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

//! Extension trait and implementation for observing and action on streamed data.

use crate::Container;
use crate::dataflow::channels::pact::Pipeline;
use crate::dataflow::{Scope, StreamCore};
use crate::dataflow::operators::generic::Operator;

/// Methods to inspect records and batches of records on a stream.
pub trait Inspect<G: Scope, C: Container>: InspectCore<G, C> + Sized {
    /// Runs a supplied closure on each observed data element.
    ///
    /// # Examples
    /// ```
    /// use timely::dataflow::operators::{ToStream, Map, Inspect};
    ///
    /// timely::example(|scope| {
    ///     (0..10).to_stream(scope)
    ///            .inspect(|x| println!("seen: {:?}", x));
    /// });
    /// ```
    fn inspect<F: 'static>(&self, mut func: F) -> Self
    where
        for<'a> F: FnMut(C::ItemRef<'a>)
    {
        self.inspect_batch(move |_, data| {
            for datum in data.iter() { func(datum); }
        })
    }

    /// Runs a supplied closure on each observed data element and associated time.
    ///
    /// # Examples
    /// ```
    /// use timely::dataflow::operators::{ToStream, Map, Inspect};
    ///
    /// timely::example(|scope| {
    ///     (0..10).to_stream(scope)
    ///            .inspect_time(|t, x| println!("seen at: {:?}\t{:?}", t, x));
    /// });
    /// ```
    fn inspect_time<F: 'static>(&self, mut func: F) -> Self
    where
        for <'a> F: FnMut(&G::Timestamp, C::ItemRef<'a>),
    {
        self.inspect_batch(move |time, data| {
            for datum in data.iter() {
                func(&time, datum);
            }
        })
    }

    /// Runs a supplied closure on each observed data batch (time and data slice).
    ///
    /// # Examples
    /// ```
    /// use timely::dataflow::operators::{ToStream, Map, Inspect};
    ///
    /// timely::example(|scope| {
    ///     (0..10).to_stream(scope)
    ///            .inspect_batch(|t,xs| println!("seen at: {:?}\t{:?} records", t, xs.len()));
    /// });
    /// ```
    fn inspect_batch(&self, mut func: impl FnMut(&G::Timestamp, &C)+'static) -> Self {
        self.inspect_core(move |event| {
            if let Ok((time, data)) = event {
                func(time, data);
            }
        })
    }

    /// Runs a supplied closure on each observed data batch, and each frontier advancement.
    ///
    /// Rust's `Result` type is used to distinguish the events, with `Ok` for time and data,
    /// and `Err` for frontiers. Frontiers are only presented when they change.
    ///
    /// # Examples
    /// ```
    /// use timely::dataflow::operators::{ToStream, Map, Inspect};
    ///
    /// timely::example(|scope| {
    ///     (0..10).to_stream(scope)
    ///            .inspect_core(|event| {
    ///                match event {
    ///                    Ok((time, data)) => println!("seen at: {:?}\t{:?} records", time, data.len()),
    ///                    Err(frontier) => println!("frontier advanced to {:?}", frontier),
    ///                }
    ///             });
    /// });
    /// ```
    fn inspect_core<F>(&self, func: F) -> Self where F: FnMut(Result<(&G::Timestamp, &C), &[G::Timestamp]>)+'static;
}

impl<G: Scope, C: Container> Inspect<G, C> for StreamCore<G, C> {
    fn inspect_core<F>(&self, mut func: F) -> Self where F: FnMut(Result<(&G::Timestamp, &C), &[G::Timestamp]>) + 'static {
        self.inspect_container(move |r| func(r))
    }
}

/// Inspect containers
pub trait InspectCore<G: Scope, C: Container> {
    /// Runs a supplied closure on each observed container, and each frontier advancement.
    ///
    /// Rust's `Result` type is used to distinguish the events, with `Ok` for time and data,
    /// and `Err` for frontiers. Frontiers are only presented when they change.
    ///
    /// # Examples
    /// ```
    /// use timely::dataflow::operators::{ToStream, Map, InspectCore};
    ///
    /// timely::example(|scope| {
    ///     (0..10).to_stream(scope)
    ///            .inspect_container(|event| {
    ///                match event {
    ///                    Ok((time, data)) => println!("seen at: {:?}\t{:?} records", time, data.len()),
    ///                    Err(frontier) => println!("frontier advanced to {:?}", frontier),
    ///                }
    ///             });
    /// });
    /// ```
    fn inspect_container<F>(&self, func: F) -> StreamCore<G, C> where F: FnMut(Result<(&G::Timestamp, &C), &[G::Timestamp]>)+'static;
}

impl<G: Scope, C: Container> InspectCore<G, C> for StreamCore<G, C> {

    fn inspect_container<F>(&self, mut func: F) -> StreamCore<G, C>
        where F: FnMut(Result<(&G::Timestamp, &C), &[G::Timestamp]>)+'static
    {
        use crate::progress::timestamp::Timestamp;
        let mut frontier = crate::progress::Antichain::from_elem(G::Timestamp::minimum());
        self.unary_frontier(Pipeline, "InspectBatch", move |_,_| move |input, output| {
            if input.frontier.frontier() != frontier.borrow() {
                frontier.clear();
                frontier.extend(input.frontier.frontier().iter().cloned());
                func(Err(frontier.elements()));
            }
            input.for_each(|time, data| {
                func(Ok((&time, &*data)));
                output.session(&time).give_container(data);
            });
        })
    }
}