/*
 * Copyright 2016-2020 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.data.repository.core.support;

import javax.annotation.Nullable;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.springframework.transaction.support.TransactionSynchronizationManager;

MethodInterceptor detecting whether a transaction is already running and exposing that fact via isSurroundingTransactionActive(). Useful in case subsequent interceptors might create transactions themselves but downstream components have to find out whether there was one running before the call entered the proxy. 
Author:
Oliver Gierke, Christoph Strobl
Since:
1.13
@soundtrack
Hendrik Freischlader Trio - Openness (Openness)/**
 * {@link MethodInterceptor} detecting whether a transaction is already running and exposing that fact via
 * {@link #isSurroundingTransactionActive()}. Useful in case subsequent interceptors might create transactions
 * themselves but downstream components have to find out whether there was one running before the call entered the
 * proxy.
 *
 * @author Oliver Gierke
 * @author Christoph Strobl
 * @since 1.13
 * @soundtrack Hendrik Freischlader Trio - Openness (Openness)
 */
public enum SurroundingTransactionDetectorMethodInterceptor implements MethodInterceptor {

	INSTANCE;

	private final ThreadLocal<Boolean> SURROUNDING_TX_ACTIVE = new ThreadLocal<>();

	
Returns whether a transaction was active before the method call entered the repository proxy.
Returns:
/**
	 * Returns whether a transaction was active before the method call entered the repository proxy.
	 *
	 * @return
	 */
	public boolean isSurroundingTransactionActive() {
		return Boolean.TRUE == SURROUNDING_TX_ACTIVE.get();
	}

	/*
	 * (non-Javadoc)
	 * @see org.aopalliance.intercept.MethodInterceptor#invoke(org.aopalliance.intercept.MethodInvocation)
	 */
	@Nullable
	@Override
	public Object invoke(@SuppressWarnings("null") MethodInvocation invocation) throws Throwable {

		SURROUNDING_TX_ACTIVE.set(TransactionSynchronizationManager.isActualTransactionActive());

		try {
			return invocation.proceed();
		} finally {
			SURROUNDING_TX_ACTIVE.remove();
		}
	}
}