/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.util;

import org.apache.flink.annotation.Internal;
import org.apache.flink.annotation.VisibleForTesting;

import javax.annotation.Nullable;

import static java.lang.String.format;

/**
 * Utilits for working with {@link WrappingProxy}.
 */
@Internal
public final class WrappingProxyUtil {

	@VisibleForTesting
	static final int SAFETY_NET_MAX_ITERATIONS = 128;

	private WrappingProxyUtil() {
		throw new AssertionError();
	}

	/**
	 * Expects a proxy, and returns the unproxied delegate.
	 *
	 * @param wrappingProxy The initial proxy.
	 * @param <T> The type of the delegate. Note that all proxies in the chain must be assignable to T.
	 * @return The unproxied delegate.
	 */
	@SuppressWarnings("unchecked")
	public static <T> T stripProxy(@Nullable final WrappingProxy<T> wrappingProxy) {
		if (wrappingProxy == null) {
			return null;
		}

		T delegate = wrappingProxy.getWrappedDelegate();

		int numProxiesStripped = 0;
		while (delegate instanceof WrappingProxy) {
			throwIfSafetyNetExceeded(++numProxiesStripped);
			delegate = ((WrappingProxy<T>) delegate).getWrappedDelegate();
		}

		return delegate;
	}

	private static void throwIfSafetyNetExceeded(final int numProxiesStripped) {
		if (numProxiesStripped >= SAFETY_NET_MAX_ITERATIONS) {
			throw new IllegalArgumentException(format("Already stripped %d proxies. " +
				"Are there loops in the object graph?", SAFETY_NET_MAX_ITERATIONS));
		}
	}
}

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.util;

import org.apache.flink.annotation.Internal;
import org.apache.flink.annotation.VisibleForTesting;

import javax.annotation.Nullable;

import static java.lang.String.format;

/**
 * Utilities for working with {@link WrappingProxy}.
 */
@Internal
public final class WrappingProxyUtil {

	@VisibleForTesting
	static final int SAFETY_NET_MAX_ITERATIONS = 128;

	private WrappingProxyUtil() {
		throw new AssertionError();
	}

	/**
	 * Expects a proxy, and returns the unproxied delegate.
	 *
	 * @param wrappingProxy The initial proxy.
	 * @param <T> The type of the delegate. Note that all proxies in the chain must be assignable to T.
	 * @return The unproxied delegate.
	 */
	@SuppressWarnings("unchecked")
	public static <T> T stripProxy(@Nullable final WrappingProxy<T> wrappingProxy) {
		if (wrappingProxy == null) {
			return null;
		}

		T delegate = wrappingProxy.getWrappedDelegate();

		int numProxiesStripped = 0;
		while (delegate instanceof WrappingProxy) {
			throwIfSafetyNetExceeded(++numProxiesStripped);
			delegate = ((WrappingProxy<T>) delegate).getWrappedDelegate();
		}

		return delegate;
	}

	private static void throwIfSafetyNetExceeded(final int numProxiesStripped) {
		if (numProxiesStripped >= SAFETY_NET_MAX_ITERATIONS) {
			throw new IllegalArgumentException(format("Already stripped %d proxies. " +
				"Are there loops in the object graph?", SAFETY_NET_MAX_ITERATIONS));
		}
	}
}

Fix typo in WrappingProxyUtil Javadoc