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.lang.ref.WeakReference; 021import java.security.AccessController; 022import java.security.PrivilegedAction; 023import java.text.DateFormat; 024import java.text.SimpleDateFormat; 025import java.util.ArrayList; 026import java.util.List; 027 028/** 029 * CallStack strategy using a {@link SecurityManager}. Obtaining the current call stack is much faster via a 030 * SecurityManger, but access to the underlying method may be restricted by the current SecurityManager. In environments 031 * where a SecurityManager cannot be created, {@link ThrowableCallStack} should be used instead. 032 * 033 * @see RuntimePermission 034 * @see SecurityManager#getClassContext() 035 * @since 2.4.3 036 */ 037public class SecurityManagerCallStack implements CallStack { 038 039 private final String messageFormat; 040 //@GuardedBy("dateFormat") 041 private final DateFormat dateFormat; 042 private final PrivateSecurityManager securityManager; 043 044 private volatile Snapshot snapshot; 045 046 /** 047 * Create a new instance. 048 * 049 * @param messageFormat message format 050 * @param useTimestamp whether to format the dates in the output message or not 051 */ 052 public SecurityManagerCallStack(final String messageFormat, final boolean useTimestamp) { 053 this.messageFormat = messageFormat; 054 this.dateFormat = useTimestamp ? new SimpleDateFormat(messageFormat) : null; 055 this.securityManager = AccessController.doPrivileged((PrivilegedAction<PrivateSecurityManager>) () -> new PrivateSecurityManager()); 056 } 057 058 @Override 059 public boolean printStackTrace(final PrintWriter writer) { 060 final Snapshot snapshotRef = this.snapshot; 061 if (snapshotRef == null) { 062 return false; 063 } 064 final String message; 065 if (dateFormat == null) { 066 message = messageFormat; 067 } else { 068 synchronized (dateFormat) { 069 message = dateFormat.format(Long.valueOf(snapshotRef.timestamp)); 070 } 071 } 072 writer.println(message); 073 for (final WeakReference<Class<?>> reference : snapshotRef.stack) { 074 writer.println(reference.get()); 075 } 076 return true; 077 } 078 079 @Override 080 public void fillInStackTrace() { 081 snapshot = new Snapshot(securityManager.getCallStack()); 082 } 083 084 @Override 085 public void clear() { 086 snapshot = null; 087 } 088 089 /** 090 * A custom security manager. 091 */ 092 private static class PrivateSecurityManager extends SecurityManager { 093 /** 094 * Get the class stack. 095 * 096 * @return class stack 097 */ 098 private List<WeakReference<Class<?>>> getCallStack() { 099 final Class<?>[] classes = getClassContext(); 100 final List<WeakReference<Class<?>>> stack = new ArrayList<>(classes.length); 101 for (final Class<?> klass : classes) { 102 stack.add(new WeakReference<Class<?>>(klass)); 103 } 104 return stack; 105 } 106 } 107 108 /** 109 * A snapshot of a class stack. 110 */ 111 private static class Snapshot { 112 private final long timestamp = System.currentTimeMillis(); 113 private final List<WeakReference<Class<?>>> stack; 114 115 /** 116 * Create a new snapshot with a class stack. 117 * 118 * @param stack class stack 119 */ 120 private Snapshot(final List<WeakReference<Class<?>>> stack) { 121 this.stack = stack; 122 } 123 } 124}