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
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

//! Utilities for performing tokio-style buffered IO

use crate::path::Path;
use crate::{
    Attributes, ObjectMeta, ObjectStore, PutMultipartOpts, PutOptions, PutPayloadMut, TagSet,
    WriteMultipart,
};
use bytes::Bytes;
use futures::future::{BoxFuture, FutureExt};
use futures::ready;
use std::cmp::Ordering;
use std::io::{Error, ErrorKind, SeekFrom};
use std::pin::Pin;
use std::sync::Arc;
use std::task::{Context, Poll};
use tokio::io::{AsyncBufRead, AsyncRead, AsyncSeek, AsyncWrite, ReadBuf};

/// The default buffer size used by [`BufReader`]
pub const DEFAULT_BUFFER_SIZE: usize = 1024 * 1024;

/// An async-buffered reader compatible with the tokio IO traits
///
/// Internally this maintains a buffer of the requested size, and uses [`ObjectStore::get_range`]
/// to populate its internal buffer once depleted. This buffer is cleared on seek.
///
/// Whilst simple, this interface will typically be outperformed by the native [`ObjectStore`]
/// methods that better map to the network APIs. This is because most object stores have
/// very [high first-byte latencies], on the order of 100-200ms, and so avoiding unnecessary
/// round-trips is critical to throughput.
///
/// Systems looking to sequentially scan a file should instead consider using [`ObjectStore::get`],
/// or [`ObjectStore::get_opts`], or [`ObjectStore::get_range`] to read a particular range.
///
/// Systems looking to read multiple ranges of a file should instead consider using
/// [`ObjectStore::get_ranges`], which will optimise the vectored IO.
///
/// [high first-byte latencies]: https://docs.aws.amazon.com/AmazonS3/latest/userguide/optimizing-performance.html
pub struct BufReader {
    /// The object store to fetch data from
    store: Arc<dyn ObjectStore>,
    /// The size of the object
    size: u64,
    /// The path to the object
    path: Path,
    /// The current position in the object
    cursor: u64,
    /// The number of bytes to read in a single request
    capacity: usize,
    /// The buffered data if any
    buffer: Buffer,
}

impl std::fmt::Debug for BufReader {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("BufReader")
            .field("path", &self.path)
            .field("size", &self.size)
            .field("capacity", &self.capacity)
            .finish()
    }
}

enum Buffer {
    Empty,
    Pending(BoxFuture<'static, std::io::Result<Bytes>>),
    Ready(Bytes),
}

impl BufReader {
    /// Create a new [`BufReader`] from the provided [`ObjectMeta`] and [`ObjectStore`]
    pub fn new(store: Arc<dyn ObjectStore>, meta: &ObjectMeta) -> Self {
        Self::with_capacity(store, meta, DEFAULT_BUFFER_SIZE)
    }

    /// Create a new [`BufReader`] from the provided [`ObjectMeta`], [`ObjectStore`], and `capacity`
    pub fn with_capacity(store: Arc<dyn ObjectStore>, meta: &ObjectMeta, capacity: usize) -> Self {
        Self {
            path: meta.location.clone(),
            size: meta.size as _,
            store,
            capacity,
            cursor: 0,
            buffer: Buffer::Empty,
        }
    }

    fn poll_fill_buf_impl(
        &mut self,
        cx: &mut Context<'_>,
        amnt: usize,
    ) -> Poll<std::io::Result<&[u8]>> {
        let buf = &mut self.buffer;
        loop {
            match buf {
                Buffer::Empty => {
                    let store = Arc::clone(&self.store);
                    let path = self.path.clone();
                    let start = self.cursor.min(self.size) as _;
                    let end = self.cursor.saturating_add(amnt as u64).min(self.size) as _;

                    if start == end {
                        return Poll::Ready(Ok(&[]));
                    }

