cs101.util.semaphore
Class GBS

java.lang.Object
  java.awt.Component
      java.awt.Container
          java.awt.Panel
              cs101.util.semaphore.GraphicalSemaphore
                  cs101.util.semaphore.GBS

All Implemented Interfaces:

javax.accessibility.Accessible, java.awt.image.ImageObserver, java.awt.MenuContainer, java.io.Serializable

public class GBS

extends GraphicalSemaphore

Implements simple binary semaphores in java witha graphical display.
Interface is gbs.request(), gbs.release().
It also provides a graphical display of the semaphores status.

This utility borrows heavily from the design and implementation of cs101.util.BS. It mearly adds a graphical display.
Copyright 1996 Massachusetts Institute of Technology

Version:

$Id: GBS.java,v 1.3 2003/09/23 15:36:21 gus Exp $

Author:

Todd C. Parnell, tparnell@ai.mit.edu, Joshua R. Brown, reuben@ai.mit.edu (added graphics), Lynn Andrea Stein, las@ai.mit.edu (semaphore design)

See Also:

Serialized Form

Nested Class Summary

Nested classes inherited from class java.awt.Panel

java.awt.Panel.AccessibleAWTPanel

Nested classes inherited from class java.awt.Container

java.awt.Container.AccessibleAWTContainer

Nested classes inherited from class java.awt.Component

java.awt.Component.AccessibleAWTComponent, java.awt.Component.BltBufferStrategy, java.awt.Component.FlipBufferStrategy

Field Summary

Fields inherited from class cs101.util.semaphore.GraphicalSemaphore

display, InstanceCounter, label, myNumber

Fields inherited from class java.awt.Component

BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT

Fields inherited from interface java.awt.image.ImageObserver

ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH

Constructor Summary

GBS(boolean initVal, java.lang.String label)
Constructs a binary semaphore with the intial value passed in.

Method Summary

void	release() Releases the semaphore.
void	request() Requests the semaphore.
protected void	setupGUI() Does all of the graphical setup on this level then calls the superclasses method to finish the setup.
protected void	showStatus() Prints out the current state of the semaphore.

Methods inherited from class cs101.util.semaphore.GraphicalSemaphore

getMinimumSize, getPreferredSize

Methods inherited from class java.awt.Panel

addNotify, getAccessibleContext

Methods inherited from class java.awt.Container

add, add, add, add, add, addContainerListener, addImpl, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, countComponents, deliverEvent, doLayout, findComponentAt, findComponentAt, getAlignmentX, getAlignmentY, getComponent, getComponentAt, getComponentAt, getComponentCount, getComponents, getContainerListeners, getFocusTraversalKeys, getFocusTraversalPolicy, getInsets, getLayout, getListeners, getMaximumSize, insets, invalidate, isAncestorOf, isFocusCycleRoot, isFocusCycleRoot, isFocusTraversalPolicySet, layout, list, list, locate, minimumSize, paint, paintComponents, paramString, preferredSize, print, printComponents, processContainerEvent, processEvent, remove, remove, removeAll, removeContainerListener, removeNotify, setFocusCycleRoot, setFocusTraversalKeys, setFocusTraversalPolicy, setFont, setLayout, transferFocusBackward, transferFocusDownCycle, update, validate, validateTree

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, disable, disableEvents, dispatchEvent, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, getBackground, getBounds, getBounds, getColorModel, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMouseListeners, getMouseMotionListeners, getMouseWheelListeners, getName, getParent, getPeer, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isOpaque, isShowing, isValid, isVisible, keyDown, keyUp, list, list, list, location, lostFocus, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paintAll, postEvent, prepareImage, prepareImage, printAll, processComponentEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeysEnabled, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setName, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusUpCycle

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

GBS

public GBS(boolean initVal,
           java.lang.String label)

Constructs a binary semaphore with the intial value passed in.

Parameters:

initVal - Initial value for semaphore. (true => in use)

label - Used to identfy the semaphore in the display.

Method Detail

setupGUI

protected void setupGUI()

Does all of the graphical setup on this level then calls the superclasses method to finish the setup. This method is primarly responsible for setting up the display Panel.

Overrides:

setupGUI in class GraphicalSemaphore

request

public void request()

Requests the semaphore. If the semaphore is currently busy, causes the requesting process to wait() until the semaphore is release()d. Unlike java.lang.Object.wait(), the requesting process is not suspended if the semaphore is currently free.

Specified by:

request in class GraphicalSemaphore

See Also:

release(), Object.wait()

release

public void release()

Releases the semaphore. Any objects currently wait()ing on the semaphore are notify()d (and one of them will be granted the semaphore). Unlike java.lang.Object.notify(), the semaphore is also freed so that if there are no wait()ing objects, the next object to request() the semaphore will receive it.

Specified by:

release in class GraphicalSemaphore

See Also:

request(), Object.notifyAll()

showStatus

protected void showStatus()

Prints out the current state of the semaphore. Changes the graphical display.

Specified by:

showStatus in class GraphicalSemaphore