initial value of accumulator
helper object defining how to add elements of type R and T
Merge two accumulable objects together
Merge two accumulable objects together
Normally, a user will not want to use this version, but will instead call +=.
the other Accumulable that will get merged with this
Add more data to this accumulator / accumulable
Add more data to this accumulator / accumulable
the data to add
Get the current value of this accumulator from within a task.
Get the current value of this accumulator from within a task.
This is NOT the global value of the accumulator. To get the global value after a
completed operation on the dataset, call value.
The typical use of this method is to directly mutate the local value, eg., to add an element to a Set.
Access the accumulator's current value; only allowed on master.
Set the accumulator's value; only allowed on master.
A datatype that can be accumulated, i.e. has an commutative and associative "add" operation, but where the result type,
R, may be different from the element type being added,T.You must define how to add data, and how to merge two of these together. For some datatypes, such as a counter, these might be the same operation. In that case, you can use the simpler Accumulator. They won't always be the same, though -- e.g., imagine you are accumulating a set. You will add items to the set, and you will union two sets together.
the full accumulated data (result type)
partial data that can be added in