/*
* JBoss, Home of Professional Open Source
* Copyright 2006, Red Hat Middleware LLC, and individual contributors
* as indicated by the @author tags.
* See the copyright.txt in the distribution for a
* full listing of individual contributors.
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU Lesser General Public License, v. 2.1.
* This program is distributed in the hope that it will be useful, but WITHOUT A
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.
* You should have received a copy of the GNU Lesser General Public License,
* v.2.1 along with this distribution; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*
* (C) 2005-2006,
* @author JBoss Inc.
*/
/*
* Copyright (C) 1998, 1999, 2000, 2001,
*
* Arjuna Solutions Limited,
* Newcastle upon Tyne,
* Tyne and Wear,
* UK.
*
* $Id: LockManager.java 2342 2006-03-30 13:06:17Z $
*/
package com.arjuna.ats.txoj;
import com.arjuna.ats.txoj.lockstore.*;
import com.arjuna.ats.txoj.semaphore.*;
import com.arjuna.ats.arjuna.*;
import com.arjuna.ats.arjuna.common.*;
import com.arjuna.ats.arjuna.StateManager;
import com.arjuna.ats.txoj.logging.txojLogger;
import com.arjuna.ats.txoj.logging.FacilityCode;
import com.arjuna.common.util.logging.*;
import com.arjuna.ats.arjuna.coordinator.*;
import com.arjuna.ats.arjuna.state.*;
import com.arjuna.ats.internal.arjuna.common.UidHelper;
import com.arjuna.ats.internal.txoj.LockList;
import com.arjuna.ats.internal.txoj.LockListIterator;
import com.arjuna.ats.internal.txoj.abstractrecords.CadaverLockRecord;
import com.arjuna.ats.internal.txoj.abstractrecords.LockRecord;
import com.arjuna.ats.internal.txoj.lockstore.BasicLockStore;
import com.arjuna.ats.internal.txoj.lockstore.BasicPersistentLockStore;
import com.arjuna.ats.internal.txoj.semaphore.BasicSemaphore;
import com.arjuna.ats.txoj.common.txojPropertyManager;
import java.io.PrintWriter;
import java.util.*;
import com.arjuna.ats.txoj.exceptions.LockStoreException;
import java.lang.InterruptedException;
import java.io.IOException;
/**
* This class provides (transactional) concurrency control for application
* objects.
*
* @author Mark Little (mark@arjuna.com)
* @version $Id: LockManager.java 2342 2006-03-30 13:06:17Z $
* @since JTS 1.0.
* @see com.arjuna.ats.arjuna.StateManager
* @message com.arjuna.ats.txoj.LockManager_1 [com.arjuna.ats.txoj.LockManager_1]
* - LockManager: lock propagation failed
* @message com.arjuna.ats.txoj.LockManager_2
* [com.arjuna.ats.txoj.LockManager_2] - LockManager::setlock() no
* lock!
* @message com.arjuna.ats.txoj.LockManager_3
* [com.arjuna.ats.txoj.LockManager_3] - LockManager::setlock() cannot
* find action hierarchy
* @message com.arjuna.ats.txoj.LockManager_4
* [com.arjuna.ats.txoj.LockManager_4] - LockManager::setlock() cannot
* load existing lock states
* @message com.arjuna.ats.txoj.LockManager_5
* [com.arjuna.ats.txoj.LockManager_5] - LockManager::setlock() cannot
* activate object
* @message com.arjuna.ats.txoj.LockManager_6
* [com.arjuna.ats.txoj.LockManager_6] - LockManager::setlock() cannot
* save new lock states
* @message com.arjuna.ats.txoj.LockManager_7
* [com.arjuna.ats.txoj.LockManager_7] - Lockmanager::releaselock()
* could not load old lock states
* @message com.arjuna.ats.txoj.LockManager_8
* [com.arjuna.ats.txoj.LockManager_8] - Lockmanager::releaselock()
* could not unload new lock states
* @message com.arjuna.ats.txoj.LockManager_10
* [com.arjuna.ats.txoj.LockManager_10] - LockManager::unloadState()
* failed to remove empty lock state for object {0} of type {1}
* @message com.arjuna.ats.txoj.LockManager_11
* [com.arjuna.ats.txoj.LockManager_11] - LockManager.unloadState -
* could not save lock state: {0}
* @message com.arjuna.ats.txoj.LockManager_12
* [com.arjuna.ats.txoj.LockManager_12] - LockManager::unloadState()
* failed to write new state for object {0} of type {1}
* @message com.arjuna.ats.txoj.LockManager_13
* [com.arjuna.ats.txoj.LockManager_13] - LockManager::unloadState()
* failed to pack up new state for object {0} of type {1}
*/
public class LockManager extends StateManager
{
/**
* The default retry value which will be used by setlock if no other value
* is given.
