I#2326 - RSS: Limit re-download on content change, if possible

Closes https://gitlab.gnome.org/GNOME/evolution/-/issues/2326

5 files changed, 182 insertions, 5 deletions

diff --git a/src/modules/rss/camel-rss-store-summary.c b/src/modules/rss/camel-rss-store-summary.c
index ec9a6bf431..f4683d1f4f 100644
--- a/src/modules/rss/camel-rss-store-summary.c
+++ b/src/modules/rss/camel-rss-store-summary.c
@@ -34,6 +34,8 @@ typedef struct _RssFeed {
 	gchar *href;
 	gchar *display_name;
 	gchar *icon_filename;
+	gchar *last_etag;
+	gchar *last_modified;
 	CamelRssContentType content_type;
 	guint32 total_count;
 	guint32 unread_count;
@@ -216,6 +218,8 @@ camel_rss_store_summary_load (CamelRssStoreSummary *self,
 				feed->href = g_key_file_get_string (key_file, group, "href", NULL);
 				feed->display_name = g_key_file_get_string (key_file, group, "display-name", NULL);
 				feed->icon_filename = g_key_file_get_string (key_file, group, "icon-filename", NULL);
+				feed->last_etag = g_key_file_get_string (key_file, group, "last-etag", NULL);
+				feed->last_modified = g_key_file_get_string (key_file, group, "last-modified", NULL);
 				feed->content_type = g_key_file_get_integer (key_file, group, "content-type", NULL);
 				feed->total_count = (guint32) g_key_file_get_uint64 (key_file, group, "total-count", NULL);
 				feed->unread_count = (guint32) g_key_file_get_uint64 (key_file, group, "unread-count", NULL);
@@ -291,6 +295,8 @@ camel_rss_store_summary_save (CamelRssStoreSummary *self,
 			g_key_file_set_string (key_file, group, "href", feed->href);
 			g_key_file_set_string (key_file, group, "display-name", feed->display_name);
 			g_key_file_set_string (key_file, group, "icon-filename", feed->icon_filename ? feed->icon_filename : "");
+			g_key_file_set_string (key_file, group, "last-etag", feed->last_etag ? feed->last_etag : "");
+			g_key_file_set_string (key_file, group, "last-modified", feed->last_modified ? feed->last_modified : "");
 			g_key_file_set_integer (key_file, group, "content-type", feed->content_type);
 			g_key_file_set_uint64 (key_file, group, "total-count", feed->total_count);
 			g_key_file_set_uint64 (key_file, group, "unread-count", feed->unread_count);
@@ -850,3 +856,103 @@ camel_rss_store_summary_set_last_updated (CamelRssStoreSummary *self,
 
