Module accum 

Defines the accumulator trait and some common accumulators.

Structs

GCounterUpdate

State for a grow-only distributed counter (GCounter CRDT).

Max

Re-export Max from algebra. Newtype wrapper for an Ord type where join is max.

Min

Re-export Min from algebra. Newtype wrapper for an Ord type where join is min.

PNCounterUpdate

State for an increment/decrement distributed counter (PNCounter CRDT).

ReducerFactory

A factory for ErasedCommReducers. This is used to register a ErasedCommReducer type. We cannot register ErasedCommReducer trait object directly because the object could have internal state, and cannot be shared.

ReducerSpec

Serializable information needed to build a comm reducer.

StreamingReducerOpts

Options for streaming reducer mode.

WatermarkUpdate

Update from ranks for watermark accumulator using Last-Writer-Wins CRDT.

Enums

ReducerMode

The mode in which a reducer operates.

Traits

Accumulator

An accumulator is a object that accumulates updates into a state.

CommReducer

Commutative reducer for an accumulator. This is used to coallesce updates. For example, if the accumulator is a sum, its reducer calculates and returns the sum of 2 updates. This is helpful in split ports, where a large number of updates can be reduced into a smaller number of updates before being sent to the parent port.

ErasedCommReducer

Type erased version of CommReducer.

Functions

join_semilattice

Create an accumulator for any JoinSemilattice type.

sum

Accumulate the sum of received updates.