desmoj.core.advancedModellingFeatures

Class CondQueue<P extends SimProcess>

java.lang.Object

desmoj.core.simulator.NamedObject

desmoj.core.simulator.ModelComponent

desmoj.core.simulator.Reportable

desmoj.core.simulator.QueueBased

desmoj.core.advancedModellingFeatures.CondQueue<P>

All Implemented Interfaces:

Subject<QueueBased,QueueBased.QueueAction>

Direct Known Subclasses:

CondQueueAnimation

public class CondQueue<P extends SimProcess>
extends QueueBased

In a CondQueue processes are waiting for a specific condition to become true. Process synchronisation happens when processes are waiting in a queue for a specific condition to become true. Each process which uses waitUntil(condition) and does not find this condition to be true, is inserted in a waiting-queue automatically. Whenever something happens which might influence the condition to become true, signal() should be used to check if the first entity (or, if the attribute checkAll is set to true, all entities) in the waiting-queue finds the desired condition now and therefore can continue. The designer of the model is responsible that this check takes place! He also has to implement the condition, this can easily be done by deriving it from the interface Condition. The flag, if only the first or all entities in the queue are checking their conditions again, can be checked and changed using getCheckAll() and setCheckAll(). The first sort criterion of the queue is highest queueing priorities first (i.e. not using scheduling priorities - note that this is a somewhat arbitrary choice, as the CondQueue combines queueing and scheduling features). The second criterion, if a tie-breaker is needed, is the queueing discipline of the underlying queue, e.g. FIFO. The capacity limit can be determined by the user. CondQueue is derived from QueueBased, which provides all the statistical functionality for a queue.

Version:

DESMO-J, Ver. 2.5.1c copyright (c) 2015

Author:

Soenke Claassen, based on DESMO-C from Thomas Schniewind, 1998 Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

See Also:

QueueBased

Nested Class Summary

Nested classes/interfaces inherited from class desmoj.core.simulator.QueueBased

QueueBased.QueueAction

Field Summary

Fields inherited from class desmoj.core.simulator.QueueBased

FIFO, LIFO, RANDOM, UNDEFINED

Constructor Summary

Constructors

Constructor and Description
CondQueue(Model owner, java.lang.String name, boolean showInReport, boolean showInTrace) Constructor for a CondQueue where processes can wait for a certain condition to become true.
CondQueue(Model owner, java.lang.String name, int sortOrder, int qCapacity, boolean showInReport, boolean showInTrace) Constructor for a CondQueue where processes can wait for a certain condition to become true.

Method Summary

Modifier and Type	Method and Description
Reporter	createDefaultReporter() Returns a Reporter to produce a report about this CondQueue.
P	first() Returns the first process waiting in the queue.
P	first(Condition<P> cond) Returns the first process waiting in the queue that complies to the given condition.
boolean	getCheckAll() Returns if all entities or only the first one in the queue are getting a signal to check their conditions.
java.lang.String	getQueueStrategy() Returns the implemented queueing discipline of the underlying queue used for sorting (and, therefore, activation order) of processes with equal queing priorities.
long	getRefused() Returns the number of entities refused to be enqueued in the queue, because the capacity limit is reached.
void	setCheckAll(boolean chckall) Sets the flag checkAll: if all entities or only the first one in the queue are getting a signal to check their conditions.
void	signal() A signal () should be sent every time when a condition has changed and might be true now.
void	waitCancel(P p) Removes the given SimProcess from the Queue.
boolean	waitUntil(Condition<P> cond) Lets the current process wait in the CondQueue until a certain condition, given as a parameter, has become true.

Methods inherited from class desmoj.core.simulator.QueueBased

addObserver, averageLength, averageWaitTime, deleteObserver, getQueueLimit, length, maxLength, maxLengthAt, maxWaitTime, maxWaitTimeAt, minLength, minLengthAt, notifyObservers, reset, setQueueImpWarning, stdDevLength, stdDevWaitTime, zeroWaits

Methods inherited from class desmoj.core.simulator.Reportable

getCorrespondingSchedulable, getDescription, getObservations, getReporter, incrementObservations, incrementObservations, reportIsOn, reportOff, reportOn, resetAt, setCorrespondingSchedulable, setDescription, setReporter

Methods inherited from class desmoj.core.simulator.ModelComponent

current, currentEntity, currentEntityAll, currentEvent, currentModel, currentSimProcess, debugIsOn, debugOff, debugOn, getModel, isExperimentCompatible, isModelCompatible, presentTime, sendDebugNote, sendMessage, sendTraceNote, sendWarning, skipTraceNote, skipTraceNote, traceIsOn, traceOff, traceOn

Methods inherited from class desmoj.core.simulator.NamedObject

getName, getQuotedName, toString

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

CondQueue

public CondQueue(Model owner,
                 java.lang.String name,
                 int sortOrder,
                 int qCapacity,
                 boolean showInReport,
                 boolean showInTrace)

Constructor for a CondQueue where processes can wait for a certain condition to become true. The processes are sorted (and thus activated) according to their queueing priorities (highest first) and (if equal) by a queuing discipline as defined by QueueBased, e.g. QueueBased.FIFO or QueueBased.LIFO. The capacity limit of the underlying queue can be chosen.