*
* @see #setlock
*/
public static final int defaultRetry = 100;
/**
* The default timeout value which will be used by setlock if no other value
* is given.
*
* @see #setlock
*/
public static final int defaultSleepTime = 250;
/**
* 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.
*
* @see #setlock
* @since JTS 2.1.
*/
public static final int waitTotalTimeout = -100;
/**
* Cleanup. Note we grab the semaphore before destroying the the lock store
* to ensure the store is deleted cleanly.
*/
public void finalize () throws Throwable
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.DESTRUCTORS,
VisibilityLevel.VIS_PUBLIC,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager.finalize()");
}
boolean doSignal = false;
cleanUp();
if (mutex != null)
{
if (mutex.lock() == Semaphore.SM_LOCKED)
doSignal = true;
}
locksHeld = null;
lockStore = null;
conflictManager = null;
if (doSignal) // mutex must be set
mutex.unlock();
mutex = null;
super.finalize();
}
/**
* 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.
*/
public final boolean propagate (Uid from, Uid to)
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PUBLIC,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::propagate(" + from + ", " + to + ")");
}
boolean result = false;
int retryCount = 10;
do
{
try
{
synchronized (locksHeldLockObject)
{
if (loadState())
{
LockList oldlist = locksHeld;
Lock current = null;
locksHeld = new LockList(); /* create a new one */
if (locksHeld != null)
{
/*
* scan through old list of held locks and propagate
* to parent.
*/
while ((current = oldlist.pop()) != null)
{
if (current.getCurrentOwner().equals(from))
{
current.propagate();
}
if (!locksHeld.insert(current))
{
current = null;
}
}
oldlist = null; /* get rid of old lock list */
result = true;
}
else
{
/*
* Cannot create new locklist - abort and try again.
*/
freeState();
throw new NullPointerException();
}
}
if (result)
result = unloadState();
}
}
catch (NullPointerException e)
{
result = false;
}
if (!result)
{
try
{
Thread.sleep(LockManager.DOZE_TIME);
}
catch (InterruptedException e)
{
}
}
}
while ((!result) && (--retryCount > 0));
if (!result)
{
if (txojLogger.aitLoggerI18N.isWarnEnabled())
{
txojLogger.aitLoggerI18N
.warn("com.arjuna.ats.txoj.LockManager_1");
}
synchronized (locksHeldLockObject)
{
freeState();
}
}
return result;
}
/**
* 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.
*/
public final boolean releaseAll (Uid actionUid)
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PUBLIC,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::releaseAll(" + actionUid + ")");
}
return doRelease(actionUid, true);
}
/**
* Release a SINGLE LOCK lock that has the given uid. Breaks two-phase
* locking rules so watch out!
*/
public final boolean releaselock (Uid lockUid)
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PUBLIC,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::releaseLock(" + lockUid + ")");
}
return doRelease(lockUid, false);
}
/*
* This is the main user visible operation. Attempts to set the given lock
* on the current object. If lock cannot be set, then the lock attempt is
* retried retry times before giving up and returning an error. This gives a
* simple handle on deadlock. Use the default timeout and retry values.
* @return <code>LockResult</code> indicating outcome.
*/
public final int setlock (Lock toSet)
{
return setlock(toSet, LockManager.defaultRetry,
LockManager.defaultSleepTime);
}
/*
* This is the main user visible operation. Attempts to set the given lock
* on the current object. If lock cannot be set, then the lock attempt is
* retried retry times before giving up and returning an error. This gives a
* simple handle on deadlock. Use the default timeout value.
