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/*
 * Javolution - Java(TM) Solution for Real-Time and Embedded Systems
 * Copyright (C) 2012 - 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 javolution.lang;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * 
 Indicates if an element has a bounded  
 *     
 *     worst-case execution time. The {@link #limit limit} behavior
 *     of the execution time with the input size may be specified (if no limit 
 *     specified the worst case execution time is assumed to be constant).

 *     
 * [code]
 * public class Equalities {
 *     @Realtime(limit = UNKNOWN)
 *     public static final Equality STANDARD = new StandardComparatorImpl();
 *     
 *     @Realtime(limit = CONSTANT)
 *     public static final Equality IDENTITY = new IdentityComparatorImpl();
 *     
 *     @Realtime(limit = LINEAR)
 *     public static final Equality ARRAY = new ArrayComparatorImpl();
 *     
 *     @Realtime(limit = LINEAR)
 *     public static final Equality LEXICAL = new LexicalComparatorImpl();
 * }[/code]      
 *     
 * 
 Analysis tools / compilers may produce warnings if program elements 
 *     use or override elements with incompatible real-time characteristics.

 *     
 * 
 Note: For multi-cores systems, if a real-time element is {@link  Parallelizable}
 *     but not {@link  Parallelizable#mutexFree() mutex-free}, response 
 *     time even for high priority threads may be unbounded due to 
 *     priority 
 *     inversion. This is no longer the case when running on real-time 
 *     VMs due to their support for priority inheritance.

 *          
 * @author  Jean-Marie Dautelle
 * @version 6.0, July 21, 2013
 * @see Real-Time Computing
 */
@Documented
@Inherited
@Target({ ElementType.TYPE, ElementType.FIELD, ElementType.METHOD,
        ElementType.CONSTRUCTOR })
@Retention(RetentionPolicy.RUNTIME)
public @interface Realtime {

    /**
     * Indicates if this element has a bounded worst-case execution time
     * (default {@code true}).
     */
    boolean value() default true;

    /**
     * Returns the limit behavior for the worst-case execution time
     * (default {@link Limit#CONSTANT}).
     */
    Limit limit() default Limit.CONSTANT;

    /**
     * Provides additional information (default {@code ""}).
     */
    String comment() default "";

    /**
     * Identifies the limit behavior for the worst case execution time.
     */
    public enum Limit {

        /**
         * The worst case execution time is constant.
         */
        CONSTANT,

        /**
         * The worst case execution time is bounded in O(log(n)) 
         * with n characteristic of the current size of the inputs.
         */
        LOG_N,

        /**
         * The worst case execution time is bounded in O(n) 
         * with n characteristic of the current size of the inputs.
         */
        LINEAR,

        /**
         * The worst case execution time is bounded in O(n log(n)) 
         * with n characteristic of the current size of the inputs.
         */
        N_LOG_N,

        /**
         * The worst case execution time is bounded in O(n²) 
         * with n characteristic of the current size of the inputs.
         */
        N_SQUARE,

        /**
         * The limit behavior of the worst case execution time is unknown
         * or unspecified.
         */
        UNKNOWN,
    }
}
    

    

    

            

    

            



    
    






    
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