Module org.eclipse.persistence.core
Package org.eclipse.persistence.sessions.interceptors

Class CacheInterceptor

  • All Implemented Interfaces:
    Cloneable, IdentityMap
    public abstract class CacheInterceptor
extends Object
implements IdentityMap

    Purpose: Define a class through which Cache access can be intercepted.

    Description: EclipseLink makes extensive use of caching functionality. This class provides the mechanism for intercepting the cache access. Once intercepted applications can allow the process to continue by calling the method on the class attribute targetIdentityMap as described in the API javadocs or redirect the process entirely. * As with IdentityMaps an entire class inheritance hierarchy will share the same interceptor.

    To implement a CacheInterceptor users should subclass this class implementing those methods they wish to intercept.

    Configuration: Interceptors may be added to a session by using a Session or Descriptor customizer to set the class name of the interceptor on the target ClassDescriptor through the method setCacheInterceptorClass(Class).

    • Field Detail

      • targetIdentityMap

        protected IdentityMap targetIdentityMap
        This attribute stores the actual IdentityMap as configured by the user.

    • Method Detail

      • acquireDeferredLock

        public CacheKey acquireDeferredLock​(Object primaryKey,
                                    boolean isCacheCheckComplete)
        Acquire a deferred lock on the object. This is used while reading if the object has relationships without indirection. This first thread will get an active lock. Other threads will get deferred locks, all threads will wait until all other threads are complete before releasing their locks.
        Specified by:
        acquireDeferredLock in interface IdentityMap

      • acquireLock

        public CacheKey acquireLock​(Object primaryKey,
                            boolean forMerge,
                            boolean isCacheCheckComplete)
        Acquire an active lock on the object. This is used by reading (when using indirection or no relationships) and by merge.
        Specified by:
        acquireLock in interface IdentityMap

      • acquireLockNoWait

        public CacheKey acquireLockNoWait​(Object primaryKey,
                                  boolean forMerge)
        Acquire an active lock on the object, if not already locked. This is used by merge for missing existing objects.
        Specified by:
        acquireLockNoWait in interface IdentityMap

      • acquireLockWithWait

        public CacheKey acquireLockWithWait​(Object primaryKey,
                                    boolean forMerge,
                                    int wait)
        Acquire an active lock on the object, if not already locked. This is used by merge for missing existing objects.
        Specified by:
        acquireLockWithWait in interface IdentityMap

      • acquireReadLockOnCacheKey

        public CacheKey acquireReadLockOnCacheKey​(Object primaryKey)
        Acquire a read lock on the object. This is used by UnitOfWork cloning. This will allow multiple users to read the same object but prevent writes to the object while the read lock is held.
        Specified by:
        acquireReadLockOnCacheKey in interface IdentityMap

      • acquireReadLockOnCacheKeyNoWait

        public CacheKey acquireReadLockOnCacheKeyNoWait​(Object primaryKey)
        Acquire a read lock on the object, if not already locked. This is used by UnitOfWork cloning. This will allow multiple users to read the same object but prevent writes to the object while the read lock is held.
        Specified by:
        acquireReadLockOnCacheKeyNoWait in interface IdentityMap

      • collectLocks

        public void collectLocks​(HashMap threadList)
        Add all locked CacheKeys to the map grouped by thread. Used to print all the locks in the identity map.
        Specified by:
        collectLocks in interface IdentityMap

      • clone

        public abstract Object clone()
        Clone the map and all of the CacheKeys. This is used by UnitOfWork commitAndResumeOnFailure to avoid corrupting the cache during a failed commit.
        Specified by:
        clone in interface IdentityMap
        Overrides:
        clone in class Object

      • containsKey

        public boolean containsKey​(Object primaryKey)
        Return true if an CacheKey with the primary key is in the map. User API.
        Specified by:
        containsKey in interface IdentityMap
        Parameters:
        primaryKey - is the primary key for the object to search for.

