zrx_stream/stream/operator/
join.rs

1// Copyright (c) Zensical LLC <https://zensical.org>
2
3// SPDX-License-Identifier: MIT
4// Third-party contributions licensed under CLA
5
6// Permission is hereby granted, free of charge, to any person obtaining a copy
7// of this software and associated documentation files (the "Software"), to
8// deal in the Software without restriction, including without limitation the
9// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
10// sell copies of the Software, and to permit persons to whom the Software is
11// furnished to do so, subject to the following conditions:
12
13// The above copyright notice and this permission notice shall be included in
14// all copies or substantial portions of the Software.
15
16// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18// FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
19// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
22// IN THE SOFTWARE.
23
24// ----------------------------------------------------------------------------
25
26//! Join operator.
27
28use std::marker::PhantomData;
29use zrx_scheduler::action::descriptor::Property;
30use zrx_scheduler::action::output::IntoOutputs;
31use zrx_scheduler::action::Descriptor;
32use zrx_scheduler::effect::Item;
33use zrx_scheduler::{Id, Value};
34
35use crate::stream::combinator::tuple::cons::IntoStreamTupleCons;
36use crate::stream::combinator::tuple::join::IntoJoin;
37use crate::stream::combinator::tuple::StreamTupleJoin;
38use crate::stream::value::tuple::{All, Any, First, Presence};
39use crate::stream::value::Tuple;
40use crate::stream::Stream;
41
42use super::Operator;
43
44// ----------------------------------------------------------------------------
45// Structs
46// ----------------------------------------------------------------------------
47
48/// Join operator.
49struct Join<T, P> {
50    /// Type marker.
51    marker: PhantomData<(T, P)>,
52}
53
54// ----------------------------------------------------------------------------
55// Implementations
56// ----------------------------------------------------------------------------
57
58impl<I, T> Stream<I, T>
59where
60    I: Id,
61    T: Value,
62{
63    pub fn join<S, O>(&self, streams: S) -> Stream<I, O::Item>
64    where
65        S: IntoStreamTupleCons<I, T, Output = O>,
66        O: IntoJoin<I, All>,
67    {
68        streams // fmt
69            .into_stream_tuple_cons(self.clone())
70            .into_join()
71    }
72
73    pub fn left_join<S, O>(&self, streams: S) -> Stream<I, O::Item>
74    where
75        S: IntoStreamTupleCons<I, T, Output = O>,
76        O: IntoJoin<I, First>,
77    {
78        streams // fmt
79            .into_stream_tuple_cons(self.clone())
80            .into_join()
81    }
82
83    pub fn full_join<S, O>(&self, streams: S) -> Stream<I, O::Item>
84    where
85        S: IntoStreamTupleCons<I, T, Output = O>,
86        O: IntoJoin<I, Any>,
87    {
88        streams // fmt
89            .into_stream_tuple_cons(self.clone())
90            .into_join()
91    }
92}
93
94// ----------------------------------------------------------------------------
95// Trait implementations
96// ----------------------------------------------------------------------------
97
98impl<I, T, P> Operator<I, T> for Join<T, P>
99where
100    I: Id,
101    T: Tuple<P>,
102{
103    type Item<'a> = Item<&'a I, T::Arguments<'a>>;
104
105    /// Handles the given item.
106    ///
107    /// Joins are one of the most complex operations in stream processing, yet
108    /// the implementation here is surprisingly straightforward. The core idea
109    /// is to leverage the [`Tuple`] trait to represent the combined state of
110    /// all streams being joined.
111    #[cfg_attr(
112        feature = "tracing",
113        tracing::instrument(level = "debug" skip_all, fields(id = %item.id))
114    )]
115    fn handle(&mut self, item: Self::Item<'_>) -> impl IntoOutputs<I> {
116        item.into_owned().map(Some)
117    }
118
119    /// Returns the descriptor.
120    #[inline]
121    fn descriptor(&self) -> Descriptor {
122        Descriptor::builder()
123            .property(Property::Pure)
124            .property(Property::Stable)
125            .property(Property::Flush)
126            .build()
127    }
128}
129
130// ----------------------------------------------------------------------------
131// Blanket implementations
132// ----------------------------------------------------------------------------
133
134impl<S, I, P> IntoJoin<I, P> for S
135where
136    S: StreamTupleJoin<I, P>,
137    I: Id,
138    P: Presence,
139{
140    fn into_join(self) -> Stream<I, Self::Item> {
141        self.workflow().add_operator(
142            self.ids(),
143            Join::<Self::Item, P> { marker: PhantomData },
144        )
145    }
146}
zrx_stream/stream/operator/join.rs

zrx_stream/stream/operator/
join.rs
