lib-storage: Avoid unnecessary stat()s in mailbox list index notifications

If mailbox list gets a notification there's no need to stat() the INBOX, and
vice versa. Also if the notification was already seen and a callback timeout
set, there's no need to keep stat()ing.

diff --git a/src/lib-storage/list/mailbox-list-index-notify.c b/src/lib-storage/list/mailbox-list-index-notify.c
index 94808710926df88f56b2eb33e2ff0b4d6dc004fd..249d09f25f39f6af61d9c07865320a8fd9a9f5c2 100644 (file)
--- a/src/lib-storage/list/mailbox-list-index-notify.c
+++ b/src/lib-storage/list/mailbox-list-index-notify.c
@@ -237,16 +237,18 @@ notify_lookup_guid(struct mailbox_list_notify_index *inotify,
        return index_node;
 }
 
-static void notify_update_stat(struct mailbox_list_notify_index *inotify)
+static void notify_update_stat(struct mailbox_list_notify_index *inotify,
+                              bool stat_list, bool stat_inbox)
 {
        bool call = FALSE;
 
-       if (stat(inotify->list_log_path, &inotify->list_last_st) < 0 &&
+       if (stat_list &&
+           stat(inotify->list_log_path, &inotify->list_last_st) < 0 &&
            errno != ENOENT) {
                i_error("stat(%s) failed: %m", inotify->list_log_path);
                call = TRUE;
        }
-       if (inotify->inbox_log_path != NULL) {
+       if (inotify->inbox_log_path != NULL && stat_inbox) {
                if (stat(inotify->inbox_log_path, &inotify->inbox_last_st) < 0 &&
                    errno != ENOENT) {
                        i_error("stat(%s) failed: %m", inotify->inbox_log_path);
@@ -262,7 +264,7 @@ mailbox_list_index_notify_sync_init(struct mailbox_list_notify_index *inotify)
 {
        struct mail_index_view_sync_rec sync_rec;
 
-       notify_update_stat(inotify);
+       notify_update_stat(inotify, TRUE, TRUE);
        (void)mail_index_refresh(inotify->view->index);
 
        /* sync the view so that map extensions gets updated */
@@ -861,28 +863,54 @@ static void notify_now_callback(struct mailbox_list_notify_index *inotify)
        inotify->wait_callback(inotify->wait_context);
 }
 
-static void notify_callback(struct mailbox_list_notify_index *inotify)
+static void list_notify_callback(struct mailbox_list_notify_index *inotify)
 {
        struct stat list_prev_st = inotify->list_last_st;
+
+       if (inotify->to_notify != NULL) {
+               /* there's a pending notification already -
+                  no need to stat() again */
+               return;
+       }
+
+       notify_update_stat(inotify, TRUE, FALSE);
+       if (ST_CHANGED(inotify->list_last_st, list_prev_st)) {
+               /* log has changed. call the callback with a small delay
+                  to allow bundling multiple changes together */
+               inotify->to_notify =
+                       timeout_add_short(NOTIFY_DELAY_MSECS,
+                                         notify_now_callback, inotify);
+       }
+}
+
+static void inbox_notify_callback(struct mailbox_list_notify_index *inotify)
+{
        struct stat inbox_prev_st = inotify->inbox_last_st;
-                        
-       notify_update_stat(inotify);
+
+       if (inotify->to_notify != NULL && inotify->inbox_event_pending) {
+               /* there's a pending INBOX notification already -
+                  no need to stat() again */
+               return;
+       }
+
+       notify_update_stat(inotify, FALSE, TRUE);
        if (ST_CHANGED(inotify->inbox_last_st, inbox_prev_st))
                inotify->inbox_event_pending = TRUE;
-       if (inotify->inbox_event_pending ||
-           ST_CHANGED(inotify->list_last_st, list_prev_st)) {
+       if (inotify->inbox_event_pending && inotify->to_notify == NULL) {
                /* log has changed. call the callback with a small delay
                   to allow bundling multiple changes together */
-               if (inotify->to_notify != NULL) {
-                       /* already doing this */
-                       return;
-               }
                inotify->to_notify =
                        timeout_add_short(NOTIFY_DELAY_MSECS,
                                          notify_now_callback, inotify);
        }
 }
 
+static void full_notify_callback(struct mailbox_list_notify_index *inotify)
+{
+       list_notify_callback(inotify);
+       inbox_notify_callback(inotify);
+}
+
 void mailbox_list_index_notify_wait(struct mailbox_list_notify *notify,
                                    void (*callback)(void *context),
                                    void *context)
@@ -904,13 +932,13 @@ void mailbox_list_index_notify_wait(struct mailbox_list_notify *notify,
                if (inotify->to_notify != NULL)
                        timeout_remove(&inotify->to_notify);
        } else if (inotify->to_wait == NULL) {
-               (void)io_add_notify(inotify->list_log_path, notify_callback,
+               (void)io_add_notify(inotify->list_log_path, list_notify_callback,
                                    inotify, &inotify->io_wait);
                /* we need to check for INBOX explicitly, because INBOX changes
                   don't get added to mailbox.list.index.log */
                if (inotify->inbox_log_path != NULL) {
                        (void)io_add_notify(inotify->inbox_log_path,
-                                           notify_callback, inotify,
+                                           inbox_notify_callback, inotify,
                                            &inotify->io_wait_inbox);
                }
                /* check with timeout as well, in case io_add_notify()
@@ -918,8 +946,8 @@ void mailbox_list_index_notify_wait(struct mailbox_list_notify *notify,
                check_interval = notify->list->mail_set->mailbox_idle_check_interval;
                i_assert(check_interval > 0);
                inotify->to_wait = timeout_add(check_interval * 1000,
-                                              notify_callback, inotify);
-               notify_update_stat(inotify);
+                                              full_notify_callback, inotify);
+               notify_update_stat(inotify, TRUE, TRUE);
        }
 }
 
@@ -931,7 +959,7 @@ void mailbox_list_index_notify_flush(struct mailbox_list_notify *notify)
        if (inotify->to_notify == NULL &&
            notify->list->mail_set->mailbox_idle_check_interval > 0) {
                /* no pending notification - check if anything had changed */
-               notify_callback(inotify);
+               full_notify_callback(inotify);
        }
        if (inotify->to_notify != NULL)
                notify_now_callback(inotify);