      • elements

        public Enumeration elements()
        Allow for the cache to be iterated on. This method is only used during debugging when validateCache() has been called to print out the contents of the cache.
        Specified by:
        elements in interface IdentityMap

      • get

        public Object get​(Object primaryKey)
        Return the object cached in the identity map or null if it could not be found. User API.
        Specified by:
        get in interface IdentityMap

      • getAllFromIdentityMapWithEntityPK

        public abstract Map<Object,​Object> getAllFromIdentityMapWithEntityPK​(Object[] pkList,
                                                                           ClassDescriptor descriptor,
                                                                           AbstractSession session)
        ADVANCED: Using a list of Entity PK this method will attempt to bulk load the entire list from the cache. In certain circumstances this can have large performance improvements over loading each item individually.
        Specified by:
        getAllFromIdentityMapWithEntityPK in interface IdentityMap
        Parameters:
        pkList - List of Entity PKs to extract from the cache
        descriptor - Descriptor type to be retrieved.
        Returns:
        Map of Entity PKs associated to the Entities that were retrieved

      • getAllCacheKeysFromIdentityMapWithEntityPK

        public abstract Map<Object,​CacheKey> getAllCacheKeysFromIdentityMapWithEntityPK​(Object[] pkList,
                                                                                      ClassDescriptor descriptor,
                                                                                      AbstractSession session)
        ADVANCED: Using a list of Entity PK this method will attempt to bulk load the entire list from the cache. In certain circumstances this can have large performance improvements over loading each item individually.
        Specified by:
        getAllCacheKeysFromIdentityMapWithEntityPK in interface IdentityMap
        Parameters:
        pkList - List of Entity PKs to extract from the cache
        descriptor - Descriptor type to be retrieved.
        Returns:
        Map of Entity PKs associated to the Entities that were retrieved

      • getCacheKey

        public CacheKey getCacheKey​(Object primaryKey,
                            boolean forMerge)
        Get the cache key (with object) for the primary key.
        Specified by:
        getCacheKey in interface IdentityMap

      • getMaxSize

        public int getMaxSize()
        Specified by:
        getMaxSize in interface IdentityMap
        Returns:
        The maxSize for the IdentityMap (NOTE: some subclasses may use this differently).

      • getSize

        public int getSize()
        Return the number of CacheKeys in the IdentityMap. This may contain weak referenced objects that have been garbage collected.
        Specified by:
        getSize in interface IdentityMap

      • getSize

        public int getSize​(Class<?> myClass,
                   boolean recurse)
        Return the number of actual objects of type myClass in the IdentityMap. Recurse = true will include subclasses of myClass in the count.
        Specified by:
        getSize in interface IdentityMap

      • getTargetIdenttyMap

        public IdentityMap getTargetIdenttyMap()
        Return the instance of the IdentityMap that this intercpetor is wrapping. Any call that is to be passed on to the underlying EclipseLink cache should be passed to this IdentityMap.

      • getWrapper

        public Object getWrapper​(Object primaryKey)
        Get the wrapper object from the cache key associated with the given primary key, this is used for EJB2.
        Specified by:
        getWrapper in interface IdentityMap

      • getWriteLockValue

        public Object getWriteLockValue​(Object primaryKey)
        Get the write lock value from the cache key associated to the primarykey. User API.
        Specified by:
        getWriteLockValue in interface IdentityMap

      • put

        public CacheKey put​(Object primaryKey,
                    Object object,
                    Object writeLockValue,
                    long readTime)
        Store the object in the cache at its primary key. This is used by InsertObjectQuery, typically into the UnitOfWork identity map. Merge and reads do not use put, but acquireLock. Also an advanced (very) user API.
        Specified by:
        put in interface IdentityMap
        Parameters:
        primaryKey - is the primary key for the object.
        object - is the domain object to cache.
        writeLockValue - is the current write lock value of object, if null the version is ignored.

      • remove

        public Object remove​(Object primaryKey,
                     Object object)
        Remove the CacheKey with the primaryKey from the map. This is used by DeleteObjectQuery and merge. This is also an advanced (very) user API.
        Specified by:
        remove in interface IdentityMap

      • updateMaxSize

        public void updateMaxSize​(int maxSize)
        This method will be used to update the max cache size, any objects exceeding the max cache size will be remove from the cache. Please note that this does not remove the object from the identityMap, except in the case of the CacheIdentityMap.
        Specified by:
        updateMaxSize in interface IdentityMap

      • setWrapper

        public void setWrapper​(Object primaryKey,
                       Object wrapper)
        Update the wrapper object in the CacheKey associated with the given primaryKey, this is used for EJB2.
        Specified by:
        setWrapper in interface IdentityMap

      • setWriteLockValue

        public void setWriteLockValue​(Object primaryKey,
                              Object writeLockValue)
        Update the write lock value of the CacheKey associated with the given primaryKey. This is used by UpdateObjectQuery, and is also an advanced (very) user API.
        Specified by:
        setWriteLockValue in interface IdentityMap