differential_dogs3/operators/
propose.rs

1use timely::dataflow::Scope;
2
3use differential_dataflow::{ExchangeData, VecCollection, Hashable};
4use differential_dataflow::difference::{Semigroup, Monoid, Multiply};
5use differential_dataflow::operators::arrange::Arranged;
6use differential_dataflow::trace::TraceReader;
7
8/// Proposes extensions to a prefix stream.
9///
10/// This method takes a collection `prefixes` and an arrangement `arrangement` and for each
11/// update in the collection joins with the accumulated arranged records at a time less or
12/// equal to that of the update. Note that this is not a join by itself, but can be used to
13/// create a join if the `prefixes` collection is also arranged and responds to changes that
14/// `arrangement` undergoes. More complicated patterns are also appropriate, as in the case
15/// of delta queries.
16pub fn propose<G, Tr, K, F, P, V>(
17    prefixes: &VecCollection<G, P, Tr::Diff>,
18    arrangement: Arranged<G, Tr>,
19    key_selector: F,
20) -> VecCollection<G, (P, V), Tr::Diff>
21where
22    G: Scope<Timestamp=Tr::Time>,
23    Tr: for<'a> TraceReader<
24        KeyOwn = K,
25        ValOwn = V,
26        Time: std::hash::Hash,
27        Diff: Monoid+Multiply<Output = Tr::Diff>+ExchangeData+Semigroup<Tr::DiffGat<'a>>,
28    >+Clone+'static,
29    K: Hashable + Default + Ord + 'static,
30    F: Fn(&P)->K+Clone+'static,
31    P: ExchangeData,
32    V: Clone + 'static,
33{
34    crate::operators::lookup_map(
35        prefixes,
36        arrangement,
37        move |p: &P, k: &mut K | { *k = key_selector(p); },
38        move |prefix, diff, value, sum| ((prefix.clone(), Tr::owned_val(value)), diff.clone().multiply(sum)),
39        Default::default(),
40        Default::default(),
41        Default::default(),
42    )
43}
44
45/// Proposes distinct extensions to a prefix stream.
46///
47/// Unlike `propose`, this method does not scale the multiplicity of matched
48/// prefixes by the number of matches in `arrangement`. This can be useful to
49/// avoid the need to prepare an arrangement of distinct extensions.
50pub fn propose_distinct<G, Tr, K, F, P, V>(
51    prefixes: &VecCollection<G, P, Tr::Diff>,
52    arrangement: Arranged<G, Tr>,
53    key_selector: F,
54) -> VecCollection<G, (P, V), Tr::Diff>
55where
56    G: Scope<Timestamp=Tr::Time>,
57    Tr: for<'a> TraceReader<
58        KeyOwn = K,
59        ValOwn = V,
60        Time: std::hash::Hash,
61        Diff : Semigroup<Tr::DiffGat<'a>>+Monoid+Multiply<Output = Tr::Diff>+ExchangeData,
62    >+Clone+'static,
63    K: Hashable + Default + Ord + 'static,
64    F: Fn(&P)->K+Clone+'static,
65    P: ExchangeData,
66    V: Clone + 'static,
67{
68    crate::operators::lookup_map(
69        prefixes,
70        arrangement,
71        move |p: &P, k: &mut K| { *k = key_selector(p); },
72        move |prefix, diff, value, _sum| ((prefix.clone(), Tr::owned_val(value)), diff.clone()),
73        Default::default(),
74        Default::default(),
75        Default::default(),
76    )
77}
differential_dogs3/operators/propose.rs

differential_dogs3/operators/
propose.rs
