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    /**
040     * A custom security manager.
041     */
042    private static class PrivateSecurityManager extends SecurityManager {
043        /**
044         * Get the class stack.
045         *
046         * @return class stack
047         */
048        private List<WeakReference<Class<?>>> getCallStack() {
049            final Class<?>[] classes = getClassContext();
050            final List<WeakReference<Class<?>>> stack = new ArrayList<>(classes.length);
051            for (final Class<?> klass : classes) {
052                stack.add(new WeakReference<>(klass));
053            }
054            return stack;
055        }
056    }
057    /**
058     * A snapshot of a class stack.
059     */
060    private static class Snapshot {
061        private final long timestampMillis = System.currentTimeMillis();
062        private final List<WeakReference<Class<?>>> stack;
063
064        /**
065         * Create a new snapshot with a class stack.
066         *
067         * @param stack class stack
068         */
069        private Snapshot(final List<WeakReference<Class<?>>> stack) {
070            this.stack = stack;
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     * Create 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        for (final WeakReference<Class<?>> reference : snapshotRef.stack) {
120            writer.println(reference.get());
121        }
122        return true;
123    }
124}