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 * 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,
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package org.apache.commons.pool2.impl;

import org.apache.commons.pool2.PooledObject;
import org.apache.commons.pool2.UsageTracking;

import java.io.PrintWriter;

Strategy for obtaining and printing the current call stack. This is primarily useful for usage tracking so that different JVMs and configurations can use more efficient strategies for obtaining the current call stack depending on metadata needs. 
See Also:
CallStackUtils
Since:
2.4.3/**
 * 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.
 *
 * @see CallStackUtils
 * @since 2.4.3
 */
public interface CallStack {

    
Prints the current stack trace if available to a PrintWriter. The format is undefined and is primarily useful for debugging issues with PooledObject usage in user code. 
Params:
writer – a PrintWriter to write the current stack trace to if available
Returns:
true if a stack trace was available to print or false if nothing was printed/**
     * 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(final PrintWriter writer);

    
Takes a snapshot of the current call stack. Subsequent calls to printStackTrace(PrintWriter) will print out that stack trace until it is cleared. /**
     * 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();

    
Clears the current stack trace snapshot. Subsequent calls to printStackTrace(PrintWriter) will be no-ops until another call to fillInStackTrace(). /**
     * Clears the current stack trace snapshot. Subsequent calls to {@link #printStackTrace(PrintWriter)} will be
     * no-ops until another call to {@link #fillInStackTrace()}.
     */
    void clear();
}