org.apache.cayenne.access

## Class ObjectStore

- java.lang.Object
- - org.apache.cayenne.access.ObjectStore

- All Implemented Interfaces:
    Serializable, EventListener, SnapshotEventListener, GraphChangeHandler, GraphManager
  Direct Known Subclasses:
    NoSyncObjectStore

      public class ObjectStore
      extends Object
      implements Serializable, SnapshotEventListener, GraphManager

  ObjectStore stores objects using their ObjectId as a key. It works as a dedicated object cache for a DataContext. Users rarely need to access ObjectStore directly, as DataContext serves as a facade, providing cover methods for most ObjectStore operations.
  Since:
    1.0
  See Also:
    Serialized Form

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected Map<Object,ObjectDiff>` | `changes`
    `protected DataContext` | `context` The DataContext that owns this ObjectStore.
    `protected DataRowStore` | `dataRowCache` Stores a reference to the DataRowStore.
    `protected boolean` | `dataRowCacheSet`
    `protected Map<Object,Persistent>` | `objectMap`
    `protected Map<Object,Map<String,ObjectId>>` | `trackedFlattenedPaths` Map that tracks flattened paths for given object Id that is present in db.

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `ObjectStore(DataRowStore dataRowCache, Map<Object,Persistent> objectMap)` Creates an ObjectStore with `DataRowStore` and a map to use for storing registered objects.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `arcCreated(Object nodeId, Object targetNodeId, ArcId arcId)` Notifies implementing object that a new arc was created between two nodes.
    `void` | `arcDeleted(Object nodeId, Object targetNodeId, ArcId arcId)` Notifies implementing object that an arc between two nodes was deleted.
    `DataRow` | `getCachedSnapshot(ObjectId oid)` Returns a snapshot for ObjectId from the underlying snapshot cache.
    `DataContext` | `getContext()`
    `DataRowStore` | `getDataRowCache()` Returns a DataRowStore associated with this ObjectStore.
    `ObjectId` | `getFlattenedId(ObjectId objectId, String path)`
    `Collection<ObjectId>` | `getFlattenedIds(ObjectId objectId)`
    `Object` | `getNode(Object nodeId)` Returns a registered DataObject or null of no object exists for the ObjectId.
    `Iterator<Persistent>` | `getObjectIterator()` Returns an iterator over the registered objects.
    `DataRow` | `getSnapshot(ObjectId oid)` Returns a snapshot for ObjectId from the underlying snapshot cache.
    `boolean` | `hasChanges()` Returns `true` if there are any modified, deleted or new objects registered with this ObjectStore, `false` otherwise.
    `void` | `markFlattenedPath(ObjectId objectId, String path, ObjectId id)` Mark that flattened path for object has data row in DB.
    `void` | `nodeCreated(Object nodeId)` Notifies implementing object that a new node was created in the graph.
    `void` | `nodeIdChanged(Object nodeId, Object newId)` Does nothing.
    `void` | `nodePropertyChanged(Object nodeId, String property, Object oldValue, Object newValue)` Records dirty object snapshot.
    `void` | `nodeRemoved(Object nodeId)` Notifies implementing object that a node was removed from the graph.
    `List<Persistent>` | `objectsInState(int state)` Return a subset of registered objects that are in a certain persistence state.
    `void` | `objectsRolledBack()` Reverts changes to all stored uncomitted objects.
    `void` | `objectsUnregistered(Collection objects)` Evicts a collection of DataObjects from the ObjectStore, invalidates the underlying cache snapshots.
    `void` | `postprocessAfterCommit(GraphDiff parentChanges)` Internal unsynchronized method to process objects state after commit.
    `Collection<Object>` | `registeredNodes()` Returns all registered DataObjects.
    `int` | `registeredObjectsCount()` Returns a number of objects currently registered with this ObjectStore.
    `void` | `registerNode(Object nodeId, Object nodeObject)` "Registers" a graph node, usually storing the node in some internal map using its id as a key.
    `void` | `setContext(DataContext context)`
    `void` | `setDataRowCache(DataRowStore dataRowCache)` Sets parent DataRowStore.
    `void` | `snapshotsChanged(SnapshotEvent event)` SnapshotEventListener implementation that processes snapshot change event, updating DataObjects that have the changes.
    `Object` | `unregisterNode(Object nodeId)` "Unregisters" a graph node, forgetting any information associated with nodeId.

