org.fuzzydb.util.context.ContextManager Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of org.fuzzydb.util Show documentation
Contains classes not specific to fuzzydb implementation which could be used in any implementation of fuzzy matching, or as general utility classes such as those in the geo package.
The newest version!
/******************************************************************************
 * Copyright (c) 2005-2008 Whirlwind Match Limited. All rights reserved.
 *
 * This is open source software; you can use, redistribute and/or modify
 * it under the terms of the Open Software Licence v 3.0 as published by the 
 * Open Source Initiative.
 *
 * You should have received a copy of the Open Software Licence along with this
 * application. if not, contact the Open Source Initiative (www.opensource.org)
 *****************************************************************************/
package org.fuzzydb.util.context;

import org.slf4j.Logger;


/**
 * Provides access to Request, Session and Application contexts
 */
public class ContextManager {

    protected static Logger log;


    /**
     * Non-null if all threads should see the same request context,
     * otherwise requestContextForThread is used to get/set one
     * per thread.
     */
    private static RequestContext globalRequestContext = null;

    /**
     * The request context when operating for each thread
     */
    private static ThreadLocal requestContextForThread = new ThreadLocal();


    /**
     * Normally, request context is isolated between threads, but in a Java GUI app
     * we want to initialise at startup, and then have all threads in the VM
     * see one ApplicationContext and ThreadContext.
     */
    public static void setSingleForAllThreads() {
        if (globalRequestContext != null) {
            return;
        }
        globalRequestContext = new RequestContext();
    }

    /**
     * See if there is a current session available
     * @return true if there is a session, false if not
     */
    public static boolean hasSession(){
        return getSession() != null;
    }

    /**
     * For internal use, as we want to make RequestContext.getCurrentSessionContext() package scope
     */
    public static SessionContext getSession() {
        return getCurrentSessionContext();
    }

    /**
     * get the user object that has been associated with the current request (usually a HttpServletRequest)
     */
    public static Object getUserRequestContext() {
        return getCurrentRequestContext().userRequestObject;
    }

    /**
     * Set a request object for the current thread.  This allows
     * data that may not be passed through a framework to be
     * used elsewhere if possible.
     * In a web environment, this should be ServletRequestWrapper( HttpServletRequest )
     * TODO: Make a nice wrapper supporting get/set to save having to cast the result everywhere.
     */
    public static void setUserRequestObject(Object context) {
        getCurrentRequestContext().userRequestObject = context;
    }

    /**
     * Get the current application context (i.e. for the current thread)
     */
    public static SessionContext getCurrentSessionContext() {
        return getCurrentRequestContext().sessionContext;
    }

    /**
     * Get the current application context (i.e. for the current thread)
     */
    public static ApplicationContext getCurrentAppContext() {
        return getCurrentRequestContext().appContext;
    }

    /**
     * Return whichever is the valid request context.
     */
    public static RequestContext getCurrentRequestContext() {
        if (globalRequestContext != null) {
            return globalRequestContext;
        }

        RequestContext threadContext = requestContextForThread.get();

        if ( threadContext == null ) {
            threadContext = new RequestContext();
            requestContextForThread.set( threadContext );
        }
        return threadContext;
    }

    /**
     * Registers a session context for the current thread/request.
     * 
     * (Note: This is registered with the request context, which is often associated
     * with a single thread, but is not necessarily.  Registering the session with the
     * request means that if multiple threads are processing a single request, then
     * the new session will become visible to others).
     * TODO: Review as to whether any atomic behaviour is needed in creation of a new
     * session.
     */
    public static void addSession(SessionContext session) {
        RequestContext currentRequestContext = ContextManager.getCurrentRequestContext();
        assert(currentRequestContext.sessionContext == null);
        currentRequestContext.sessionContext = session;
    }

    public static void initForThread(ApplicationContext applicationContext, SessionContext sessionContext, Object request) {
        getCurrentRequestContext().initForThread(applicationContext, sessionContext, request);
    }
}