[elpa] externals/ement b8a2e65ed0 3/5: Change: (ement-room-retro-callback) Ignore duplicate events

[ELPA Syncer]

branch: externals/ement
commit b8a2e65ed080ef61cb025bcb4c1544985eeb626a
Author: Adam Porter <adam@alphapapa.net>
Commit: Adam Porter <adam@alphapapa.net>

    Change: (ement-room-retro-callback) Ignore duplicate events
    
    When loading old events, we may sometimes receive
    duplicates (e.g. after joining a room but not having received its
    events in an initial sync response, we have no "from" token, so the
    first "retro" request will receive events from the end of its
    timeline, which may include ones we already have).
    
    Now we ignore events we've already received rather than inserting them
    into the timeline (and buffer).
    
    See #148.
---
 ement-room.el | 20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/ement-room.el b/ement-room.el
index a10d30a935..ed818bb4e2 100644
--- a/ement-room.el
+++ b/ement-room.el
@@ -2504,13 +2504,23 @@ before the earliest-seen message)."
                               (append (ement-room-state room) (append state 
nil))))
     (ement-with-progress-reporter (:reporter ("Ement: Processing earlier 
events..." 0 progress-max-value))
       ;; Append timeline events (in the "chunk").
+      ;; NOTE: It's regrettable that we have to turn the chunk vector into a 
list before
+      ;; appending it to the timeline, but we have to discard events that 
we've already
+      ;; seen.
+      ;; TODO: Consider looping over the vector and pushing one-by-one instead 
of using
+      ;; `seq-remove' and `append' (might be faster).
       (cl-loop for event across-ref chunk
-               do (setf event (ement--make-event event))
-               ;; HACK: Put events on events table.  See FIXME above about 
using the event hook.
-               (ement--put-event event nil session)
+               do (if (gethash (alist-get 'event_id event) 
(ement-session-events session))
+                      ;; Duplicate event: set to nil to be ignored.
+                      (setf event nil)
+                    ;; New event.
+                    (setf event (ement--make-event event))
+                    ;; HACK: Put events on events table.  See FIXME above 
about using the event hook.
+                    (ement--put-event event nil session))
                (ement-progress-update)
-               finally do (setf (ement-room-timeline room)
-                                (append (ement-room-timeline room) (append 
chunk nil))))
+               finally do
+               (setf chunk (seq-remove #'null chunk)
+                     (ement-room-timeline room) (append (ement-room-timeline 
room) chunk)))
       (when buffer
         ;; Insert events into the room's buffer.
         (with-current-buffer buffer