adjust SortKey to have fragmentKey instead of gapKey

with FragmentIndex to compare fragment keys

doc/FRAGMENTS.md

@@ -1,5 +1,10 @@
  - DONE: write FragmentIndex
- - adapt SortKey
+ - adapt SortKey ... naming! :
+    - FragmentIndex (index as in db index)
+        - compare(fragmentKeyA, fragmentKeyB)
+    - SortKey
+        - FragmentKey
+        - EventKey (we don't use id here because we already have event_id in the event)
  - write fragmentStore
  - adapt timelineStore
  - adapt persister

src/matrix/room/persister.js

@@ -1,4 +1,4 @@
-import SortKey from "../storage/sortkey.js";
+import SortKey from "./timeline/SortKey.js";
 import FragmentIndex from "./timeline/FragmentIndex.js";
 
 function gapEntriesAreEqual(a, b) {
@@ -31,6 +31,7 @@ export default class RoomPersister {
 	constructor({roomId, storage}) {
 		this._roomId = roomId;
         this._storage = storage;
+        // TODO: load fragmentIndex?
 		this._lastSortKey = new SortKey();
 	}
 
@@ -38,6 +39,7 @@ export default class RoomPersister {
 		//fetch key here instead?
 		const [lastEvent] = await txn.roomTimeline.lastEvents(this._roomId, 1);
 		if (lastEvent) {
+            // TODO: load fragmentIndex?
 			this._lastSortKey = new SortKey(lastEvent.sortKey);
 			console.log("room persister load", this._roomId, this._lastSortKey.toString());
 		} else {

src/matrix/room/timeline/FragmentIndex.js

@@ -1,10 +1,3 @@
-class Fragment {
-    constructor(previousId, nextId) {
-        this.previousId = previousId;
-        this.nextId = nextId;
-    }
-}
-
 /*
 lookups will be far more frequent than changing fragment order,
 so data structure should be optimized for fast lookup
@@ -93,7 +86,7 @@ class Island {
         });
     }
 
-    compareIds(idA, idB) {
+    compare(idA, idB) {
         const sortIndexA = this._idToSortIndex.get(idA);
         if (sortIndexA === undefined) {
             throw new Error(`first id ${idA} isn't part of this island`);
@@ -126,7 +119,7 @@ export default class FragmentIndex {
         return island;
     }
 
-    compareIds(idA, idB) {
+    compare(idA, idB) {
         if (idA === idB) {
             return 0;
         }
@@ -135,7 +128,7 @@ export default class FragmentIndex {
         if (islandA !== islandB) {
             throw new Error(`${idA} and ${idB} are on different islands, can't tell order`);
         }
-        return islandA.compareIds(idA, idB);
+        return islandA.compare(idA, idB);
     }
 
     rebuild(fragments) {
@@ -166,6 +159,7 @@ export default class FragmentIndex {
     // }
 }
 
+//#ifdef TESTS
 export function tests() {
     return {
         test_1_island_3_fragments(assert) {
@@ -174,24 +168,24 @@ export function tests() {
                 {id: 1, nextId: 2},
                 {id: 2, nextId: 3, previousId: 1},
             ]);
-            assert(index.compareIds(1, 2) < 0);
-            assert(index.compareIds(2, 1) > 0);
+            assert(index.compare(1, 2) < 0);
+            assert(index.compare(2, 1) > 0);
 
-            assert(index.compareIds(1, 3) < 0);
-            assert(index.compareIds(3, 1) > 0);
+            assert(index.compare(1, 3) < 0);
+            assert(index.compare(3, 1) > 0);
             
-            assert(index.compareIds(2, 3) < 0);
-            assert(index.compareIds(3, 2) > 0);
+            assert(index.compare(2, 3) < 0);
+            assert(index.compare(3, 2) > 0);
             
-            assert.equal(index.compareIds(1, 1), 0);
+            assert.equal(index.compare(1, 1), 0);
         },
         test_2_island_dont_compare(assert) {
             const index = new FragmentIndex([
                 {id: 1},
                 {id: 2},
             ]);
-            assert.throws(() => index.compareIds(1, 2));
-            assert.throws(() => index.compareIds(2, 1));
+            assert.throws(() => index.compare(1, 2));
+            assert.throws(() => index.compare(2, 1));
         },
         test_2_island_compare_internally(assert) {
             const index = new FragmentIndex([
@@ -202,16 +196,16 @@ export function tests() {
                 
             ]);
 
-            assert(index.compareIds(1, 2) < 0);
-            assert(index.compareIds(11, 12) < 0);
+            assert(index.compare(1, 2) < 0);
+            assert(index.compare(11, 12) < 0);
             
