FastMerge

All Known Implementing Classes:

GCounter, GSet, ORSet
```
public interface FastMerge
```
INTERNAL API
Optimization for add/remove followed by merge and merge should just fast forward to the new instance.
It's like a cache between calls of the same thread, you can think of it as a thread local. The Replicator actor invokes the user's modify function, which returns a new ReplicatedData instance, with the ancestor field set (see for example the add method in ORSet). Then (in same thread) the Replication calls merge, which makes use of the ancestor field to perform quick merge (see for example merge method in ORSet).
It's not thread safe if the modifying function and merge are called from different threads, i.e. if used outside the Replicator infrastructure, but the worst thing that can happen is that a full merge is performed instead of the fast forward merge.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`ancestor_$eq(FastMerge x$1)`
`FastMerge`	`assignAncestor(akka.cluster.ddata.ReplicatedData.T newData)`	INTERNAL API: should be called from "updating" methods, and `resetDelta`
`FastMerge`	`clearAncestor()`	INTERNAL API: should be called from merge
`boolean`	`isAncestorOf(akka.cluster.ddata.ReplicatedData.T that)`	INTERNAL API: should be used from merge

- Method Detail
  - ancestor_$eq
```
void ancestor_$eq(FastMerge x$1)
```
  - assignAncestor
```
FastMerge assignAncestor(akka.cluster.ddata.ReplicatedData.T newData)
```
    INTERNAL API: should be called from "updating" methods, and `resetDelta`
  - clearAncestor
```
FastMerge clearAncestor()
```
    INTERNAL API: should be called from merge
  - isAncestorOf
```
boolean isAncestorOf(akka.cluster.ddata.ReplicatedData.T that)
```
    INTERNAL API: should be used from merge