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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.collections;
import com.yahoo.concurrent.CopyOnWriteHashMap;
import java.lang.ref.WeakReference;
import java.lang.reflect.Method;
import java.util.function.Consumer;
/**
* This will cache methods solved by reflection as reflection is expensive.
* Note that if the bundle from which the method is removed/changed you might have
* a problem... A ClassCastException might be one indication. Then clearing the cache and retrying it
* once to see if it goes away might be a solution.
* @author baldersheim
*/
public final class MethodCache {
private final String methodName;
private final CopyOnWriteHashMap<String, WeakReference<Pair<Class<?>, Method>>> cache = new CopyOnWriteHashMap<>();
public MethodCache(String methodName) {
this.methodName = methodName;
}
/*
Clear all cached methods. Might be a wise thing to do, if you have cached some methods
that have changed due to new bundles being reloaded.
*/
public void clear() {
cache.clear();
}
public Method get(Object object) {
return get(object, null);
}
public Method get(Object object, Consumer<String> onPut) {
WeakReference<Pair<Class<?>, Method>> value = cache.get(object.getClass().getName());
Pair<Class<?>, Method> pair = value == null ? null : value.get();
if (pair == null || pair.getFirst() != object.getClass()) {
cache.clear();
pair = null;
}
Method method = pair == null ? null : pair.getSecond();
if (method == null) {
method = lookupMethod(object);
if (method != null) {
pair = new Pair<>(object.getClass(), method);
if (onPut != null)
onPut.accept(object.getClass().getName());
cache.put(object.getClass().getName(), new WeakReference<>(pair));
}
}
return method;
}
private Method lookupMethod(Object object) {
try {
return object.getClass().getMethod(methodName);
} catch (NoSuchMethodException e) {
return null;
}
}
}
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