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
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
/*
 * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 * SPDX-License-Identifier: Apache-2.0
 */

use bytes::Bytes;
use http::{HeaderMap, HeaderValue};
use http_body::{Body, SizeHint};
use pin_project_lite::pin_project;
use std::error::Error as StdError;
use std::fmt::{self, Debug, Formatter};
use std::pin::Pin;
use std::sync::Arc;
use std::task::{Context, Poll};

pub type Error = Box<dyn StdError + Send + Sync>;

pin_project! {
    /// SdkBody type
    ///
    /// This is the Body used for dispatching all HTTP Requests.
    /// For handling responses, the type of the body will be controlled
    /// by the HTTP stack.
    ///
    // TODO(naming): Consider renaming to simply `Body`, although I'm concerned about naming headaches
    // between hyper::Body and our Body
    pub struct SdkBody {
        #[pin]
        inner: Inner,
        // An optional function to recreate the inner body
        //
        // In the event of retry, this function will be called to generate a new body. See
        // [`try_clone()`](SdkBody::try_clone)
        rebuild: Option<Arc<dyn (Fn() -> Inner) + Send + Sync>>,
    }
}

impl Debug for SdkBody {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        f.debug_struct("SdkBody")
            .field("inner", &self.inner)
            .field("retryable", &self.rebuild.is_some())
            .finish()
    }
}

pub type BoxBody = http_body::combinators::BoxBody<Bytes, Error>;

pin_project! {
    #[project = InnerProj]
    enum Inner {
        // An in-memory body
        Once {
            inner: Option<Bytes>
        },
        // A streaming body
        Streaming {
            #[pin]
            inner: hyper::Body
        },
        // Also a streaming body
        Dyn {
            #[pin]
            inner: BoxBody
        },

        /// When a streaming body is transferred out to a stream parser, the body is replaced with
        /// `Taken`. This will return an Error when polled. Attempting to read data out of a `Taken`
        /// Body is a bug.
        Taken,
    }
}

impl Debug for Inner {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        match &self {
            Inner::Once { inner: once } => f.debug_tuple("Once").field(once).finish(),
            Inner::Streaming { inner: streaming } => {
                f.debug_tuple("Streaming").field(streaming).finish()
            }
            Inner::Taken => f.debug_tuple("Taken").finish(),
            Inner::Dyn { .. } => write!(f, "BoxBody"),
        }
    }
}

impl SdkBody {
    /// Construct an SdkBody from a Boxed implementation of http::Body
    pub fn from_dyn(body: BoxBody) -> Self {
        Self {
            inner: Inner::Dyn { inner: body },
            rebuild: None,
        }
    }

    /// Construct an explicitly retryable SDK body
    ///
    /// _Note: This is probably not what you want_
    ///
    /// All bodies constructed from in-memory data (`String`, `Vec<u8>`, `Bytes`, etc.) will be
    /// retryable out of the box. If you want to read data from a file, you should use
    /// [`ByteStream::from_path`](crate::byte_stream::ByteStream::from_path). This function
    /// is only necessary when you need to enable retries for your own streaming container.
    pub fn retryable(f: impl Fn() -> SdkBody + Send + Sync + 'static) -> Self {
        let initial = f();
        SdkBody {
            inner: initial.inner,
            rebuild: Some(Arc::new(move || f().inner)),
        }
    }

    pub fn taken() -> Self {
        Self {
            inner: Inner::Taken,
            rebuild: None,
        }
    }

    pub fn empty() -> Self {
        Self {
            inner: Inner::Once { inner: None },
            rebuild: Some(Arc::new(|| Inner::Once { inner: None })),
        }
    }

    fn poll_inner(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> Poll<Option<Result<Bytes, Error>>> {
        let this = self.project();
        match this.inner.project() {
            InnerProj::Once { ref mut inner } => {
                let data = inner.take();
                match data {
                    Some(bytes) if bytes.is_empty() => Poll::Ready(None),
                    Some(bytes) => Poll::Ready(Some(Ok(bytes))),
                    None => Poll::Ready(None),
                }
            }
            InnerProj::Streaming { inner: body } => body.poll_data(cx).map_err(|e| e.into()),
            InnerProj::Dyn { inner: box_body } => box_body.poll_data(cx),
            InnerProj::Taken => {
                Poll::Ready(Some(Err("A `Taken` body should never be polled".into())))
            }
        }
    }

