Trait differential_dataflow::operators::reduce::ReduceCore
source · pub trait ReduceCore<G: Scope, K: ToOwned + ?Sized, V: Data, R: Semigroup>{
// Required method
fn reduce_core<L, T2>(
&self,
name: &str,
logic: L,
) -> Arranged<G, TraceAgent<T2>>
where T2: for<'a> Trace<Key<'a> = &'a K, Time = G::Timestamp> + 'static,
for<'a> T2::Val<'a>: IntoOwned<'a, Owned = V>,
T2::Batch: Batch,
T2::Builder: Builder<Input = Vec<((K::Owned, V), T2::Time, T2::Diff)>>,
L: FnMut(&K, &[(&V, R)], &mut Vec<(V, T2::Diff)>, &mut Vec<(V, T2::Diff)>) + 'static;
// Provided method
fn reduce_abelian<L, T2>(
&self,
name: &str,
logic: L,
) -> Arranged<G, TraceAgent<T2>>
where T2: for<'a> Trace<Key<'a> = &'a K, Time = G::Timestamp> + 'static,
for<'a> T2::Val<'a>: IntoOwned<'a, Owned = V>,
T2::Diff: Abelian,
T2::Batch: Batch,
T2::Builder: Builder<Input = Vec<((K::Owned, V), T2::Time, T2::Diff)>>,
L: FnMut(&K, &[(&V, R)], &mut Vec<(V, T2::Diff)>) + 'static { ... }
}
Expand description
Extension trait for the reduce_core
differential dataflow method.
Required Methods§
sourcefn reduce_core<L, T2>(
&self,
name: &str,
logic: L,
) -> Arranged<G, TraceAgent<T2>>
fn reduce_core<L, T2>( &self, name: &str, logic: L, ) -> Arranged<G, TraceAgent<T2>>
Solves for output updates when presented with inputs and would-be outputs.
Unlike reduce_arranged
, this method may be called with an empty input
,
and it may not be safe to index into the first element.
At least one of the two collections will be non-empty.
Provided Methods§
sourcefn reduce_abelian<L, T2>(
&self,
name: &str,
logic: L,
) -> Arranged<G, TraceAgent<T2>>
fn reduce_abelian<L, T2>( &self, name: &str, logic: L, ) -> Arranged<G, TraceAgent<T2>>
Applies reduce
to arranged data, and returns an arrangement of output data.
This method is used by the more ergonomic reduce
, distinct
, and count
methods, although
it can be very useful if one needs to manually attach and re-use existing arranged collections.
§Examples
use differential_dataflow::input::Input;
use differential_dataflow::operators::reduce::ReduceCore;
use differential_dataflow::trace::Trace;
use differential_dataflow::trace::implementations::ValSpine;
::timely::example(|scope| {
let trace =
scope.new_collection_from(1 .. 10u32).1
.map(|x| (x, x))
.reduce_abelian::<_,ValSpine<_,_,_,_>>(
"Example",
move |_key, src, dst| dst.push((*src[0].0, 1))
)
.trace;
});
Object Safety§
This trait is not object safe.