-            assert.throws(() => index.compareIds(1, 11));
-            assert.throws(() => index.compareIds(12, 2));
+            assert.throws(() => index.compare(1, 11));
+            assert.throws(() => index.compare(12, 2));
         },
         test_unknown_id(assert) {
             const index = new FragmentIndex([{id: 1}]);
-            assert.throws(() => index.compareIds(1, 2));
-            assert.throws(() => index.compareIds(2, 1));
+            assert.throws(() => index.compare(1, 2));
+            assert.throws(() => index.compare(2, 1));
         },
         test_rebuild_flushes_old_state(assert) {
             const index = new FragmentIndex([
@@ -223,8 +217,9 @@ export function tests() {
                 {id: 12, previousId: 11},
             ]);
             
-            assert.throws(() => index.compareIds(1, 2));
-            assert(index.compareIds(11, 12) < 0);
+            assert.throws(() => index.compare(1, 2));
+            assert(index.compare(11, 12) < 0);
         },
     }
 }
+//#endif

src/matrix/room/timeline/SortKey.js

@@ -0,0 +1,197 @@
+const MIN_INT32 = -2147483648;
+const MID_INT32 = 0;
+const MAX_INT32 = 2147483647;
+
+const MIN_UINT32 = 0;
+const MID_UINT32 = 2147483647;
+const MAX_UINT32 = 4294967295;
+
+const MIN = MIN_UINT32;
+const MID = MID_UINT32;
+const MAX = MAX_UINT32;
+
+export default class SortKey {
+	constructor(fragmentIndex, buffer) {
+		if (buffer) {
+			this._keys = new DataView(buffer);
+		} else {
+			this._keys = new DataView(new ArrayBuffer(8));
+			// start default key right at the middle fragment key, min event key
+			// so we have the same amount of key address space either way
+			this.fragmentKey = MID;
+			this.eventKey = MIN;
+		}
+        this._fragmentIndex = fragmentIndex;
+	}
+
+	get fragmentKey() {
+		return this._keys.getUint32(0, false);
+	}
+
+	set fragmentKey(value) {
+		return this._keys.setUint32(0, value, false);
+	}
+
+	get eventKey() {
+		return this._keys.getUint32(4, false);
+	}
+
+	set eventKey(value) {
+		return this._keys.setUint32(4, value, false);
+	}
+
+	get buffer() {
+		return this._keys.buffer;
+	}
+
+	nextFragmentKey() {
+		const k = new SortKey(this._fragmentIndex);
+		k.fragmentKey = this.fragmentKey + 1;
+		k.eventKey = MIN;
+		return k;
+	}
+
+	nextKey() {
+		const k = new SortKey(this._fragmentIndex);
+		k.fragmentKey = this.fragmentKey;
+		k.eventKey = this.eventKey + 1;
+		return k;
+	}
+
+	previousKey() {
+		const k = new SortKey(this._fragmentIndex);
+		k.fragmentKey = this.fragmentKey;
+		k.eventKey = this.eventKey - 1;
+		return k;
+	}
+
+	clone() {
+		const k = new SortKey();
+		k.fragmentKey = this.fragmentKey;
+		k.eventKey = this.eventKey;	
+		return k;
+	}
+
+	static get maxKey() {
+		const maxKey = new SortKey(null);
+		maxKey.fragmentKey = MAX;
+		maxKey.eventKey = MAX;
+		return maxKey;
+	}
+
+	static get minKey() {
+		const minKey = new SortKey(null);
+		minKey.fragmentKey = MIN;
+		minKey.eventKey = MIN;
+		return minKey;
+	}
+
+    compare(otherKey) {
+        const fragmentDiff = this.fragmentKey - otherKey.fragmentKey;
