[evolution] MailFolderCache can sometimes block folder 'changed' notifications

[Milan Crha <mcrha src gnome org>]

commit 3df39f3d08e70f3f028cc08d61ac23ee03828f24
Author: Milan Crha <mcrha redhat com>
Date:   Wed May 3 11:45:04 2017 +0200

    MailFolderCache can sometimes block folder 'changed' notifications
    
    One way to have lost folder 'changed' notifications from MailFolderCache
    is to fail to connect to the account after start, in which case the folder
    tree in the Mail view doesn't update unread counts properly. It had been
    due to the MailFolderCache still considering the store being initializing
    for the first time, while piling the folder notifications to be emitted
    when the initialization of the store is over.

 src/libemail-engine/mail-folder-cache.c |   36 +++++++++++++++++++++++++------
 1 files changed, 29 insertions(+), 7 deletions(-)
---
diff --git a/src/libemail-engine/mail-folder-cache.c b/src/libemail-engine/mail-folder-cache.c
index 5662019..cfe0503 100644
--- a/src/libemail-engine/mail-folder-cache.c
+++ b/src/libemail-engine/mail-folder-cache.c
@@ -91,6 +91,12 @@ enum {
 
 static guint signals[LAST_SIGNAL];
 
+typedef enum {
+       E_FIRST_UPDATE_RUNNING,
+       E_FIRST_UPDATE_FAILED,
+       E_FIRST_UPDATE_DONE
+} EFirstUpdateState;
+
 struct _StoreInfo {
        volatile gint ref_count;
 
@@ -107,7 +113,7 @@ struct _StoreInfo {
        gulong reachable_handler_id;
 
        GHashTable *folder_info_ht;     /* by full_name */
-       gboolean first_update;          /* TRUE, then FALSE forever */
+       EFirstUpdateState first_update;
        GSList *pending_folder_notes;   /* Gather note_folder calls during first_update period */
 
        /* Hold a reference to keep them alive. */
@@ -263,7 +269,7 @@ store_info_new (CamelStore *store)
        store_info = g_slice_new0 (StoreInfo);
        store_info->ref_count = 1;
        store_info->store = g_object_ref (store);
-       store_info->first_update = TRUE;
+       store_info->first_update = E_FIRST_UPDATE_RUNNING;
 
        store_info->folder_info_ht = g_hash_table_new_full (
                (GHashFunc) g_str_hash,
@@ -2036,7 +2042,7 @@ mail_folder_cache_first_update (MailFolderCache *cache,
        g_object_unref (session);
 
        g_mutex_lock (&store_info->lock);
-       store_info->first_update = FALSE;
+       store_info->first_update = E_FIRST_UPDATE_DONE;
        folders = store_info->pending_folder_notes;
        store_info->pending_folder_notes = NULL;
        g_mutex_unlock (&store_info->lock);
@@ -2060,6 +2066,7 @@ mail_folder_cache_note_store_thread (GSimpleAsyncResult *simple,
        StoreInfo *store_info;
        GQueue result_queue = G_QUEUE_INIT;
        AsyncContext *async_context;
+       gboolean success = FALSE;
        GError *local_error = NULL;
 
        cache = MAIL_FOLDER_CACHE (source_object);
@@ -2132,17 +2139,22 @@ mail_folder_cache_note_store_thread (GSimpleAsyncResult *simple,
 
        /* Do some extra work for the first update. */
        g_mutex_lock (&store_info->lock);
-       if (store_info->first_update) {
+       if (store_info->first_update != E_FIRST_UPDATE_DONE) {
                g_mutex_unlock (&store_info->lock);
                mail_folder_cache_first_update (cache, store_info);
        } else {
                g_mutex_unlock (&store_info->lock);
        }
 
+       success = TRUE;
 exit:
        /* We don't want finish() functions being invoked while holding a
         * locked mutex, so flush the StoreInfo's queue to a local queue. */
        g_mutex_lock (&store_info->lock);
+
+       if (store_info->first_update != E_FIRST_UPDATE_DONE)
+               store_info->first_update = success ? E_FIRST_UPDATE_DONE : E_FIRST_UPDATE_FAILED;
+
        e_queue_transfer (&store_info->folderinfo_updates, &result_queue);
        g_mutex_unlock (&store_info->lock);
 
@@ -2202,6 +2214,9 @@ mail_folder_cache_note_store (MailFolderCache *cache,
 
        g_mutex_lock (&store_info->lock);
 
+       if (store_info->first_update != E_FIRST_UPDATE_DONE)
+               store_info->first_update = E_FIRST_UPDATE_RUNNING;
+
        g_queue_push_tail (
                &store_info->folderinfo_updates,
                g_object_ref (simple));
@@ -2283,18 +2298,23 @@ mail_folder_cache_note_folder (MailFolderCache *cache,
         *     warnings on startup which might be worth tracking down. */
        if (folder_info == NULL) {
                StoreInfo *store_info;
-               gboolean retry = FALSE;
+               gboolean retry = FALSE, renote_store = FALSE;
 
                store_info = mail_folder_cache_ref_store_info (cache, parent_store);
                if (!store_info)
                        return;
 
                g_mutex_lock (&store_info->lock);
-               if (store_info->first_update) {
+               if (store_info->first_update != E_FIRST_UPDATE_DONE) {
                        /* The first update did not finish yet, thus add this as a pending
                           folder to be noted once the first update finishes */
                        store_info->pending_folder_notes = g_slist_prepend (
                                store_info->pending_folder_notes, g_object_ref (folder));
+
+                       if (store_info->first_update == E_FIRST_UPDATE_FAILED) {
+                               store_info->first_update = E_FIRST_UPDATE_RUNNING;
+                               renote_store = TRUE;
+                       }
                } else {
                        /* It can be that certain threading interleaving made
                           the first store update finished before we reached
@@ -2305,7 +2325,9 @@ mail_folder_cache_note_folder (MailFolderCache *cache,
 
                store_info_unref (store_info);
 
-               if (retry)
+               if (renote_store)
+                       mail_folder_cache_note_store (cache, parent_store, NULL, NULL, NULL);
+               else if (retry)
                        folder_info = mail_folder_cache_ref_folder_info (
                                cache, parent_store, full_name);