/*
 * Copyright 2002-2020 the original author or authors.
 *
 * Licensed 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
 *
 *      https://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.springframework.aop.interceptor;

import java.io.Serializable;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

import org.springframework.lang.Nullable;
import org.springframework.util.ConcurrencyThrottleSupport;

Interceptor that throttles concurrent access, blocking invocations
if a specified concurrency limit is reached.
Can be applied to methods of local services that involve heavy use
of system resources, in a scenario where it is more efficient to
throttle concurrency for a specific service rather than restricting
the entire thread pool (e.g. the web container's thread pool).
The default concurrency limit of this interceptor is 1.
Specify the "concurrencyLimit" bean property to change this value.
Author:
Juergen Hoeller
See Also:
ConcurrencyThrottleSupport.setConcurrencyLimit
Since:
11.02.2004/**
 * Interceptor that throttles concurrent access, blocking invocations
 * if a specified concurrency limit is reached.
 *
 * <p>Can be applied to methods of local services that involve heavy use
 * of system resources, in a scenario where it is more efficient to
 * throttle concurrency for a specific service rather than restricting
 * the entire thread pool (e.g. the web container's thread pool).
 *
 * <p>The default concurrency limit of this interceptor is 1.
 * Specify the "concurrencyLimit" bean property to change this value.
 *
 * @author Juergen Hoeller
 * @since 11.02.2004
 * @see #setConcurrencyLimit
 */
@SuppressWarnings("serial")
public class ConcurrencyThrottleInterceptor extends ConcurrencyThrottleSupport
		implements MethodInterceptor, Serializable {

	public ConcurrencyThrottleInterceptor() {
		setConcurrencyLimit(1);
	}

	@Override
	@Nullable
	public Object invoke(MethodInvocation methodInvocation) throws Throwable {
		beforeAccess();
		try {
			return methodInvocation.proceed();
		}
		finally {
			afterAccess();
		}
	}

}