RelatedThread.java
/*
** Module : RelatedThread.java
** Abstract : a new thread which inherits the account of the creating thread but uses a related
** security context (one that shares only thread-safe context)
**
** Copyright (c) 2020, Golden Code Development Corporation.
**
** -#- -I- --Date-- -----------------------Description------------------------
** 001 GES 20200204 First version.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
** GNU Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
** Under Section 7 of the GNU Affero GPL version 3, the following additional
** terms apply to the works covered under the License. These additional terms
** are non-permissive additional terms allowed under Section 7 of the GNU
** Affero GPL version 3 and may not be removed by you.
**
** 0. Attribution Requirement.
**
** You must preserve all legal notices or author attributions in the covered
** work or Appropriate Legal Notices displayed by works containing the covered
** work. You may not remove from the covered work any author or developer
** credit already included within the covered work.
**
** 1. No License To Use Trademarks.
**
** This license does not grant any license or rights to use the trademarks
** Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
** of Golden Code Development Corporation. You are not authorized to use the
** name Golden Code, FWD, or the names of any author or contributor, for
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**
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**
** You may not represent yourself as Golden Code Development Corporation or FWD.
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** the covered work, without written authorization.
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**
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** versions of the covered work must be marked in a reasonable way to make it
** clear that the modified work is not originating from Golden Code Development
** Corporation or FWD. All modified versions must contain the notices of
** attribution required in this license.
*/
package com.goldencode.p2j.security;
import java.util.*;
/**
* Provides a thread which automatically inherits the account of the creating thread but uses a
* "related" security context. A related context is one that shares only thread-safe context.
* When the thread exits, it will automatically cleanup the context (decrementing the reference
* counts of any related resources and so forth). This makes it easy to implement additional
* threads which all share the same thread-safe resources, the same subjects and the same rights
* without sharing all context-local data.
*/
public class RelatedThread
extends ContextAwareThread
{
/** Stores a map that is shared between all related sessions. */
private final static HashMap<Thread, Map<Object, Object>> storage = new HashMap<>();
/** The "main" thread of the related threads. */
private final Thread main;
/**
* Constructor which allows the core logic to be specified.
*
* @param core
* The logic to execute when the thread is started. Must not be {@code null}.
*
* @throws NullPointerException
* If the instantiating thread has no security context or if {@code core} is
* {@code null}.
*/
public RelatedThread(Runnable core)
throws NullPointerException
{
super(core, sm.isServer() ? SecurityContextStack.getContext().related() : null);
Thread current = Thread.currentThread();
if (current instanceof RelatedThread)
{
main = ((RelatedThread) current).main;
}
else
{
main = current;
synchronized (RelatedThread.class)
{
if (!storage.containsKey(main))
{
storage.put(main, new HashMap<Object, Object>());
}
}
}
}
/**
* Obtain the common object mapped by the given key for the current thread's related thread
* group. If the current thread is not part of a group of related threads (either as the
* main thread or as a {@code RelatedThread} instance), then there will be no object returned.
*
* @param key
* Object used as a key in the lookup.
*
* @return The object mapped for the related thread group or {@code null} if there is no
* object mapped under that key OR if the current thread is not part of a related
* thread group.
*/
public synchronized static Object get(Object key)
{
Map<Object, Object> related = relatedStorage();
return (related != null) ? related.get(key) : null;
}
/**
* Store the common object using the given key for the current thread's related thread
* group. If the current thread is not part of a group of related threads (either as the
* main thread or as a {@code RelatedThread} instance), then there will be no object stored.
* <p>
* <b>Do NOT use an easily guessed key (e.g. a string) for any stored resource. This storage
* facility is by nature a public facility. Any code that can run on the current thread can
* read a stored value if the key is known. If you have a named resource that you need to
* store, do not use the name as a key. Keep your own private map of the names to keys and
* use a new Object instance as the keys.</b>
*
* @param key
* Object used as a key in the mapping.
* @param value
* The object to be stored.
*/
public synchronized static void set(Object key, Object value)
{
Map<Object, Object> related = relatedStorage();
if (related != null)
{
related.put(key, value);
}
}
/**
* Remove the mapping (both the key and the value), if one is present for that key.
*
* @param key
* Object used as a key in the mapping.
*
* @return The object which was mapped, if present, otherwise {@code null}.
*/
public synchronized static Object remove(Object key)
{
Map<Object, Object> related = relatedStorage();
if (related != null)
{
return related.remove(key);
}
return null;
}
/**
* Report if this thread should create a new session when the security context is pushed or if
* the existing session should be reused.
*
* @return {@code true} if a new session must be created.
*/
public boolean needsSession()
{
return false;
}
/**
* Lookup the related thread storage for the given thread. If the current thread is not part
* of a group of related threads (either as the main thread or as a {@code RelatedThread}
* instance), then there will be no storage returned.
*
* @return The related thread storage or {@code null} if this thread is not part of a group
* of related threads.
*/
private synchronized static Map<Object, Object> relatedStorage()
{
Thread current = Thread.currentThread();
return storage.get((current instanceof RelatedThread) ? ((RelatedThread) current).main
: current);
}
}