[gthumb] comments: metadata is unreadable if the comment folder does not exist

[Paolo Bacchilega <paobac src gnome org>]

commit 18a619d1a7f6dfe98c3fedc5386b10ffc6a911f8
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Sun Aug 1 12:22:48 2021 +0200

    comments: metadata is unreadable if the comment folder does not exist
    
    Do not try to read the metadata if the comment folder does not exist.
    
    Added a cache of the checked folders to speed-up folder loading on
    remote/slow locations.

 .../comments/gth-metadata-provider-comment.c       | 89 +++++++++++++++++++---
 .../comments/gth-metadata-provider-comment.h       |  4 +-
 2 files changed, 82 insertions(+), 11 deletions(-)
---
diff --git a/extensions/comments/gth-metadata-provider-comment.c 
b/extensions/comments/gth-metadata-provider-comment.c
index 74adecc9..0dcad4b5 100644
--- a/extensions/comments/gth-metadata-provider-comment.c
+++ b/extensions/comments/gth-metadata-provider-comment.c
@@ -26,7 +26,15 @@
 #include "gth-metadata-provider-comment.h"
 
 
-G_DEFINE_TYPE (GthMetadataProviderComment, gth_metadata_provider_comment, GTH_TYPE_METADATA_PROVIDER)
+struct _GthMetadataProviderCommentPrivate {
+       GHashTable *checked_folders;
+};
+
+
+G_DEFINE_TYPE_WITH_CODE (GthMetadataProviderComment,
+                        gth_metadata_provider_comment,
+                        GTH_TYPE_METADATA_PROVIDER,
+                        G_ADD_PRIVATE (GthMetadataProviderComment))
 
 
 static gboolean
@@ -36,14 +44,52 @@ gth_metadata_provider_comment_can_read (GthMetadataProvider  *base,
                                        char                **attribute_v)
 
 {
-       return _g_file_attributes_matches_any_v ("comment::*,"
-                                                "general::datetime,"
-                                                "general::title,"
-                                                "general::description,"
-                                                "general::location,"
-                                                "general::tags,"
-                                                "general::rating",
-                                                attribute_v);
+       GthMetadataProviderComment *self = GTH_METADATA_PROVIDER_COMMENT (base);
+       gboolean                    can_read;
+
+       can_read = _g_file_attributes_matches_any_v ("comment::*,"
+                                                    "general::datetime,"
+                                                    "general::title,"
+                                                    "general::description,"
+                                                    "general::location,"
+                                                    "general::tags,"
+                                                    "general::rating",
+                                                    attribute_v);
+
+       if (! can_read)
+               return FALSE;
+
+       if (file_data != NULL) {
+               GFile    *comment_file;
+               GFile    *comment_folder;
+               gboolean  comment_folder_exists;
+               gpointer  value;
+
+               comment_file = gth_comment_get_comment_file (file_data->file);
+               if (comment_file == NULL)
+                       return FALSE;
+
+               comment_folder = g_file_get_parent (comment_file);
+               if (comment_folder == NULL)
+                       return FALSE;
+
+               value = g_hash_table_lookup (self->priv->checked_folders, comment_folder);
+               if (value == NULL) {
+                       comment_folder_exists = g_file_query_exists (comment_folder, NULL);
+                       g_hash_table_insert (self->priv->checked_folders,
+                                            g_object_ref (comment_folder),
+                                            GINT_TO_POINTER (comment_folder_exists ? 1 : 2));
+               }
+               else
+                       comment_folder_exists = GPOINTER_TO_INT (value) == 1;
+
+               can_read = comment_folder_exists;
+
+               g_object_unref (comment_folder);
+               g_object_unref (comment_file);
+       }
+
+       return can_read;
 }
 
 
@@ -222,11 +268,32 @@ gth_metadata_provider_comment_write (GthMetadataProvider   *self,
 }
 
 
+static void
+gth_metadata_provider_comment_finalize (GObject *object)
+{
+       GthMetadataProviderComment *self;
+
+       g_return_if_fail (object != NULL);
+       g_return_if_fail (GTH_IS_METADATA_PROVIDER_COMMENT (object));
+
+       self = GTH_METADATA_PROVIDER_COMMENT (object);
+       g_hash_table_unref (self->priv->checked_folders);
+
+       /* Chain up */
+       G_OBJECT_CLASS (gth_metadata_provider_comment_parent_class)->finalize (object);
+}
+
+
 static void
 gth_metadata_provider_comment_class_init (GthMetadataProviderCommentClass *klass)
+
 {
+       GObjectClass             *gobject_class;
        GthMetadataProviderClass *mp_class;
 
+       gobject_class = G_OBJECT_CLASS (klass);
+       gobject_class->finalize = gth_metadata_provider_comment_finalize;
+
        mp_class = GTH_METADATA_PROVIDER_CLASS (klass);
        mp_class->can_read = gth_metadata_provider_comment_can_read;
        mp_class->can_write = gth_metadata_provider_comment_can_write;
@@ -234,8 +301,10 @@ gth_metadata_provider_comment_class_init (GthMetadataProviderCommentClass *klass
        mp_class->write = gth_metadata_provider_comment_write;
 }
 
+
 static void
 gth_metadata_provider_comment_init (GthMetadataProviderComment *self)
 {
-       /* void */
+       self->priv = gth_metadata_provider_comment_get_instance_private (self);
+       self->priv->checked_folders = g_hash_table_new_full (g_file_hash, (GEqualFunc) g_file_equal, 
g_object_unref, NULL);
 }
diff --git a/extensions/comments/gth-metadata-provider-comment.h 
b/extensions/comments/gth-metadata-provider-comment.h
index 96c938f0..f706ad70 100644
--- a/extensions/comments/gth-metadata-provider-comment.h
+++ b/extensions/comments/gth-metadata-provider-comment.h
@@ -35,15 +35,17 @@
 
 typedef struct _GthMetadataProviderComment         GthMetadataProviderComment;
 typedef struct _GthMetadataProviderCommentClass    GthMetadataProviderCommentClass;
+typedef struct _GthMetadataProviderCommentPrivate  GthMetadataProviderCommentPrivate;
 
 struct _GthMetadataProviderComment
 {
        GthMetadataProvider __parent;
+       GthMetadataProviderCommentPrivate *priv;
 };
 
 struct _GthMetadataProviderCommentClass
 {
-       GthMetadataProviderClass __parent_class;        
+       GthMetadataProviderClass __parent_class;
 };
 
 GType gth_metadata_provider_comment_get_type (void) G_GNUC_CONST;