Package org.jgroups.blocks

Class DistributedLockManager

java.lang.Object

org.jgroups.blocks.DistributedLockManager

All Implemented Interfaces:

LockManager, TwoPhaseVotingListener, VoteResponseProcessor, MembershipListener

public class DistributedLockManager
extends java.lang.Object
implements TwoPhaseVotingListener, LockManager, VoteResponseProcessor, MembershipListener

Distributed lock manager is responsible for maintaining the lock information consistent on all participating nodes.

Version:

$Id: DistributedLockManager.java,v 1.9.4.2 2008/05/22 09:51:25 belaban Exp $

Author:

Roman Rokytskyy (rrokytskyy@acm.org), Robert Schaffar-Taurok (robert@fusion.at)

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	DistributedLockManager.AcquireLockDecree	This class represents the lock to be released.
static class	DistributedLockManager.LockDecree	This class represents the lock
static class	DistributedLockManager.MultiLockDecree	This class represents the lock that has to be marked as multilocked
static class	DistributedLockManager.ReleaseLockDecree	This class represents the lock to be released.

Field Summary

Fields

Modifier and Type	Field	Description
protected org.apache.commons.logging.Log	log

Constructor Summary

Constructors

Constructor	Description
DistributedLockManager(TwoPhaseVotingAdapter channel, java.lang.Object id)	Constructor for the DistributedLockManager_cl object.
DistributedLockManager(VotingAdapter voteChannel, java.lang.Object id)	Create instance of this class.

Method Summary

Modifier and Type	Method	Description
void	abort(java.lang.Object decree)	Abort phase for the lock acquisition or release.
void	block()	Called (usually by the FLUSH protocol), as an indication that the member should stop sending messages.
boolean	commit(java.lang.Object decree)	Commit phase for the lock acquisition or release.
void	lock(java.lang.Object lockId, java.lang.Object owner, int timeout)	Locks an object with lockId on behalf of the specified owner.
boolean	prepare(java.lang.Object decree)	Prepare phase for the lock acquisition or release.
boolean	processResponses(RspList responses, int consensusType, java.lang.Object decree)	Processes the response list and votes like the default processResponses method with the consensusType VOTE_ALL If the result of the voting is false, but this DistributedLockManager owns the lock, the result is changed to true and the lock is released, but marked as multiple locked.
void	suspect(Address suspected_mbr)	Called whenever a member is suspected of having crashed, but has not yet been excluded.
void	unlock(java.lang.Object lockId, java.lang.Object owner)	Unlocks an object with lockId on behalf of the specified owner.
void	unlock(java.lang.Object lockId, java.lang.Object owner, boolean releaseMultiLocked)	Unlocks an object with lockId on behalf of the specified owner.
void	unlock(java.lang.Object lockId, java.lang.Object owner, boolean releaseMultiLocked, long timeout)
void	unlock(java.lang.Object lockId, java.lang.Object owner, long timeout)
void	viewAccepted(View new_view)	Remove all locks held by members who left the previous view

Methods inherited from class java.lang.Object

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

Field Detail

log

protected final org.apache.commons.logging.Log log

Constructor Detail

DistributedLockManager

public DistributedLockManager(VotingAdapter voteChannel,
                              java.lang.Object id)

Create instance of this class.

Parameters:

voteChannel - instance of VotingAdapter that will be used for voting purposes on the lock decrees. voteChannel() will be wrapped by the instance of the TwoPhaseVotingAdapter.

id - the unique identifier of this lock manager. todo check if the node with the same id is already in the group.

DistributedLockManager

public DistributedLockManager(TwoPhaseVotingAdapter channel,
                              java.lang.Object id)

Constructor for the DistributedLockManager_cl object.

Parameters:

channel - instance of TwoPhaseVotingAdapter that will be used for voting purposes on the lock decrees.

id - the unique identifier of this lock manager.

To do:

check if the node with the same id is already in the group.

Method Detail

lock

public void lock(java.lang.Object lockId,
                 java.lang.Object owner,
                 int timeout)
          throws LockNotGrantedException,
                 ChannelException

Locks an object with lockId on behalf of the specified owner.

Specified by:

lock in interface LockManager

Parameters:

lockId - Object representing the object to be locked.

owner - object that requests the lock. This should be the Address of a JGroups member, otherwise we cannot release the locks for a crashed member !

timeout - time during which group members should decide whether to grant a lock or not.

Throws:

LockNotGrantedException - when the lock cannot be granted.

java.lang.ClassCastException - if lockId or owner are not serializable.

