messengerstate.java

jxta_src_2.41b jxta 2.41b 最新版源码 from www.jxta.org

/*
 *
 * $Id: MessengerState.java,v 1.4 2005/12/20 18:30:01 bondolo Exp $
 *
 * Copyright (c) 2004 Sun Microsystems, Inc.  All rights reserved.
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 * modification, are permitted provided that the following conditions
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 *    notice, this list of conditions and the following disclaimer in
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 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA"
 *    must not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
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 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
 */

package net.jxta.endpoint;

/**
 *  The complete standard messenger life cycle state machine that all messengers 
 *  must obey. Compliant messengers can be built by implementing and using this 
 *  class as an engine to orchestrate discrete operations.
 *
 *  <p/>In order to use this class, one must implement the various abstract 
 *  Action methods, so that they trigger the required operations.
 *
 *  <p/>Synchronization has to be externally provided and usualy needs to extend
 *  around sections wider than just the invocation of this class' methods. For 
 *  example, if the user of this class maintains a queue, the state of the
 *  queue must be kept consistent with the invocation of {@link #msgsEvent}, 
 *  {@link #saturatedEvent}, and {@link #idleEvent}, which all denote different
 *  states of that queue. It is suggested to use the instance of this class as
 *  the synchronization object.
 **/
public abstract class MessengerState {
    
    // All the transition map setup is rather terse because java tends to make 
    // it extremely verbose. We do not want to end up with 1000 lines of code 
    // for what amounts to initializing a table.
    
    // Below is a method reference. It permits to put "what to do" in a variable.
    // The <tt>doIt</tt> method is given the target object because we want our
    // entire transition table to be a static singleton. Otherwise it would cost
    // too much initializing each instance of this class.
    
    private interface Action {
        public void doIt(MessengerState s);
    }
    
    // Action method "pointers".
    // The transition table is static. Otherwise it would cost too much initializing each instance of this class.
    
    private final static Action Connect   = new Action(){public void doIt(MessengerState s){s.connectAction();}                         };
    private final static Action Closein   = new Action(){public void doIt(MessengerState s){s.closeInputAction();}                      };
    private final static Action Start     = new Action(){public void doIt(MessengerState s){s.startAction();}                           };
    private final static Action Closeout  = new Action(){public void doIt(MessengerState s){s.closeOutputAction();}                     };
    private final static Action Failall   = new Action(){public void doIt(MessengerState s){s.failAllAction();}                         };
    private final static Action Closeio   = new Action(){public void doIt(MessengerState s){s.closeInputAction();s.closeOutputAction();}};
    private final static Action Closefail = new Action(){public void doIt(MessengerState s){s.closeInputAction();s.failAllAction();}    };
    private final static Action Nop       = new Action(){public void doIt(MessengerState s){};                                          };
    
    // A state: what transition each event causes when in that state.
    private static class State {
        int number;
        State stResolve   ; Action acResolve   ;
        State stMsgs      ; Action acMsgs      ;
        State stSaturated ; Action acSaturated ;
        State stClose     ; Action acClose     ;
        State stShutdown  ; Action acShutdown  ;
        State stUp        ; Action acUp        ;
        State stDown      ; Action acDown      ;
        State stIdle      ; Action acIdle      ;
        
        void init(int stateNum, Object[] data) {
            number = stateNum;
            stResolve   = (State) data[0];  acResolve   = (Action) data[1];
            stMsgs      = (State) data[2];  acMsgs      = (Action) data[3];
            stSaturated = (State) data[4];  acSaturated = (Action) data[5];
            stClose     = (State) data[6];  acClose     = (Action) data[7];
            stShutdown  = (State) data[8];  acShutdown  = (Action) data[9];
            stUp        = (State) data[10]; acUp        = (Action) data[11];
            stDown      = (State) data[12]; acDown      = (Action) data[13];
            stIdle      = (State) data[14]; acIdle      = (Action) data[15];
        }
    }
    
    
    // All the states. (We put them together in a class essentially to simplify initialization).
    private static class TransitionMap {
        
        final static State Unresolved  = new State();
        final static State ResPending  = new State();
        final static State Resolving   = new State();
        final static State ResolSat    = new State();
        final static State Connected   = new State();
        final static State Disconned   = new State();
        final static State Reconning   = new State();
        final static State ReconSat    = new State();
        final static State Sending     = new State();
        final static State SendingSat  = new State();
        final static State ResClosing  = new State();
        final static State ReconClosing= new State();
        final static State Closing     = new State();