    /// If possible, return a reference to this body as `&[u8]`
    ///
    /// If this SdkBody is NOT streaming, this will return the byte slab
    /// If this SdkBody is streaming, this will return `None`
    pub fn bytes(&self) -> Option<&[u8]> {
        match &self.inner {
            Inner::Once { inner: Some(b) } => Some(b),
            Inner::Once { inner: None } => Some(&[]),
            _ => None,
        }
    }

    pub fn try_clone(&self) -> Option<Self> {
        self.rebuild.as_ref().map(|rebuild| {
            let next = rebuild();
            Self {
                inner: next,
                rebuild: self.rebuild.clone(),
            }
        })
    }

    pub fn content_length(&self) -> Option<u64> {
        http_body::Body::size_hint(self).exact()
    }

    pub fn map(self, f: impl Fn(SdkBody) -> SdkBody + Sync + Send + 'static) -> SdkBody {
        if self.rebuild.is_some() {
            SdkBody::retryable(move || f(self.try_clone().unwrap()))
        } else {
            f(self)
        }
    }
}

impl From<&str> for SdkBody {
    fn from(s: &str) -> Self {
        Self::from(s.as_bytes())
    }
}

impl From<Bytes> for SdkBody {
    fn from(bytes: Bytes) -> Self {
        SdkBody {
            inner: Inner::Once {
                inner: Some(bytes.clone()),
            },
            rebuild: Some(Arc::new(move || Inner::Once {
                inner: Some(bytes.clone()),
            })),
        }
    }
}

impl From<hyper::Body> for SdkBody {
    fn from(body: hyper::Body) -> Self {
        SdkBody {
            inner: Inner::Streaming { inner: body },
            rebuild: None,
        }
    }
}

impl From<Vec<u8>> for SdkBody {
    fn from(data: Vec<u8>) -> Self {
        Self::from(Bytes::from(data))
    }
}

impl From<String> for SdkBody {
    fn from(s: String) -> Self {
        Self::from(s.into_bytes())
    }
}

impl From<&[u8]> for SdkBody {
    fn from(data: &[u8]) -> Self {
        Self::from(Bytes::copy_from_slice(data))
    }
}

impl http_body::Body for SdkBody {
    type Data = Bytes;
    type Error = Error;

    fn poll_data(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> Poll<Option<Result<Self::Data, Self::Error>>> {
        self.poll_inner(cx)
    }

    fn poll_trailers(
        self: Pin<&mut Self>,
        _cx: &mut Context<'_>,
    ) -> Poll<Result<Option<HeaderMap<HeaderValue>>, Self::Error>> {
        Poll::Ready(Ok(None))
    }

    fn is_end_stream(&self) -> bool {
        match &self.inner {
            Inner::Once { inner: None } => true,
            Inner::Once { inner: Some(bytes) } => bytes.is_empty(),
            Inner::Streaming { inner: hyper_body } => hyper_body.is_end_stream(),
            Inner::Dyn { inner: box_body } => box_body.is_end_stream(),
            Inner::Taken => true,
        }
    }

    fn size_hint(&self) -> SizeHint {
        match &self.inner {
            Inner::Once { inner: None } => SizeHint::with_exact(0),
            Inner::Once { inner: Some(bytes) } => SizeHint::with_exact(bytes.len() as u64),
            Inner::Streaming { inner: hyper_body } => hyper_body.size_hint(),
            Inner::Dyn { inner: box_body } => box_body.size_hint(),
            Inner::Taken => SizeHint::new(),
        }
    }
}

#[cfg(test)]
mod test {
    use crate::body::{BoxBody, SdkBody};
    use http_body::Body;
    use std::pin::Pin;

    #[test]
    fn valid_size_hint() {
        assert_eq!(SdkBody::from("hello").size_hint().exact(), Some(5));
        assert_eq!(SdkBody::from("").size_hint().exact(), Some(0));
    }

    #[test]
    fn valid_eos() {
        assert_eq!(SdkBody::from("hello").is_end_stream(), false);
        assert_eq!(SdkBody::from("").is_end_stream(), true);
    }

    #[tokio::test]
    async fn http_body_consumes_data() {
        let mut body = SdkBody::from("hello!");
        let mut body = Pin::new(&mut body);
        let data = body.data().await;
        assert!(data.is_some());
        let data = body.data().await;
        assert!(data.is_none());
    }

    #[tokio::test]
    async fn empty_body_returns_none() {
        // Its important to avoid sending empty chunks of data to avoid H2 data frame problems
        let mut body = SdkBody::from("");
        let mut body = Pin::new(&mut body);
        let data = body.data().await;
        assert!(data.is_none());
    }

    #[test]
    fn sdkbody_debug_once() {
        let body = SdkBody::from("123");
        // actually don't really care what the debug impl is, just that it doesn't crash
        let _ = format!("{:?}", body);
    }

    #[test]
    fn sdkbody_debug_dyn() {
        let hyper_body = hyper::Body::channel().1;
        let body = SdkBody::from_dyn(BoxBody::new(hyper_body.map_err(|e| e.into())));
        // actually don't really care what the debug impl is, just that it doesn't crash
        let _ = format!("{:?}", body);
    }

    #[test]
    fn sdkbody_debug_hyper() {
        let hyper_body = hyper::Body::channel().1;
        let body = SdkBody::from(hyper_body);
        // actually don't really care what the debug impl is, just that it doesn't crash
        let _ = format!("{:?}", body);
    }

    #[test]
    fn sdk_body_is_send() {
        fn is_send<T: Send>() {}
        is_send::<SdkBody>()
    }
}