/*
* 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
*
* 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.apache.tomcat.dbcp.pool2.impl;
import java.io.PrintWriter;
import org.apache.tomcat.dbcp.pool2.PooledObject;
import org.apache.tomcat.dbcp.pool2.UsageTracking;
/**
* Strategy for obtaining and printing the current call stack. This is primarily useful for
* {@linkplain UsageTracking usage tracking} so that different JVMs and configurations can use more efficient strategies
* for obtaining the current call stack depending on metadata needs.
*
* @since 2.4.3
*/
public interface CallStack {
/**
* Clears the current stack trace snapshot. Subsequent calls to {@link #printStackTrace(PrintWriter)} will be
* no-ops until another call to {@link #fillInStackTrace()}.
*/
void clear();
/**
* Takes a snapshot of the current call stack. Subsequent calls to {@link #printStackTrace(PrintWriter)} will print
* out that stack trace until it is {@linkplain #clear() cleared}.
*/
void fillInStackTrace();
/**
* Prints the current stack trace if available to a PrintWriter. The format is undefined and is primarily useful
* for debugging issues with {@link PooledObject} usage in user code.
*
* @param writer a PrintWriter to write the current stack trace to if available
* @return true if a stack trace was available to print or false if nothing was printed
*/
boolean printStackTrace(PrintWriter writer);
}