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Fix Subclassed WeakReference to be GCed #3347

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merged 4 commits into from
Jun 29, 2023
Merged

Fix Subclassed WeakReference to be GCed #3347

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5bb3a96
Subclassed WeakRef fix
mox692 Jun 24, 2023
358cc33
update test
mox692 Jun 25, 2023
9be1750
minor fix
mox692 Jun 25, 2023
cd03d0e
workaround for flaky on windows
mox692 Jun 27, 2023
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6 changes: 4 additions & 2 deletions nativelib/src/main/resources/scala-native/gc/immix_commix/headers/ObjectHeader.h
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,8 @@
#include "GCTypes.h"

extern int __object_array_id;
extern int __weak_ref_id;
extern int __weak_ref_ids_min;
extern int __weak_ref_ids_max;
extern int __weak_ref_field_offset;
extern int __array_ids_min;
extern int __array_ids_max;
Expand Down Expand Up @@ -86,7 +87,8 @@ static inline size_t Object_Size(Object *object) {
}

static inline bool Object_IsWeakReference(Object *object) {
return object->rtti->rt.id == __weak_ref_id;
int32_t id = object->rtti->rt.id;
return __weak_ref_ids_min <= id && id <= __weak_ref_ids_max;
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[note] range is closed set 👍

scala-native/tools/src/main/scala/scala/scalanative/codegen/Metadata.scala

Lines 53 to 62 in 6d20a92

def loop(node: Class): Unit = {
out += node
val start = id
id += 1
val directSubclasses =
node.subclasses.filter(_.parent == Some(node)).toArray
directSubclasses.sortBy(_.name.show).foreach { subcls => loop(subcls) }
val end = id - 1
ids(node) = start
ranges(node) = start to end

}

static inline bool Object_IsReferantOfWeakReference(Object *object,
Expand Down
16 changes: 11 additions & 5 deletions tools/src/main/scala/scala/scalanative/codegen/Generate.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -500,10 +500,10 @@ object Generate {
Val.Int(value)
)

val (weakRefId, modifiedFieldOffset) = linked.infos
val (weakRefIdsMin, weakRefIdsMax, modifiedFieldOffset) = linked.infos
.get(Global.Top("java.lang.ref.WeakReference"))
.collect { case cls: Class if cls.allocated => cls }
.fold((-1, -1)) { weakRef =>
.fold((-1, -1, -1)) { weakRef =>
// if WeakReferences are being compiled and therefore supported
val gcModifiedFieldIndexes: Seq[Int] =
meta.layout(weakRef).entries.zipWithIndex.collect {
Expand All @@ -517,9 +517,14 @@ object Generate {
"Exactly one field should have the \"_gc_modified_\" modifier in java.lang.ref.WeakReference"
)

(meta.ids(weakRef), gcModifiedFieldIndexes.head)
(
meta.ranges(weakRef).start,
meta.ranges(weakRef).end,
gcModifiedFieldIndexes.head
)
}
addToBuf(weakRefIdName, weakRefId)
addToBuf(weakRefIdsMaxName, weakRefIdsMax)
addToBuf(weakRefIdsMinName, weakRefIdsMin)
addToBuf(weakRefFieldOffsetName, modifiedFieldOffset)
}

Expand Down Expand Up @@ -621,7 +626,8 @@ object Generate {
val moduleArrayName = extern("__modules")
val moduleArraySizeName = extern("__modules_size")
val objectArrayIdName = extern("__object_array_id")
val weakRefIdName = extern("__weak_ref_id")
val weakRefIdsMaxName = extern("__weak_ref_ids_max")
val weakRefIdsMinName = extern("__weak_ref_ids_min")
val weakRefFieldOffsetName = extern("__weak_ref_field_offset")
val registryOffsetName = extern("__weak_ref_registry_module_offset")
val registryFieldOffsetName = extern("__weak_ref_registry_field_offset")
Expand Down
27 changes: 25 additions & 2 deletions .../native/src/test/scala/org/scalanative/testsuite/javalib/lang/ref/WeakReferenceTest.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,8 @@ import org.scalanative.testsuite.utils.Platform
class WeakReferenceTest {

case class A()
class SubclassedWeakRef[A](a: A, referenceQueue: ReferenceQueue[A])
extends WeakReference[A](a, referenceQueue)

def gcAssumption(): Unit = {
assumeTrue(
Expand All @@ -36,6 +38,16 @@ class WeakReferenceTest {
weakRef
}

@noinline def allocSubclassedWeakRef(
referenceQueue: ReferenceQueue[A]
): SubclassedWeakRef[A] = {
var a = A()
val weakRef = new SubclassedWeakRef(a, referenceQueue)
assertEquals("get() should return object reference", weakRef.get(), A())
a = null
weakRef
}

@deprecated @nooptimize @Test def addsToReferenceQueueAfterGC(): Unit = {
assumeFalse(
"In the CI Scala 3 sometimes SN fails to clean weak references in some of Windows build configurations",
Expand Down Expand Up @@ -72,22 +84,33 @@ class WeakReferenceTest {
val refQueue = new ReferenceQueue[A]()
val weakRef1 = allocWeakRef(refQueue)
val weakRef2 = allocWeakRef(refQueue)
val weakRefList = List(weakRef1, weakRef2)
val weakRef3 = allocSubclassedWeakRef(refQueue)
val weakRefList = List(weakRef1, weakRef2, weakRef3)

GC.collect()
def newDeadline() = System.currentTimeMillis() + 60 * 1000
assertEventuallyIsCollected("weakRef1", weakRef1, deadline = newDeadline())
assertEventuallyIsCollected("weakRef2", weakRef2, deadline = newDeadline())
assertEventuallyIsCollected("weakRef3", weakRef3, deadline = newDeadline())

assertEquals("weakRef1", null, weakRef1.get())
assertEquals("weakRef2", null, weakRef2.get())
assertEquals("weakRef3", null, weakRef3.get())
val a = refQueue.poll()
assertNotNull("a was null", a)
val b = refQueue.poll()
assertNotNull("b was null", b)
val c = refQueue.poll()
assertNotNull("c was null", c)
assertTrue("!contains a", weakRefList.contains(a))
assertTrue("!contains b", weakRefList.contains(b))
assertNotEquals(a, b)
assertTrue("!contains c", weakRefList.contains(c))
def allDistinct(list: List[_]): Unit = list match {
case head :: next =>
next.foreach(assertNotEquals(_, head)); allDistinct(next)
case Nil => ()
}
allDistinct(List(a, b, c))
assertEquals("pool not null", null, refQueue.poll())
}

Expand Down