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
/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0
 */

//! Test connectors that never return data

use std::marker::PhantomData;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use std::task::{Context, Poll};

use http::Uri;
use tower::BoxError;

use aws_smithy_async::future::never::Never;
use aws_smithy_http::body::SdkBody;
use aws_smithy_http::result::ConnectorError;

use crate::erase::boxclone::BoxFuture;

/// A service that will never return whatever it is you want
///
/// Returned futures will return Pending forever
#[non_exhaustive]
#[derive(Debug)]
pub struct NeverService<Req, Resp, Err> {
    _resp: PhantomData<(Req, Resp, Err)>,
    invocations: Arc<AtomicUsize>,
}

impl<Req, Resp, Err> Clone for NeverService<Req, Resp, Err> {
    fn clone(&self) -> Self {
        Self {
            _resp: Default::default(),
            invocations: self.invocations.clone(),
        }
    }
}

impl<Req, Resp, Err> Default for NeverService<Req, Resp, Err> {
    fn default() -> Self {
        Self::new()
    }
}

impl<Req, Resp, Err> NeverService<Req, Resp, Err> {
    /// Create a new NeverService
    pub fn new() -> Self {
        NeverService {
            _resp: Default::default(),
            invocations: Default::default(),
        }
    }

    /// Returns the number of invocations made to this service
    pub fn num_calls(&self) -> usize {
        self.invocations.load(Ordering::SeqCst)
    }
}

/// A Connector that can be use with [`Client`](crate::Client) that never returns a response.
pub type NeverConnector =
    NeverService<http::Request<SdkBody>, http::Response<SdkBody>, ConnectorError>;

/// A service where the underlying TCP connection never connects.
pub type NeverConnected = NeverService<Uri, stream::EmptyStream, BoxError>;

/// Streams that never return data
pub(crate) mod stream {
    use std::io::Error;
    use std::pin::Pin;
    use std::task::{Context, Poll};

    use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};

    /// A stream that will never return or accept any data
    #[non_exhaustive]
    #[derive(Debug, Default)]
    pub struct EmptyStream;

    impl EmptyStream {
        pub fn new() -> Self {
            Self
        }
    }

    impl AsyncRead for EmptyStream {
        fn poll_read(
            self: Pin<&mut Self>,
            _cx: &mut Context<'_>,
            _buf: &mut ReadBuf<'_>,
        ) -> Poll<std::io::Result<()>> {
            Poll::Pending
        }
    }

    impl AsyncWrite for EmptyStream {
        fn poll_write(
            self: Pin<&mut Self>,
            _cx: &mut Context<'_>,
            _buf: &[u8],
        ) -> Poll<Result<usize, Error>> {
            Poll::Pending
        }

        fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), Error>> {
            Poll::Pending
        }

        fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), Error>> {
            Poll::Pending
        }
    }
}

/// A service that will connect but never send any data
#[derive(Clone, Debug, Default)]
pub struct NeverReplies;
impl NeverReplies {
    /// Create a new NeverReplies service
    pub fn new() -> Self {
        Self
    }
}

impl tower::Service<Uri> for NeverReplies {
    type Response = stream::EmptyStream;
    type Error = BoxError;
    type Future = std::future::Ready<Result<Self::Response, Self::Error>>;

    fn poll_ready(&mut self, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
        Poll::Ready(Ok(()))
    }

    fn call(&mut self, _req: Uri) -> Self::Future {
        std::future::ready(Ok(stream::EmptyStream::new()))
    }
}

impl<Req, Resp, Err> tower::Service<Req> for NeverService<Req, Resp, Err> {
    type Response = Resp;
    type Error = Err;
    type Future = BoxFuture<Self::Response, Self::Error>;

    fn poll_ready(&mut self, _cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
        Poll::Ready(Ok(()))
    }

    fn call(&mut self, _req: Req) -> Self::Future {
        self.invocations.fetch_add(1, Ordering::SeqCst);
        Box::pin(async move {
            Never::new().await;
            unreachable!()
        })
    }
}