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perf: improve speed of TreeSetView.elementAt
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@rbellens
rbellens committed Feb 28, 2024
1 parent a3b9c33 commit 1e771fe
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Showing 3 changed files with 122 additions and 43 deletions.
142 changes: 99 additions & 43 deletions lib/src/treeset.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -141,6 +141,61 @@ class ReversedTreeSet<V> extends SetMixin<V> implements TreeSet<V> {
TreeSet<V> get reversed => baseMap;
}

class _TreeSetViewCache<V> {
final AvlNode<V>? node;
final TreeSetView<V> view;

_TreeSetViewCache(this.view) : node = view.baseMap._root;

late final _Path<V>? first = _first;
_Path<V>? get _first {
if (view.limit == 0) return null;
if (node == null) return null;
var v = view.startAt == null
? _Path.minimum(node!)
: view.baseMap._firstAfter(view.startAt!, view.startInclusive);
if (v == null) return null;

var c =
view.endAt == null ? 1 : view.comparator(view.endAt!, v.node.object);
if (c < 0 || (c == 0 && !view.endInclusive)) return null;

if (view.limit != null && !view.limitFromStart) {
var indexFromEnd = _endIndex! - v.index;
if (indexFromEnd >= view.limit!) {
return node!.elementAt(_endIndex! - view.limit! + 1, v);
}
}
return v;
}

late final _Path<V>? last = _last;
_Path<V>? get _last {
if (view.limit == 0) return null;
if (node == null) return null;
var v = view.endAt == null
? _Path.maximum(node!)
: view.baseMap._lastBefore(view.endAt!, view.endInclusive);
if (v == null) return null;

var c = view.startAt == null
? -1
: view.comparator(view.startAt!, v.node.object);
if (c > 0 || (c == 0 && !view.startInclusive)) return null;

if (view.limit != null && view.limitFromStart) {
var indexFromStart = v.index - _startIndex!;
if (indexFromStart >= view.limit!) {
return node!.elementAt(_startIndex! + view.limit! - 1, v);
}
}
return v;
}

late final int? _endIndex = last?.index;
late final int? _startIndex = first?.index;
}

class TreeSetView<V> extends _BaseTreeSet<V> {
final AvlTreeSet<V> baseMap;
final V? startAt;
Expand All @@ -151,6 +206,8 @@ class TreeSetView<V> extends _BaseTreeSet<V> {
final int? limit;
final bool limitFromStart;

_TreeSetViewCache<V>? _cache;

TreeSetView(
{required this.baseMap,
this.startAt,
Expand All @@ -160,6 +217,13 @@ class TreeSetView<V> extends _BaseTreeSet<V> {
this.limit,
this.limitFromStart = true});

_TreeSetViewCache<V> _getCache() {
if (_cache != null && _cache!.node == baseMap._root) {
return _cache!;
}
return _cache = _TreeSetViewCache(this);
}

@override
bool add(V value) {
throw UnsupportedError('add is not supported on a TreeSetView');
Expand All @@ -174,44 +238,12 @@ class TreeSetView<V> extends _BaseTreeSet<V> {

@override
_Path<V>? get _first {
if (limit == 0) return null;
if (baseMap._root == null) return null;
var v = startAt == null
? _Path.minimum(baseMap._root!)
: baseMap._firstAfter(startAt!, startInclusive);
if (v == null) return null;

var c = endAt == null ? 1 : comparator(endAt!, v.node.object);
if (c < 0 || (c == 0 && !endInclusive)) return null;

if (limit != null && !limitFromStart) {
var indexFromEnd = _endIndex! - v.index;
if (indexFromEnd >= limit!) {
return baseMap._root!.elementAt(_endIndex! - limit! + 1, v);
}
}
return v;
return _getCache().first;
}

