 1/9] fileexistsasync: Async version of file_exists

[Marinus Schraal <mschraal src gnome org>]

commit b39855794849b985cb54df22ef30d36e7fa228e5
Author: Marinus Schraal <mschraal gnome org>
Date:   Sun Aug 15 22:18:24 2021 +0200

    fileexistsasync: Async version of file_exists
    
    Gio.File.file_exists is a blocking operation, provide an async version.

 gnomemusic/fileexistsasync.py | 62 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)
---
diff --git a/gnomemusic/fileexistsasync.py b/gnomemusic/fileexistsasync.py
new file mode 100644
index 000000000..c97a521fa
--- /dev/null
+++ b/gnomemusic/fileexistsasync.py
@@ -0,0 +1,62 @@
+# Copyright 2021 The GNOME Music developers
+#
+# GNOME Music is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# GNOME Music 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with GNOME Music; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#
+# The GNOME Music authors hereby grant permission for non-GPL compatible
+# GStreamer plugins to be used and distributed together with GStreamer
+# and GNOME Music.  This permission is above and beyond the permissions
+# granted by the GPL license by which GNOME Music is covered.  If you
+# modify this code, you may extend this exception to your version of the
+# code, but you are not obligated to do so.  If you do not wish to do so,
+# delete this exception statement from your version.
+
+from gi.repository import GLib, GObject, Gio
+
+
+class FileExistsAsync(GObject.GObject):
+    """Gio.File.file_exists async variant
+    """
+
+    __gtype_name__ = "FileExistsAsync"
+
+    __gsignals__ = {
+        "finished": (GObject.SignalFlags.RUN_FIRST, None, (bool, ))
+    }
+
+    def __init__(self) -> None:
+        """Initialize FileExistsAsync
+        """
+        super().__init__()
+
+    def start(self, thumb_file: Gio.File) -> None:
+        """Start async file_exists lookup
+
+        :param Gio.File thumb_file: File to check
+        """
+        thumb_file.query_info_async(
+            Gio.FILE_ATTRIBUTE_STANDARD_TYPE, Gio.FileQueryInfoFlags.NONE,
+            GLib.PRIORITY_HIGH_IDLE, None, self._on_query_info_finished)
+
+    def _on_query_info_finished(
+            self, thumb_file: Gio.File, res: Gio.AsyncResult) -> None:
+        exists = True
+        try:
+            thumb_file.query_info_finish(res)
+        except GLib.Error:
+            # This indicates that the file has not been created, so
+            # there is no art in the MediaArt cache.
+            exists = False
+
+        self.emit("finished", exists)