* @return <code>LockResult</code> indicating outcome.
*/
public final int setlock (Lock toSet, int retry)
{
return setlock(toSet, retry, LockManager.defaultSleepTime);
}
/*
* This is the main user visible operation. Attempts to set the given lock
* on the current object. If lock cannot be set, then the lock attempt is
* retried retry times before giving up and returning an error. This gives a
* simple handle on deadlock.
* @return <code>LockResult</code> indicating outcome.
*/
public final int setlock (Lock toSet, int retry, int sleepTime)
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PUBLIC,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::setlock(" + toSet + ", " + retry + ", "
+ sleepTime + ")");
}
int conflict = ConflictType.CONFLICT;
int returnStatus = LockResult.REFUSED;
LockRecord newLockR = null;
boolean modifyRequired = false;
BasicAction currAct = null;
if (toSet == null)
{
if (txojLogger.aitLoggerI18N.isWarnEnabled())
{
txojLogger.aitLoggerI18N
.warn("com.arjuna.ats.txoj.LockManager_2");
}
return LockResult.REFUSED;
}
currAct = BasicAction.Current();
if (currAct != null)
{
ActionHierarchy ah = currAct.getHierarchy();
if (ah != null)
toSet.changeHierarchy(ah);
else
{
if (txojLogger.aitLoggerI18N.isWarnEnabled())
{
txojLogger.aitLoggerI18N
.warn("com.arjuna.ats.txoj.LockManager_3");
}
toSet = null;
return LockResult.REFUSED;
}
}
if (super.loadObjectState())
super.setupStore();
while ((conflict == ConflictType.CONFLICT)
&& ((retry >= 0) || (retry == LockManager.waitTotalTimeout)))
{
Object syncObject = ((currAct == null) ? getMutex() : currAct);
synchronized (syncObject)
{
synchronized (locksHeldLockObject)
{
conflict = ConflictType.CONFLICT;
if (loadState())
{
conflict = lockConflict(toSet);
}
else
{
if (txojLogger.aitLoggerI18N.isWarnEnabled())
{
txojLogger.aitLoggerI18N
.warn("com.arjuna.ats.txoj.LockManager_4");
}
}
if (conflict != ConflictType.CONFLICT)
{
/*
* When here the conflict was resolved or the retry limit
* expired.
*/
/* no conflict so set lock */
modifyRequired = toSet.modifiesObject();
/* trigger object load from store */
if (super.activate())
{
returnStatus = LockResult.GRANTED;
if (conflict == ConflictType.COMPATIBLE)
{
int lrStatus = AddOutcome.AR_ADDED;
if (currAct != null)
{
/* add new lock record to action list */
newLockR = new LockRecord(this,
(modifyRequired ? false : true),
currAct);
if ((lrStatus = currAct.add(newLockR)) != AddOutcome.AR_ADDED)
{
newLockR = null;
if (lrStatus == AddOutcome.AR_REJECTED)
returnStatus = LockResult.REFUSED;
}
}
if (returnStatus == LockResult.GRANTED)
{
locksHeld.insert(toSet); /*
* add to local lock
* list
*/
}
}
}
else
{
/* activate failed - refuse request */
if (txojLogger.aitLoggerI18N.isWarnEnabled())
{
txojLogger.aitLoggerI18N
.warn("com.arjuna.ats.txoj.LockManager_5");
}
returnStatus = LockResult.REFUSED;
}
}
/*
* Unload internal state into lock store only if lock list was
* modified if this fails claim the setlock failed. If we are
* using the lock daemon we can arbitrarily throw the lock away
* as the daemon has it.
*/
if ((returnStatus == LockResult.GRANTED)
&& (conflict == ConflictType.COMPATIBLE))
{
if (!unloadState())
{
if (txojLogger.aitLoggerI18N.isWarnEnabled())
{
txojLogger.aitLoggerI18N
.warn("com.arjuna.ats.txoj.LockManager_6");
}
returnStatus = LockResult.REFUSED;
}
}
else
freeState();
/*
* Postpone call on modified to here so that semaphore will have
* been released. This means when modified invokes save_state
* that routine may set another lock without blocking.
