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package org.graalvm.compiler.hotspot;

import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.util.Iterator;
import java.util.Objects;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.UnaryOperator;

import jdk.internal.vm.compiler.collections.EconomicSet;
import jdk.internal.vm.compiler.collections.Equivalence;

A set of weak references to ClassLoaders.
/** * A set of weak references to {@link ClassLoader}s. */
public final class WeakClassLoaderSet {
Copy-on-write set of loaders.
/** * Copy-on-write set of loaders. */
private volatile AtomicReference<EconomicSet<Reference<ClassLoader>>> loaders = new AtomicReference<>(EconomicSet.create(RefEquivalence.INSTANCE)); public WeakClassLoaderSet(ClassLoader... initialEntries) { for (ClassLoader loader : initialEntries) { loaders.get().add(new WeakReference<>(loader)); } }
Adds loader to this set.
/** * Adds {@code loader} to this set. */
public void add(ClassLoader loader) { Reference<ClassLoader> addNewRef = new WeakReference<>(loader); EconomicSet<Reference<ClassLoader>> currentLoaders = loaders.get(); if (!currentLoaders.contains(addNewRef)) { this.loaders.getAndUpdate(new UnaryOperator<EconomicSet<Reference<ClassLoader>>>() { @Override public EconomicSet<Reference<ClassLoader>> apply(EconomicSet<Reference<ClassLoader>> t) { EconomicSet<Reference<ClassLoader>> newLoaders = EconomicSet.create(RefEquivalence.INSTANCE, t); newLoaders.add(addNewRef); return newLoaders; } }); } }
Tries to resolve className to Class instances with the loaders in this set.
Params:
  • className – name of a class to resolve
  • resolutionFailures – all resolution failures are returned in this set
Returns:the set of classes successfully resolved
/** * Tries to resolve {@code className} to {@link Class} instances with the loaders in this set. * * @param className name of a class to resolve * @param resolutionFailures all resolution failures are returned in this set * @return the set of classes successfully resolved */
public EconomicSet<Class<?>> resolve(String className, EconomicSet<ClassNotFoundException> resolutionFailures) { EconomicSet<Class<?>> found = EconomicSet.create(); Iterator<Reference<ClassLoader>> it = loaders.get().iterator(); while (it.hasNext()) { Reference<ClassLoader> ref = it.next(); ClassLoader loader = ref.get(); if (loader == null) { it.remove(); continue; } try { Class<?> clazz = Class.forName(className, false, loader); found.add(clazz); } catch (ClassNotFoundException ex) { resolutionFailures.add(ex); } } return found; } private static final class RefEquivalence extends Equivalence { static final Equivalence INSTANCE = new RefEquivalence(); private RefEquivalence() { } @Override public boolean equals(Object a, Object b) { Reference<?> refA = (Reference<?>) a; Reference<?> refB = (Reference<?>) b; Object referentA = refA.get(); Object referentB = refB.get(); return Objects.equals(referentA, referentB); } @Override public int hashCode(Object o) { Reference<?> ref = (Reference<?>) o; Object obj = ref.get(); return obj == null ? 0 : obj.hashCode(); } } }