Package com.gigaspaces.internal.client.mutators

Class AddToCollectionSpaceEntryMutator

java.lang.Object
com.gigaspaces.client.mutators.SpaceEntryMutator
com.gigaspaces.internal.client.mutators.SpaceEntryPathMutator
com.gigaspaces.internal.client.mutators.AddToCollectionSpaceEntryMutator
All Implemented Interfaces:
Textualizable, SmartExternalizable, ChangeOperation, Externalizable, Serializable
public final class AddToCollectionSpaceEntryMutator extends SpaceEntryPathMutator
Since:
9.1
Author:
Niv Ingberg
See Also:

  • Constructor Details

    • AddToCollectionSpaceEntryMutator

      public AddToCollectionSpaceEntryMutator()

    • AddToCollectionSpaceEntryMutator

      public AddToCollectionSpaceEntryMutator(String path, Serializable item)

  • Method Details

    • change

      public CollectionChangeSpaceEntryMutatorResult change(MutableServerEntry entry)
      Description copied from class: SpaceEntryMutator
      Changes an entry. The provided MutableServerEntry is wrapping the actual object which is kept in space, therefore it is crucial to understand when a value is retrieved from the entry it points to the actual reference in the data structure of the space. The content of this reference should not be changed as it will affect directly the object in space and will break data integrity, transaction and visibility scoping (transaction abort will not restore the previous value). Changing a value should always be done via the MutableServerEntry.setPathValue(String, Object). Moreover, if you want to change a property within that value by invoking a method on that object (e.g. if the value is a list, adding an item to the list) first you must clone the fetched value first, and invoke the method on the cloned copy otherwise, for the reason explained before, you will change the existing data structure in the space without going the proper data update path and break data integrity.

      Note that when using a replicated topology (e.g. backup space, gateway, mirror) the change operation itself is replicated (and *NOT* the modified entry). Hence, it is imperative that this method will always cause the exact same affect on the entry assuming the same entry was provided, for example it should not rely on variables that may change between executions, such as system time, random, machine name etc. If the operation is not structured that way, the state can be inconsistent in the different locations after being replicated When creating a custom change operation always have this in the back of your mind - "With great power comes great responsibility".

      Following is an example that reads propertyA and set its value into propertyB and returns nothing. 

      
 public Object change(MutableServerEntry entry)
 {
     Object value entry.getPathValue("propertyA");
     entry.setPathValue("propertyB", newValue);
     return null;
 }

      Following is an example that adds the element 2 into an ArrayList that exists in the entry under a property named "listProperty", the result sent to client if requested is the size of the collection after the change, note that we clone the ArrayList before modifying it as explained before. 

      
 public Object change(MutableServerEntry entry)
 {
     ArrayList oldValue = (ArrayList)entry.getPathValue("listPropery");
     if (oldValue == null)
         throw new IllegalStateException("No collection instance exists under the given path
 'listProperty', in order to add a value a collection instance must exist");
     Collection newValue = (ArrayList)oldValue.clone()
     newValue.add(2);
     int size = newValue.size();
     entry.setPathValue("listProperty", newValue);
     return size;
 }
      Specified by:
      change in class SpaceEntryMutator
      Parameters:
      entry - the entry to change.
      Returns:
      a result value of this change which will be sent to the client if the change operation was executed with ChangeModifiers.RETURN_DETAILED_RESULTS modifier.

    • writeExternal

      public void writeExternal(ObjectOutput out) throws IOException
      Specified by:
      writeExternal in interface Externalizable
      Overrides:
      writeExternal in class SpaceEntryPathMutator
      Throws:
      IOException

    • readExternal

      public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException
      Specified by:
      readExternal in interface Externalizable
      Overrides:
      readExternal in class SpaceEntryPathMutator
      Throws:
      IOException
      ClassNotFoundException

    • toText

      public void toText(Textualizer textualizer)
      Specified by:
      toText in interface Textualizable
      Overrides:
      toText in class SpaceEntryPathMutator

    • getName

      public String getName()
      Returns:
      the name of the operation.

    • getItem

      public Serializable getItem()