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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.tomcat.dbcp.pool2.impl;
import java.io.PrintWriter;
import java.lang.ref.WeakReference;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;
/**
* A {@link CallStack} strategy using a {@link SecurityManager}. Obtaining the current call stack is much faster via a
* SecurityManger, but access to the underlying method may be restricted by the current SecurityManager. In environments
* where a SecurityManager cannot be created, {@link ThrowableCallStack} should be used instead.
*
* @see RuntimePermission
* @see SecurityManager#getClassContext()
* @since 2.4.3
*/
public class SecurityManagerCallStack implements CallStack {
/**
* A custom security manager.
*/
private static class PrivateSecurityManager extends SecurityManager {
/**
* Gets the class stack.
*
* @return class stack
*/
private List<WeakReference<Class<?>>> getCallStack() {
final Stream<WeakReference<Class<?>>> map = Stream.of(getClassContext()).map(WeakReference::new);
return map.collect(Collectors.toList());
}
}
/**
* A snapshot of a class stack.
*/
private static class Snapshot {
private final long timestampMillis = System.currentTimeMillis();
private final List<WeakReference<Class<?>>> stack;
/**
* Constructs a new snapshot with a class stack.
*
* @param stack class stack
*/
private Snapshot(final List<WeakReference<Class<?>>> stack) {
this.stack = stack;
}
}
private final String messageFormat;
//@GuardedBy("dateFormat")
private final DateFormat dateFormat;
private final PrivateSecurityManager securityManager;
private volatile Snapshot snapshot;
/**
* Creates a new instance.
*
* @param messageFormat message format
* @param useTimestamp whether to format the dates in the output message or not
*/
public SecurityManagerCallStack(final String messageFormat, final boolean useTimestamp) {
this.messageFormat = messageFormat;
this.dateFormat = useTimestamp ? new SimpleDateFormat(messageFormat) : null;
this.securityManager = AccessController.doPrivileged((PrivilegedAction<PrivateSecurityManager>) PrivateSecurityManager::new);
}
@Override
public void clear() {
snapshot = null;
}
@Override
public void fillInStackTrace() {
snapshot = new Snapshot(securityManager.getCallStack());
}
@Override
public boolean printStackTrace(final PrintWriter writer) {
final Snapshot snapshotRef = this.snapshot;
if (snapshotRef == null) {
return false;
}
final String message;
if (dateFormat == null) {
message = messageFormat;
} else {
synchronized (dateFormat) {
message = dateFormat.format(Long.valueOf(snapshotRef.timestampMillis));
}
}
writer.println(message);
snapshotRef.stack.forEach(reference -> writer.println(reference.get()));
return true;
}
}
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