/* An optimized scheduler for the SR domain.
Copyright (c) 2000-2006 The Regents of the University of California.
All rights reserved.
Permission is hereby granted, without written agreement and without
license or royalty fees, to use, copy, modify, and distribute this
software and its documentation for any purpose, provided that the above
copyright notice and the following two paragraphs appear in all copies
of this software.
IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
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THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
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ENHANCEMENTS, OR MODIFICATIONS.
PT_COPYRIGHT_VERSION_2
COPYRIGHTENDKEY
*/
package ptolemy.domains.sr.kernel;
import ptolemy.actor.Actor;
import ptolemy.actor.CompositeActor;
import ptolemy.actor.Director;
import ptolemy.actor.IOPort;
import ptolemy.actor.sched.Firing;
import ptolemy.actor.sched.NotSchedulableException;
import ptolemy.actor.sched.Schedule;
import ptolemy.actor.sched.Scheduler;
import ptolemy.actor.sched.StaticSchedulingDirector;
import ptolemy.actor.util.FunctionDependencyOfCompositeActor;
import ptolemy.graph.DirectedAcyclicGraph;
import ptolemy.kernel.util.IllegalActionException;
import ptolemy.kernel.util.NameDuplicationException;
import ptolemy.kernel.util.Nameable;
import ptolemy.kernel.util.Workspace;
import ptolemy.util.MessageHandler;
//////////////////////////////////////////////////////////////////////////
//// SROptimizedScheduler
/**
A scheduler the Synchronous Reactive (SR) domain. This scheduler returns
a static schedule for the graph. The schedule guarantees that the values will
converge to a fixed-point.
<p>
The recursive scheduling algorithm is due to Stephen Edwards, and is
described in his Ph.D. thesis. First, a dependency graph is constructed, and
the strongly connected components (SCC) are determined. A schedule for each
SCC is obtained by separating the sub-graph into a head and a tail, and then
recursively applying this algorithm to both the head and the tail. The
schedule for the SCC is (<i>TH</i>)<super><i>n</i></super><i>T</i> where
<i>H</i> and <i>T</i> are the schedules of the head and tail, respectively, and
<i>n</i> is the number of nodes in the head and represents the number of
repetitions of the parenthesized expression. Finally, the schedules of the
top-level SCCs are concatenated in topological order to obtain the schedule
for the entire graph.
@author Paul Whitaker
@version $Id: SROptimizedScheduler.java,v 1.46 2006/03/29 00:02:30 cxh Exp $
@since Ptolemy II 2.0
@Pt.ProposedRating Red (pwhitake)
@Pt.AcceptedRating Red (pwhitake)
@see ptolemy.domains.sr.kernel.SRDirector
*/
public class SROptimizedScheduler extends Scheduler {
/** Construct a SR scheduler with no container (director)
* in the default workspace.
*/
public SROptimizedScheduler() {
super();
}
/** Construct a SR scheduler in the given workspace.
* If the workspace argument is null, use the default workspace.
* The scheduler is added to the list of objects in the workspace.
* Increment the version number of the workspace.
* @param workspace Object for synchronization and version tracking.
*/
public SROptimizedScheduler(Workspace workspace) {
super(workspace);
}
/** Construct a scheduler in the given container with the given name.
* The container argument must not be null, or a
* NullPointerException will be thrown. This attribute will use the
* workspace of the container for synchronization and version counts.
* If the name argument is null, then the name is set to the empty string.
* Increment the version of the workspace.
* @param container The container.
* @param name The name of this scheduler.
* @exception IllegalActionException If the scheduler is not of an
* acceptable class for the container, or if the name contains a period.
* @exception NameDuplicationException If the name coincides with
* an attribute already in the container.
*/
public SROptimizedScheduler(Director container, String name)
throws IllegalActionException, NameDuplicationException {
super(container, name);
}
///////////////////////////////////////////////////////////////////
//// protected methods ////
/** Return the scheduling sequence.
* Overrides _getSchedule() method in the base class.
*
* This method should not be called directly, rather the getSchedule()
* method (which is defined in the superclass) will call it when the
* schedule is invalid. This method is not synchronized on the workspace.
*
* @return A schedule representing the scheduling sequence.
* @exception NotSchedulableException If the CompositeActor is not
* schedulable.
*/
protected Schedule _getSchedule() throws NotSchedulableException {
StaticSchedulingDirector director = (StaticSchedulingDirector) getContainer();
if (director == null) {
throw new NotSchedulableException(this, "SROptimizedScheduler "
+ "cannot schedule graph with no director.");
}
CompositeActor compositeActor = (CompositeActor) (director
.getContainer());
if (compositeActor == null) {
throw new NotSchedulableException(this, "SROptimizedScheduler "
+ "cannot schedule graph with no container.");
}
FunctionDependencyOfCompositeActor functionDependency = (FunctionDependencyOfCompositeActor) compositeActor
.getFunctionDependency();
Object[] cycleNodes = functionDependency.getCycleNodes();
if (cycleNodes.length != 0) {
StringBuffer names = new StringBuffer();
for (int i = 0; i < cycleNodes.length; i++) {
if (cycleNodes[i] instanceof Nameable) {
if (i > 0) {
names.append(", ");
}
names.append(((Nameable) cycleNodes[i]).getContainer()
.getFullName());
}
}
MessageHandler.error("There are strict cycle loops in the model:"
+ names.toString() + "\n"
+ " The results may contain unknowns. This optimized "
+ "scheduler does not handle this model. Try the "
+ "randomized scheduler instead.");
}
DirectedAcyclicGraph dependencyGraph = functionDependency
.getDetailedDependencyGraph().toDirectedAcyclicGraph();
if (_debugging) {
_debug("## dependency graph is:" + dependencyGraph.toString());
}
Object[] sort = dependencyGraph.topologicalSort();
if (_debugging) {
_debug("## Result of topological sort (highest depth to lowest):");
}
Schedule schedule = new Schedule();
Actor lastActor = null;
Actor actor = null;
for (int i = 0; i < sort.length; i++) {
IOPort ioPort = (IOPort) sort[i];
// If this ioPort is input but has no connections,
// we ignore it.
if (ioPort.isInput() && (ioPort.numLinks() == 0)) {
continue;
}
actor = (Actor) ioPort.getContainer();
// If the actor is the container of this director (which
// can occur if this director is not at the top level),
// then skip this actor. The container of the director
// should not be listed in the schedule.
if (actor == compositeActor) {
continue;
}
// We record the information of last actor.
// If some consecutive ports belong to the
// same actor, we only schedule that actor once.
if (lastActor == null) {
lastActor = actor;
} else {
if (lastActor.equals(actor)) {
continue;
} else {
lastActor = actor;
}
}
Firing firing = new Firing(actor);
schedule.add(firing);
if (_debugging) {
_debug(((Nameable) actor).getFullName(), "depth: " + i);
}
}
if (_debugging) {
_debug("## End of topological sort.");
}
return schedule;
}
}