OpenJDK 27 · sun.awt.AWTAutoShutdown · APIdia, the JavaDoc alternative

This class is to let AWT shutdown automatically when a user is done with AWT. It tracks AWT state using the following parameters:

peerMap - the map between the existing peer objects and their associated targets
toolkitThreadBusy - whether the toolkit thread is waiting for a new native event to appear in its queue or is dispatching an event
busyThreadSet - a set of all the event dispatch threads that are busy at this moment, i.e. those that are not waiting for a new event to appear in their event queue.

AWT is considered to be in ready-to-shutdown state when peerMap is empty and toolkitThreadBusy is false and busyThreadSet is empty. The internal AWTAutoShutdown logic secures that the single non-daemon thread (blockerThread) is running when AWT is not in ready-to-shutdown state. This blocker thread is to prevent AWT from exiting since the toolkit thread is now daemon and all the event dispatch threads are started only when needed. Once it is detected that AWT is in ready-to-shutdown state this blocker thread waits for a certain timeout and if AWT state doesn't change during timeout this blocker thread terminates all the event dispatch threads and exits.

Field Summary

Modifier and Type	Field and Description
private final Object	activationLock This lock object is to secure that when a new blocker thread is started it will be the first who acquire the main lock after the thread that created the new blocker released the main lock by calling lock.wait() to wait for the blocker to start.
private Thread	blockerThread References the alive non-daemon thread that is currently used for keeping AWT from exiting.
private final Set<Thread>	busyThreadSet This set keeps references to all the event dispatch threads that are busy at this moment, i.e. those that are not waiting for a new event to appear in their event queue.
private final Object	mainLock This lock object is used to synchronize shutdown operations.
private final Map<Object, Object>	peerMap This is a map between components and their peers.
private static final int	SAFETY_TIMEOUT Once we detect that AWT is ready to shutdown we wait for a certain timeout to pass before stopping event dispatch threads.
private static final AWTAutoShutdown	theInstance
private boolean	timeoutPassed We need this flag to secure that AWT state hasn't changed while we were waiting for the safety timeout to pass.
private boolean	toolkitThreadBusy Indicates whether the toolkit thread is waiting for a new native event to appear or is dispatching an event.

Constructor Summary

Access	Constructor and Description
private	AWTAutoShutdown() Constructor method is intentionally made private to secure a single instance.

Method Summary

Modifier and Type	Method and Description
private void	activateBlockerThread() Creates and starts a new blocker thread.
pack-priv void	dumpPeers(final PlatformLogger aLog)
public static AWTAutoShutdown	getInstance() Returns reference to a single AWTAutoShutdown instance.
pack-priv Object	getPeer(final Object target)
pack-priv static AWTEvent	getShutdownEvent()
private boolean	Returns: true if AWT is in ready-to-shutdown state. isReadyToShutdown() Determine whether AWT is currently in ready-to-shutdown state.
pack-priv void	notifyPeerMapUpdated() Notify that the peermap has been updated, that means a new peer has been created or some existing peer has been disposed.
public void	notifyThreadBusy(final Thread thread to be added to this set, if not present. thread) Add a specified thread to the set of busy event dispatch threads.
public void	notifyThreadFree(final Thread thread to be removed from this set, if present. thread) Remove a specified thread from the set of busy event dispatch threads.
public static void	notifyToolkitThreadBusy() Notify that the toolkit thread is not waiting for a native event to appear in its queue.
public static void	notifyToolkitThreadFree() Notify that the toolkit thread is waiting for a native event to appear in its queue.
pack-priv void	registerPeer(final Object target, final Object peer)
public void	run() Implements java.lang.Runnable.run. Implementation of the Runnable interface.
private void	setToolkitBusy(final boolean true if the toolkit thread state changes from idle to busy. busy) Notify about the toolkit thread state change.
pack-priv void	unregisterPeer(final Object target, final Object peer)

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Detail

activationLock	back to summary
private final Object activationLock This lock object is to secure that when a new blocker thread is started it will be the first who acquire the main lock after the thread that created the new blocker released the main lock by calling lock.wait() to wait for the blocker to start.

blockerThread	back to summary
private Thread blockerThread References the alive non-daemon thread that is currently used for keeping AWT from exiting.

busyThreadSet	back to summary
private final Set<Thread> busyThreadSet This set keeps references to all the event dispatch threads that are busy at this moment, i.e. those that are not waiting for a new event to appear in their event queue. Access is synchronized on the main lock object.

mainLock	back to summary
private final Object mainLock This lock object is used to synchronize shutdown operations.

peerMap	back to summary
private final Map<Object, Object> peerMap This is a map between components and their peers. we should work with in under activationLock&mainLock lock.

SAFETY_TIMEOUT	back to summary
private static final int SAFETY_TIMEOUT Once we detect that AWT is ready to shutdown we wait for a certain timeout to pass before stopping event dispatch threads.

theInstance	back to summary
private static final AWTAutoShutdown theInstance

timeoutPassed	back to summary
private boolean timeoutPassed We need this flag to secure that AWT state hasn't changed while we were waiting for the safety timeout to pass.

toolkitThreadBusy	back to summary
private boolean toolkitThreadBusy Indicates whether the toolkit thread is waiting for a new native event to appear or is dispatching an event.

Constructor Detail

AWTAutoShutdown back to summary

AWTAutoShutdown	back to summary
private AWTAutoShutdown() Constructor method is intentionally made private to secure a single instance. Use getInstance() to reference it. See Also `AWTAutoShutdown#getInstance`

private AWTAutoShutdown()

Constructor method is intentionally made private to secure a single instance. Use getInstance() to reference it.