 	camel_rss_store_summary_unlock (self);
 }
+
+const gchar *
+camel_rss_store_summary_get_last_etag (CamelRssStoreSummary *self,
+				       const gchar *id)
+{
+	RssFeed *feed;
+	const gchar *result = NULL;
+
+	g_return_val_if_fail (CAMEL_IS_RSS_STORE_SUMMARY (self), NULL);
+	g_return_val_if_fail (id != NULL, NULL);
+
+	camel_rss_store_summary_lock (self);
+
+	feed = g_hash_table_lookup (self->priv->feeds, id);
+	if (feed)
+		result = feed->last_etag;
+
+	camel_rss_store_summary_unlock (self);
+
+	return result;
+}
+
+void
+camel_rss_store_summary_set_last_etag (CamelRssStoreSummary *self,
+				       const gchar *id,
+				       const gchar *last_etag)
+{
+	RssFeed *feed;
+	gboolean changed = FALSE;
+
+	g_return_if_fail (CAMEL_IS_RSS_STORE_SUMMARY (self));
+	g_return_if_fail (id != NULL);
+
+	camel_rss_store_summary_lock (self);
+
+	feed = g_hash_table_lookup (self->priv->feeds, id);
+	if (feed) {
+		if (g_strcmp0 (feed->last_etag, last_etag) != 0) {
+			g_free (feed->last_etag);
+			feed->last_etag = g_strdup (last_etag);
+			self->priv->dirty = TRUE;
+			changed = TRUE;
+		}
+	}
+
+	camel_rss_store_summary_unlock (self);
+
+	if (changed)
+		camel_rss_store_summary_schedule_feed_changed (self, id);
+}
+
+const gchar *
+camel_rss_store_summary_get_last_modified (CamelRssStoreSummary *self,
+					   const gchar *id)
+{
+	RssFeed *feed;
+	const gchar *result = NULL;
+
+	g_return_val_if_fail (CAMEL_IS_RSS_STORE_SUMMARY (self), NULL);
+	g_return_val_if_fail (id != NULL, NULL);
+
+	camel_rss_store_summary_lock (self);
+
+	feed = g_hash_table_lookup (self->priv->feeds, id);
+	if (feed)
+		result = feed->last_modified;
+
+	camel_rss_store_summary_unlock (self);
+
+	return result;
+}
+
+void
+camel_rss_store_summary_set_last_modified (CamelRssStoreSummary *self,
+					   const gchar *id,
+					   const gchar *last_modified)
+{
+	RssFeed *feed;
+	gboolean changed = FALSE;
+
+	g_return_if_fail (CAMEL_IS_RSS_STORE_SUMMARY (self));
+	g_return_if_fail (id != NULL);
+
+	camel_rss_store_summary_lock (self);
+
+	feed = g_hash_table_lookup (self->priv->feeds, id);
+	if (feed) {
+		if (g_strcmp0 (feed->last_modified, last_modified) != 0) {
+			g_free (feed->last_modified);
+			feed->last_modified = g_strdup (last_modified);
+			self->priv->dirty = TRUE;
+			changed = TRUE;
+		}
+	}
+
+	camel_rss_store_summary_unlock (self);
+
+	if (changed)
+		camel_rss_store_summary_schedule_feed_changed (self, id);
+}
diff --git a/src/modules/rss/camel-rss-store-summary.h b/src/modules/rss/camel-rss-store-summary.h
index 9c1b2b36e0..2272a8f429 100644
--- a/src/modules/rss/camel-rss-store-summary.h
+++ b/src/modules/rss/camel-rss-store-summary.h
@@ -110,6 +110,18 @@ gint64		camel_rss_store_summary_get_last_updated(CamelRssStoreSummary *self,
 void		camel_rss_store_summary_set_last_updated(CamelRssStoreSummary *self,
 							 const gchar *id,
 							 gint64 last_updated);
+const gchar *	camel_rss_store_summary_get_last_etag	(CamelRssStoreSummary *self,
+							 const gchar *id);
+void		camel_rss_store_summary_set_last_etag	(CamelRssStoreSummary *self,
+							 const gchar *id,
+							 const gchar *last_etag);
+const gchar *	camel_rss_store_summary_get_last_modified
+							(CamelRssStoreSummary *self,
+							 const gchar *id);
+void		camel_rss_store_summary_set_last_modified
+							(CamelRssStoreSummary *self,
+							 const gchar *id,
+							 const gchar *last_modified);
 
 G_END_DECLS
 
diff --git a/src/modules/rss/camel/camel-rss-folder.c b/src/modules/rss/camel/camel-rss-folder.c
index 13a783efd7..d6bd517be0 100644
--- a/src/modules/rss/camel/camel-rss-folder.c
+++ b/src/modules/rss/camel/camel-rss-folder.c
@@ -240,6 +240,8 @@ rss_folder_refresh_info_sync (CamelFolder *folder,
 	CamelFolderChangeInfo *changes = NULL;
 	CamelSession *session;
 	gchar *href;
+	gchar *last_etag;
+	gchar *last_modified;
 	gint64 last_updated;
 	gboolean success = TRUE;
 
@@ -260,14 +262,18 @@ rss_folder_refresh_info_sync (CamelFolder *folder,
 	camel_rss_store_summary_lock (rss_store_summary);
 
 	href = g_strdup (camel_rss_store_summary_get_href (rss_store_summary, self->priv->id));
+	last_etag = g_strdup (camel_rss_store_summary_get_last_etag (rss_store_summary, self->priv->id));
+	last_modified = g_strdup (camel_rss_store_summary_get_last_modified (rss_store_summary, self->priv->id));
 	last_updated = camel_rss_store_summary_get_last_updated (rss_store_summary, self->priv->id);
 
 	camel_rss_store_summary_unlock (rss_store_summary);
 
 	if (href && *href) {
 		SoupSession *soup_session;
+		SoupMessageHeaders *request_headers;
 		SoupMessage *message;
 		GBytes *bytes;
+		GError *local_error = NULL;
 
 		message = soup_message_new (SOUP_METHOD_GET, href);
 		if (!message) {
@@ -290,10 +296,22 @@ rss_folder_refresh_info_sync (CamelFolder *folder,
 			g_object_unref (logger);
 		}
 
-		bytes = soup_session_send_and_read (soup_session, message, cancellable, error);
+		request_headers = soup_message_get_request_headers (message);
+
+		soup_message_headers_append (request_headers, "Connection", "close");
+
+		if (last_etag && *last_etag)
+			soup_message_headers_append (request_headers, "If-None-Match", last_etag);
+		else if (last_modified && *last_modified)
+			soup_message_headers_append (request_headers, "If-Modified-Since", last_modified);
 
