com.antelmann.db
Class LockManager

java.lang.Object
  com.antelmann.db.LockManager

All Implemented Interfaces:

Wrapped<DBClassStore<LockEntry>>

public class LockManager
extends Object
implements Wrapped<DBClassStore<LockEntry>>

provides methods for persistent locks on DBEntry objects. This class requires a proper store capable of handling LockEntry objects (including a working DBClassStore.generateNewID() method). Generally, reference may be locked even though the do not exist in the database.

Since:

27.04.2011, 19:44:51

Author:

holger

Constructor Summary

LockManager(DBClassStore<LockEntry> store)

Method Summary

boolean	forceUnlock(DBReference ref, long lockTime) if you don't have the token, you may first obtain the LockInfo and then use its time to release the given lock
int	forceUnlockForAll(long anyLockAquiredBeforeThisTime)
String	generateToken()
Filter<LockEntry>	getFilterFor(DBReference ref) this may want to be overridden to be more efficient based on the mapping in use
LockInfo	getLockInfo(DBReference ref)
DBClassStore<LockEntry>	getStore()
TimeSystem	getTimeSystem()
boolean	isLocked(DBReference ref)
boolean	isLockedWithToken(DBReference ref, String token)
String	lock(DBReference ref, String who, String where, String why)
boolean	release(DBReference ref, String token)
void	setTimeSystem(TimeSystem ts)
void	setWriteLockTask(Task<Exception> task)
boolean	unlock(DBReference ref, String token)
DBClassStore<LockEntry>	unwrap() returns the embedded instance that this wrapper encloses
void	writeLock() provides a way to put a write lock on the associated data from the store so that we can avoid deadlocks

Methods inherited from class java.lang.Object

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

Constructor Detail

LockManager

public LockManager(DBClassStore<LockEntry> store)

Method Detail

getStore

public DBClassStore<LockEntry> getStore()

unwrap

public DBClassStore<LockEntry> unwrap()

Description copied from interface: Wrapped

returns the embedded instance that this wrapper encloses

Specified by:

unwrap in interface Wrapped<DBClassStore<LockEntry>>

isLocked

public boolean isLocked(DBReference ref)
                 throws DatabaseException

Throws:

DatabaseException

isLockedWithToken

public boolean isLockedWithToken(DBReference ref,
                                 String token)
                          throws DatabaseException

Throws:

DatabaseException

getLockInfo

public LockInfo getLockInfo(DBReference ref)
                     throws DatabaseException

Returns:

a LockInfo for the given reference or null if the ref is not locked

Throws:

DatabaseException

writeLock

public void writeLock()
               throws Exception

provides a way to put a write lock on the associated data from the store so that we can avoid deadlocks

Throws:

Exception

See Also:

setWriteLockTask(Task)

setWriteLockTask

public void setWriteLockTask(Task<Exception> task)

See Also:

writeLock()

lock

public String lock(DBReference ref,
                   String who,
                   String where,
                   String why)
            throws DatabaseException,
                   NotApplicableDataWarning

Returns:

the token for this lock

Throws:

DatabaseException

NotApplicableDataWarning

unlock

public boolean unlock(DBReference ref,
                      String token)
               throws NotApplicableDataWarning,
                      DatabaseException

Throws:

NotApplicableDataWarning

DatabaseException

See Also:

release(DBReference, String)

release

public boolean release(DBReference ref,
                       String token)
                throws NotApplicableDataWarning,
                       DatabaseException

Throws:

NotApplicableDataWarning

DatabaseException

forceUnlock

public boolean forceUnlock(DBReference ref,
                           long lockTime)
                    throws DatabaseException

if you don't have the token, you may first obtain the LockInfo and then use its time to release the given lock

Throws:

DatabaseException

forceUnlockForAll

@Warning(value="goes through all entries and deletes all those that qualify; use w/ caution!")
public int forceUnlockForAll(long anyLockAquiredBeforeThisTime)
                      throws DatabaseException

Throws:

DatabaseException

getTimeSystem

public TimeSystem getTimeSystem()

setTimeSystem

public void setTimeSystem(TimeSystem ts)

generateToken

public String generateToken()

getFilterFor

public Filter<LockEntry> getFilterFor(DBReference ref)

this may want to be overridden to be more efficient based on the mapping in use