                    *buf = Buffer::Pending(Box::pin(async move {
                        Ok(store.get_range(&path, start..end).await?)
                    }))
                }
                Buffer::Pending(fut) => match ready!(fut.poll_unpin(cx)) {
                    Ok(b) => *buf = Buffer::Ready(b),
                    Err(e) => return Poll::Ready(Err(e)),
                },
                Buffer::Ready(r) => return Poll::Ready(Ok(r)),
            }
        }
    }
}

impl AsyncSeek for BufReader {
    fn start_seek(mut self: Pin<&mut Self>, position: SeekFrom) -> std::io::Result<()> {
        self.cursor = match position {
            SeekFrom::Start(offset) => offset,
            SeekFrom::End(offset) => checked_add_signed(self.size, offset).ok_or_else(|| {
                Error::new(
                    ErrorKind::InvalidInput,
                    format!(
                        "Seeking {offset} from end of {} byte file would result in overflow",
                        self.size
                    ),
                )
            })?,
            SeekFrom::Current(offset) => {
                checked_add_signed(self.cursor, offset).ok_or_else(|| {
                    Error::new(
                        ErrorKind::InvalidInput,
                        format!(
                            "Seeking {offset} from current offset of {} would result in overflow",
                            self.cursor
                        ),
                    )
                })?
            }
        };
        self.buffer = Buffer::Empty;
        Ok(())
    }

    fn poll_complete(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<std::io::Result<u64>> {
        Poll::Ready(Ok(self.cursor))
    }
}

impl AsyncRead for BufReader {
    fn poll_read(
        mut self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        out: &mut ReadBuf<'_>,
    ) -> Poll<std::io::Result<()>> {
        // Read the maximum of the internal buffer and `out`
        let to_read = out.remaining().max(self.capacity);
        let r = match ready!(self.poll_fill_buf_impl(cx, to_read)) {
            Ok(buf) => {
                let to_consume = out.remaining().min(buf.len());
                out.put_slice(&buf[..to_consume]);
                self.consume(to_consume);
                Ok(())
            }
            Err(e) => Err(e),
        };
        Poll::Ready(r)
    }
}

impl AsyncBufRead for BufReader {
    fn poll_fill_buf(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<std::io::Result<&[u8]>> {
        let capacity = self.capacity;
        self.get_mut().poll_fill_buf_impl(cx, capacity)
    }

    fn consume(mut self: Pin<&mut Self>, amt: usize) {
        match &mut self.buffer {
            Buffer::Empty => assert_eq!(amt, 0, "cannot consume from empty buffer"),
            Buffer::Ready(b) => match b.len().cmp(&amt) {
                Ordering::Less => panic!("{amt} exceeds buffer sized of {}", b.len()),
                Ordering::Greater => *b = b.slice(amt..),
                Ordering::Equal => self.buffer = Buffer::Empty,
            },
            Buffer::Pending(_) => panic!("cannot consume from pending buffer"),
        }
        self.cursor += amt as u64;
    }
}

/// An async buffered writer compatible with the tokio IO traits
///
/// This writer adaptively uses [`ObjectStore::put`] or
/// [`ObjectStore::put_multipart`] depending on the amount of data that has
/// been written.
///
/// Up to `capacity` bytes will be buffered in memory, and flushed on shutdown
/// using [`ObjectStore::put`]. If `capacity` is exceeded, data will instead be
/// streamed using [`ObjectStore::put_multipart`]
pub struct BufWriter {
    capacity: usize,
    max_concurrency: usize,
    attributes: Option<Attributes>,
    tags: Option<TagSet>,
    state: BufWriterState,
    store: Arc<dyn ObjectStore>,
}

impl std::fmt::Debug for BufWriter {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("BufWriter")
            .field("capacity", &self.capacity)
            .finish()
    }
}

enum BufWriterState {
    /// Buffer up to capacity bytes
    Buffer(Path, PutPayloadMut),
    /// [`ObjectStore::put_multipart`]
    Prepare(BoxFuture<'static, crate::Result<WriteMultipart>>),
    /// Write to a multipart upload
    Write(Option<WriteMultipart>),
    /// [`ObjectStore::put`]
    Flush(BoxFuture<'static, crate::Result<()>>),
}

impl BufWriter {
    /// Create a new [`BufWriter`] from the provided [`ObjectStore`] and [`Path`]
    pub fn new(store: Arc<dyn ObjectStore>, path: Path) -> Self {
        Self::with_capacity(store, path, 10 * 1024 * 1024)
    }

    /// Create a new [`BufWriter`] from the provided [`ObjectStore`], [`Path`] and `capacity`
    pub fn with_capacity(store: Arc<dyn ObjectStore>, path: Path, capacity: usize) -> Self {
        Self {
            capacity,
            store,
            max_concurrency: 8,
            attributes: None,
            tags: None,
            state: BufWriterState::Buffer(path, PutPayloadMut::new()),
        }
    }

