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Merged
lahma merged 2 commits into from
Aug 1, 2026
Merged

Ask once per loop, not once per element, how to call a built-in's callback #2876

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02c1aa9
Ask once per loop, not once per element, how to call a built-in's cal…
lahma Jul 30, 2026
fdf75ed
Keep the sort comparers on a plain argument array
lahma Jul 31, 2026
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24 changes: 6 additions & 18 deletions Jint/Native/Array/ArrayConstructor.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -95,7 +95,7 @@ private JsArray ConstructFromIterator(JsValue items, ICallable usingIterator, IC
var iterator = items.GetIterator(_realm, method: usingIterator);

var builder = new JsValueListBuilder(16);
var args = callable is not null ? _engine._jsValueArrayPool.RentArray(2) : null;
var invoker = callable is not null ? CallbackInvoker.Rent(_engine, callable, 2) : default;
try
{
var iterations = 0;
Expand All @@ -119,9 +119,7 @@ private JsArray ConstructFromIterator(JsValue items, ICallable usingIterator, IC

if (callable is not null)
{
args![0] = jsValue;
args[1] = index;
jsValue = callable.Call(thisArg, args);
jsValue = invoker.Call(thisArg, jsValue, index);
}

builder.Add(jsValue);
Expand All @@ -138,10 +136,7 @@ private JsArray ConstructFromIterator(JsValue items, ICallable usingIterator, IC
finally
{
builder.Dispose();
if (args is not null)
{
_engine._jsValueArrayPool.ReturnArray(args);
}
invoker.Return();
}
}

Expand Down Expand Up @@ -665,9 +660,7 @@ private ObjectInstance ConstructArrayFromArrayLike(
a = ArrayCreate(length);
}

var args = callable is not null
? _engine._jsValueArrayPool.RentArray(2)
: null;
var invoker = callable is not null ? CallbackInvoker.Rent(_engine, callable, 2) : default;

var target = ArrayOperations.For(a, forWrite: true);
uint n = 0;
Expand All @@ -682,9 +675,7 @@ private ObjectInstance ConstructArrayFromArrayLike(
var value = source.Get(i);
if (callable is not null)
{
args![0] = value;
args[1] = i;
value = callable.Call(thisArg, args);
value = invoker.Call(thisArg, value, i);

// function can alter data
length = source.GetLength();
Expand All @@ -694,10 +685,7 @@ private ObjectInstance ConstructArrayFromArrayLike(
n++;
}

if (callable is not null)
{
_engine._jsValueArrayPool.ReturnArray(args!);
}
invoker.Return();

target.SetLength(length);
return a;
Expand Down
37 changes: 10 additions & 27 deletions Jint/Native/Array/ArrayInstance.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1667,17 +1667,12 @@ internal JsArray Map(JsCallArguments arguments)

var callable = GetCallable(callbackfn);
var a = _engine.Realm.Intrinsics.Array.ArrayCreate(len);
// args is rented from the pool whose factory allocates new JsValue[3], so it is an exact
// JsValue[]; the per-element fills below bypass the covariant array store type check.
var args = _engine._jsValueArrayPool.RentArray(3);
Arguments.WriteNoTypeCheck(args, 2, this);
var invoker = CallbackInvoker.Rent(_engine, callable, 3, this);
for (uint k = 0; k < len; k++)
{
if (TryGetValue(k, out var kvalue))
{
Arguments.WriteNoTypeCheck(args, 0, kvalue);
Arguments.WriteNoTypeCheck(args, 1, k);
var mappedValue = callable.Call(thisArg, args);
var mappedValue = invoker.Call(thisArg, kvalue, k);
if (a._dense != null && k < (uint) a._dense.Length)
{
a._dense[k] = mappedValue;
Expand All @@ -1689,7 +1684,7 @@ internal JsArray Map(JsCallArguments arguments)
}
}

_engine._jsValueArrayPool.ReturnArray(args);
invoker.Return();
return a;
}

Expand All @@ -1706,10 +1701,7 @@ internal JsArray Filter(JsCallArguments arguments)
// materialize an exact-size result instead of growing the result's dense backing by
// doubling. Capped initial rent so a large low-selectivity source doesn't rent ~len slots.
var builder = new JsValueListBuilder((int) System.Math.Min(len, 1024));
// args is rented from the pool whose factory allocates new JsValue[3], so it is an exact
// JsValue[]; the per-element fills below bypass the covariant array store type check.
var args = _engine._jsValueArrayPool.RentArray(3);
Arguments.WriteNoTypeCheck(args, 2, this);
var invoker = CallbackInvoker.Rent(_engine, callable, 3, this);

// try/finally so the rented args array and the pooled builder buffer are released
// when the callback or a periodic Check() throws.
Expand All @@ -1724,9 +1716,7 @@ internal JsArray Filter(JsCallArguments arguments)

if (TryGetValue(k, out var kvalue))
{
Arguments.WriteNoTypeCheck(args, 0, kvalue);
Arguments.WriteNoTypeCheck(args, 1, k);
var selected = callable.Call(thisArg, args);
var selected = invoker.Call(thisArg, kvalue, k);
if (TypeConverter.ToBoolean(selected))
{
builder.Add(kvalue);
Expand All @@ -1739,7 +1729,7 @@ internal JsArray Filter(JsCallArguments arguments)
finally
{
builder.Dispose();
_engine._jsValueArrayPool.ReturnArray(args);
invoker.Return();
}
}

Expand All @@ -1762,10 +1752,7 @@ internal sealed override bool FindWithCallback(
return false;
}

// args is rented from the pool whose factory allocates new JsValue[3], so it is an exact
// JsValue[]; the per-element fills below bypass the covariant array store type check.
var args = _engine._jsValueArrayPool.RentArray(3);
Arguments.WriteNoTypeCheck(args, 2, this);
var invoker = CallbackInvoker.Rent(_engine, callable, 3, this);

// try/finally so the rented pool array is returned on every exit path: the early
// return-on-match below and a periodic Check() throw both previously leaked it.
Expand All @@ -1783,9 +1770,7 @@ internal sealed override bool FindWithCallback(
if (TryGetValue(k, out var kvalue) || visitUnassigned)
{
kvalue ??= Undefined;
Arguments.WriteNoTypeCheck(args, 0, kvalue);
Arguments.WriteNoTypeCheck(args, 1, k);
var testResult = callable.Call(thisArg, args);
var testResult = invoker.Call(thisArg, kvalue, k);
if (TypeConverter.ToBoolean(testResult))
{
index = k;
Expand All @@ -1808,9 +1793,7 @@ internal sealed override bool FindWithCallback(
if (TryGetValue(idx, out var kvalue) || visitUnassigned)
{
kvalue ??= Undefined;
Arguments.WriteNoTypeCheck(args, 0, kvalue);
Arguments.WriteNoTypeCheck(args, 1, idx);
var testResult = callable.Call(thisArg, args);
var testResult = invoker.Call(thisArg, kvalue, idx);
if (TypeConverter.ToBoolean(testResult))
{
index = idx;
Expand All @@ -1823,7 +1806,7 @@ internal sealed override bool FindWithCallback(
}
finally
{
_engine._jsValueArrayPool.ReturnArray(args);
invoker.Return();
}

index = 0;
Expand Down
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