plug-ins: revert the multi-threading code.

The whole multi-threading changes in the help plug-in seem to badly
break on macOS. See discussion in reopened #12898.
We decided to get rid of it for now and see later if we need to
reimplement this (after understanding what is going on).

Revert "plug-ins: fix #13049 Calling help on unknown help-id causes..."

This reverts commit 7d153bcc6d.

Revert "plug-ins/help: fix thread unnecessarily waiting when locale_parse failed"

This reverts commit fd0ccfa16c.

Revert "plug-ins/help: fix crash when locale is NULL"

This reverts commit 4075add5b4.

Revert "plug-ins: fix failing to access help from within GIMP"

This reverts commit 38f0527ebc.

Revert "plug-ins: add some better error handling when the docs XML request/parsing fails."

This reverts commit 543bb374a8.

Revert "plug-ins: try to load the gimp-help.xml file in a thread."

This reverts commit f2d47e910b.

plug-ins/help/gimphelpdomain.c

@@ -42,22 +42,8 @@
 #endif
 
 
-typedef struct
-{
-  gboolean          *success;
-  gboolean          *done;
-
-  GimpHelpLocale    *locale;
-  const gchar       *uri;
-  const gchar       *domain;
-  GimpHelpProgress  *progress;
-  GCancellable      *cancellable;
-  GError           **error;
-} HelpThreadData;
-
 /*  local function prototypes  */
 
-static gboolean   parse_thread_func   (HelpThreadData    *data);
 static gboolean   domain_locale_parse (GimpHelpDomain    *domain,
                                        GimpHelpLocale    *locale,
                                        GimpHelpProgress  *progress,
@@ -118,12 +104,10 @@ gimp_help_domain_lookup_locale (GimpHelpDomain    *domain,
     return locale;
 
   locale = gimp_help_locale_new (locale_id);
-
-  if (! domain_locale_parse (domain, locale, progress, NULL))
-    g_clear_pointer (&locale, gimp_help_locale_free);
-  else
   g_hash_table_insert (domain->help_locales, g_strdup (locale_id), locale);
 
+  domain_locale_parse (domain, locale, progress, NULL);
+
   return locale;
 }
 
@@ -146,24 +130,25 @@ gimp_help_domain_map (GimpHelpDomain    *domain,
   if (fatal_error)
     *fatal_error = FALSE;
 
-  /*  Look for a reference matching the help_id  */
+  /*  first pass: look for a reference matching the help_id  */
   for (list = help_locales; list && !ref; list = list->next)
     {
       locale = gimp_help_domain_lookup_locale (domain,
                                                (const gchar *) list->data,
                                                progress);
-      if (locale)
-        {
       ref = gimp_help_locale_map (locale, help_id);
-          /* It doesn't make sense to keep looking since all available locales
-           * have the same pages available. If the first locale present
-           * doesn't have it, the others won't have it either. */
-          if (! ref)
-            ref = locale->help_missing;
-        }
     }
 
-  if (ret_locale && locale)
+  /*  second pass: look for a fallback                 */
+  for (list = help_locales; list && !ref; list = list->next)
+    {
+      locale = gimp_help_domain_lookup_locale (domain,
+                                               (const gchar *) list->data,
+                                               progress);
+      ref = locale->help_missing;
+    }
+
+  if (ret_locale)
     *ret_locale = locale;
 
   if (ref)
@@ -185,7 +170,7 @@ gimp_help_domain_map (GimpHelpDomain    *domain,
       locale = gimp_help_domain_lookup_locale (domain,
                                                GIMP_HELP_DEFAULT_LOCALE, NULL);
 
-      if (locale && ! domain_locale_parse (domain, locale, NULL, &error))
+      if (! domain_locale_parse (domain, locale, NULL, &error))
         {
           switch (error->code)
             {
@@ -243,34 +228,14 @@ gimp_help_domain_map (GimpHelpDomain    *domain,
 
 /*  private functions  */
 
-G_LOCK_DEFINE (done);
-
-static gboolean
-parse_thread_func (HelpThreadData *data)
-{
-
-  *data->success = gimp_help_locale_parse (data->locale, data->uri, data->domain,
-                                           data->progress, data->cancellable, data->error);
-  G_LOCK (done);
-  *data->done = TRUE;
-  G_UNLOCK (done);
-
-  return *data->success;
-}
-
 static gboolean
 domain_locale_parse (GimpHelpDomain    *domain,
                      GimpHelpLocale    *locale,
                      GimpHelpProgress  *progress,
                      GError           **error)
 {
-  GCancellable   *cancellable;
   gchar    *uri;
-  GThread        *thread;
+  gboolean  success;
-  GTimer         *timer;
-  gboolean        success = FALSE;
-  gboolean        done    = FALSE;
-  HelpThreadData  data;
 
   g_return_val_if_fail (domain != NULL, FALSE);
   g_return_val_if_fail (locale != NULL, FALSE);
@@ -279,41 +244,10 @@ domain_locale_parse (GimpHelpDomain    *domain,
   uri = g_strdup_printf ("%s/%s/gimp-help.xml",
                          domain->help_uri, locale->locale_id);
 