    /// Override the maximum number of in-flight requests for this writer
    ///
    /// Defaults to 8
    pub fn with_max_concurrency(self, max_concurrency: usize) -> Self {
        Self {
            max_concurrency,
            ..self
        }
    }

    /// Set the attributes of the uploaded object
    pub fn with_attributes(self, attributes: Attributes) -> Self {
        Self {
            attributes: Some(attributes),
            ..self
        }
    }

    /// Set the tags of the uploaded object
    pub fn with_tags(self, tags: TagSet) -> Self {
        Self {
            tags: Some(tags),
            ..self
        }
    }

    /// Write data to the writer in [`Bytes`].
    ///
    /// Unlike [`AsyncWrite::poll_write`], `put` can write data without extra copying.
    ///
    /// This API is recommended while the data source generates [`Bytes`].
    pub async fn put(&mut self, bytes: Bytes) -> crate::Result<()> {
        loop {
            return match &mut self.state {
                BufWriterState::Write(Some(write)) => {
                    write.wait_for_capacity(self.max_concurrency).await?;
                    write.put(bytes);
                    Ok(())
                }
                BufWriterState::Write(None) | BufWriterState::Flush(_) => {
                    panic!("Already shut down")
                }
                // NOTE
                //
                // This case should never happen in practice, but rust async API does
                // make it possible for users to call `put` before `poll_write` returns `Ready`.
                //
                // We allow such usage by `await` the future and continue the loop.
                BufWriterState::Prepare(f) => {
                    self.state = BufWriterState::Write(f.await?.into());
                    continue;
                }
                BufWriterState::Buffer(path, b) => {
                    if b.content_length().saturating_add(bytes.len()) < self.capacity {
                        b.push(bytes);
                        Ok(())
                    } else {
                        let buffer = std::mem::take(b);
                        let path = std::mem::take(path);
                        let opts = PutMultipartOpts {
                            attributes: self.attributes.take().unwrap_or_default(),
                            tags: self.tags.take().unwrap_or_default(),
                        };
                        let upload = self.store.put_multipart_opts(&path, opts).await?;
                        let mut chunked =
                            WriteMultipart::new_with_chunk_size(upload, self.capacity);
                        for chunk in buffer.freeze() {
                            chunked.put(chunk);
                        }
                        chunked.put(bytes);
                        self.state = BufWriterState::Write(Some(chunked));
                        Ok(())
                    }
                }
            };
        }
    }

    /// Abort this writer, cleaning up any partially uploaded state
    ///
    /// # Panic
    ///
    /// Panics if this writer has already been shutdown or aborted
    pub async fn abort(&mut self) -> crate::Result<()> {
        match &mut self.state {
            BufWriterState::Buffer(_, _) | BufWriterState::Prepare(_) => Ok(()),
            BufWriterState::Flush(_) => panic!("Already shut down"),
            BufWriterState::Write(x) => x.take().unwrap().abort().await,
        }
    }
}

impl AsyncWrite for BufWriter {
    fn poll_write(
        mut self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &[u8],
    ) -> Poll<Result<usize, Error>> {
        let cap = self.capacity;
        let max_concurrency = self.max_concurrency;
        loop {
            return match &mut self.state {
                BufWriterState::Write(Some(write)) => {
                    ready!(write.poll_for_capacity(cx, max_concurrency))?;
                    write.write(buf);
                    Poll::Ready(Ok(buf.len()))
                }
                BufWriterState::Write(None) | BufWriterState::Flush(_) => {
                    panic!("Already shut down")
                }
                BufWriterState::Prepare(f) => {
                    self.state = BufWriterState::Write(ready!(f.poll_unpin(cx)?).into());
                    continue;
                }
                BufWriterState::Buffer(path, b) => {
                    if b.content_length().saturating_add(buf.len()) >= cap {
                        let buffer = std::mem::take(b);
                        let path = std::mem::take(path);
                        let opts = PutMultipartOpts {
                            attributes: self.attributes.take().unwrap_or_default(),
                            tags: self.tags.take().unwrap_or_default(),
                        };
                        let store = Arc::clone(&self.store);
                        self.state = BufWriterState::Prepare(Box::pin(async move {
                            let upload = store.put_multipart_opts(&path, opts).await?;
                            let mut chunked = WriteMultipart::new_with_chunk_size(upload, cap);
                            for chunk in buffer.freeze() {
                                chunked.put(chunk);
                            }
                            Ok(chunked)
                        }));
                        continue;
                    }
                    b.extend_from_slice(buf);
                    Poll::Ready(Ok(buf.len()))
                }
            };
        }
    }

    fn poll_flush(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Error>> {
        loop {
            return match &mut self.state {
                BufWriterState::Write(_) | BufWriterState::Buffer(_, _) => Poll::Ready(Ok(())),
                BufWriterState::Flush(_) => panic!("Already shut down"),
                BufWriterState::Prepare(f) => {
                    self.state = BufWriterState::Write(ready!(f.poll_unpin(cx)?).into());
                    continue;
                }
            };
        }
    }

    fn poll_shutdown(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Error>> {
        loop {
            match &mut self.state {
                BufWriterState::Prepare(f) => {
                    self.state = BufWriterState::Write(ready!(f.poll_unpin(cx)?).into());
                }
                BufWriterState::Buffer(p, b) => {
                    let buf = std::mem::take(b);
                    let path = std::mem::take(p);
                    let opts = PutOptions {
                        attributes: self.attributes.take().unwrap_or_default(),
                        tags: self.tags.take().unwrap_or_default(),
                        ..Default::default()
                    };
                    let store = Arc::clone(&self.store);
                    self.state = BufWriterState::Flush(Box::pin(async move {
                        store.put_opts(&path, buf.into(), opts).await?;
                        Ok(())
                    }));
                }
                BufWriterState::Flush(f) => return f.poll_unpin(cx).map_err(std::io::Error::from),
                BufWriterState::Write(x) => {
                    let upload = x.take().ok_or_else(|| {
                        std::io::Error::new(
                            ErrorKind::InvalidInput,
                            "Cannot shutdown a writer that has already been shut down",
                        )
                    })?;
                    self.state = BufWriterState::Flush(
                        async move {
                            upload.finish().await?;
                            Ok(())
                        }
                        .boxed(),
                    )
                }
            }
        }
    }
}

/// Port of standardised function as requires Rust 1.66
///
/// <https://github.com/rust-lang/rust/pull/87601/files#diff-b9390ee807a1dae3c3128dce36df56748ad8d23c6e361c0ebba4d744bf6efdb9R1533>
#[inline]
fn checked_add_signed(a: u64, rhs: i64) -> Option<u64> {
    let (res, overflowed) = a.overflowing_add(rhs as _);
    let overflow = overflowed ^ (rhs < 0);
    (!overflow).then_some(res)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::memory::InMemory;
    use crate::path::Path;
    use crate::{Attribute, GetOptions};
    use itertools::Itertools;
    use tokio::io::{AsyncBufReadExt, AsyncReadExt, AsyncSeekExt, AsyncWriteExt};

    #[tokio::test]
    async fn test_buf_reader() {
        let store = Arc::new(InMemory::new()) as Arc<dyn ObjectStore>;

        let existent = Path::from("exists.txt");
        const BYTES: usize = 4096;

        let data: Bytes = b"12345678".iter().cycle().copied().take(BYTES).collect();
        store.put(&existent, data.clone().into()).await.unwrap();

        let meta = store.head(&existent).await.unwrap();

        let mut reader = BufReader::new(Arc::clone(&store), &meta);
        let mut out = Vec::with_capacity(BYTES);
        let read = reader.read_to_end(&mut out).await.unwrap();

        assert_eq!(read, BYTES);
        assert_eq!(&out, &data);

        let err = reader.seek(SeekFrom::Current(i64::MIN)).await.unwrap_err();
        assert_eq!(
            err.to_string(),
            "Seeking -9223372036854775808 from current offset of 4096 would result in overflow"
        );

        reader.rewind().await.unwrap();

        let err = reader.seek(SeekFrom::Current(-1)).await.unwrap_err();
        assert_eq!(
            err.to_string(),
            "Seeking -1 from current offset of 0 would result in overflow"
        );

