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 /** 034 * A snapshot of a throwable. 035 */ 036 private static class Snapshot extends Throwable { 037 private static final long serialVersionUID = 1L; 038 private final long timestampMillis = System.currentTimeMillis(); 039 } 040 private final String messageFormat; 041 042 //@GuardedBy("dateFormat") 043 private final DateFormat dateFormat; 044 045 private volatile Snapshot snapshot; 046 047 /** 048 * Create a new instance. 049 * 050 * @param messageFormat message format 051 * @param useTimestamp whether to format the dates in the output message or not 052 */ 053 public ThrowableCallStack(final String messageFormat, final boolean useTimestamp) { 054 this.messageFormat = messageFormat; 055 this.dateFormat = useTimestamp ? new SimpleDateFormat(messageFormat) : null; 056 } 057 058 @Override 059 public void clear() { 060 snapshot = null; 061 } 062 063 @Override 064 public void fillInStackTrace() { 065 snapshot = new Snapshot(); 066 } 067 068 @Override 069 public synchronized boolean printStackTrace(final PrintWriter writer) { 070 final Snapshot snapshotRef = this.snapshot; 071 if (snapshotRef == null) { 072 return false; 073 } 074 final String message; 075 if (dateFormat == null) { 076 message = messageFormat; 077 } else { 078 synchronized (dateFormat) { 079 message = dateFormat.format(Long.valueOf(snapshotRef.timestampMillis)); 080 } 081 } 082 writer.println(message); 083 snapshotRef.printStackTrace(writer); 084 return true; 085 } 086}