Package io.hekate.util

Class StampedStateGuard

java.lang.Object

io.hekate.util.StampedStateGuard

public class StampedStateGuard
extends Object

Helper class that provides support for components lifecycle management and locking.

Internally this class is backed by StampedLock.

See Also:

StateGuard

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	StampedStateGuard.State	Enumeration of StampedStateGuard states.

Constructor Summary

Constructors

Constructor	Description
StampedStateGuard(Class<?> type)	Constructs new instance.

Method Summary

Modifier and Type	Method	Description
void	becomeInitialized()	Switches this guard to StampedStateGuard.State.INITIALIZED state.
void	becomeInitializing()	Switches this guard to StampedStateGuard.State.INITIALIZING state.
boolean	becomeTerminated()	Switches this guard to StampedStateGuard.State.TERMINATED state if guard is currently in any other state besides StampedStateGuard.State.TERMINATED.
boolean	becomeTerminating()	Switches this guard to StampedStateGuard.State.TERMINATING state if guard is currently in StampedStateGuard.State.INITIALIZING or StampedStateGuard.State.INITIALIZED state.
boolean	isInitialized()	Returns true if this guard is in StampedStateGuard.State.INITIALIZED state.
boolean	isInitializing()	Returns true if this guard is in StampedStateGuard.State.INITIALIZING state.
boolean	isWriteLocked()	Returns true if current thread hold the write lock.
long	lockRead()	Acquires the read lock.
long	lockReadWithStateCheck()	Acquires the read lock on this guard and checks its current state.
long	lockWrite()	Acquires the write lock.
long	lockWriteWithStateCheck()	Acquires the write lock on this guard and checks its current state.
String	toString()
void	unlockRead(long stamp)	Releases the read lock.
void	unlockWrite(long stamp)	Releases the write lock.

Methods inherited from class java.lang.Object

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

Constructor Detail

StampedStateGuard

public StampedStateGuard(Class<?> type)

Constructs new instance.

Parameters:

type - Type of a guarded component (for errors reporting).

Method Detail

becomeInitializing

public void becomeInitializing()

Switches this guard to StampedStateGuard.State.INITIALIZING state.

Important!!! This method must be invoked with write lock being held.

isInitializing

public boolean isInitializing()

Returns true if this guard is in StampedStateGuard.State.INITIALIZING state.

Important!!! This method must be invoked with write lock or read lock being held.

Returns:

true if this guard is in StampedStateGuard.State.INITIALIZING state.

becomeInitialized

public void becomeInitialized()

Switches this guard to StampedStateGuard.State.INITIALIZED state.

Important!!! This method must be invoked with write lock being held.

isInitialized

public boolean isInitialized()

Returns true if this guard is in StampedStateGuard.State.INITIALIZED state.

Important!!! This method must be invoked with write lock or read lock being held.

Returns:

true if this guard is in StampedStateGuard.State.INITIALIZED state.

becomeTerminating

public boolean becomeTerminating()

Switches this guard to StampedStateGuard.State.TERMINATING state if guard is currently in StampedStateGuard.State.INITIALIZING or StampedStateGuard.State.INITIALIZED state.

Important!!! This method must be invoked with write lock being held.

Returns:

true if successfully switched to StampedStateGuard.State.TERMINATING state.

becomeTerminated

public boolean becomeTerminated()

Switches this guard to StampedStateGuard.State.TERMINATED state if guard is currently in any other state besides StampedStateGuard.State.TERMINATED.

Important!!! This method must be invoked with write lock being held.

Returns:

true if successfully switched to StampedStateGuard.State.TERMINATED state.

lockReadWithStateCheck

public long lockReadWithStateCheck()

Acquires the read lock on this guard and checks its current state. If state is anything other than StampedStateGuard.State.INITIALIZED then IllegalStateException will be thrown and lock will be released.

Returns:

Stamp that can be used to unlock.

Throws:

IllegalStateException - If guard is not in StampedStateGuard.State.INITIALIZED state.

lockRead

public long lockRead()

Acquires the read lock.

Returns:

Stamp that can be used to unlock.

See Also:

StampedLock.readLock()

unlockRead

public void unlockRead(long stamp)

Releases the read lock.

Parameters:

stamp - Lock stamp (see lockRead()).

See Also:

StampedLock.unlockRead(long)

lockWriteWithStateCheck

public long lockWriteWithStateCheck()

Acquires the write lock on this guard and checks its current state. If state is anything other than StampedStateGuard.State.INITIALIZED then IllegalStateException will be thrown and lock will be released.

Returns:

Stamp that can be used to unlock.

Throws:

IllegalStateException - If guard is not in StampedStateGuard.State.INITIALIZED state.

lockWrite

public long lockWrite()

Acquires the write lock.

Returns:

Stamp that can be used to unlock.

See Also:

StampedLock.writeLock()

unlockWrite

public void unlockWrite(long stamp)

Releases the write lock.

Parameters:

stamp - Lock stamp (see lockWrite()).

See Also:

StampedLock.unlockWrite(long)

isWriteLocked

public boolean isWriteLocked()

Returns true if current thread hold the write lock.

Returns:

true if current thread hold the write lock.

See Also:

StampedLock.isWriteLocked()

toString

public String toString()

Overrides:

toString in class Object