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8304164: jdk/classfile/CorpusTest.java still fails after JDK-8303910 #13037

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8304164: jdk/classfile/CorpusTest.java still fails after JDK-8303910 #13037

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12 changes: 9 additions & 3 deletions src/java.base/share/classes/jdk/internal/classfile/impl/ClassHierarchyImpl.java
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Original file line number Diff line number Diff line change
@@ -110,6 +110,10 @@ public boolean isAssignableFrom(ClassDesc thisClass, ClassDesc fromClass) {

public static final class CachedClassHierarchyResolver implements ClassHierarchyResolver {

//this instance should never appear in the cache nor leak out
private static final ClassHierarchyResolver.ClassHierarchyInfo NOPE =
new ClassHierarchyResolver.ClassHierarchyInfo(null, false, null);

private final Function<ClassDesc, InputStream> streamProvider;
private final Map<ClassDesc, ClassHierarchyResolver.ClassHierarchyInfo> resolvedCache;

@@ -124,9 +128,11 @@ public CachedClassHierarchyResolver(Function<ClassDesc, InputStream> classStream
// empty ClInfo is stored in case of an exception to avoid repeated scanning failures
@Override
public ClassHierarchyResolver.ClassHierarchyInfo getClassInfo(ClassDesc classDesc) {
var res = resolvedCache.get(classDesc);
//additional test for null value is important to avoid repeated resolution attempts
if (res == null && !resolvedCache.containsKey(classDesc)) {
//using NOPE to distinguish between null value and non-existent record in the cache
//this code is on JDK bootstrap critical path, so cannot use lambdas here
var res = resolvedCache.getOrDefault(classDesc, NOPE);
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resolvedCache is a Collections.synchronizedMap backed by a HashMap. So the getOrDefault() (internally) synchronizes on the resolvedCache instance itself and thus this operation would be thread safe in context of access to this cache in rest of this code. So what you propose here looks good to me.

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Thank you.

if (res == NOPE) {
res = null;
var ci = streamProvider.apply(classDesc);
if (ci != null) {
try (var in = new DataInputStream(new BufferedInputStream(ci))) {