-  timer            = g_timer_new ();
+  success = gimp_help_locale_parse (locale, uri, domain->help_domain,
-  cancellable      = g_cancellable_new ();
+                                    progress, error);
-  data.done        = &done;
-  data.success     = &success;
-  data.locale      = locale;
-  data.uri         = uri;
-  data.domain      = domain->help_domain;
-  data.progress    = progress;
-  data.cancellable = cancellable;
-  data.error       = error;
-  thread           = g_thread_new (NULL, (GThreadFunc) parse_thread_func, &data);
-
-  while (TRUE)
-    {
-      gboolean exit;
-
-      G_LOCK (done);
-      exit = *data.done;
-      G_UNLOCK (done);
-
-      if (! exit && g_timer_elapsed (timer, NULL) > 10.0)
-        {
-          g_cancellable_cancel (cancellable);
-          exit = TRUE;
-        }
-
-      if (exit)
-        break;
-    }
-
-  g_thread_join (thread);
 
   g_free (uri);
-  g_timer_destroy (timer);
-  g_object_unref (cancellable);
 
   return success;
 }

plug-ins/help/gimphelplocale.c

@@ -169,11 +169,11 @@ gimp_help_locale_parse (GimpHelpLocale    *locale,
                         const gchar       *uri,
                         const gchar       *help_domain,
                         GimpHelpProgress  *progress,
-                        GCancellable      *cancellable,
                         GError           **error)
 {
   GMarkupParseContext *context;
   GFile               *file        = NULL;
+  GCancellable        *cancellable = NULL;
   LocaleParser         parser      = { NULL, };
 #ifdef PLATFORM_OSX
   NSURL               *fileURL;
@@ -213,15 +213,12 @@ gimp_help_locale_parse (GimpHelpLocale    *locale,
     {
       gchar *name = g_file_get_parse_name (file);
 
+      cancellable = g_cancellable_new ();
       _gimp_help_progress_start (progress, cancellable,
                                  _("Loading index from '%s'"), name);
 
+      g_clear_object (&cancellable);
       g_free (name);
-      if (g_cancellable_is_cancelled (cancellable))
-        {
-          _gimp_help_progress_finish (progress);
-          return FALSE;
-        }
     }
 
 #ifdef PLATFORM_OSX
@@ -241,8 +238,6 @@ gimp_help_locale_parse (GimpHelpLocale    *locale,
       locale_set_error (error,
                         _("Could not load data from '%s': %s"), file);
       g_object_unref (file);
-      if (progress)
-        _gimp_help_progress_finish (progress);
       return FALSE;
     }
 
@@ -254,13 +249,12 @@ gimp_help_locale_parse (GimpHelpLocale    *locale,
       GFileInfo *info = g_file_query_info (file,
                                            G_FILE_ATTRIBUTE_STANDARD_SIZE, 0,
                                            cancellable, error);
-      if (! info || g_cancellable_is_cancelled (cancellable))
+      if (! info)
         {
           locale_set_error (error,
                             _("Could not open '%s' for reading: %s"), file);
           g_object_unref (file);
 
-          _gimp_help_progress_finish (progress);
           return FALSE;
         }
 
@@ -271,15 +265,12 @@ gimp_help_locale_parse (GimpHelpLocale    *locale,
 
   stream = g_file_read (file, cancellable, error);
 
-  if (! stream || g_cancellable_is_cancelled (cancellable))
+  if (! stream)
     {
       locale_set_error (error,
                         _("Could not open '%s' for reading: %s"), file);
       g_object_unref (file);
 
-      if (progress)
-        _gimp_help_progress_finish (progress);
-
       return FALSE;
     }
 #endif /* ! PLATFORM_OSX */
@@ -316,7 +307,7 @@ gimp_help_locale_parse (GimpHelpLocale    *locale,
   g_string_free (parser.value, TRUE);
   g_free (parser.id_attr_name);
 
-  if (! success || g_cancellable_is_cancelled (cancellable))
+  if (! success)
     locale_set_error (error, _("Parse error in '%s':\n%s"), file);
 
   g_object_unref (file);

plug-ins/help/gimphelplocale.h

@@ -45,7 +45,6 @@ gboolean         gimp_help_locale_parse (GimpHelpLocale    *locale,
                                          const gchar       *uri,
                                          const gchar       *help_domain,
                                          GimpHelpProgress  *progress,
-                                         GCancellable      *cancellable,
                                          GError           **error);