1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
//! Create cycles in a timely dataflow graph.
use crate::{Container, Data};
use crate::progress::{Timestamp, PathSummary};
use crate::progress::frontier::Antichain;
use crate::order::Product;
use crate::dataflow::channels::pushers::TeeCore;
use crate::dataflow::channels::pact::Pipeline;
use crate::dataflow::{StreamCore, Scope, Stream};
use crate::dataflow::scopes::child::Iterative;
use crate::dataflow::operators::generic::builder_rc::OperatorBuilder;
use crate::dataflow::operators::generic::OutputWrapper;
/// Creates a `Stream` and a `Handle` to later bind the source of that `Stream`.
pub trait Feedback<G: Scope> {
/// Creates a `Stream` and a `Handle` to later bind the source of that `Stream`.
///
/// The resulting `Stream` will have its data defined by a future call to `connect_loop` with
/// its `Handle` passed as an argument. Data passed through the stream will have their
/// timestamps advanced by `summary`.
///
/// # Examples
/// ```
/// use timely::dataflow::Scope;
/// use timely::dataflow::operators::{Feedback, ConnectLoop, ToStream, Concat, Inspect, BranchWhen};
///
/// timely::example(|scope| {
/// // circulate 0..10 for 100 iterations.
/// let (handle, cycle) = scope.feedback(1);
/// (0..10).to_stream(scope)
/// .concat(&cycle)
/// .inspect(|x| println!("seen: {:?}", x))
/// .branch_when(|t| t < &100).1
/// .connect_loop(handle);
/// });
/// ```
fn feedback<D: Data>(&mut self, summary: <G::Timestamp as Timestamp>::Summary) -> (Handle<G, D>, Stream<G, D>);
/// Creates a [StreamCore] and a [HandleCore] to later bind the source of that `Stream`.
///
/// The resulting `Stream` will have its data defined by a future call to `connect_loop` with
/// its `Handle` passed as an argument. Data passed through the stream will have their
/// timestamps advanced by `summary`, and will be dropped if the result exceeds `limit`.
///
/// # Examples
/// ```
/// use timely::dataflow::Scope;
/// use timely::dataflow::operators::{Feedback, ConnectLoop, ToStream, Concat, Inspect, BranchWhen};
///
/// timely::example(|scope| {
/// // circulate 0..10 for 100 iterations.
/// let (handle, cycle) = scope.feedback_core::<Vec<_>>(1);
/// (0..10).to_stream(scope)
/// .concat(&cycle)
/// .inspect(|x| println!("seen: {:?}", x))
/// .branch_when(|t| t < &100).1
/// .connect_loop(handle);
/// });
/// ```
fn feedback_core<D: Container>(&mut self, summary: <G::Timestamp as Timestamp>::Summary) -> (HandleCore<G, D>, StreamCore<G, D>);
}
/// Creates a `Stream` and a `Handle` to later bind the source of that `Stream`.
pub trait LoopVariable<'a, G: Scope, T: Timestamp> {
/// Creates a `Stream` and a `Handle` to later bind the source of that `Stream`.
///
/// The resulting `Stream` will have its data defined by a future call to `connect_loop` with
/// its `Handle` passed as an argument. Data passed through the stream will have their
/// timestamps advanced by `summary`.
///
/// # Examples
/// ```
/// use timely::dataflow::Scope;
/// use timely::dataflow::operators::{LoopVariable, ConnectLoop, ToStream, Concat, Inspect, BranchWhen};
///
/// timely::example(|scope| {
/// // circulate 0..10 for 100 iterations.
/// scope.iterative::<usize,_,_>(|inner| {
/// let (handle, cycle) = inner.loop_variable(1);
/// (0..10).to_stream(inner)
/// .concat(&cycle)
/// .inspect(|x| println!("seen: {:?}", x))
/// .branch_when(|t| t.inner < 100).1
/// .connect_loop(handle);
/// });
/// });
/// ```
fn loop_variable<D: Container>(&mut self, summary: T::Summary) -> (HandleCore<Iterative<'a, G, T>, D>, StreamCore<Iterative<'a, G, T>, D>);
}
impl<G: Scope> Feedback<G> for G {
fn feedback<D: Data>(&mut self, summary: <G::Timestamp as Timestamp>::Summary) -> (Handle<G, D>, Stream<G, D>) {
self.feedback_core(summary)
}
fn feedback_core<D: Container>(&mut self, summary: <G::Timestamp as Timestamp>::Summary) -> (HandleCore<G, D>, StreamCore<G, D>) {
let mut builder = OperatorBuilder::new("Feedback".to_owned(), self.clone());
let (output, stream) = builder.new_output();
(HandleCore { builder, summary, output }, stream)
}
}
impl<'a, G: Scope, T: Timestamp> LoopVariable<'a, G, T> for Iterative<'a, G, T> {
fn loop_variable<D: Container>(&mut self, summary: T::Summary) -> (HandleCore<Iterative<'a, G, T>, D>, StreamCore<Iterative<'a, G, T>, D>) {
self.feedback_core(Product::new(Default::default(), summary))
}
}
/// Connect a `Stream` to the input of a loop variable.
pub trait ConnectLoop<G: Scope, D: Container> {
/// Connect a `Stream` to be the input of a loop variable.
///
/// # Examples
/// ```
/// use timely::dataflow::Scope;
/// use timely::dataflow::operators::{Feedback, ConnectLoop, ToStream, Concat, Inspect, BranchWhen};
///
/// timely::example(|scope| {
/// // circulate 0..10 for 100 iterations.
/// let (handle, cycle) = scope.feedback(1);
/// (0..10).to_stream(scope)
/// .concat(&cycle)
/// .inspect(|x| println!("seen: {:?}", x))
/// .branch_when(|t| t < &100).1
/// .connect_loop(handle);
/// });
/// ```
fn connect_loop(&self, _: HandleCore<G, D>);
}
impl<G: Scope, D: Container> ConnectLoop<G, D> for StreamCore<G, D> {
fn connect_loop(&self, helper: HandleCore<G, D>) {
let mut builder = helper.builder;
let summary = helper.summary;
let mut output = helper.output;
let mut input = builder.new_input_connection(self, Pipeline, vec![Antichain::from_elem(summary.clone())]);
let mut vector = Default::default();
builder.build(move |_capability| move |_frontier| {
let mut output = output.activate();
input.for_each(|cap, data| {
data.swap(&mut vector);
if let Some(new_time) = summary.results_in(cap.time()) {
let new_cap = cap.delayed(&new_time);
output
.session(&new_cap)
.give_container(&mut vector);
}
});
});
}
}
/// A handle used to bind the source of a loop variable.
#[derive(Debug)]
pub struct HandleCore<G: Scope, D: Container> {
builder: OperatorBuilder<G>,
summary: <G::Timestamp as Timestamp>::Summary,
output: OutputWrapper<G::Timestamp, D, TeeCore<G::Timestamp, D>>,
}
/// A `HandleCore` specialized for using `Vec` as container
pub type Handle<G, D> = HandleCore<G, Vec<D>>;