See Also: AWTAutoShutdown#getInstance

Method Detail

activateBlockerThread	back to summary
private void activateBlockerThread() Creates and starts a new blocker thread. Doesn't return until the new blocker thread starts.

dumpPeers	back to summary
pack-priv void dumpPeers(final PlatformLogger aLog)

getInstance	back to summary
public static AWTAutoShutdown getInstance() Returns reference to a single AWTAutoShutdown instance.

getPeer	back to summary
pack-priv Object getPeer(final Object target)

getShutdownEvent	back to summary
pack-priv static AWTEvent getShutdownEvent()

isReadyToShutdown back to summary

isReadyToShutdown	back to summary
private boolean isReadyToShutdown() Determine whether AWT is currently in ready-to-shutdown state. AWT is considered to be in ready-to-shutdown state if `peerMap` is empty and `toolkitThreadBusy` is false and `busyThreadSet` is empty. Returns:boolean true if AWT is in ready-to-shutdown state.

private boolean isReadyToShutdown()

Determine whether AWT is currently in ready-to-shutdown state. AWT is considered to be in ready-to-shutdown state if peerMap is empty and toolkitThreadBusy is false and busyThreadSet is empty.

Returns:boolean: true if AWT is in ready-to-shutdown state.

notifyPeerMapUpdated back to summary

notifyPeerMapUpdated	back to summary
pack-priv void notifyPeerMapUpdated() Notify that the peermap has been updated, that means a new peer has been created or some existing peer has been disposed. See Also `AWTAutoShutdown#isReadyToShutdown`

pack-priv void notifyPeerMapUpdated()

Notify that the peermap has been updated, that means a new peer has been created or some existing peer has been disposed.

See Also: AWTAutoShutdown#isReadyToShutdown

notifyThreadBusy back to summary

notifyThreadBusy	back to summary
public void notifyThreadBusy(final Thread thread) Add a specified thread to the set of busy event dispatch threads. If this set already contains the specified thread or the thread is null, the call leaves this set unchanged and returns silently. Parameters thread:Thread thread to be added to this set, if not present. See Also `AWTAutoShutdown#notifyThreadFree`, `AWTAutoShutdown#isReadyToShutdown`

public void notifyThreadBusy(final Thread thread)

Add a specified thread to the set of busy event dispatch threads. If this set already contains the specified thread or the thread is null, the call leaves this set unchanged and returns silently.

Parameters

thread:Thread: thread to be added to this set, if not present.

notifyThreadFree back to summary

notifyThreadFree	back to summary
public void notifyThreadFree(final Thread thread) Remove a specified thread from the set of busy event dispatch threads. If this set doesn't contain the specified thread or the thread is null, the call leaves this set unchanged and returns silently. Parameters thread:Thread thread to be removed from this set, if present. See Also `AWTAutoShutdown#notifyThreadBusy`, `AWTAutoShutdown#isReadyToShutdown`

public void notifyThreadFree(final Thread thread)

Remove a specified thread from the set of busy event dispatch threads. If this set doesn't contain the specified thread or the thread is null, the call leaves this set unchanged and returns silently.

Parameters

thread:Thread: thread to be removed from this set, if present.

notifyToolkitThreadBusy back to summary

notifyToolkitThreadBusy	back to summary
public static void notifyToolkitThreadBusy() Notify that the toolkit thread is not waiting for a native event to appear in its queue. See Also `AWTAutoShutdown#notifyToolkitThreadFree`, `AWTAutoShutdown#setToolkitBusy`, `AWTAutoShutdown#isReadyToShutdown`

public static void notifyToolkitThreadBusy()

Notify that the toolkit thread is not waiting for a native event to appear in its queue.

See Also: AWTAutoShutdown#notifyToolkitThreadFree, AWTAutoShutdown#setToolkitBusy, AWTAutoShutdown#isReadyToShutdown

notifyToolkitThreadFree back to summary

notifyToolkitThreadFree	back to summary
public static void notifyToolkitThreadFree() Notify that the toolkit thread is waiting for a native event to appear in its queue. See Also `AWTAutoShutdown#notifyToolkitThreadFree`, `AWTAutoShutdown#setToolkitBusy`, `AWTAutoShutdown#isReadyToShutdown`

public static void notifyToolkitThreadFree()

Notify that the toolkit thread is waiting for a native event to appear in its queue.

See Also: AWTAutoShutdown#notifyToolkitThreadFree, AWTAutoShutdown#setToolkitBusy, AWTAutoShutdown#isReadyToShutdown

registerPeer	back to summary
pack-priv void registerPeer(final Object target, final Object peer)

run back to summary

run	back to summary
public void run() Implements java.lang.Runnable.run. Implementation of the Runnable interface. Encapsulates the blocker thread functionality. See Also `AWTAutoShutdown#isReadyToShutdown`

public void run()

Implements java.lang.Runnable.run.

Implementation of the Runnable interface. Encapsulates the blocker thread functionality.

See Also: AWTAutoShutdown#isReadyToShutdown

setToolkitBusy back to summary

setToolkitBusy	back to summary
private void setToolkitBusy(final boolean busy) Notify about the toolkit thread state change. Parameters busy:boolean true if the toolkit thread state changes from idle to busy. See Also `AWTAutoShutdown#notifyToolkitThreadBusy`, `AWTAutoShutdown#notifyToolkitThreadFree`, `AWTAutoShutdown#isReadyToShutdown`

private void setToolkitBusy(final boolean busy)

Notify about the toolkit thread state change.

Parameters

busy:boolean: true if the toolkit thread state changes from idle to busy.

unregisterPeer	back to summary
pack-priv void unregisterPeer(final Object target, final Object peer)

public final Class AWTAutoShutdown

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail