fix(Caching): sweep archived threads in all channel caches (#6312)

src/util/Util.js

@@ -635,6 +635,21 @@ class Util extends null {
       setTimeout(resolve, ms);
     });
   }
+
+  /**
+   * Creates a sweep filter that sweeps archived threads
+   * @param {number} [lifetime=14400] How long a thread has to be archived to be valid for sweeping
+   * @returns {SweepFilter}
+   */
+  static archivedThreadSweepFilter(lifetime = 14400) {
+    const filter = require('./LimitedCollection').filterByLifetime({
+      lifetime,
+      getComparisonTimestamp: e => e.archiveTimestamp,
+      excludeFromSweep: e => !e.archived,
+    });
+    filter.isDefault = true;
+    return filter;
+  }
 }
 
 module.exports = Util;