/*
 * Javolution - Java(TM) Solution for Real-Time and Embedded Systems
 * Copyright (C) 2005 - Javolution (http://javolution.org/)
 * All rights reserved.
 * 
 * Permission to use, copy, modify, and distribute this software is
 * freely granted, provided that this notice is preserved.
 */
package javolution37.javolution.realtime;

import javolution37.javolution.JavolutionError;
import javolution37.javolution.lang.Reflection;

/**
 * 
 This class represents a heap context; it is used to allocate objects
 *     from the heap exclusively.
 *
 * @author  Jean-Marie Dautelle
 * @version 3.6, September 24, 2005
 */
public class HeapContext extends Context {

    /**
     * Holds the class object (cannot use .class with j2me).
     */
    private static final Class CLASS = Reflection
            .getClass("javolution37.javolution.realtime.HeapContext");

    /**
     * Default constructor.
     */
    public HeapContext() {
    }

    /**
     * Returns the current heap context or null if the current
     * thread executes within a pool context.  
     *
     * @return the current heap context.
     */
    public static HeapContext current() {
        Context ctx = Context.current();
        if (ctx.inheritedPoolContext != null)
            return null;
        while (ctx != null) {
            if (ctx instanceof HeapContext)
                return (HeapContext) ctx;
            ctx = ctx.getOuter();
        }
        throw new JavolutionError("No heap context or pool context");
    }

    /**
     * Enters a {@link HeapContext}.
     */
    public static void enter() {
        Context.enter(HeapContext.CLASS);
    }

    /**
     * Exits the current {@link HeapContext}.
     *
     * @throws java.lang.IllegalStateException if the current context 
     *         is not an instance of HeapContext. 
     */
    public static void exit() {
        Context.exit(HeapContext.CLASS);
    }

    // Implements Context abstract method.
    protected void enterAction() {
        inheritedPoolContext = null; // Overrides inherited.
        PoolContext outer = getOuter().inheritedPoolContext;
        if (outer != null) {
            outer.setInUsePoolsLocal(false);
        }
    }

    // Implements Context abstract method.
    protected void exitAction() {
        PoolContext outer = getOuter().inheritedPoolContext;
        if (outer != null) {
            outer.setInUsePoolsLocal(true);
        }
    }

}