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 import java.text.DateFormat;
21 import java.text.SimpleDateFormat;
22
23 /**
24 * CallStack strategy that uses the stack trace from a {@link Throwable}. This strategy, while slower than the
25 * SecurityManager implementation, provides call stack method names and other metadata in addition to the call stack
26 * of classes.
27 *
28 * @see Throwable#fillInStackTrace()
29 * @since 2.4.3
30 */
31 public class ThrowableCallStack implements CallStack {
32
33 /**
34 * A snapshot of a throwable.
35 */
36 private static class Snapshot extends Throwable {
37 private static final long serialVersionUID = 1L;
38 private final long timestampMillis = System.currentTimeMillis();
39 }
40
41 private final String messageFormat;
42
43 //@GuardedBy("dateFormat")
44 private final DateFormat dateFormat;
45
46 private volatile Snapshot snapshot;
47
48 /**
49 * Creates a new instance.
50 *
51 * @param messageFormat message format
52 * @param useTimestamp whether to format the dates in the output message or not
53 */
54 public ThrowableCallStack(final String messageFormat, final boolean useTimestamp) {
55 this.messageFormat = messageFormat;
56 this.dateFormat = useTimestamp ? new SimpleDateFormat(messageFormat) : null;
57 }
58
59 @Override
60 public void clear() {
61 snapshot = null;
62 }
63
64 @Override
65 public void fillInStackTrace() {
66 snapshot = new Snapshot();
67 }
68
69 @Override
70 public synchronized boolean printStackTrace(final PrintWriter writer) {
71 final Snapshot snapshotRef = this.snapshot;
72 if (snapshotRef == null) {
73 return false;
74 }
75 final String message;
76 if (dateFormat == null) {
77 message = messageFormat;
78 } else {
79 synchronized (dateFormat) {
80 message = dateFormat.format(Long.valueOf(snapshotRef.timestampMillis));
81 }
82 }
83 writer.println(message);
84 snapshotRef.printStackTrace(writer);
85 return true;
86 }
87 }