org.datanucleus.store.types.sco.backed
Class Map

java.lang.Object
  extended by java.util.AbstractMap
      extended by org.datanucleus.store.types.sco.simple.Map
          extended by org.datanucleus.store.types.sco.backed.Map
All Implemented Interfaces:
java.io.Serializable, java.lang.Cloneable, java.util.Map, SCO, SCOContainer, SCOMap

public class Map
extends Map

A mutable second-class Map object. Uses a "delegate" as a local store for the Map. Uses a "backing store" (SetStore) to represent the datastore. The "delegate" is updated with the "backing store" information at necessary intervals.

Modes of Operation

The user can operate the map in 2 modes. The cached mode will use an internal cache of the elements (in the "delegate") reading them at the first opportunity and then using the cache thereafter. The non-cached mode will just go direct to the "backing store" each call.

Mutators

When the backing store is present any updates are passed direct to the datastore as well as to the "delegate". If the "backing store" isn't present the changes are made to the "delegate" only.

Accessors

When any accessor method is invoked, it typically checks whether the map has been loaded from its backing store and does this as necessary. Some methods (size(), containsKey()) just check if everything is loaded and use the delegate if possible, otherwise going direct to the datastore.

See Also:
Serialized Form

Nested Class Summary
 
Nested classes/interfaces inherited from class java.util.AbstractMap
java.util.AbstractMap.SimpleEntry<K,V>, java.util.AbstractMap.SimpleImmutableEntry<K,V>
 
Nested classes/interfaces inherited from interface java.util.Map
java.util.Map.Entry<K,V>
 
Field Summary
protected  boolean allowNulls
           
protected  MapStore backingStore
           
protected  boolean isCacheLoaded
           
protected  OperationQueue<MapStore> operationQueue
           
protected  boolean queued
           
protected  boolean useCache
           
 
Fields inherited from class org.datanucleus.store.types.sco.simple.Map
delegate, fieldName, fieldNumber, LOCALISER, owner, ownerSM
 
Constructor Summary
Map(ObjectProvider ownerSM, java.lang.String fieldName)
          Constructor, using the StateManager of the "owner" and the field name.
 
Method Summary
protected  void addQueuedOperation(QueuedOperation<? super MapStore> op)
          Convenience method to add a queued operation to the operations we perform at commit.
 void clear()
          Method to clear the Map.
 java.lang.Object clone()
          Creates and returns a copy of this object.
 boolean containsKey(java.lang.Object key)
          Utility to check if a key is contained in the Map.
 boolean containsValue(java.lang.Object value)
          Utility to check if a value is contained in the Map.
 java.util.Set entrySet()
          Accessor for the set of entries in the Map.
 boolean equals(java.lang.Object o)
          Method to check the equality of this map, and another.
 void flush()
          Method to flush the changes to the datastore when operating in queued mode.
 java.lang.Object get(java.lang.Object key)
          Accessor for the value stored against a key.
 java.lang.Object getValue()
          Accessor for the unwrapped value that we are wrapping.
 int hashCode()
          Method to generate a hashcode for this Map.
 void initialise()
          Method to initialise the SCO for use.
 void initialise(java.lang.Object o, boolean forInsert, boolean forUpdate)
          Method to initialise the SCO from an existing value.
 boolean isEmpty()
          Method to return if the Map is empty.
 boolean isLoaded()
          Method to return if the SCO has its contents loaded.
 java.util.Set keySet()
          Accessor for the set of keys in the Map.
 void load()
          Method to effect the load of the data in the SCO.
protected  void loadFromStore()
          Method to load all elements from the "backing store" where appropriate.
 java.lang.Object put(java.lang.Object key, java.lang.Object value)
          Method to add a value to the Map.
 void putAll(java.util.Map m)
          Method to add a Map of values to this map.
 java.lang.Object remove(java.lang.Object key)
          Method to remove a value from the Map.
 int size()
          Method to return the size of the Map.
 java.lang.String toString()
          Method to return a string form of this Map.
 void unsetOwner()
          Method to unset the owner and field information.
 void updateEmbeddedKey(java.lang.Object key, int fieldNumber, java.lang.Object newValue)
          Method to update an embedded key in this map.
 void updateEmbeddedValue(java.lang.Object value, int fieldNumber, java.lang.Object newValue)
          Method to update an embedded value in this map.
 java.util.Collection values()
          Accessor for the set of values in the Map.
protected  java.lang.Object writeReplace()
          The writeReplace method is called when ObjectOutputStream is preparing to write the object to the stream.
 