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### objectMap

          protected Map<Object,Persistent> objectMap

    - #### changes

          protected Map<Object,ObjectDiff> changes

    - #### trackedFlattenedPaths

          protected Map<Object,Map<String,ObjectId>> trackedFlattenedPaths

      Map that tracks flattened paths for given object Id that is present in db. Presence of path in this map is used to separate insert from update case of flattened records.
      Since:
        4.1

    - #### dataRowCache

          protected transient DataRowStore dataRowCache

      Stores a reference to the DataRowStore.

      Serialization note: It is up to the owner of this ObjectStore to initialize DataRowStore after deserialization of this object. ObjectStore will not know how to restore the DataRowStore by itself.

    - #### dataRowCacheSet

          protected boolean dataRowCacheSet

    - #### context

          protected DataContext context

      The DataContext that owns this ObjectStore.

  - ### Constructor Detail

    - #### ObjectStore

          public ObjectStore(DataRowStore dataRowCache,
                             Map<Object,Persistent> objectMap)

      Creates an ObjectStore with `DataRowStore` and a map to use for storing registered objects. Passed map doesn't require any special synchronization behavior, as ObjectStore is synchronized itself.
      Since:
        3.0

  - ### Method Detail

    - #### registeredObjectsCount

          public int registeredObjectsCount()

      Returns a number of objects currently registered with this ObjectStore.
      Since:
        1.2

    - #### getDataRowCache

          public DataRowStore getDataRowCache()

      Returns a DataRowStore associated with this ObjectStore.

    - #### setDataRowCache

          public void setDataRowCache(DataRowStore dataRowCache)

      Sets parent DataRowStore. Registers to receive SnapshotEvents if the cache is configured to allow ObjectStores to receive such events.

    - #### objectsUnregistered

          public void objectsUnregistered(Collection objects)

      Evicts a collection of DataObjects from the ObjectStore, invalidates the underlying cache snapshots. Changes objects state to TRANSIENT. This method can be used for manual cleanup of Cayenne cache.

    - #### objectsRolledBack

          public void objectsRolledBack()

      Reverts changes to all stored uncomitted objects.
      Since:
        1.1

    - #### postprocessAfterCommit

          public void postprocessAfterCommit(GraphDiff parentChanges)

      Internal unsynchronized method to process objects state after commit.
      Since:
        1.2

    - #### getCachedSnapshot

          public DataRow getCachedSnapshot(ObjectId oid)

      Returns a snapshot for ObjectId from the underlying snapshot cache. If cache contains no snapshot, a null is returned.
      Since:
        1.1

    - #### getSnapshot

          public DataRow getSnapshot(ObjectId oid)

      Returns a snapshot for ObjectId from the underlying snapshot cache. If cache contains no snapshot, it will attempt fetching it using provided QueryEngine. If fetch attempt fails or inconsistent data is returned, underlying cache will throw a CayenneRuntimeException.
      Since:
        1.2

    - #### getObjectIterator

          public Iterator<Persistent> getObjectIterator()

      Returns an iterator over the registered objects.

    - #### hasChanges

          public boolean hasChanges()

      Returns `true` if there are any modified, deleted or new objects registered with this ObjectStore, `false` otherwise. This method will treat "phantom" modifications are real ones. I.e. if you "change" an object property to an equivalent value, this method will still think such object is modified. Phantom modifications are only detected and discarded during commit.

    - #### objectsInState

          public List<Persistent> objectsInState(int state)

      Return a subset of registered objects that are in a certain persistence state. Collection is returned by copy.

