sim.engine
Class SimState

java.lang.Object
  extended by sim.engine.SimState
All Implemented Interfaces:
java.io.Serializable

public class SimState
extends java.lang.Object
implements java.io.Serializable

SimState represents the simulation proper. Your simulations generally will contain one top-level object which subclasses from SimState.

A SimState contains the random number generator and the simulator's schedule. You should not change the schedule to another Schedule object.

When a simulation is begun, SimState's start() method is called. Then the schedule is stepped some N times. Last, the SimState's finish() method is called, and the simulation is over.

SimStates are serializable; if you wish to be able to checkpoint your simulation and read from checkpoints, you should endeavor to make all objects in the simulation serializable as well. Prior to serializing to a checkpoint, preCheckpoint() is called. Then after serialization, postCheckpoint() is called. When a SimState is loaded from a checkpoint, awakeFromCheckpoint() is called to give you a chance to make any adjustments. SimState also implements several methods which call these methods and then serialize the SimState to files and to streams.

SimState also maintains a private registry of Asynchronous objects (such as AsynchronousSteppable), and handles pausing and resuming them during the checkpointing process, and killing them during finish() in case they had not completed yet.

If you override any of the methods foo() in SimState, should remember to always call super.foo() for any such method foo().

See Also:
Serialized Form

Field Summary
 boolean cleaningAsynchronous
           
 MersenneTwisterFast random
          The SimState's random number generator
 Schedule schedule
          SimState's schedule
 
Constructor Summary
SimState(long seed)
          Creates a SimState with a new random number generator initialized to the given seed, plus a new, empty schedule.
SimState(MersenneTwisterFast random)
          Creates a SimState with a new, empty Schedule and the provided random number generator.
SimState(MersenneTwisterFast random, Schedule schedule)
          Creates a SimState with the provided random number generator and schedule.
 
Method Summary
 boolean addToAsynchronousRegistry(Asynchronous stop)
          Registers an Asynchronous to get its pause() method called prior to checkpointing, its resume() method to be called after checkpointing or recovery, and its stop() method to be called at finish() time.
 Asynchronous[] asynchronousRegistry()
          Returns all the Asynchronous items presently in the registry.
 void awakeFromCheckpoint()
          Called after the SimState was created by reading from a checkpointed object.
static void doLoop(java.lang.Class c, java.lang.String[] args)
          Calls doLoop(MakesSimState,args), passing in a MakesSimState which creates SimStates of the provided Class c, using the constructor new ().
static void doLoop(MakesSimState generator, java.lang.String[] args)
          A convenient top-level loop for the simulation command-line.
 void finish()
          Called either at the proper or a premature end to the simulation.
 long job()
          Returns the job number set by the doLoop(...) facility.
 void kill()
          A Steppable on the schedule can call this method to cancel the simulation.
 void postCheckpoint()
          Called just after the SimState was checkpointed (serialized out to a file to be unserialized and fired up at a future time).
 void preCheckpoint()
          Called just before the SimState is being checkpointed (serialized out to a file to be unserialized and fired up at a future time).
static SimState readFromCheckpoint(java.io.File file)
          Creates a SimState from checkpoint.
static SimState readFromCheckpoint(java.io.InputStream stream)
          Creates and returns a new SimState object read in from the provided stream.
 void removeFromAsynchronousRegistry(Asynchronous stop)
          Unregisters an Asynchronous from the asynchronous registry.
 void setRandom(MersenneTwisterFast random)
           
 void start()
          Called immediately prior to starting the simulation, or in-between simulation runs.
static double version()
           
 SimState writeToCheckpoint(java.io.File file)
          Writes the state to a checkpoint and returns the state.
 void writeToCheckpoint(java.io.OutputStream stream)
          Serializes out the SimState, and the entire simulation state (not including the graphical interfaces) to the provided stream.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

random

public MersenneTwisterFast random
The SimState's random number generator


schedule

public Schedule schedule
SimState's schedule


cleaningAsynchronous

public boolean cleaningAsynchronous
Constructor Detail

SimState

public SimState(long seed)
Creates a SimState with a new random number generator initialized to the given seed, plus a new, empty schedule.


SimState

public SimState(MersenneTwisterFast random)
Creates a SimState with a new, empty Schedule and the provided random number generator.


SimState

public SimState(MersenneTwisterFast random,
                Schedule schedule)
Creates a SimState with the provided random number generator and schedule.

