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 import java.time.Instant;
23
24 /**
25 * CallStack strategy that uses the stack trace from a {@link Throwable}. This strategy, while slower than the
26 * SecurityManager implementation, provides call stack method names and other metadata in addition to the call stack
27 * of classes.
28 *
29 * @see Throwable#fillInStackTrace()
30 * @since 2.4.3
31 */
32 public class ThrowableCallStack implements CallStack {
33
34 /**
35 * A snapshot of a throwable.
36 */
37 private static final class Snapshot extends Throwable {
38
39 private static final long serialVersionUID = 1L;
40 private final Instant timestamp;
41
42 /**
43 * Constructs a new instance with its message set to the now instant.
44 */
45 public Snapshot() {
46 this(Instant.now());
47 }
48
49 /**
50 * Constructs a new instance and use the timestamp as the message with using {@link DateTimeFormatter#ISO_INSTANT} for more precision.
51 *
52 * @param timestamp normally the now instant.
53 */
54 private Snapshot(final Instant timestamp) {
55 super(timestamp.toString());
56 this.timestamp = timestamp;
57 }
58 }
59
60 private final String messageFormat;
61
62 // We keep the SimpleDateFormat for backward compatibility instead of a DateTimeFormatter.
63 //@GuardedBy("dateFormat")
64 private final DateFormat dateFormat;
65
66 private volatile Snapshot snapshot;
67
68 /**
69 * Creates a new instance.
70 *
71 * @param messageFormat message format
72 * @param useTimestamp whether to format the dates in the output message or not
73 */
74 public ThrowableCallStack(final String messageFormat, final boolean useTimestamp) {
75 this.messageFormat = messageFormat;
76 this.dateFormat = useTimestamp ? new SimpleDateFormat(messageFormat) : null;
77 }
78
79 @Override
80 public void clear() {
81 snapshot = null;
82 }
83
84 @Override
85 public void fillInStackTrace() {
86 snapshot = new Snapshot();
87 }
88
89 @Override
90 public synchronized boolean printStackTrace(final PrintWriter writer) {
91 final Snapshot snapshotRef = this.snapshot;
92 if (snapshotRef == null) {
93 return false;
94 }
95 final String message;
96 if (dateFormat == null) {
97 message = messageFormat;
98 } else {
99 synchronized (dateFormat) {
100 // The throwable message is in {@link DateTimeFormatter#ISO_INSTANT} format for more precision.
101 message = dateFormat.format(Long.valueOf(snapshotRef.timestamp.toEpochMilli()));
102 }
103 }
104 writer.println(message);
105 snapshotRef.printStackTrace(writer);
106 return true;
107 }
108 }