1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.pool2.impl;
18
19 import java.io.PrintWriter;
20
21 import org.apache.commons.pool2.PooledObject;
22 import org.apache.commons.pool2.UsageTracking;
23
24 /**
25 * Strategy for obtaining and printing the current call stack. This is primarily useful for
26 * {@linkplain UsageTracking usage tracking} so that different JVMs and configurations can use more efficient strategies
27 * for obtaining the current call stack depending on metadata needs.
28 *
29 * @see CallStackUtils
30 * @since 2.4.3
31 */
32 public interface CallStack {
33
34 /**
35 * Clears the current stack trace snapshot. Subsequent calls to {@link #printStackTrace(PrintWriter)} will be
36 * no-ops until another call to {@link #fillInStackTrace()}.
37 */
38 void clear();
39
40 /**
41 * Takes a snapshot of the current call stack. Subsequent calls to {@link #printStackTrace(PrintWriter)} will print
42 * out that stack trace until it is {@linkplain #clear() cleared}.
43 */
44 void fillInStackTrace();
45
46 /**
47 * Prints the current stack trace if available to a PrintWriter. The format is undefined and is primarily useful
48 * for debugging issues with {@link PooledObject} usage in user code.
49 *
50 * @param writer a PrintWriter to write the current stack trace to if available
51 * @return true if a stack trace was available to print or false if nothing was printed
52 */
53 boolean printStackTrace(final PrintWriter writer);
54 }