Parameters:

owner - Model : The model this CondQueue is associated to.

name - java.lang.String : The CondQueue's name

sortOrder - int : determines the sort order of the underlying queue implementation to use for sorting processes with equal queing priorities. Choose a constant from QueueBased like QueueBased.FIFO or QueueBased.LIFO or ...

qCapacity - int : The capacity of the queue, that is how many processes can be enqueued. Zero (0) means unlimited capacity.

showInReport - boolean : Flag, if CondQueue should produce a report or not.

showInTrace - boolean : Flag for trace to produce trace messages.

CondQueue

public CondQueue(Model owner,
                 java.lang.String name,
                 boolean showInReport,
                 boolean showInTrace)

Constructor for a CondQueue where processes can wait for a certain condition to become true. The processes are sorted (and thus activated) according to their queueing priorities (highest first) and (if equal) FIFO. The underlying queue has unlimited capacity.

Parameters:

owner - Model : The model this CondQueue is associated to.

name - java.lang.String : The CondQueue's name

showInReport - boolean : Flag, if CondQueue should produce a report or not.

showInTrace - boolean : Flag for trace to produce trace messages.

Method Detail

createDefaultReporter

public Reporter createDefaultReporter()

Returns a Reporter to produce a report about this CondQueue.

Returns:

desmoj.report.Reporter : The Reporter for the queue inside this CondQueue.

getCheckAll

public boolean getCheckAll()

Returns if all entities or only the first one in the queue are getting a signal to check their conditions.

Returns:

boolean : Are all entities in the queue checking their conditions? Default is false, so that only the first process in the queue is checking its condition.

getQueueStrategy

public java.lang.String getQueueStrategy()

Returns the implemented queueing discipline of the underlying queue used for sorting (and, therefore, activation order) of processes with equal queing priorities. Return type is String, inteded to be displayed in the report.

Returns:

String : The String indicating the queueing discipline.

getRefused

public long getRefused()

Returns the number of entities refused to be enqueued in the queue, because the capacity limit is reached.

Returns:

long : The number of entities refused to be enqueued in the queue.

setCheckAll

public void setCheckAll(boolean chckall)

Sets the flag checkAll: if all entities or only the first one in the queue are getting a signal to check their conditions.

Parameters:

chckall - boolean : Flag if all entities in the queue should check their conditions? Default is false, so that only the first entity in the queue is checking its condition.

signal

public void signal()

A signal () should be sent every time when a condition has changed and might be true now. It activates the first process in the queue to check its condition again. Other processes might follow. The order of process activation depends on the order of the internal _queue, which is based on the processes' queueing priorities and (if queueing priorities are equal, requiring a tie-breaker) by FIFO or a different discipline as defined in the constructor.

first

public P first()

Returns the first process waiting in the queue. If there is no process waiting, null is returned.

Returns:

SimProcess : Returns the first process in the queue (or null if no process is waiting).

first

public P first(Condition<P> cond)

Returns the first process waiting in the queue that complies to the given condition. If there is no such process waiting, null is returned.

Parameters:

cond - Condition : The Condition cond is describing the condition to which the process must comply to. This has to be implemented by the user in the class: Condition in the method: check().

Returns:

SimProcess : Returns the first process in the queue which complies to the given condition.

waitCancel

public void waitCancel(P p)

Removes the given SimProcess from the Queue. The process no longer waits for its condition to become true and resumes its lifecycle.

Parameters:

p - P : The P to be removed from the queue

waitUntil

public boolean waitUntil(Condition<P> cond)
                  throws SuspendExecution

Lets the current process wait in the CondQueue until a certain condition, given as a parameter, has become true. When the process finds its condition to have become true or checkAll is set to true the next process in the queue will be activated, too. If the capacity limit of the queue is reached, the process will not be enqueued and false returned.

Parameters:

cond - Condition : The condition that has to become true before the process can continue.

Returns:

boolean : Is true if the process can be enqueued successfully, false otherwise (i.e. capacity limit of the queue is reached).

Throws:

SuspendExecution

See Also:

Condition