ChannelException - if something bad happened to underlying channel.

unlock

public void unlock(java.lang.Object lockId,
                   java.lang.Object owner)
            throws LockNotReleasedException,
                   ChannelException

Unlocks an object with lockId on behalf of the specified owner. since 2.2.9 this method is only a wrapper for unlock(Object lockId, Object owner, boolean releaseMultiLocked). Use that with releaseMultiLocked set to true if you want to be able to release multiple locked locks (for example after a merge)

Specified by:

unlock in interface LockManager

Parameters:

lockId - long representing the object to be unlocked.

owner - object that releases the lock.

Throws:

LockNotReleasedException - when the lock cannot be released.

java.lang.ClassCastException - if lockId or owner are not serializable.

ChannelException - if something bad happened to communication channel.

unlock

public void unlock(java.lang.Object lockId,
                   java.lang.Object owner,
                   long timeout)
            throws LockNotReleasedException,
                   ChannelException

Throws:

LockNotReleasedException

ChannelException

unlock

public void unlock(java.lang.Object lockId,
                   java.lang.Object owner,
                   boolean releaseMultiLocked)
            throws LockNotReleasedException,
                   ChannelException,
                   LockMultiLockedException

Unlocks an object with lockId on behalf of the specified owner.

Specified by:

unlock in interface LockManager

Parameters:

lockId - long representing the object to be unlocked.

owner - object that releases the lock.

releaseMultiLocked - releases also multiple locked locks. (eg. locks that are locked by another DLM after a merge)

Throws:

LockNotReleasedException - when the lock cannot be released.

java.lang.ClassCastException - if lockId or owner are not serializable.

LockMultiLockedException - if releaseMultiLocked is true and a multiple locked lock has been released.

ChannelException - if something bad happened to communication channel.

unlock

public void unlock(java.lang.Object lockId,
                   java.lang.Object owner,
                   boolean releaseMultiLocked,
                   long timeout)
            throws LockNotReleasedException,
                   ChannelException,
                   LockMultiLockedException

Throws:

LockNotReleasedException

ChannelException

LockMultiLockedException

prepare

public boolean prepare(java.lang.Object decree)
                throws VoteException

Prepare phase for the lock acquisition or release.

Specified by:

prepare in interface TwoPhaseVotingListener

Parameters:

decree - should be an instance LockDecree, if not, we throw VoteException to be ignored by the VoteChannel.

Returns:

true when preparing the lock operation succeeds.

Throws:

VoteException - if we should be ignored during voting.

commit

public boolean commit(java.lang.Object decree)
               throws VoteException

Commit phase for the lock acquisition or release.

Specified by:

commit in interface TwoPhaseVotingListener

Parameters:

decree - should be an instance LockDecree, if not, we throw VoteException to be ignored by the VoteChannel.

Returns:

true when commiting the lock operation succeeds.

Throws:

VoteException - if we should be ignored during voting.

abort

public void abort(java.lang.Object decree)
           throws VoteException

Abort phase for the lock acquisition or release.

Specified by:

abort in interface TwoPhaseVotingListener

Parameters:

decree - should be an instance LockDecree, if not, we throw VoteException to be ignored by the VoteChannel.

Throws:

VoteException - if we should be ignored during voting.

processResponses

public boolean processResponses(RspList responses,
                                int consensusType,
                                java.lang.Object decree)
                         throws ChannelException

Processes the response list and votes like the default processResponses method with the consensusType VOTE_ALL If the result of the voting is false, but this DistributedLockManager owns the lock, the result is changed to true and the lock is released, but marked as multiple locked. (only in the prepare state to reduce traffic)

Note: we do not support voting in case of Byzantine failures, i.e. when the node responds with the fault message.

Specified by:

processResponses in interface VoteResponseProcessor

Parameters:

responses - The responses

consensusType - The consensusType of the vote

decree - The vote decree

Returns:

boolean

Throws:

ChannelException

viewAccepted

public void viewAccepted(View new_view)

Remove all locks held by members who left the previous view

Specified by:

viewAccepted in interface MembershipListener

suspect

public void suspect(Address suspected_mbr)

Description copied from interface: MembershipListener

Called whenever a member is suspected of having crashed, but has not yet been excluded.

Specified by:

suspect in interface MembershipListener

block

public void block()

Description copied from interface: MembershipListener

Called (usually by the FLUSH protocol), as an indication that the member should stop sending messages. Any messages sent after returning from this callback might get blocked by the FLUSH protocol. When the FLUSH protocol is done, and messages can be sent again, the FLUSH protocol will simply unblock all pending messages. If a callback for unblocking is desired, implement ExtendedMembershipListener.unblock(). Note that block() is the equivalent of reception of a BlockEvent in the pull mode.

Specified by:

block in interface MembershipListener