*/
if (returnStatus == LockResult.GRANTED)
{
if (modifyRequired)
{
if (super.modified())
hasBeenLocked = true;
else
{
conflict = ConflictType.CONFLICT;
returnStatus = LockResult.REFUSED;
}
}
}
/*
* Make sure we free state while we still have the lock.
*/
if (conflict == ConflictType.CONFLICT)
freeState();
}
if (conflict == ConflictType.CONFLICT)
{
if (retry != 0)
{
if (sleepTime > 0)
{
sleepTime -= conflictManager.wait(retry, sleepTime);
}
else
retry = 0;
}
if (retry != LockManager.waitTotalTimeout)
retry--;
}
}
}
return returnStatus;
}
/**
* Print information about this instance on the specified
* <code>PrintWriter</code>.
*/
public void print (PrintWriter strm)
{
LockListIterator next = new LockListIterator(locksHeld);
Lock current;
strm.println("LocalLockManager for object " + get_uid());
if (!stateLoaded)
strm.println("No loaded state");
else if (locksHeld != null)
{
strm.println("\tCurrently holding : " + locksHeld.entryCount()
+ " locks");
while ((current = next.iterate()) != null)
current.print(strm);
}
else
strm.println("Currently holding : 0 locks");
}
/**
* Load state into object prior to doing the printing.
*/
public void printState (PrintWriter strm)
{
synchronized (locksHeldLockObject)
{
boolean iDeleteState = false;
if (!stateLoaded)
{
loadState();
iDeleteState = true;
}
print(strm);
if (iDeleteState)
freeState();
}
}
/**
* Overload StateManager.type()
*/
public String type ()
{
return "StateManager/LockManager";
}
/*
* Pass on some args to StateManager and initialise internal state. The lock
* store and semaphore are set up lazily since they depend upon the result
* of the type() operation which if run in the constructor always give the
* same answer!
*/
protected LockManager(Uid storeUid)
{
this(storeUid, ObjectType.ANDPERSISTENT, ObjectModel.SINGLE);
}
protected LockManager(Uid storeUid, int ot)
{
this(storeUid, ot, ObjectModel.SINGLE);
}
// make default SINGLE
protected LockManager (Uid storeUid, int ot, int om)
{
super(storeUid, ot, om);
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.CONSTRUCTORS,
VisibilityLevel.VIS_PROTECTED,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::LockManager(" + storeUid + ")");
}
systemKey = null;
locksHeld = new LockList();
lockStore = null;
mutex = null;
stateLoaded = false;
hasBeenLocked = false;
objectLocked = false;
conflictManager = new LockConflictManager();
}
/*
* Pass on some args to StateManager and initialise internal state. The lock
* store and semaphore are set up lazily since they depend upon the result
* of the type() operation which if run in the constructor always give the
* same answer!
*/
protected LockManager()
{
this(ObjectType.RECOVERABLE);
}
protected LockManager(int ot)
{
this(ot, ObjectModel.SINGLE);
}
protected LockManager (int ot, int om)
{
super(ot, om);
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.CONSTRUCTORS,
VisibilityLevel.VIS_PROTECTED,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::LockManager(" + ot + ")");
}
systemKey = null;
locksHeld = new LockList();
lockStore = null;
mutex = null;
stateLoaded = false;
hasBeenLocked = false;
objectLocked = false;
conflictManager = new LockConflictManager();
}
/**
* 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.
*/
protected void terminate ()
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PROTECTED,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::terminate() for object-id " + get_uid());
}
cleanUp();
super.terminate();
}
private final void cleanUp ()
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PRIVATE,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::cleanUp() for object-id " + get_uid());
}
if (hasBeenLocked)
{
if ((super.objectModel == ObjectModel.MULTIPLE)
&& (systemKey == null))
{
initialise();
}
/*
* Unlike in the original version of Arjuna, we don't check to see
* if the invoking thread is within a transaction. We look at
* whether this object has been used within a transaction, and then
* act accordingly.