@override
_Path<V>? get _last {
if (limit == 0) return null;
if (baseMap._root == null) return null;
var v = endAt == null
? _Path.maximum(baseMap._root!)
: baseMap._lastBefore(endAt!, endInclusive);
if (v == null) return null;

var c = startAt == null ? -1 : comparator(startAt!, v.node.object);
if (c > 0 || (c == 0 && !startInclusive)) return null;

if (limit != null && limitFromStart) {
var indexFromStart = v.index - _startIndex!;
if (indexFromStart >= limit!) {
return baseMap._root!.elementAt(_startIndex! + limit! - 1, v);
}
}
return v;
return _getCache().last;
}

bool _limitsContain(V element) {
Expand All @@ -232,22 +264,22 @@ class TreeSetView<V> extends _BaseTreeSet<V> {

var p = baseMap._getPath(element);
if (p == null) return -1;

var c = _getCache();
if (!limitFromStart && limit != null) {
var indexFromEnd = _endIndex! - p.index;
var indexFromEnd = c._endIndex! - p.index;
if (indexFromEnd < limit!) return -1;
}
var index = p.index - _startIndex!;
var index = p.index - c._startIndex!;
return limit == null || index < limit! ? index : -1;
}

int? get _endIndex => _last?.index;
int? get _startIndex => _first?.index;

@override
int get length {
var a = _startIndex;
var c = _getCache();
var a = c._startIndex;
if (a == null) return -1;
return _endIndex! - a + 1;
return c._endIndex! - a + 1;
}

@override
Expand All @@ -270,14 +302,38 @@ class TreeSetView<V> extends _BaseTreeSet<V> {
AvlTreeSet<V> get _avlTreeSet => baseMap;
}

class _AvlTreeSetCache<V> {
final AvlNode<V>? node;
final AvlTreeSet<V> set;

_AvlTreeSetCache(this.set) : node = set._root;

late final _Path<V>? first = node == null ? null : _Path.minimum(node!);

late final _Path<V>? last = node == null ? null : _Path.maximum(node!);

TreeCursor<V> createCursor() {
return TreeCursor(set, first: first, last: last);
}
}

class AvlTreeSet<V> extends _BaseTreeSet<V> {
@override
final Comparator<V> comparator;

AvlNode<V>? _root;

_AvlTreeSetCache<V>? _cache;

AvlTreeSet({required this.comparator});

_AvlTreeSetCache<V> _getCache() {
if (_cache != null && _cache!.node == _root) {
return _cache!;
}
return _cache = _AvlTreeSetCache(this);
}

@override
int get length => _root?.length ?? 0;

Expand Down Expand Up @@ -580,7 +636,7 @@ class AvlTreeSet<V> extends _BaseTreeSet<V> {
}

_Path<V>? _firstAfter(V anchor, bool inclusive) {
var it = TreeCursor(this);
var it = _getCache().createCursor();
if (inclusive) {
it
..positionOn(anchor)
Expand All @@ -594,7 +650,7 @@ class AvlTreeSet<V> extends _BaseTreeSet<V> {
}

_Path<V>? _lastBefore(V anchor, bool inclusive) {
var it = TreeCursor(this);
var it = _getCache().createCursor();
if (inclusive) {
it
..positionOn(anchor)
Expand Down
9 changes: 9 additions & 0 deletions test/benchmarks_test.dart
View file
Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,15 @@ Future<void> main() async {
set.elementAt(n ~/ 3);
});

late TreeSetView setView;
setUpEach(() {
setView = TreeSetView(
baseMap: set,
startAt: set.elementAt(n ~/ 4),
startInclusive: false,
endAt: set.elementAt(3 * n ~/ 4),
endInclusive: true);
});
benchmark('of TreeSetView', () {
setView.elementAt(n ~/ 3);
});
Expand Down
14 changes: 14 additions & 0 deletions test/util/benchmark.dart
View file
Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
import 'dart:async';
import 'dart:io';
import 'dart:math' as math;

Expand All @@ -9,6 +10,15 @@ import 'dart:developer';

final bool isProfileMode = Platform.environment['PROFILE_MODE'] == 'true';

final _setUpsEach = <dynamic Function()>[];

void setUpEach(FutureOr<void> Function() callback) {
setUp(() {
_setUpsEach.add(callback);
});
tearDown(() => _setUpsEach.clear());
}

@isTest
void benchmark(String description, dynamic Function() body,
{Duration minDuration = const Duration(seconds: 2),
Expand All @@ -27,9 +37,13 @@ void benchmark(String description, dynamic Function() body,
var sum2 = 0;

var d = minDuration.inMicroseconds;

while (sum < d || i < minSamples) {
i++;

for (var setup in _setUpsEach) {
await setup();
}
var s = Timeline.now;
await body();
var v = Timeline.now - s;
Expand Down

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