+        if (fragmentDiff === 0) {
+            return this.eventKey - otherKey.eventKey;
+        } else {
+            // minKey and maxKey might not have fragmentIndex, so short-circuit this first ...
+            if (this.fragmentKey === MIN || otherKey.fragmentKey === MAX) {
+                return -1;
+            }
+            if (this.fragmentKey === MAX || otherKey.fragmentKey === MIN) {
+                return 1;
+            }
+            // ... then delegate to fragmentIndex.
+            // This might throw if the relation of two fragments is unknown.
+            return this._fragmentIndex.compare(this.fragmentKey, otherKey.fragmentKey);
+        }
+    }
+
+	toString() {
+		return `[${this.fragmentKey}/${this.eventKey}]`;
+	}
+}
+
+//#ifdef TESTS
+export function tests() {
+    const fragmentIndex = {compare: (a, b) => a - b};
+
+	return {
+		test_default_key(assert) {
+			const k = new SortKey(fragmentIndex);
+			assert.equal(k.fragmentKey, MID);
+			assert.equal(k.eventKey, MIN);
+		},
+
+		test_inc(assert) {
+			const a = new SortKey(fragmentIndex);
+			const b = a.nextKey();
+			assert.equal(a.fragmentKey, b.fragmentKey);
+			assert.equal(a.eventKey + 1, b.eventKey);
+			const c = b.previousKey();
+			assert.equal(b.fragmentKey, c.fragmentKey);
+			assert.equal(c.eventKey + 1, b.eventKey);
+			assert.equal(a.eventKey, c.eventKey);
+		},
+
+		test_min_key(assert) {
+			const minKey = SortKey.minKey;
+			const k = new SortKey(fragmentIndex);
+			assert(minKey.fragmentKey <= k.fragmentKey);
+			assert(minKey.eventKey <= k.eventKey);
+            assert(k.compare(minKey) > 0);
+            assert(minKey.compare(k) < 0);
+		},
+
+		test_max_key(assert) {
+			const maxKey = SortKey.maxKey;
+			const k = new SortKey(fragmentIndex);
+			assert(maxKey.fragmentKey >= k.fragmentKey);
+			assert(maxKey.eventKey >= k.eventKey);
+            assert(k.compare(maxKey) < 0);
+            assert(maxKey.compare(k) > 0);
+		},
+
+		test_immutable(assert) {
+			const a = new SortKey(fragmentIndex);
+			const fragmentKey = a.fragmentKey;
+			const eventKey = a.eventKey;
+			a.nextFragmentKey();
+			assert.equal(a.fragmentKey, fragmentKey);
+			assert.equal(a.eventKey, eventKey);
+		},
+
+		test_cmp_fragmentkey_first(assert) {
+			const a = new SortKey(fragmentIndex);
+			const b = new SortKey(fragmentIndex);
+			a.fragmentKey = 2;
+			a.eventKey = 1;
+			b.fragmentKey = 1;
+			b.eventKey = 100000;
+			assert(a.compare(b) > 0);
+		},
+
+		test_cmp_eventkey_second(assert) {
+			const a = new SortKey(fragmentIndex);
+			const b = new SortKey(fragmentIndex);
+			a.fragmentKey = 1;
+			a.eventKey = 100000;
+			b.fragmentKey = 1;
+			b.eventKey = 2;
+			assert(a.compare(b) > 0);
+		},
+
+		test_cmp_max_larger_than_min(assert) {
+			assert(SortKey.minKey.compare(SortKey.maxKey) < 0);
+		},
+
+		test_cmp_fragmentkey_first_large(assert) {
+			const a = new SortKey(fragmentIndex);
+			const b = new SortKey(fragmentIndex);
+			a.fragmentKey = MAX;
+			a.eventKey = MIN;
+			b.fragmentKey = MIN;
+			b.eventKey = MAX;
+			assert(b < a);
+			assert(a > b);
+		}
+	};
+}
+//#endif

