001/* Attribute that regulates the passage of time to wait for real time to catch up.
002
003 Copyright (c) 2007-2015 The Regents of the University of California.
004 All rights reserved.
005 Permission is hereby granted, without written agreement and without
006 license or royalty fees, to use, copy, modify, and distribute this
007 software and its documentation for any purpose, provided that the above
008 copyright notice and the following two paragraphs appear in all copies
009 of this software.
010
011 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
012 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
013 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
014 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
015 SUCH DAMAGE.
016
017 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
018 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
019 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
020 PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
021 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
022 ENHANCEMENTS, OR MODIFICATIONS.
023
024 PT_COPYRIGHT_VERSION_2
025 COPYRIGHTENDKEY
026 */
027package ptolemy.actor.lib;
028
029import ptolemy.actor.AbstractInitializableAttribute;
030import ptolemy.actor.Actor;
031import ptolemy.actor.Director;
032import ptolemy.actor.TimeRegulator;
033import ptolemy.actor.util.Time;
034import ptolemy.data.DoubleToken;
035import ptolemy.data.expr.Parameter;
036import ptolemy.data.type.BaseType;
037import ptolemy.kernel.CompositeEntity;
038import ptolemy.kernel.util.IllegalActionException;
039import ptolemy.kernel.util.NameDuplicationException;
040import ptolemy.kernel.util.NamedObj;
041
042///////////////////////////////////////////////////////////////////
043//// SynchronizeToRealTime
044
045/**
046 * Attribute that regulates the passage of time to wait for real time to catch up.
047 *
048 * <p>The scaleFactor parameter is here to set up how many seconds in wallclock
049 * time should pass for a single second in model time. So a scale factor of 0.5
050 * will make the model time passes twice as fast as real time, while make it
051 * equals 2 means that 2 seconds in wallclock are needed for a single unit
052 * of time in the model.</p>
053 *
054 * <p>The default value is 1.</p>
055 *
056 @author Edward A. Lee, Gilles Lasnier, Patricia Derler
057 @version $Id$
058 @since Ptolemy II 10.0
059 @Pt.ProposedRating Yellow (eal)
060 @Pt.AcceptedRating Red (cxh)
061 */
062public class SynchronizeToRealTime extends AbstractInitializableAttribute
063        implements TimeRegulator {
064
065    /** Construct an instance of the attribute.
066     * @param container The container.
067     * @param name The name.
068     * @exception IllegalActionException If the superclass throws it.
069     * @exception NameDuplicationException If the superclass throws it.
070     */
071    public SynchronizeToRealTime(CompositeEntity container, String name)
072            throws IllegalActionException, NameDuplicationException {
073        super(container, name);
074
075        scaleFactor = new Parameter(this, "scaleFactor");
076        scaleFactor.setDisplayName("Time scale factor");
077        scaleFactor.setTypeEquals(BaseType.DOUBLE);
078        scaleFactor.setExpression("1.0");
079        attributeChanged(scaleFactor);
080    }
081
082    ///////////////////////////////////////////////////////////////////
083    ////                         public methods                    ////
084
085    /**
086     * This class does not create change request for new actor in proposeTime.
087     * Always return true then.
088     */
089    @Override
090    public boolean noNewActors() {
091        return true;
092    }
093
094    /** Propose a time to advance to.
095     *  @param proposedTime The proposed time.
096     *  @return The proposed time or a smaller time.
097     *  @exception IllegalActionException If this attribute is not
098     *   contained by an Actor.
099     */
100    @Override
101    public Time proposeTime(Time proposedTime) throws IllegalActionException {
102        NamedObj container = getContainer();
103        if (!(container instanceof Actor)) {
104            throw new IllegalActionException(this,
105                    "SynchronizeToRealTime has to be contained by an Actor");
106        }
107
108        Director director = ((Actor) container).getDirector();
109        Object mutexLockObject = director.mutexLockObject();
110
111        int depth = 0;
112        try {
113            synchronized (mutexLockObject) {
114                while (true) {
115
116                    // NOTE: We assume that the elapsed time can be
117                    // safely cast to a double.  This means that
118                    // the SR domain has an upper limit on running
119                    // time of Double.MAX_VALUE milliseconds.
120                    double elapsedTime_s = director.elapsedTimeSinceStart()
121                            / 1000.0;
122                    double currentTime_s = director.getModelTime()
123                            .getDoubleValue();
124
125                    double scale = ((DoubleToken) scaleFactor.getToken())
126                            .doubleValue();
127                    if (currentTime_s * scale <= elapsedTime_s) {
128                        break;
129                    }
130
131                    long timeToWait_ms = (long) ((currentTime_s * scale
132                            - elapsedTime_s) * 1000.0);
133
134                    if (_debugging) {
135                        _debug("Waiting for real time to pass: " + timeToWait_ms
136                                + " before " + proposedTime.getDoubleValue());
137                    }
138
139                    try {
140                        // NOTE: The built-in Java wait() method
141                        // does not release the
142                        // locks on the workspace, which would block
143                        // UI interactions and may cause deadlocks.
144                        // SOLUTION: explicitly release read permissions.
145                        if (timeToWait_ms > 0) {
146                            // Bug fix from J. S. Senecal:
147                            //
148                            //  The problem was that sometimes, the
149                            //  method Object.wait(timeout) was called
150                            //  with timeout = 0. According to java
151                            //  documentation:
152                            //
153                            // " If timeout is zero, however, then
154                            // real time is not taken into
155                            // consideration and the thread simply
156                            // waits until notified."
157                            depth = _workspace.releaseReadPermission();
158                            mutexLockObject.wait(timeToWait_ms);
159                        }
160                    } catch (InterruptedException ex) {
161                        // Continue executing.
162                    }
163                }
164            }
165        } finally {
166            if (depth > 0) {
167                _workspace.reacquireReadPermission(depth);
168            }
169        }
170        return proposedTime;
171    }
172
173    ///////////////////////////////////////////////////////////////////
174    ////                         public members                    ////
175
176    /** How many seconds in wallclock time should pass for a single
177     * second in model time. So a scaleFactor of 0.5 will make the
178     * model time passes twice as fast as real time, while make it
179     * equals 2 means that 2 seconds in wallclock are needed for a
180     * single unit of time in the model.  The default value is 1.0.
181     */
182    public Parameter scaleFactor;
183}