Added decent caching support; but index is still never cached

config.h.in

@@ -3,10 +3,12 @@
 // enables non-standard api connection (the only one supported at the moment)
 #define EPFL
 
-#define USERNAME "afontain"
-
 #mesondefine CACHE_ROOT
 
+// how long we consider the cache «up to date»: for index files,
+// the default is one hour; but for regular file, it is 10 years.
+#define CACHE_TIME_HTML  3600
+#define CACHE_TIME_FILES (10*365*24*3600)
 
 // how verbose the http requests are:
 //  0  – none
@@ -21,3 +23,5 @@
 #include "epfl.h"
 #endif // EPFL
 
+
+

src/moodle-provider.c

@@ -118,6 +118,27 @@ get_index_filename (void)
 }
 
 
+static gboolean
+cache_is_usable_for (const gchar *filename)
+{
+  g_autoptr (GFile) file = g_file_new_for_uri (filename);
+  g_autoptr (GFileInfo) fileinfo = g_file_query_info (file,
+                                                      G_FILE_ATTRIBUTE_TIME_MODIFIED,
+                                                      G_FILE_QUERY_INFO_NONE,
+                                                      NULL,
+                                                      NULL);
+  if (fileinfo) {
+    guint64 mtime = g_file_info_get_attribute_uint64 (fileinfo, G_FILE_ATTRIBUTE_TIME_MODIFIED);
+    guint64 now = g_get_real_time () / 1000000; // that one is in µs
+
+    if (g_str_has_suffix (filename, ".html")) {
+      return CACHE_TIME_HTML > (now - mtime); // if we updated recently enough, that's good
+    }
+    return CACHE_TIME_FILES > (now - mtime); // non-html files are less likely to be updated
+  }
+  return FALSE; // no file info: this file doesn't exists; we better not rely on cache
+}
+
 static void
 request_url_cb (GObject      *unused,
                 GAsyncResult *res,
@@ -158,7 +179,8 @@ request_url (const gchar         *url,
              provider_cb          final_cb,
              gpointer             user_data)
 {
-  if (self.online_mode == MOODLE_MODE_ONLINE) {
+
+  if (!cache_is_usable_for (filename) && self.online_mode == MOODLE_MODE_ONLINE) {
 
     SoupMessage *msg;
     msg = soup_message_new ("GET", url);
@@ -170,7 +192,7 @@ request_url (const gchar         *url,
     soup_session_send_async (self.session, msg, NULL, request_url_cb, (gpointer)cb_info);
 
   } else { // offline_mode
-
+g_print ("using cache for %s\n", filename);
     // this is not quite async, but works «fast enough»
     g_autoptr (GFile) file = g_file_new_for_uri (filename);
     GInputStream *is;