    - #### snapshotsChanged

          public void snapshotsChanged(SnapshotEvent event)

      SnapshotEventListener implementation that processes snapshot change event, updating DataObjects that have the changes.

      Implementation note: This method should not attempt to alter the underlying DataRowStore, since it is normally invoked *AFTER* the DataRowStore was modified as a result of some external interaction.

      Specified by:
        `snapshotsChanged` in interface `SnapshotEventListener`
      Since:
        1.1

    - #### getContext

          public DataContext getContext()

      Since:
        1.2

    - #### setContext

          public void setContext(DataContext context)

      Since:
        1.2

    - #### getNode

          public Object getNode(Object nodeId)

      Returns a registered DataObject or null of no object exists for the ObjectId.
      Specified by:
        `getNode` in interface `GraphManager`
      Since:
        1.2

    - #### registeredNodes

          public Collection<Object> registeredNodes()

      Returns all registered DataObjects. List is returned by copy and can be modified by the caller.
      Specified by:
        `registeredNodes` in interface `GraphManager`
      Since:
        1.2

    - #### registerNode

          public void registerNode(Object nodeId,
                                   Object nodeObject)

      Description copied from interface: `GraphManager`
      "Registers" a graph node, usually storing the node in some internal map using its id as a key.
      Specified by:
        `registerNode` in interface `GraphManager`
      Since:
        1.2

    - #### unregisterNode

          public Object unregisterNode(Object nodeId)

      Description copied from interface: `GraphManager`
      "Unregisters" a graph node, forgetting any information associated with nodeId.
      Specified by:
        `unregisterNode` in interface `GraphManager`
      Since:
        1.2

    - #### nodeIdChanged

          public void nodeIdChanged(Object nodeId,
                                    Object newId)

      Does nothing.
      Specified by:
        `nodeIdChanged` in interface `GraphChangeHandler`
      Since:
        1.2

    - #### nodeCreated

          public void nodeCreated(Object nodeId)

      Description copied from interface: `GraphChangeHandler`
      Notifies implementing object that a new node was created in the graph.
      Specified by:
        `nodeCreated` in interface `GraphChangeHandler`
      Since:
        1.2

    - #### nodeRemoved

          public void nodeRemoved(Object nodeId)

      Description copied from interface: `GraphChangeHandler`
      Notifies implementing object that a node was removed from the graph.
      Specified by:
        `nodeRemoved` in interface `GraphChangeHandler`
      Since:
        1.2

    - #### nodePropertyChanged

          public void nodePropertyChanged(Object nodeId,
                                          String property,
                                          Object oldValue,
                                          Object newValue)

      Records dirty object snapshot.
      Specified by:
        `nodePropertyChanged` in interface `GraphChangeHandler`
      Since:
        1.2

    - #### arcCreated

          public void arcCreated(Object nodeId,
                                 Object targetNodeId,
                                 ArcId arcId)

      Description copied from interface: `GraphChangeHandler`
      Notifies implementing object that a new arc was created between two nodes.
      Specified by:
        `arcCreated` in interface `GraphChangeHandler`
      Since:
        1.2

    - #### arcDeleted

          public void arcDeleted(Object nodeId,
                                 Object targetNodeId,
                                 ArcId arcId)

      Description copied from interface: `GraphChangeHandler`
      Notifies implementing object that an arc between two nodes was deleted.
      Specified by:
        `arcDeleted` in interface `GraphChangeHandler`
      Since:
        1.2

    - #### getFlattenedId

          public ObjectId getFlattenedId(ObjectId objectId,
                                         String path)

      Since:
        4.2

    - #### getFlattenedIds

          public Collection<ObjectId> getFlattenedIds(ObjectId objectId)

      Since:
        4.2

    - #### markFlattenedPath

          public void markFlattenedPath(ObjectId objectId,
                                        String path,
                                        ObjectId id)

      Mark that flattened path for object has data row in DB.
      Since:
        4.1

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