*/
synchronized (super.usingActions)
{
if (super.usingActions != null)
{
Enumeration e = super.usingActions.keys();
while (e.hasMoreElements())
{
BasicAction action = (BasicAction) e.nextElement();
while (action != null)
{
/*
* Pop actions off using list. Don't check if action
* is running below so that cadavers can be created
* in commit protocol too.
*/
/*
* We need to create a cadaver lock record to
* maintain the locks because this object is being
* deleted.
*/
AbstractRecord A = new CadaverLockRecord(lockStore,
this, action);
if (action.add(A) != AddOutcome.AR_ADDED)
A = null;
}
}
}
}
hasBeenLocked = false;
}
}
/*
* doRelease: Does all the hard work of lock release. Either releases all
* locks for a given tx uid, or simply one lock with a given uid as
* appropriate.
*/
private final boolean doRelease (Uid u, boolean all)
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PRIVATE,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::doRelease(" + u + ", " + all + ")");
}
Lock previous = null;
Lock current = null;
boolean deleted = false;
boolean result = false;
int retryCount = 10;
boolean loaded = false;
do
{
synchronized (locksHeldLockObject)
{
if (loadState())
{
loaded = true;
/*
* Must declare iterator after loadstate or it sees an empty
* list!
*/
LockListIterator next = new LockListIterator(locksHeld);
/*
* Now scan through held lock list to find which locks to
* release u is either the unique id of the lock owner
* (oneOrAll = ALL_LOCKS) or the uid of the actual lock
* itself (oneOrAll = SINGLE_LOCK).
*/
previous = null;
while ((current = next.iterate()) != null)
{
Uid checkUid = null;
if (all)
checkUid = current.getCurrentOwner();
else
checkUid = current.get_uid();
/*
* Is this the right lock?
*/
if (u.equals(checkUid))
{
locksHeld.forgetNext(previous);
current = null;
deleted = true;
if (!all)
{
break;
}
}
else
previous = current;
}
result = true;
}
else
{
/*
* Free state while we still have the lock.
*/
freeState();
result = false;
}
}
if (!result)
{
try
{
Thread.sleep(LockManager.DOZE_TIME);
}
catch (InterruptedException e)
{
}
}
}
while ((!result) && (--retryCount > 0));
boolean releasedOK = false;
// if (!stateLoaded)
if (!loaded)
{
if (txojLogger.aitLoggerI18N.isWarnEnabled())
txojLogger.aitLoggerI18N
.warn("com.arjuna.ats.txoj.LockManager_7");
/*
* No need to freeState since we will have done that by now.
*/
}
else
{
if (!deleted)
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PRIVATE,
FacilityCode.FAC_CONCURRENCY_CONTROL,
" *** CANNOT locate locks ***");
}
}
retryCount = 10;
synchronized (locksHeldLockObject)
{
do
{
if (!unloadState())
{
if (txojLogger.aitLoggerI18N.isWarnEnabled())
txojLogger.aitLoggerI18N
.warn("com.arjuna.ats.txoj.LockManager_8");
}
else
releasedOK = true;
}
while ((--retryCount > 0) && (!releasedOK));
}
}
/*
* Now signal to any waiting threads that they may try to acquire the
* lock.
*/
conflictManager.signal();
return releasedOK;
}
/*
* Simply free up the semaphore. We do this if we detect conflict. Since the
* list has not been modified it can simply be discarded. Does not need
* 'synchronized' as can only be called from synchronized methods.
*/
private final void freeState ()
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PRIVATE,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::freeState()");
}
if (mutex != null)
{
/*
* If we are working in a shared lock store mode, then clear the
* cached lock list. Otherwise, do nothing.
*/
if (super.objectModel != ObjectModel.SINGLE)
{
/* clear out the existing list */
while (locksHeld.pop() != null)
;
stateLoaded = false;
if (objectLocked)
{
objectLocked = false;
mutex.unlock();
}
}
else
stateLoaded = false;
}
else
{
stateLoaded = false;
objectLocked = false;
}
}
/*
* Don't need to protect with a synchronization as this routine can only be
* called from within other protected methods. Only called if multiple
* object model is used.
