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