From 447b0aa03cbbf7e5f8723e0bc805486988ff2828 Mon Sep 17 00:00:00 2001
From: Bruno Windels <brunow@matrix.org>
Date: Sat, 1 Jun 2019 16:42:57 +0200
Subject: [PATCH] allow adding fragments to comparer, instead of reloading from
 db.

This is a suboptimal implementation now,
but is the API we want to end up with. Readers and Writers
in persistence add fragments to the comparer when they become
aware of, create, or link up fragments.
---
 src/matrix/room/timeline/FragmentIdComparer.js       |  5 +++++
 src/matrix/room/timeline/persistence/GapWriter.js    |  5 +++--
 src/matrix/room/timeline/persistence/SyncWriter.js   |  7 ++-----
 .../room/timeline/persistence/TimelineReader.js      | 12 ++----------
 4 files changed, 12 insertions(+), 17 deletions(-)

diff --git a/src/matrix/room/timeline/FragmentIdComparer.js b/src/matrix/room/timeline/FragmentIdComparer.js
index df5c3ac7..029c1333 100644
--- a/src/matrix/room/timeline/FragmentIdComparer.js
+++ b/src/matrix/room/timeline/FragmentIdComparer.js
@@ -108,6 +108,7 @@ index for fast lookup of how two fragments can be sorted
 */
 export default class FragmentIdComparer {
     constructor(fragments) {
+        this._fragmentsById = fragments.reduce((map, f) => {map.set(f.id, f); return map;}, new Map());
         this.rebuild(fragments);
     }
 
@@ -157,6 +158,10 @@ export default class FragmentIdComparer {
     // linkFragments(txn, firstFragmentId, secondFragmentId) {
 
     // }
+    add(fragment) {
+        this._fragmentsById[fragment.id] = fragment;
+        this.rebuild(this._fragmentsById.values());
+    }
 }
 
 //#ifdef TESTS
diff --git a/src/matrix/room/timeline/persistence/GapWriter.js b/src/matrix/room/timeline/persistence/GapWriter.js
index 06d450a6..415f2292 100644
--- a/src/matrix/room/timeline/persistence/GapWriter.js
+++ b/src/matrix/room/timeline/persistence/GapWriter.js
@@ -64,8 +64,9 @@ export default class GapWriter {
             txn.timelineFragments.set(neighbourFragmentEntry.fragment);
             directionalAppend(entries, neighbourFragmentEntry, direction);
 
-            // update fragmentIdComparer here after linking up fragments?
-            this._fragmentIdComparer.rebuild(await txn.timelineFragments.all());
+            // update fragmentIdComparer here after linking up fragments
+            this._fragmentIdComparer.add(fragmentEntry.fragment);
+            this._fragmentIdComparer.add(neighbourFragmentEntry.fragment);
         }
         fragmentEntry.token = end;
         txn.timelineFragments.set(fragmentEntry.fragment);
diff --git a/src/matrix/room/timeline/persistence/SyncWriter.js b/src/matrix/room/timeline/persistence/SyncWriter.js
index f27e8a2e..ebec1bae 100644
--- a/src/matrix/room/timeline/persistence/SyncWriter.js
+++ b/src/matrix/room/timeline/persistence/SyncWriter.js
@@ -40,6 +40,7 @@ export default class SyncWriter {
                 nextToken: null
             };
             txn.timelineFragments.add(fragment);
+            this._fragmentIdComparer.add(fragment);
             return fragment;
         } else {
             return liveFragment;
@@ -62,6 +63,7 @@ export default class SyncWriter {
             nextToken: null
         };
         txn.timelineFragments.add(newFragment);
+        this._fragmentIdComparer.add(newFragment);
         return {oldFragment, newFragment};
     }
 
@@ -117,11 +119,6 @@ export default class SyncWriter {
             }
         }
 
-        if (timeline.limited) {
-            const fragments = await txn.timelineFragments.all(this._roomId);
-            this._fragmentIdComparer.rebuild(fragments);
-        }
-
         return entries;
     }
 }
diff --git a/src/matrix/room/timeline/persistence/TimelineReader.js b/src/matrix/room/timeline/persistence/TimelineReader.js
index 75402aee..ee7c7865 100644
--- a/src/matrix/room/timeline/persistence/TimelineReader.js
+++ b/src/matrix/room/timeline/persistence/TimelineReader.js
@@ -16,7 +16,6 @@ export default class TimelineReader {
             this._storage.storeNames.timelineFragments,
         ]);
         let entries = [];
-        let loadedFragment = false;
 
         const timelineStore = txn.timelineEvents;
         const fragmentStore = txn.timelineFragments;
@@ -36,28 +35,21 @@ export default class TimelineReader {
                 const fragment = await fragmentStore.get(this._roomId, eventKey.fragmentId);
                 // this._fragmentIdComparer.addFragment(fragment);
                 let fragmentEntry = new FragmentBoundaryEntry(fragment, direction.isBackward, this._fragmentIdComparer);
-                // append or prepend fragmentEntry, reuse func from GapPersister?
+                // append or prepend fragmentEntry, reuse func from GapWriter?
                 directionalAppend(entries, fragmentEntry, direction);
                 // don't count it in amount perhaps? or do?
                 if (fragmentEntry.linkedFragmentId) {
                     const nextFragment = await fragmentStore.get(this._roomId, fragmentEntry.linkedFragmentId);
-                    // this._fragmentIdComparer.addFragment(nextFragment);
+                    this._fragmentIdComparer.add(nextFragment);
                     const nextFragmentEntry = new FragmentBoundaryEntry(nextFragment, direction.isForward, this._fragmentIdComparer);
                     directionalAppend(entries, nextFragmentEntry, direction);
                     eventKey = new EventKey(nextFragmentEntry.fragmentId, nextFragmentEntry.eventIndex);
-                    loadedFragment = true;
                 } else {
                     eventKey = null;
                 }
             }
         }
 
-        // reload fragments
-        if (loadedFragment) {
-            const fragments = await fragmentStore.all(this._roomId);
-            this._fragmentIdComparer.rebuild(fragments);
-        }
-
         return entries;
     }
 }