Cleanup logic added

README.md

@@ -4,5 +4,6 @@ What DataScript-driven application looks like? Does DataScript really makes the
 
 <img src="http://tonsky.me/blog/datascript-chat/datascript_chat.png" style="width: 620px; height: 420px;" />
 
-Code walkthrough http://tonsky.me/blog/datascript-chat/
-Live version http://tonsky.me/datascript-chat/
+Code walkthrough http://tonsky.me/blog/datascript-chat/  
+
+Live version http://tonsky.me/datascript-chat/  

index_dev.html

@@ -16,7 +16,8 @@
     <script type="text/javascript">goog.require("datascript_chat");</script>
 
     <script>
-      datascript_chat.ui._STAR_debug_render_STAR_ = true;
+      datascript_chat.ui._STAR_debug_render_STAR_ = false;
+      datascript_chat.util._STAR_debug_q_STAR_ = false;
       window.onload = function() { datascript_chat.start(); }
     </script>
 

src/datascript_chat.cljs

@@ -12,6 +12,8 @@
 
 (enable-console-print!)
 
+(def ^:dynamic *room-msg-limit* 30)
+
 ;; DATABASE
 
 ;; schema is required only for :db.type/ref and :db.cardinality/many
@@ -139,3 +141,25 @@
   ]))
 
 
+;; Clean-up: keeping last N messages per room
+(go-loop-sub event-bus-pub :recv-msg [_ msg]
+  (let [db @conn
+        room-id     (:message/room msg)
+        ;; Last ?lim messages
+        keep-msgs   (->> (u/q1 '[:find (max ?lim ?m)
+                                 :in $ ?room-id ?lim
+                                 :where [?m :message/room ?room-id]]
+                               db
+                               room-id
+                               *room-msg-limit*)
+                         set)
+        ;; All other messages in same room
+        remove-msgs (u/q1s '[:find ?m
+                             :in $ ?room-id ?remove-pred 
+                             :where [?m :message/room ?room-id]
+                                    [(?remove-pred ?m)]] ;; filter by custom predicate
+                             db
+                             room-id
+                             #(not (contains? keep-msgs %)))]
+    (d/transact! conn
+      (map #(vector :db.fn/retractEntity %) remove-msgs))))

src/datascript_chat/ui.cljs

@@ -45,7 +45,7 @@
           [:img.topic__avatar {:src (:user/avatar user)}]
           [:.topic__title (:room/title room)
             (when (pos? unread)
-              [:span.topic__unread (str unread)])]
+              [:span.topic__unread (str unread (when (>= unread 30) "+"))])]
           [:.topic__msg (:message/text last-msg)]
           [:.topic__ts
             (:user/name user)
@@ -81,7 +81,8 @@
 
 (r/defc message [msg]
   (let [user (:message/author msg)]
-    [:.message {:class [(when (:message/unread msg) "message_unread")
+    [:.message {:key   (:db/id msg)
+                :class [(when (:message/unread msg) "message_unread")
                         (when (:user/me user)       "me")]}
       (avatar user)
       [:.message__name