org.infinispan.util.concurrent.locks
Class LockManagerImpl

java.lang.Object
  org.infinispan.util.concurrent.locks.LockManagerImpl

All Implemented Interfaces:

LockManager

Direct Known Subclasses:

DeadlockDetectingLockManager

public class LockManagerImpl
extends Object
implements LockManager

Handles locks for the MVCC based LockingInterceptor

Since:

4.0

Author:

Manik Surtani (manik@jboss.org)

Field Summary

protected Configuration	configuration
protected LockContainer	lockContainer
protected static boolean	trace

Constructor Summary

LockManagerImpl()

Method Summary

int	getConcurrencyLevel()
protected long	getLockAcquisitionTimeout(InvocationContext ctx)
int	getLockId(Object key) Returns the 'id' of the lock that will be used to guard access to a given key in the cache.
int	getNumberOfLocksAvailable()
int	getNumberOfLocksHeld() Retrieves the number of locks currently held.
Object	getOwner(Object key) Retrieves the write lock owner, if any, for the specified cache entry.
void	injectDependencies(Configuration configuration, TransactionManager transactionManager, InvocationContextContainer invocationContextContainer)
boolean	isLocked(Object key) Returns true if the cache entry is locked (either for reading or writing) by anyone, and false otherwise.
boolean	lockAndRecord(Object key, InvocationContext ctx) Acquires a lock of type lockType, on a specific entry in the cache.
boolean	ownsLock(Object key, Object owner) Tests whether a given owner owns a lock of lockType on a particular cache entry.
boolean	possiblyLocked(CacheEntry entry) Inspects the entry for signs that it is possibly locked, and hence would need to be unlocked.
String	printLockInfo() Prints lock information for all locks.
void	releaseLocks(InvocationContext ctx) Cleanups the locks within the given context.
void	startLockManager()
void	unlock(InvocationContext ctx) Releases locks present in an invocation context and transaction entry, if one is available.
void	unlock(Object key) Releases the lock passed in, held by the specified owner

Methods inherited from class java.lang.Object

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

Field Detail

configuration

protected Configuration configuration

lockContainer

protected LockContainer lockContainer

trace

protected static final boolean trace

Constructor Detail

LockManagerImpl

public LockManagerImpl()

Method Detail

injectDependencies

public void injectDependencies(Configuration configuration,
                               TransactionManager transactionManager,
                               InvocationContextContainer invocationContextContainer)

startLockManager

public void startLockManager()

lockAndRecord

public boolean lockAndRecord(Object key,
                             InvocationContext ctx)
                      throws InterruptedException

Description copied from interface: LockManager

Acquires a lock of type lockType, on a specific entry in the cache. This method will try for a period of time and give up if it is unable to acquire the required lock. The period of time is specified in Configuration.getLockAcquisitionTimeout().

Specified by:

lockAndRecord in interface LockManager

Parameters:

key - key to lock

ctx - invocation context associated with this invocation

Returns:

true if the lock was acquired, false otherwise.

Throws:

InterruptedException - if interrupted

getLockAcquisitionTimeout

protected long getLockAcquisitionTimeout(InvocationContext ctx)

unlock

public void unlock(Object key)

Description copied from interface: LockManager

Releases the lock passed in, held by the specified owner

Specified by:

unlock in interface LockManager

unlock

public void unlock(InvocationContext ctx)

Description copied from interface: LockManager

Releases locks present in an invocation context and transaction entry, if one is available.

Locks are released in reverse order of which they are acquired and registered.

Specified by:

unlock in interface LockManager

Parameters:

ctx - invocation context to inspect

ownsLock

public boolean ownsLock(Object key,
                        Object owner)

Description copied from interface: LockManager

Tests whether a given owner owns a lock of lockType on a particular cache entry.

Specified by:

ownsLock in interface LockManager

owner - owner

Returns:

true if the owner does own the specified lock type on the specified cache entry, false otherwise.

isLocked

public boolean isLocked(Object key)

Description copied from interface: LockManager

Returns true if the cache entry is locked (either for reading or writing) by anyone, and false otherwise.

Specified by:

isLocked in interface LockManager

Returns:

true of locked; false if not.

getOwner

public Object getOwner(Object key)

Description copied from interface: LockManager

Retrieves the write lock owner, if any, for the specified cache entry.

Specified by:

getOwner in interface LockManager

Returns:

the owner of the lock, or null if not locked.

printLockInfo

public String printLockInfo()

Description copied from interface: LockManager

Prints lock information for all locks.

Specified by:

printLockInfo in interface LockManager

Returns:

lock information

possiblyLocked

public final boolean possiblyLocked(CacheEntry entry)

Description copied from interface: LockManager

Inspects the entry for signs that it is possibly locked, and hence would need to be unlocked. Note that this is not deterministic, and is pessimistic in that even if an entry is not locked but *might* be locked, this will return true.

As such, this should only be used to determine whether *unlocking* is necessary, not whether locking is necessary. Unlocking an entry that has not been locked has no effect, so this is just an optimisation.

Specified by:

possiblyLocked in interface LockManager

Parameters:

entry - entry to inspect

Returns:

true if the entry *might* be locked, false if the entry definitely is *not* locked.

releaseLocks

public void releaseLocks(InvocationContext ctx)

Description copied from interface: LockManager

Cleanups the locks within the given context.

Specified by:

releaseLocks in interface LockManager

getConcurrencyLevel

public int getConcurrencyLevel()

getNumberOfLocksHeld

public int getNumberOfLocksHeld()

Description copied from interface: LockManager

Retrieves the number of locks currently held.

Specified by:

getNumberOfLocksHeld in interface LockManager

Returns:

an integer

getNumberOfLocksAvailable

public int getNumberOfLocksAvailable()

getLockId

public int getLockId(Object key)

Description copied from interface: LockManager

Returns the 'id' of the lock that will be used to guard access to a given key in the cache. Particularly useful if Lock Striping is used and locks may guard more than one key. This mechanism can be used to check whether keys may end up sharing the same lock.

If lock-striping is not used, the identity hash code of the lock created for this specific key is returned. While this may not be of much value, it is done to maintain API compatibility of this method regardless of underlying locking scheme.

Specified by:

getLockId in interface LockManager

Parameters:

key - key to test for

Returns:

the ID of the lock.