Method Detail

setRandom

public void setRandom(MersenneTwisterFast random)

start

public void start()
Called immediately prior to starting the simulation, or in-between simulation runs. This gives you a chance to set up initially, or reset from the last simulation run. The default version simply replaces the Schedule with a completely new one.


finish

public void finish()
Called either at the proper or a premature end to the simulation. If the user quits the program, this function may not be called. It is possible for this method to be called multiple times. If you need to check for this possibility, the easiest way is to set a flag in start() and clear it in the first finish().


kill

public void kill()
A Steppable on the schedule can call this method to cancel the simulation. All existing AsynchronousSteppables are stopped, and then the schedule is reset. AsynchronousSteppables should not call this method directly -- it will deadlock. Instead, an AsynchronousSteppable may kill the simulation by scheduling a Steppable for the next timestep which calls state.kill().


addToAsynchronousRegistry

public boolean addToAsynchronousRegistry(Asynchronous stop)
Registers an Asynchronous to get its pause() method called prior to checkpointing, its resume() method to be called after checkpointing or recovery, and its stop() method to be called at finish() time. The purpose of the addToCleanup() method is to provide the simulation with a way of stopping existing threads which the user has created in the background.

An Asynchronous cannot be added multiple times to the same registry -- if it's there it's there. Returns false if the Asynchronous could not be added, either because the simulation is stopped or in the process of finish()ing.


removeFromAsynchronousRegistry

public void removeFromAsynchronousRegistry(Asynchronous stop)
Unregisters an Asynchronous from the asynchronous registry.


asynchronousRegistry

public Asynchronous[] asynchronousRegistry()
Returns all the Asynchronous items presently in the registry. The returned array is not used internally -- you are free to modify it.


preCheckpoint

public void preCheckpoint()
Called just before the SimState is being checkpointed (serialized out to a file to be unserialized and fired up at a future time). You should override this to prepare your SimState object appropriately. Be sure to call super.preCheckpoint().


postCheckpoint

public void postCheckpoint()
Called just after the SimState was checkpointed (serialized out to a file to be unserialized and fired up at a future time). You cam override this as you see fit. Be sure to call super.postCheckpoint().


awakeFromCheckpoint

public void awakeFromCheckpoint()
Called after the SimState was created by reading from a checkpointed object. You should set up your SimState in any way necessary (reestablishing file connections, etc.) to fix anything that may no longer exist. Be sure to call super.awakeFromCheckpoint().


writeToCheckpoint

public void writeToCheckpoint(java.io.OutputStream stream)
                       throws java.io.IOException
Serializes out the SimState, and the entire simulation state (not including the graphical interfaces) to the provided stream. Calls preCheckpoint() before and postCheckpoint() afterwards. Throws an IOException if the stream becomes invalid (prematurely closes, etc.). Does not close or flush the stream.

Throws:
java.io.IOException

writeToCheckpoint

public SimState writeToCheckpoint(java.io.File file)
Writes the state to a checkpoint and returns the state. If an exception is raised, it is printed and null is returned.


readFromCheckpoint

public static SimState readFromCheckpoint(java.io.File file)
Creates a SimState from checkpoint. If an exception is raised, it is printed and null is returned.


readFromCheckpoint

public static SimState readFromCheckpoint(java.io.InputStream stream)
                                   throws java.io.IOException,
                                          java.lang.ClassNotFoundException,
                                          java.io.OptionalDataException,
                                          java.lang.ClassCastException
Creates and returns a new SimState object read in from the provided stream. Calls awakeFromCheckpoint(). Throws an IOException if the stream becomes invalid (prematurely closes etc.). Throws a ClassNotFoundException if a serialized object is not found in the CLASSPATH and thus cannot be created. Throws an OptionalDataException if the stream is corrupted. Throws a ClassCastException if the top-level object is not actually a SimState. Does not close or flush the stream.

Throws:
java.io.IOException
java.lang.ClassNotFoundException
java.io.OptionalDataException
java.lang.ClassCastException

job

public long job()
Returns the job number set by the doLoop(...) facility. This number is not incremented by the GUI.


doLoop

public static void doLoop(java.lang.Class c,
                          java.lang.String[] args)
Calls doLoop(MakesSimState,args), passing in a MakesSimState which creates SimStates of the provided Class c, using the constructor new ().


doLoop

public static void doLoop(MakesSimState generator,
                          java.lang.String[] args)
A convenient top-level loop for the simulation command-line. Takes a MakesSimState which is responsible for providing a SimState to run the simulation on, plus the application's argument list in args. This loop is capable of:


version

public static double version()