Methods inherited from class org.datanucleus.store.types.sco.simple.Map
attachCopy, detachCopy, getFieldName, getOwner, makeDirty
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

allowNulls

protected transient boolean allowNulls

backingStore

protected transient MapStore backingStore

useCache

protected transient boolean useCache

isCacheLoaded

protected transient boolean isCacheLoaded

queued

protected transient boolean queued

operationQueue

protected transient OperationQueue<MapStore> operationQueue
Constructor Detail

Map

public Map(ObjectProvider ownerSM,
           java.lang.String fieldName)
Constructor, using the StateManager of the "owner" and the field name.

Parameters:
ownerSM - The owner StateManager
fieldName - The name of the field of the SCO.
Method Detail

initialise

public void initialise(java.lang.Object o,
                       boolean forInsert,
                       boolean forUpdate)
Method to initialise the SCO from an existing value.

Specified by:
initialise in interface SCO
Overrides:
initialise in class Map
Parameters:
o - The object to set from
forInsert - Whether the object needs inserting in the datastore with this value
forUpdate - Whether to update the datastore with this value

initialise

public void initialise()
Method to initialise the SCO for use.

Specified by:
initialise in interface SCO
Overrides:
initialise in class Map

getValue

public java.lang.Object getValue()
Accessor for the unwrapped value that we are wrapping.

Specified by:
getValue in interface SCO
Overrides:
getValue in class Map
Returns:
The unwrapped value

load

public void load()
Method to effect the load of the data in the SCO. Used when the SCO supports lazy-loading to tell it to load all now.

Specified by:
load in interface SCOContainer
Overrides:
load in class Map

isLoaded

public boolean isLoaded()
Method to return if the SCO has its contents loaded. If the SCO doesn't support lazy loading will just return true.

Specified by:
isLoaded in interface SCOContainer
Overrides:
isLoaded in class Map
Returns:
Whether it is loaded

loadFromStore

protected void loadFromStore()
Method to load all elements from the "backing store" where appropriate.


flush

public void flush()
Method to flush the changes to the datastore when operating in queued mode. Does nothing in "direct" mode.

Specified by:
flush in interface SCOContainer
Overrides:
flush in class Map

addQueuedOperation

protected void addQueuedOperation(QueuedOperation<? super MapStore> op)
Convenience method to add a queued operation to the operations we perform at commit.

Parameters:
op - The operation

updateEmbeddedKey

public void updateEmbeddedKey(java.lang.Object key,
                              int fieldNumber,
                              java.lang.Object newValue)
Method to update an embedded key in this map.

Specified by:
updateEmbeddedKey in interface SCOMap
Overrides:
updateEmbeddedKey in class Map
Parameters:
key - The key
fieldNumber - Number of field in the key
newValue - New value for this field

updateEmbeddedValue

public void updateEmbeddedValue(java.lang.Object value,
                                int fieldNumber,
                                java.lang.Object newValue)
Method to update an embedded value in this map.

Specified by:
updateEmbeddedValue in interface SCOMap
Overrides:
updateEmbeddedValue in class Map
Parameters:
value - The value
fieldNumber - Number of field in the value
newValue - New value for this field

unsetOwner

public void unsetOwner()
Method to unset the owner and field information.

Specified by:
unsetOwner in interface SCO
Overrides:
unsetOwner in class Map

clone

public java.lang.Object clone()
Creates and returns a copy of this object.