        // Seeking beyond the bounds of the file is permitted but should return no data
        reader.seek(SeekFrom::Start(u64::MAX)).await.unwrap();
        let buf = reader.fill_buf().await.unwrap();
        assert!(buf.is_empty());

        let err = reader.seek(SeekFrom::Current(1)).await.unwrap_err();
        assert_eq!(
            err.to_string(),
            "Seeking 1 from current offset of 18446744073709551615 would result in overflow"
        );

        for capacity in [200, 1024, 4096, DEFAULT_BUFFER_SIZE] {
            let store = Arc::clone(&store);
            let mut reader = BufReader::with_capacity(store, &meta, capacity);

            let mut bytes_read = 0;
            loop {
                let buf = reader.fill_buf().await.unwrap();
                if buf.is_empty() {
                    assert_eq!(bytes_read, BYTES);
                    break;
                }
                assert!(buf.starts_with(b"12345678"));
                bytes_read += 8;
                reader.consume(8);
            }

            let mut buf = Vec::with_capacity(76);
            reader.seek(SeekFrom::Current(-76)).await.unwrap();
            reader.read_to_end(&mut buf).await.unwrap();
            assert_eq!(&buf, &data[BYTES - 76..]);

            reader.rewind().await.unwrap();
            let buffer = reader.fill_buf().await.unwrap();
            assert_eq!(buffer, &data[..capacity.min(BYTES)]);

            reader.seek(SeekFrom::Start(325)).await.unwrap();
            let buffer = reader.fill_buf().await.unwrap();
            assert_eq!(buffer, &data[325..(325 + capacity).min(BYTES)]);

            reader.seek(SeekFrom::End(0)).await.unwrap();
            let buffer = reader.fill_buf().await.unwrap();
            assert!(buffer.is_empty());
        }
    }

    // Note: `BufWriter::with_tags` functionality is tested in `crate::tests::tagging`
    #[tokio::test]
    async fn test_buf_writer() {
        let store = Arc::new(InMemory::new()) as Arc<dyn ObjectStore>;
        let path = Path::from("file.txt");
        let attributes = Attributes::from_iter([
            (Attribute::ContentType, "text/html"),
            (Attribute::CacheControl, "max-age=604800"),
        ]);

        // Test put
        let mut writer = BufWriter::with_capacity(Arc::clone(&store), path.clone(), 30)
            .with_attributes(attributes.clone());
        writer.write_all(&[0; 20]).await.unwrap();
        writer.flush().await.unwrap();
        writer.write_all(&[0; 5]).await.unwrap();
        writer.shutdown().await.unwrap();
        let response = store
            .get_opts(
                &path,
                GetOptions {
                    head: true,
                    ..Default::default()
                },
            )
            .await
            .unwrap();
        assert_eq!(response.meta.size, 25);
        assert_eq!(response.attributes, attributes);

        // Test multipart
        let mut writer = BufWriter::with_capacity(Arc::clone(&store), path.clone(), 30)
            .with_attributes(attributes.clone());
        writer.write_all(&[0; 20]).await.unwrap();
        writer.flush().await.unwrap();
        writer.write_all(&[0; 20]).await.unwrap();
        writer.shutdown().await.unwrap();
        let response = store
            .get_opts(
                &path,
                GetOptions {
                    head: true,
                    ..Default::default()
                },
            )
            .await
            .unwrap();
        assert_eq!(response.meta.size, 40);
        assert_eq!(response.attributes, attributes);
    }

    #[tokio::test]
    async fn test_buf_writer_with_put() {
        let store = Arc::new(InMemory::new()) as Arc<dyn ObjectStore>;
        let path = Path::from("file.txt");

        // Test put
        let mut writer = BufWriter::with_capacity(Arc::clone(&store), path.clone(), 30);
        writer
            .put(Bytes::from((0..20).collect_vec()))
            .await
            .unwrap();
        writer
            .put(Bytes::from((20..25).collect_vec()))
            .await
            .unwrap();
        writer.shutdown().await.unwrap();
        let response = store
            .get_opts(
                &path,
                GetOptions {
                    head: true,
                    ..Default::default()
                },
            )
            .await
            .unwrap();
        assert_eq!(response.meta.size, 25);
        assert_eq!(response.bytes().await.unwrap(), (0..25).collect_vec());

        // Test multipart
        let mut writer = BufWriter::with_capacity(Arc::clone(&store), path.clone(), 30);
        writer
            .put(Bytes::from((0..20).collect_vec()))
            .await
            .unwrap();
        writer
            .put(Bytes::from((20..40).collect_vec()))
            .await
            .unwrap();
        writer.shutdown().await.unwrap();
        let response = store
            .get_opts(
                &path,
                GetOptions {
                    head: true,
                    ..Default::default()
                },
            )
            .await
            .unwrap();
        assert_eq!(response.meta.size, 40);
        assert_eq!(response.bytes().await.unwrap(), (0..40).collect_vec());
    }
}