org.infinispan.loaders
Class LockSupportCacheStore

java.lang.Object
  org.infinispan.loaders.AbstractCacheLoader
      org.infinispan.loaders.AbstractCacheStore
          org.infinispan.loaders.LockSupportCacheStore

All Implemented Interfaces:

CacheLoader, CacheStore

Direct Known Subclasses:

BucketBasedCacheStore, JdbcStringBasedCacheStore

public abstract class LockSupportCacheStore
extends AbstractCacheStore

This class extends AbstractCacheStore adding lock support for consistently accessing stored data.

In-memory locking is needed by aggregation operations(e.g. loadAll, toStream, fromStream) to make sure that manipulated data won't be corrupted by concurrent access to Store. It also assures atomic data access for each stored entry.

Locking is based on a StripedLock. You can tune the concurrency level of the striped lock (see the Javadocs of StripedLock for details on what this is) by using the LockSupportCacheStoreConfig.setLockConcurrencyLevel(int) setter.

Author:

Mircea.Markus@jboss.com

Field Summary

Fields inherited from class org.infinispan.loaders.AbstractCacheStore

cache, marshaller, multiThreadedPurge, purgerService

Constructor Summary

LockSupportCacheStore()

Method Summary

protected void	acquireGlobalLock(boolean exclusive) Based on the supplied param, acquires a global read(false) or write (true) lock.
void	clear() Clears all entries in the store
protected abstract void	clearLockSafe()
void	fromStream(ObjectInput objectInput) Writes contents of the stream to the store.
protected abstract void	fromStreamLockSafe(ObjectInput ois)
protected abstract String	getLockFromKey(Object key)
int	getTotalLockCount()
protected boolean	immediateLockForWriting(String key) Same as lockForWriting(String), but with 0 timeout.
void	init(CacheLoaderConfig config, Cache<?,?> cache, Marshaller m) Used to initialize a cache loader.
InternalCacheEntry	load(Object key) Loads an entry mapped to by a given key.
Set<InternalCacheEntry>	loadAll() Loads all entries in the loader.
protected abstract Set<InternalCacheEntry>	loadAllLockSafe()
protected abstract InternalCacheEntry	loadLockSafe(Object key, String lockingKey)
protected void	lockForReading(String key) Acquires read lock on the given key.
protected void	lockForWriting(String key) Acquires write lock on the given key.
protected void	releaseGlobalLock(boolean exclusive) Based on the supplied param, releases a global read(false) or write (true) lock.
boolean	remove(Object key) Removes an entry in the store.
protected abstract boolean	removeLockSafe(Object key, String lockingKey)
void	start()
void	store(InternalCacheEntry ed) Stores an entry
protected abstract void	storeLockSafe(InternalCacheEntry ed, String lockingKey)
void	toStream(ObjectOutput objectOutput) Loads the entire state into a stream, using whichever format is most efficient for the cache loader implementation.
protected abstract void	toStreamLockSafe(ObjectOutput oos)
protected void	unlock(String key) Release the locks (either read or write).

Methods inherited from class org.infinispan.loaders.AbstractCacheStore

applyModifications, commit, getCacheStoreConfig, getConcurrencyLevel, getMarshaller, prepare, purgeExpired, purgeInternal, removeAll, rollback, safeClose, safeClose, stop, supportsMultiThreadedPurge

Methods inherited from class org.infinispan.loaders.AbstractCacheLoader

containsKey

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.infinispan.loaders.CacheLoader

containsKey, getConfigurationClass

Constructor Detail

LockSupportCacheStore

public LockSupportCacheStore()

Method Detail

init

public void init(CacheLoaderConfig config,
                 Cache<?,?> cache,
                 Marshaller m)
          throws CacheLoaderException

Description copied from interface: CacheLoader

Used to initialize a cache loader. Typically invoked by the CacheLoaderManager when setting up cache loaders.

Specified by:

init in interface CacheLoader

Overrides:

init in class AbstractCacheStore

Parameters:

config - the cache loader configuration bean

cache - cache associated with this cache loader. Implementations may use this to determine cache name when selecting where refer to state in storage, for example, a different database table name.

m - marshaller to use when loading state from a stream, if supported by the implementation.

Throws:

CacheLoaderException

start

public void start()
           throws CacheLoaderException

Specified by:

start in interface CacheLoader

Overrides:

start in class AbstractCacheStore

Throws:

CacheLoaderException

unlock

protected final void unlock(String key)

Release the locks (either read or write).

lockForWriting

protected final void lockForWriting(String key)
                             throws CacheLoaderException

Acquires write lock on the given key.

Throws:

CacheLoaderException

lockForReading

protected final void lockForReading(String key)
                             throws CacheLoaderException

Acquires read lock on the given key.

Throws:

CacheLoaderException

immediateLockForWriting

protected final boolean immediateLockForWriting(String key)
                                         throws CacheLoaderException

Same as lockForWriting(String), but with 0 timeout.