-		if (bytes) {
+		bytes = soup_session_send_and_read (soup_session, message, cancellable, &local_error);
+
+		if (soup_message_get_status (message) == SOUP_STATUS_NOT_MODIFIED) {
+			g_clear_error (&local_error);
+		} else if (bytes) {
 			GSList *feeds = NULL;
+			gboolean save_summary = FALSE;
 
 			success = SOUP_STATUS_IS_SUCCESSFUL (soup_message_get_status (message));
 
@@ -392,13 +410,49 @@ rss_folder_refresh_info_sync (CamelFolder *folder,
 					camel_rss_store_summary_set_last_updated (rss_store_summary, self->priv->id, max_last_modified);
 					camel_rss_store_summary_unlock (rss_store_summary);
 
-					success = camel_rss_store_summary_save (rss_store_summary, error);
+					save_summary = TRUE;
 				}
 			}
 
 			g_slist_free_full (feeds, e_rss_feed_free);
+
+			if (success) {
+				SoupMessageHeaders *response_headers;
+
+				response_headers = soup_message_get_response_headers (message);
+
+				if (response_headers) {
+					const gchar *tmp;
+
+					camel_rss_store_summary_lock (rss_store_summary);
+
+					tmp = soup_message_headers_get_one (response_headers, "ETag");
+					/* ignore weak ETag-s */
+					if (tmp && (g_ascii_strncasecmp (tmp, "W/", 2) == 0 || g_ascii_strncasecmp (tmp, "\"W/", 3) == 0))
+						tmp = NULL;
+					if (tmp && !*tmp)
+						tmp = NULL;
+
+					camel_rss_store_summary_set_last_etag (rss_store_summary, self->priv->id, tmp);
+
+					tmp = soup_message_headers_get_one (response_headers, "Last-Modified");
+					if (tmp && !*tmp)
+						tmp = NULL;
+
+					camel_rss_store_summary_set_last_modified (rss_store_summary, self->priv->id, tmp);
+
+					camel_rss_store_summary_unlock (rss_store_summary);
+
+					save_summary = TRUE;
+				}
+			}
+
+			if (success && save_summary)
+				success = camel_rss_store_summary_save (rss_store_summary, error);
 		} else {
 			success = FALSE;
+			if (local_error)
+				g_propagate_error (error, local_error);
 		}
 
 		g_clear_pointer (&bytes, g_bytes_unref);
@@ -409,6 +463,8 @@ rss_folder_refresh_info_sync (CamelFolder *folder,
 		success = FALSE;
 	}
 
+	g_free (last_modified);
+	g_free (last_etag);
 	g_free (href);
 
 	if (changes) {
diff --git a/src/modules/rss/e-rss-parser.c b/src/modules/rss/e-rss-parser.c
index 54b5a9bfc8..3bc0a7c329 100644
--- a/src/modules/rss/e-rss-parser.c
+++ b/src/modules/rss/e-rss-parser.c
@@ -592,11 +592,12 @@ e_rss_parser_parse (const gchar *xml,
 	xmlDoc *doc;
 	xmlNodePtr root;
 
-	g_return_val_if_fail (xml != NULL, FALSE);
-
 	if (out_feeds)
 		*out_feeds = NULL;
 
+	if (!xml || !xml_len)
+		return FALSE;
+
 	doc = e_xml_parse_data (xml, xml_len);
 
 	if (!doc)
diff --git a/src/modules/rss/evolution/e-rss-shell-view-extension.c b/src/modules/rss/evolution/e-rss-shell-view-extension.c
index ecb5ef6cdf..948bd4eb61 100644
--- a/src/modules/rss/evolution/e-rss-shell-view-extension.c
+++ b/src/modules/rss/evolution/e-rss-shell-view-extension.c
@@ -124,6 +124,8 @@ action_rss_mail_folder_reload_cb (GtkAction *action,
 	g_object_get (store, "summary", &store_summary, NULL);
 
 	camel_rss_store_summary_set_last_updated (store_summary, folder_path, 0);
+	camel_rss_store_summary_set_last_etag (store_summary, folder_path, NULL);
+	camel_rss_store_summary_set_last_modified (store_summary, folder_path, NULL);
 
 	camel_store_get_folder (store, folder_path, CAMEL_STORE_FOLDER_NONE, G_PRIORITY_DEFAULT, NULL,
 		e_rss_mail_folder_reload_got_folder_cb, shell_view);