*/
private final boolean initialise ()
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PRIVATE,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::initialise()");
}
boolean result = false;
if (systemKey == null)
{
systemKey = type();
if (mutex == null)
{
// TODO add a factory if we ever have more than one implementation
mutex = new BasicSemaphore(systemKey);
}
if (mutex != null)
{
if (mutex.lock() == Semaphore.SM_LOCKED)
{
/*
* At some point we may want to add a factory to hide this, but
* since we only have two implementations at the moment it is perhaps
* overkill.
*
* TODO add factory.
*/
if (lockStore == null)
{
try
{
if (lockStoreType.equals(BasicLockStore.class.getName()))
lockStore = new BasicLockStore(systemKey);
else
lockStore = new BasicPersistentLockStore(systemKey);
}
catch (final Exception ex)
{
lockStore = null;
}
}
}
mutex.unlock();
}
}
result = (lockStore != null);
return result;
}
private final boolean isAncestorOf (Lock heldLock)
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PRIVATE,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::isAncestorOf(" + heldLock.getCurrentOwner()
+ ")");
}
BasicAction action = BasicAction.Current();
if (action == null)
return false; /* no action no ancestry! */
return action.isAncestor(heldLock.getCurrentOwner());
}
/*
* Lock and load the concurrency control state. First we grab the semaphore
* to ensure exclusive access and then we build the held lock list by
* retreiving the locks from the lock repository. If there is only one
* server we do not bother doing this since all the locks can stay in the
* server's memory. This is yet another consequence of not having
* multi-threaded servers. Does not require synchronized since it can only
* be called from other synchronized methods.
*/
private final boolean loadState ()
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PRIVATE,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::loadState()");
}
if (super.objectModel == ObjectModel.SINGLE)
{
stateLoaded = true;
return true;
}
else
{
InputObjectState S = null;
if ((systemKey == null) && !initialise())
{
return false; /* init failed */
}
if ((mutex == null) || (mutex.tryLock() == Semaphore.SM_WOULD_BLOCK))
{
return false;
}
stateLoaded = false;
objectLocked = true;
/*
* An exception indicates some form of error and NOT that the state
* cannot be found, which is indicated by S being null.
*/
try
{
S = lockStore.read_state(get_uid(), type());
/* Pick returned state apart again */
if (S != null)
{
Uid u = null; /*
* avoid system calls in Uid
* creation
*/
Lock current = null;
int count = 0;
try
{
count = S.unpackInt();
boolean cleanLoad = true;
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PRIVATE,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::loadState() loading " + count
+ " lock(s)");
}
/*
* Carefully rebuild the internal state - if we fail
* throw it away and return.
*/
for (int i = 0; (i < count) && cleanLoad; i++)
{
try
{
u = UidHelper.unpackFrom(S);
current = new Lock(u);
if (current != null)
{
if (current.restore_state(S,
ObjectType.ANDPERSISTENT))
{
locksHeld.push(current);
}
else
{
current = null;
cleanLoad = false;
}
}
else
cleanLoad = false;
}
catch (IOException e)
{
cleanLoad = false;
}
}
if (cleanLoad)
stateLoaded = true;
else
{
while ((current = locksHeld.pop()) != null)
current = null;
}
}
catch (IOException e)
{
}
S = null;
}
else
stateLoaded = true;
}
catch (LockStoreException e)
{
if (txojLogger.aitLogger.isWarnEnabled())
txojLogger.aitLogger.warn(e);
}
}
return stateLoaded;
}
/*
* lockconflict: Here we attempt to determine if the provided lock is in
* conflict with any of the existing locks. If it is we use nested locking
* rules to allow children to lock objects already locked by their
* ancestors.
