001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.pool2.impl; 018 019import java.io.PrintWriter; 020import java.text.DateFormat; 021import java.text.SimpleDateFormat; 022 023/** 024 * CallStack strategy that uses the stack trace from a {@link Throwable}. This strategy, while slower than the 025 * SecurityManager implementation, provides call stack method names and other metadata in addition to the call stack 026 * of classes. 027 * 028 * @see Throwable#fillInStackTrace() 029 * @since 2.4.3 030 */ 031public class ThrowableCallStack implements CallStack { 032 033 private final String messageFormat; 034 //@GuardedBy("dateFormat") 035 private final DateFormat dateFormat; 036 037 private volatile Snapshot snapshot; 038 039 /** 040 * Create a new instance. 041 * 042 * @param messageFormat message format 043 * @param useTimestamp whether to format the dates in the output message or not 044 */ 045 public ThrowableCallStack(final String messageFormat, final boolean useTimestamp) { 046 this.messageFormat = messageFormat; 047 this.dateFormat = useTimestamp ? new SimpleDateFormat(messageFormat) : null; 048 } 049 050 @Override 051 public synchronized boolean printStackTrace(final PrintWriter writer) { 052 final Snapshot snapshotRef = this.snapshot; 053 if (snapshotRef == null) { 054 return false; 055 } 056 final String message; 057 if (dateFormat == null) { 058 message = messageFormat; 059 } else { 060 synchronized (dateFormat) { 061 message = dateFormat.format(Long.valueOf(snapshotRef.timestamp)); 062 } 063 } 064 writer.println(message); 065 snapshotRef.printStackTrace(writer); 066 return true; 067 } 068 069 @Override 070 public void fillInStackTrace() { 071 snapshot = new Snapshot(); 072 } 073 074 @Override 075 public void clear() { 076 snapshot = null; 077 } 078 079 /** 080 * A snapshot of a throwable. 081 */ 082 private static class Snapshot extends Throwable { 083 private static final long serialVersionUID = 1L; 084 private final long timestamp = System.currentTimeMillis(); 085 } 086}