Throws:

CacheLoaderException

acquireGlobalLock

protected final void acquireGlobalLock(boolean exclusive)
                                throws CacheLoaderException

Based on the supplied param, acquires a global read(false) or write (true) lock.

Throws:

CacheLoaderException

releaseGlobalLock

protected final void releaseGlobalLock(boolean exclusive)

Based on the supplied param, releases a global read(false) or write (true) lock.

load

public final InternalCacheEntry load(Object key)
                              throws CacheLoaderException

Description copied from interface: CacheLoader

Loads an entry mapped to by a given key. Should return null if the entry does not exist. Expired entries are not returned.

Parameters:

key - key

Returns:

an entry

Throws:

CacheLoaderException - in the event of problems reading from source

loadAll

public final Set<InternalCacheEntry> loadAll()
                                      throws CacheLoaderException

Description copied from interface: CacheLoader

Loads all entries in the loader. Expired entries are not returned.

Returns:

a set of entries, or an empty set if the loader is emptied.

Throws:

CacheLoaderException - in the event of problems reading from source

store

public final void store(InternalCacheEntry ed)
                 throws CacheLoaderException

Description copied from interface: CacheStore

Stores an entry

Parameters:

ed - entry to store

Throws:

CacheLoaderException - in the event of problems writing to the store

remove

public final boolean remove(Object key)
                     throws CacheLoaderException

Description copied from interface: CacheStore

Removes an entry in the store.

Parameters:

key - key to remove

Returns:

true if the entry was removed; false if the entry wasn't found.

Throws:

CacheLoaderException - in the event of problems writing to the store

fromStream

public final void fromStream(ObjectInput objectInput)
                      throws CacheLoaderException

Description copied from interface: CacheStore

Writes contents of the stream to the store. Implementations should expect that the stream contains data in an implementation-specific format, typically generated using CacheStore.toStream(java.io.ObjectOutput). While not a requirement, it is recommended that implementations make use of the Marshaller when dealing with the stream to make use of efficient marshalling.

It is imperative that implementations do not close the stream after finishing with it.

It is also recommended that implementations use their own start and end markers on the stream since other processes may write additional data to the stream after the cache store has written to it. As such, either markers or some other mechanism to prevent the store from reading too much information should be employed when writing to the stream in CacheStore.fromStream(java.io.ObjectInput) to prevent data corruption.

It can be assumed that the stream passed in already performs buffering such that the cache store implementation doesn't have to.

Parameters:

objectInput - stream to read from

Throws:

CacheLoaderException - in the event of problems writing to the store

toStream

public void toStream(ObjectOutput objectOutput)
              throws CacheLoaderException

Description copied from interface: CacheStore

Loads the entire state into a stream, using whichever format is most efficient for the cache loader implementation. Typically read and parsed by CacheStore.fromStream(java.io.ObjectInput).

While not a requirement, it is recommended that implementations make use of the Marshaller when dealing with the stream to make use of efficient marshalling.

It is imperative that implementations do not flush or close the stream after finishing with it.

It is also recommended that implementations use their own start and end markers on the stream since other processes may write additional data to the stream after the cache store has written to it. As such, either markers or some other mechanism to prevent the store from reading too much information in CacheStore.fromStream(java.io.ObjectInput) should be employed, to prevent data corruption.

It can be assumed that the stream passed in already performs buffering such that the cache store implementation doesn't have to.

Parameters:

objectOutput - stream to write to

Throws:

CacheLoaderException - in the event of problems reading from the store

clear

public final void clear()
                 throws CacheLoaderException

Description copied from interface: CacheStore

Clears all entries in the store

Throws:

CacheLoaderException - in the event of problems writing to the store

getTotalLockCount

public int getTotalLockCount()

clearLockSafe

protected abstract void clearLockSafe()
                               throws CacheLoaderException

Throws:

CacheLoaderException

loadAllLockSafe

protected abstract Set<InternalCacheEntry> loadAllLockSafe()
                                                    throws CacheLoaderException

Throws:

CacheLoaderException

toStreamLockSafe

protected abstract void toStreamLockSafe(ObjectOutput oos)
                                  throws CacheLoaderException

Throws:

CacheLoaderException

fromStreamLockSafe

protected abstract void fromStreamLockSafe(ObjectInput ois)
                                    throws CacheLoaderException

Throws:

CacheLoaderException

removeLockSafe

protected abstract boolean removeLockSafe(Object key,
                                          String lockingKey)
                                   throws CacheLoaderException

Throws:

CacheLoaderException

storeLockSafe

protected abstract void storeLockSafe(InternalCacheEntry ed,
                                      String lockingKey)
                               throws CacheLoaderException

Throws:

CacheLoaderException

loadLockSafe

protected abstract InternalCacheEntry loadLockSafe(Object key,
                                                   String lockingKey)
                                            throws CacheLoaderException

Throws:

CacheLoaderException

getLockFromKey

protected abstract String getLockFromKey(Object key)
                                  throws CacheLoaderException

Throws:

CacheLoaderException