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Diffstat (limited to 'develop/development/room-dag-concepts.html')
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diff --git a/develop/development/room-dag-concepts.html b/develop/development/room-dag-concepts.html index 19788fcf7e..fb8ab94a61 100644 --- a/develop/development/room-dag-concepts.html +++ b/develop/development/room-dag-concepts.html @@ -208,19 +208,18 @@ representation of the state of the room as others were seeing it at the time.</p <h2 id="forward-extremity"><a class="header" href="#forward-extremity">Forward extremity</a></h2> <p>Most-recent-in-time events in the DAG which are not referenced by any other events' <code>prev_events</code> yet.</p> <p>The forward extremities of a room are used as the <code>prev_events</code> when the next event is sent.</p> -<h2 id="backwards-extremity"><a class="header" href="#backwards-extremity">Backwards extremity</a></h2> +<h2 id="backward-extremity"><a class="header" href="#backward-extremity">Backward extremity</a></h2> <p>The current marker of where we have backfilled up to and will generally be the -oldest-in-time events we know of in the DAG.</p> -<p>This is an event where we haven't fetched all of the <code>prev_events</code> for.</p> -<p>Once we have fetched all of its <code>prev_events</code>, it's unmarked as a backwards -extremity (although we may have formed new backwards extremities from the prev -events during the backfilling process).</p> +<code>prev_events</code> of the oldest-in-time events we have in the DAG. This gives a starting point when +backfilling history.</p> +<p>When we persist a non-outlier event, we clear it as a backward extremity and set +all of its <code>prev_events</code> as the new backward extremities if they aren't already +persisted in the <code>events</code> table.</p> <h2 id="outliers"><a class="header" href="#outliers">Outliers</a></h2> <p>We mark an event as an <code>outlier</code> when we haven't figured out the state for the room at that point in the DAG yet.</p> <p>We won't <em>necessarily</em> have the <code>prev_events</code> of an <code>outlier</code> in the database, -but it's entirely possible that we <em>might</em>. The status of whether we have all of -the <code>prev_events</code> is marked as a <a href="#backwards-extremity">backwards extremity</a>.</p> +but it's entirely possible that we <em>might</em>.</p> <p>For example, when we fetch the event auth chain or state for a given event, we mark all of those claimed auth events as outliers because we haven't done the state calculation ourself.</p> |