Package com.arjuna.ats.txoj

Class LockManager

java.lang.Object

com.arjuna.ats.arjuna.StateManager

com.arjuna.ats.txoj.LockManager

public class LockManager
extends StateManager

This class provides (transactional) concurrency control for application objects.

Since:

JTS 1.0.

Version:

$Id: LockManager.java 2342 2006-03-30 13:06:17Z $

Author:

Mark Little (mark@arjuna.com)

See Also:

StateManager

Field Summary

Fields

Modifier and Type	Field	Description
protected com.arjuna.ats.internal.txoj.LockConflictManager	conflictManager
static int	defaultRetry	The default retry value which will be used by setlock if no other value is given.
static int	defaultSleepTime	The default timeout value which will be used by setlock if no other value is given.
protected static int	DOZE_TIME
protected boolean	hasBeenLocked
protected com.arjuna.ats.internal.txoj.LockList	locksHeld
protected Object	locksHeldLockObject
protected LockStore	lockStore
protected String	lockStoreType
protected ReentrantLock	mutex
protected static boolean	nestedLocking
protected boolean	objectLocked
protected boolean	stateLoaded
protected String	systemKey
static int	waitTotalTimeout	By default, threads which call setlock with conflicting locks will spin for the specified (or default) number of timeout and retry attempts, and then return failure if the lock could not be acquired.

Fields inherited from class com.arjuna.ats.arjuna.StateManager

modifyingActions, objectModel, objectUid, synchronizationLock, usingActions

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	LockManager()
protected	LockManager(int ot)
protected	LockManager(int ot, int om)
protected	LockManager(Uid storeUid)
protected	LockManager(Uid storeUid, int ot)
protected	LockManager(Uid storeUid, int ot, int om)

Method Summary

Modifier and Type	Method	Description
protected void	cleanUp()
protected boolean	doRelease(Uid u, boolean all)
void	finalize()	Cleanup.
protected void	freeState()
protected boolean	initialise()
protected boolean	isAncestorOf(Lock heldLock)
protected boolean	loadState()
protected int	lockConflict(Lock otherLock)
void	print(PrintWriter strm)	Print information about this instance on the specified PrintWriter.
void	printState(PrintWriter strm)	Load state into object prior to doing the printing.
boolean	propagate(Uid from, Uid to)	Change lock ownership as nested action commits.
boolean	releaseAll(Uid actionUid)	Clear out all locks for a given action.
boolean	releaselock(Uid lockUid)	Release a SINGLE LOCK lock that has the given uid.
int	setlock(Lock toSet)
int	setlock(Lock toSet, int retry)
int	setlock(Lock toSet, int retry, int sleepTime)
protected void	terminate()	This method *must* be called in the finalizer of every object.
String	type()	Overload StateManager.type()
protected boolean	unloadState()

Methods inherited from class com.arjuna.ats.arjuna.StateManager

activate, activate, cleanup, createLists, deactivate, deactivate, deactivate, destroy, disable, forgetAction, get_uid, getCreationTimeMillis, getMutex, getObjectModel, getStore, getStoreRoot, loadObjectState, lockMutex, modified, objectType, packHeader, persist, rememberAction, restore_state, save_state, setStatus, setupStore, setupStore, setupStore, status, tryLockMutex, unlockMutex, unpackHeader

Methods inherited from class java.lang.Object

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

Field Detail

defaultRetry

public static final int defaultRetry

The default retry value which will be used by setlock if no other value is given.

See Also:

setlock(com.arjuna.ats.txoj.Lock), Constant Field Values

defaultSleepTime

public static final int defaultSleepTime

The default timeout value which will be used by setlock if no other value is given. Milliseconds.

See Also:

setlock(com.arjuna.ats.txoj.Lock), Constant Field Values

waitTotalTimeout

public static final int waitTotalTimeout

By default, threads which call setlock with conflicting locks will spin for the specified (or default) number of timeout and retry attempts, and then return failure if the lock could not be acquired. If the *retry* period is set to this value, then such threads will sleep for their total wait period and be signalled if the lock is released within this period of time.

Since:

JTS 2.1.

See Also:

setlock(com.arjuna.ats.txoj.Lock), Constant Field Values

lockStoreType

protected String lockStoreType

systemKey

protected String systemKey

locksHeld

protected com.arjuna.ats.internal.txoj.LockList locksHeld

locksHeldLockObject

protected final Object locksHeldLockObject

lockStore

protected LockStore lockStore

stateLoaded

protected boolean stateLoaded

hasBeenLocked

protected boolean hasBeenLocked

objectLocked

protected boolean objectLocked

mutex

protected ReentrantLock mutex

conflictManager

protected com.arjuna.ats.internal.txoj.LockConflictManager conflictManager

DOZE_TIME

protected static final int DOZE_TIME

See Also:

Constant Field Values

nestedLocking

protected static final boolean nestedLocking

Constructor Detail

LockManager

protected LockManager(Uid storeUid)

LockManager

protected LockManager(Uid storeUid,
                      int ot)

LockManager

protected LockManager(Uid storeUid,
                      int ot,
                      int om)

LockManager

protected LockManager()

LockManager

protected LockManager(int ot)

LockManager

protected LockManager(int ot,
                      int om)

Method Detail

finalize

public void finalize()
              throws Throwable

Cleanup. Note we grab the semaphore before destroying the lock store to ensure the store is deleted cleanly.

Overrides:

finalize in class Object

Throws:

Throwable

propagate

public boolean propagate(Uid from,
                         Uid to)

Change lock ownership as nested action commits. All locks owned by the committing action have their owners changed to be the parent of the committing action. BasicAction ensures this is only called at nested commit. This function works by copying the old LockList pointer and then creating a new held lock list. Locks are then moved from the old to the new, propagating en route.

releaseAll

public final boolean releaseAll(Uid actionUid)

Clear out all locks for a given action. Should be triggered automatically at top-level commit but is also user callable so is potentially dangerous.

releaselock

public final boolean releaselock(Uid lockUid)

Release a SINGLE LOCK lock that has the given uid. Breaks two-phase locking rules so watch out!

setlock

public final int setlock(Lock toSet)

setlock

public final int setlock(Lock toSet,
                         int retry)

setlock

public int setlock(Lock toSet,
                   int retry,
                   int sleepTime)

print

public void print(PrintWriter strm)

Print information about this instance on the specified PrintWriter.

Overrides:

print in class StateManager

printState

public void printState(PrintWriter strm)

Load state into object prior to doing the printing.

type

public String type()

Overload StateManager.type()

Overrides:

type in class StateManager

terminate

protected void terminate()

This method *must* be called in the finalizer of every object. It ensures that any necessary cleanup work is done in the event that the object goes out of scope within a transaction.

Overrides:

terminate in class StateManager

cleanUp

protected final void cleanUp()

doRelease

protected boolean doRelease(Uid u,
                            boolean all)

freeState

protected final void freeState()

initialise

protected final boolean initialise()

isAncestorOf

protected final boolean isAncestorOf(Lock heldLock)

loadState

protected boolean loadState()

lockConflict

protected final int lockConflict(Lock otherLock)

unloadState

protected final boolean unloadState()