Module org.eclipse.persistence.core
Package org.eclipse.persistence.internal.identitymaps

Class AbstractIdentityMap

java.lang.Object
org.eclipse.persistence.internal.identitymaps.AbstractIdentityMap
All Implemented Interfaces:
Serializable, Cloneable, IdentityMap
Direct Known Subclasses:
FullIdentityMap, NoIdentityMap
public abstract class AbstractIdentityMap extends Object implements IdentityMap, Serializable, Cloneable

Purpose: Caches objects, and allows their retrieval by their primary key.

Responsibilities:

  • Store CacheKeys containing objects and possibly writeLockValues.
  • Insert & retrieve objects from the cache.
  • Allow retrieval and modification of writeLockValue for a cached object.
Since:
TOPLink/Java 1.0
See Also:

  • Field Details

    • maxSize

      protected int maxSize
      The initial or maximum size of the cache depending upon the concrete implementation.

    • descriptor

      protected transient ClassDescriptor descriptor
      PERF: Store the descriptor to allow lastAccessed cache lookup optimization.

    • isIsolated

      protected boolean isIsolated
      Is this identity map within an IsolatedClientSession

    • session

      protected AbstractSession session
      Session that the map is on

  • Constructor Details

    • AbstractIdentityMap

      protected AbstractIdentityMap()

    • AbstractIdentityMap

      protected AbstractIdentityMap(int size, ClassDescriptor descriptor, AbstractSession session, boolean isolated)
      Instantiate an new IdentityMap with it's maximum size.

      NOTE: Subclasses may provide different behavior for maxSize.

      Parameters:
      size - is the maximum size to be allocated for the receiver.

  • Method Details

    • 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 abstract 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 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.

    • createCacheKey

      public CacheKey createCacheKey(Object primaryKey, Object object, Object writeLockValue, long readTime)
      Create the correct type of CacheKey for this map.

    • elements

      public abstract Enumeration elements()
      Allow for the cache to be iterated on.
      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 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 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 abstract CacheKey getCacheKey(Object primaryKey, boolean forMerge)
      Get the cache key (with object) for the primary key.
      Specified by:
      getCacheKey in interface IdentityMap

    • getCacheKeyForLock

      public CacheKey getCacheKeyForLock(Object primaryKey)
      Get the cache key (with object) for the primary key.
      Specified by:
      getCacheKeyForLock in interface IdentityMap

    • putCacheKeyIfAbsent

      protected abstract CacheKey putCacheKeyIfAbsent(CacheKey cacheKey)
      Return the CacheKey (with object) matching the searchKey. If the CacheKey is missing then put the searchKey in the map. The searchKey should have already been locked.

    • getCacheKeyWithReadLock

      protected CacheKey getCacheKeyWithReadLock(Object primaryKey)
      Get the cache key (with object) for the primary key with read lock.

    • getDefaultIdentityMapClass

      public static Class<? extends IdentityMap> getDefaultIdentityMapClass()
      Returns the class which should be used as an identity map in a descriptor by default.

    • 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 abstract 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 abstract 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

    • 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

    • keys

      public abstract Enumeration keys()
      Allow for the CacheKeys to be iterated on.
      Specified by:
      keys in interface IdentityMap

    • put

      public abstract 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.

    • release

      public void release()
      This method may be called during initialize all identity maps. It allows the identity map or interceptor the opportunity to release any resources before being thrown away.
      Specified by:
      release in interface IdentityMap

    • 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

    • remove

      public abstract Object remove(CacheKey cacheKey)
      Remove the CacheKey from the map.
      Specified by:
      remove in interface IdentityMap

    • setMaxSize

      protected void setMaxSize(int size)
      Set the maximum size for the receiver.
      Parameters:
      size - is the new maximum size.

    • 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

    • getDescriptor

      public ClassDescriptor getDescriptor()
      Return the class that this is the map for.
      Specified by:
      getDescriptor in interface IdentityMap

    • getDescriptorClass

      public Class<?> getDescriptorClass()
      Return the class that this is the map for.
      Specified by:
      getDescriptorClass in interface IdentityMap

    • setDescriptor

      public void setDescriptor(ClassDescriptor descriptor)
      Set the descriptor that this is the map for.
      Specified by:
      setDescriptor 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

    • toString

      public String toString()
      Specified by:
      toString in interface IdentityMap
      Overrides:
      toString in class Object