src/matrix/storage/idb/stores/RoomTimelineStore.js

@@ -1,4 +1,4 @@
-import SortKey from "../../sortkey.js";
+import SortKey from "../../../room/timeline/SortKey.js";
 
 class Range {
     constructor(only, lower, upper, lowerOpen, upperOpen) {

src/matrix/storage/memory/stores/RoomTimelineStore.js

@@ -1,6 +1,6 @@
-import SortKey from "../sortkey.js";
+import SortKey from "../../room/timeline/SortKey.js";
 import sortedIndex from "../../../utils/sortedIndex.js";
-import Store from "./Store";
+import Store from "./Store.js";
 
 function compareKeys(key, entry) {
     if (key.roomId === entry.roomId) {

src/matrix/storage/sortkey.js

@@ -1,181 +0,0 @@
-const MIN_INT32 = -2147483648;
-const MID_INT32 = 0;
-const MAX_INT32 = 2147483647;
-
-const MIN_UINT32 = 0;
-const MID_UINT32 = 2147483647;
-const MAX_UINT32 = 4294967295;
-
-const MIN = MIN_UINT32;
-const MID = MID_UINT32;
-const MAX = MAX_UINT32;
-
-export default class SortKey {
-	constructor(buffer) {
-		if (buffer) {
-			this._keys = new DataView(buffer);
-		} else {
-			this._keys = new DataView(new ArrayBuffer(8));
-			// start default key right at the middle gap key, min event key
-			// so we have the same amount of key address space either way
-			this.gapKey = MID;
-			this.eventKey = MIN;
-		}
-	}
-
-	get gapKey() {
-		return this._keys.getUint32(0, false);
-	}
-
-	set gapKey(value) {
-		return this._keys.setUint32(0, value, false);
-	}
-
-	get eventKey() {
-		return this._keys.getUint32(4, false);
-	}
-
-	set eventKey(value) {
-		return this._keys.setUint32(4, value, false);
-	}
-
-	get buffer() {
-		return this._keys.buffer;
-	}
-
-	nextKeyWithGap() {
-		const k = new SortKey();
-		k.gapKey = this.gapKey + 1;
-		k.eventKey = MIN;
-		return k;
-	}
-
-	nextKey() {
-		const k = new SortKey();
-		k.gapKey = this.gapKey;
-		k.eventKey = this.eventKey + 1;
-		return k;
-	}
-
-	previousKey() {
-		const k = new SortKey();
-		k.gapKey = this.gapKey;
-		k.eventKey = this.eventKey - 1;
-		return k;
-	}
-
-	clone() {
-		const k = new SortKey();
-		k.gapKey = this.gapKey;
-		k.eventKey = this.eventKey;	
-		return k;
-	}
-
-	static get maxKey() {
-		const maxKey = new SortKey();
-		maxKey.gapKey = MAX;
-		maxKey.eventKey = MAX;
-		return maxKey;
-	}
-
-	static get minKey() {
-		const minKey = new SortKey();
-		minKey.gapKey = MIN;
-		minKey.eventKey = MIN;
-		return minKey;
-	}
-
-    compare(otherKey) {
-        const gapDiff = this.gapKey - otherKey.gapKey;
-        if (gapDiff === 0) {
-            return this.eventKey - otherKey.eventKey;
-        } else {
-            return gapDiff;
-        }
-    }
-
-	toString() {
-		return `[${this.gapKey}/${this.eventKey}]`;
-	}
-}
-
-//#ifdef TESTS
-export function tests() {
-	return {
-		test_default_key(assert) {
-			const k = new SortKey();
-			assert.equal(k.gapKey, MID);
-			assert.equal(k.eventKey, MIN);
-		},
-
-		test_inc(assert) {
-			const a = new SortKey();
-			const b = a.nextKey();
-			assert.equal(a.gapKey, b.gapKey);
-			assert.equal(a.eventKey + 1, b.eventKey);
-			const c = b.previousKey();
-			assert.equal(b.gapKey, c.gapKey);
-			assert.equal(c.eventKey + 1, b.eventKey);
-			assert.equal(a.eventKey, c.eventKey);
-		},
-
-		test_min_key(assert) {
-			const minKey = SortKey.minKey;
-			const k = new SortKey();
-			assert(minKey.gapKey <= k.gapKey);
-			assert(minKey.eventKey <= k.eventKey);
-		},
-
-		test_max_key(assert) {
-			const maxKey = SortKey.maxKey;
-			const k = new SortKey();
-			assert(maxKey.gapKey >= k.gapKey);
-			assert(maxKey.eventKey >= k.eventKey);
-		},
-
-		test_immutable(assert) {
-			const a = new SortKey();
-			const gapKey = a.gapKey;
-			const eventKey = a.eventKey;
-			a.nextKeyWithGap();
-			assert.equal(a.gapKey, gapKey);
-			assert.equal(a.eventKey, eventKey);
-		},
-
-		test_cmp_gapkey_first(assert) {
-			const a = new SortKey();
-			const b = new SortKey();
-			a.gapKey = 2;
-			a.eventKey = 1;
-			b.gapKey = 1;
-			b.eventKey = 100000;
-			assert(a.compare(b) > 0);
-		},
-
-		test_cmp_eventkey_second(assert) {
-			const a = new SortKey();
-			const b = new SortKey();
-			a.gapKey = 1;
-			a.eventKey = 100000;
-			b.gapKey = 1;
-			b.eventKey = 2;
-			assert(a.compare(b) > 0);
-		},
-
-		test_cmp_max_larger_than_min(assert) {
-			assert(SortKey.minKey.compare(SortKey.maxKey) < 0);
-		},
-
-		test_cmp_gapkey_first_large(assert) {
-			const a = new SortKey();
-			const b = new SortKey();
-			a.gapKey = MAX;
-			a.eventKey = MIN;
-			b.gapKey = MIN;
-			b.eventKey = MAX;
-			assert(b < a);
-			assert(a > b);
-		}
-	};
-}
-//#endif