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Fix O(n^2) performance bug in uniqArr; avoid duplicate keyF evaluations #575

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Merged
stephenamar-db merged 1 commit into from
Dec 22, 2025
+11 −14
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Fix O(n^2) performance bug in uniqArr; avoid duplicate keyF evaluations #575

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25 changes: 11 additions & 14 deletions sjsonnet/src/sjsonnet/stdlib/SetModule.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -65,22 +65,19 @@ object SetModule extends AbstractFunctionModule {
val out = new mutable.ArrayBuilder.ofRef[Lazy]
// Set a reasonable size hint - in the worst case (no duplicates), we'll need arrValue.length elements
out.sizeHint(arrValue.length)
for (v <- arrValue) {
val outResult = out.result()
if (outResult.length == 0) {

var lastAddedKey: Val = null
var i = 0
while (i < arrValue.length) {
val v = arrValue(i)
val vKey =
if (keyF.isInstanceOf[Val.False]) v.force
else keyF.asInstanceOf[Val.Func].apply1(v, pos.noOffset)(ev, TailstrictModeDisabled)
if (lastAddedKey == null || !ev.equal(vKey, lastAddedKey)) {
out.+=(v)
} else if (keyF.isInstanceOf[Val.False]) {
if (!ev.equal(outResult.last.force, v.force)) {
out.+=(v)
}
} else if (!keyF.isInstanceOf[Val.False]) {
val keyFFunc = keyF.asInstanceOf[Val.Func]
val o1Key = keyFFunc.apply1(v, pos.noOffset)(ev, TailstrictModeDisabled)
val o2Key = keyFFunc.apply1(outResult.last, pos.noOffset)(ev, TailstrictModeDisabled)
if (!ev.equal(o1Key, o2Key)) {
out.+=(v)
}
lastAddedKey = vKey
}
i += 1
}

Val.Arr(pos, out.result())
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