UpdateFunction (apache-cassandra API)

All Known Implementing Classes:

BTreePartitionUpdater, ColumnData.Reconciler, UpdateFunction.Simple
```
public interface UpdateFunction<K,V>
```
An interface defining the method to be applied to the existing and replacing object in a BTree. The objects returned by the methods will be the object that need to be stored in the BTree.

Nested Class Summary

Nested Classes
Modifier and Type Interface Description

static class UpdateFunction.Simple<V>

Field Summary

Fields
Modifier and Type Field Description

static UpdateFunction.Simple<java.lang.Object> noOp

Method Summary

All Methods Static Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`V`	`insert(K insert)`	Computes the value that should be inserted in the BTree.
`V`	`merge(V replacing, K update)`	Computes the result of merging the existing value with the one from the update.
`static <K> UpdateFunction<K,K>`	`noOp()`
`void`	`onAllocatedOnHeap(long heapSize)`

- Field Detail
  - noOp
```
static final UpdateFunction.Simple<java.lang.Object> noOp
```
- Method Detail
  - insert
```
V insert(K insert)
```
    Computes the value that should be inserted in the BTree.
    
    Parameters:
    
    insert - the update value
    
    Returns:
    
    the value that should be inserted in the BTree
  - merge
```
V merge(V replacing,
        K update)
```
    Computes the result of merging the existing value with the one from the update.
    
    Parameters:
    
    replacing - the value in the original tree we have matched
    
    update - the value in the updating collection that matched
    
    Returns:
    
    the value to insert into the new tree
  - onAllocatedOnHeap
```
void onAllocatedOnHeap(long heapSize)
```
    Parameters:
    
    heapSize - extra heap space allocated (over previous tree)
  - noOp
```
static <K> UpdateFunction<K,K> noOp()
```