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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,
* 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 java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.time.Instant;
/**
* CallStack strategy that uses the stack trace from a {@link Throwable}. This strategy, while slower than the
* SecurityManager implementation, provides call stack method names and other metadata in addition to the call stack
* of classes.
*
* @see Throwable#fillInStackTrace()
* @since 2.4.3
*/
public class ThrowableCallStack implements CallStack {
/**
* A snapshot of a throwable.
*/
private static final class Snapshot extends Throwable {
private static final long serialVersionUID = 1L;
private final Instant timestamp;
/**
* Constructs a new instance with its message set to the now instant.
*/
Snapshot() {
this(Instant.now());
}
/**
* Constructs a new instance and use the timestamp as the message with using {@link DateTimeFormatter#ISO_INSTANT} for more precision.
*
* @param timestamp normally the now instant.
*/
private Snapshot(final Instant timestamp) {
super(timestamp.toString());
this.timestamp = timestamp;
}
}
private final String messageFormat;
// We keep the SimpleDateFormat for backward compatibility instead of a DateTimeFormatter.
//@GuardedBy("dateFormat")
private final DateFormat dateFormat;
private volatile Snapshot snapshot;
/**
* Creates a new instance.
*
* @param messageFormat message format
* @param useTimestamp whether to format the dates in the output message or not
*/
public ThrowableCallStack(final String messageFormat, final boolean useTimestamp) {
this.messageFormat = messageFormat;
this.dateFormat = useTimestamp ? new SimpleDateFormat(messageFormat) : null;
}
@Override
public void clear() {
snapshot = null;
}
@Override
public void fillInStackTrace() {
snapshot = new Snapshot();
}
@Override
public synchronized boolean printStackTrace(final PrintWriter writer) {
final Snapshot snapshotRef = this.snapshot;
if (snapshotRef == null) {
return false;
}
final String message;
if (dateFormat == null) {
message = messageFormat;
} else {
synchronized (dateFormat) {
// The throwable message is in {@link DateTimeFormatter#ISO_INSTANT} format for more precision.
message = dateFormat.format(Long.valueOf(snapshotRef.timestamp.toEpochMilli()));
}
}
writer.println(message);
snapshotRef.printStackTrace(writer);
return true;
}
}
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