*/
private final int lockConflict (Lock otherLock)
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PRIVATE,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::lockConflict(" + otherLock.get_uid() + ")");
}
boolean matching = false;
Lock heldLock = null;
LockListIterator next = new LockListIterator(locksHeld);
while ((heldLock = next.iterate()) != null)
{
if (heldLock.conflictsWith(otherLock))
{
if (LockManager.nestedLocking)
{
if (!isAncestorOf(heldLock)) /* not quite Moss's rules */
{
return ConflictType.CONFLICT;
}
}
else
return ConflictType.CONFLICT;
}
else
{
if (heldLock.equals(otherLock))
matching = true;
}
}
return (matching ? ConflictType.PRESENT : ConflictType.COMPATIBLE);
}
/*
* Unload the state by writing all the locks to the repository and then
* freeing the semaphore.
*/
private final boolean unloadState ()
{
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PRIVATE,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::unloadState()");
}
/*
* Single object model means we don't need a lock store at all.
*/
if (super.objectModel == ObjectModel.SINGLE)
{
stateLoaded = false;
return true;
}
else
{
boolean unloadOk = false;
Lock current = null;
String otype = type();
Uid u = get_uid();
OutputObjectState S = new OutputObjectState(u, otype);
int lockCount = locksHeld.entryCount();
/* destroy old state from lock store */
if (txojLogger.aitLogger.isDebugEnabled())
{
txojLogger.aitLogger.debug(DebugLevel.FUNCTIONS,
VisibilityLevel.VIS_PRIVATE,
FacilityCode.FAC_CONCURRENCY_CONTROL,
"LockManager::unloadState() unloading " + lockCount
+ " lock(s)");
}
if (lockCount == 0)
{
if (lockStore.remove_state(u, otype))
{
unloadOk = true;
}
else
{
if (txojLogger.aitLoggerI18N.isWarnEnabled())
{
txojLogger.aitLoggerI18N.warn(
"com.arjuna.ats.txoj.LockManager_10",
new Object[]
{ u, otype });
}
}
}
else
{
try
{
/* generate new state */
S.packInt(lockCount);
unloadOk = true;
while ((current = locksHeld.pop()) != null)
{
UidHelper.packInto(current.get_uid(), S);
if (!current.save_state(S, ObjectType.ANDPERSISTENT))
{
if (txojLogger.aitLoggerI18N.isWarnEnabled())
{
txojLogger.aitLoggerI18N.warn(
"com.arjuna.ats.txoj.LockManager_11",
new Object[]
{ current });
}
unloadOk = false;
}
current = null;
}
if (unloadOk)
{
unloadOk = false;
/* load image into store */
if (S.valid() && lockStore.write_committed(u, otype, S))
{
unloadOk = true;
}
else
{
if (txojLogger.aitLoggerI18N.isWarnEnabled())
{
txojLogger.aitLoggerI18N.warn(
"com.arjuna.ats.txoj.LockManager_12",
new Object[]
{ u, otype });
}
}
}
}
catch (IOException e)
{
unloadOk = false;
if (txojLogger.aitLoggerI18N.isWarnEnabled())
{
txojLogger.aitLoggerI18N.warn(
"com.arjuna.ats.txoj.LockManager_13",
new Object[]
{ u, otype });
}
}
}
stateLoaded = false;
if (objectLocked)
{
objectLocked = false;
if (mutex != null) // means object model != SINGLE
mutex.unlock(); // and exit mutual exclusion
}
return unloadOk;
}
}
private String lockStoreType = txojPropertyManager.getTxojEnvironmentBean().getLockStoreType();
private String systemKey; /* used in accessing system resources */
private LockList locksHeld; /* the actual list of locks set */
private final Object locksHeldLockObject = new Object(); // mutex for sync
// on locksHeld.
// Can't use
// locksHeld
// itself, it's
// mutable.
private LockStore lockStore; /* locks held in shared memory */
private boolean stateLoaded;
private boolean hasBeenLocked;/* Locked at least once */
private boolean objectLocked;/* Semaphore grabbed */
private Semaphore mutex; /* Controls access to the lock store */
private LockConflictManager conflictManager;
private static final int DOZE_TIME = 1000000;
private static boolean nestedLocking = true;
static
{
nestedLocking = txojPropertyManager.getTxojEnvironmentBean().isAllowNestedLocking();
}
}