Mutable second-class Objects are required to provide a public clone method in order to allow for copying PersistenceCapable objects. In contrast to Object.clone(), this method must not throw a CloneNotSupportedException.

Specified by:
clone in interface SCO
Overrides:
clone in class Map
Returns:
Clone of the object

containsKey

public boolean containsKey(java.lang.Object key)
Utility to check if a key is contained in the Map.

Specified by:
containsKey in interface java.util.Map
Overrides:
containsKey in class Map
Parameters:
key - The key to check
Returns:
Whether it is contained

containsValue

public boolean containsValue(java.lang.Object value)
Utility to check if a value is contained in the Map.

Specified by:
containsValue in interface java.util.Map
Overrides:
containsValue in class Map
Parameters:
value - The value to check
Returns:
Whether it is contained

entrySet

public java.util.Set entrySet()
Accessor for the set of entries in the Map.

Specified by:
entrySet in interface java.util.Map
Overrides:
entrySet in class Map
Returns:
Set of entries

equals

public boolean equals(java.lang.Object o)
Method to check the equality of this map, and another.

Specified by:
equals in interface java.util.Map
Overrides:
equals in class Map
Parameters:
o - The map to compare against.
Returns:
Whether they are equal.

get

public java.lang.Object get(java.lang.Object key)
Accessor for the value stored against a key.

Specified by:
get in interface java.util.Map
Overrides:
get in class Map
Parameters:
key - The key
Returns:
The value.

hashCode

public int hashCode()
Method to generate a hashcode for this Map.

Specified by:
hashCode in interface java.util.Map
Overrides:
hashCode in class Map
Returns:
The hashcode.

isEmpty

public boolean isEmpty()
Method to return if the Map is empty.

Specified by:
isEmpty in interface java.util.Map
Overrides:
isEmpty in class Map
Returns:
Whether it is empty.

keySet

public java.util.Set keySet()
Accessor for the set of keys in the Map.

Specified by:
keySet in interface java.util.Map
Overrides:
keySet in class Map
Returns:
Set of keys.

size

public int size()
Method to return the size of the Map.

Specified by:
size in interface java.util.Map
Overrides:
size in class Map
Returns:
The size

values

public java.util.Collection values()
Accessor for the set of values in the Map.

Specified by:
values in interface java.util.Map
Overrides:
values in class Map
Returns:
Set of values.

toString

public java.lang.String toString()
Method to return a string form of this Map.

Overrides:
toString in class java.util.AbstractMap
Returns:
String form of this Map.

clear

public void clear()
Method to clear the Map.

Specified by:
clear in interface java.util.Map
Overrides:
clear in class Map

put

public java.lang.Object put(java.lang.Object key,
                            java.lang.Object value)
Method to add a value to the Map.

Specified by:
put in interface java.util.Map
Overrides:
put in class Map
Parameters:
key - The key for the value.
value - The value
Returns:
The previous value against this key (if any).

putAll

public void putAll(java.util.Map m)
Method to add a Map of values to this map.

Specified by:
putAll in interface java.util.Map
Overrides:
putAll in class Map
Parameters:
m - The Map to add

remove

public java.lang.Object remove(java.lang.Object key)
Method to remove a value from the Map.

Specified by:
remove in interface java.util.Map
Overrides:
remove in class Map
Parameters:
key - The key for the value.
Returns:
The value removed.

writeReplace

protected java.lang.Object writeReplace()
                                 throws java.io.ObjectStreamException
The writeReplace method is called when ObjectOutputStream is preparing to write the object to the stream. The ObjectOutputStream checks whether the class defines the writeReplace method. If the method is defined, the writeReplace method is called to allow the object to designate its replacement in the stream. The object returned should be either of the same type as the object passed in or an object that when read and resolved will result in an object of a type that is compatible with all references to the object.

Overrides:
writeReplace in class Map
Returns:
the replaced object
Throws:
java.io.ObjectStreamException


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