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

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 LockManagerAttribute	lmAttributes
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, objectName, objectUid, smAttributes, usingActions

Constructor Summary

protected	LockManager()
protected	LockManager(int ot)
protected	LockManager(int ot, ObjectName attr)
protected	LockManager(Uid storeUid)
protected	LockManager(Uid storeUid, int ot)
protected	LockManager(Uid storeUid, int ot, ObjectName attr)
protected	LockManager(Uid storeUid, ObjectName attr)

Method Summary

java.lang.Object	attributes()
void	finalize() Cleanup.
void	print(java.io.PrintWriter strm) Print information about this instance on the specified PrintWriter.
void	printState(java.io.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.
java.lang.String	type() Overload StateManager.type()

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

activate, activate, cleanup, deactivate, deactivate, deactivate, destroy, disable, forgetAction, get_uid, getMutex, getStore, getStoreRoot, loadObjectState, lockMutex, modified, ObjectType, packHeader, persist, rememberAction, restore_state, save_state, setStatus, 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.

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

lmAttributes

protected LockManagerAttribute lmAttributes

Constructor Detail

LockManager

protected LockManager(Uid storeUid)

LockManager

protected LockManager(Uid storeUid,
                      ObjectName attr)

LockManager

protected LockManager(Uid storeUid,
                      int ot)

LockManager

protected LockManager(Uid storeUid,
                      int ot,
                      ObjectName attr)

LockManager

protected LockManager()

LockManager

protected LockManager(int ot)

LockManager

protected LockManager(int ot,
                      ObjectName attr)

Method Detail

finalize

public void finalize()
              throws java.lang.Throwable

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

Overrides:

finalize in class StateManager

Throws:

java.lang.Throwable

propagate

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

print

public void print(java.io.PrintWriter strm)

Print information about this instance on the specified PrintWriter.

Overrides:

print in class StateManager

printState

public void printState(java.io.PrintWriter strm)

Load state into object prior to doing the printing.

type

public java.lang.String type()

Overload StateManager.type()

Overrides:

type in class StateManager

attributes

public java.lang.Object attributes()

Overrides:

attributes in class StateManager

Returns:

the LockManagerAttribute object for this instance. Must be returned as an Object because it overrides StateManager.attributes.

See Also:

LockManagerAttribute

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