iroh_blobs/api/blobs/reader.rs
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
use std::{
io::{self, ErrorKind, SeekFrom},
pin::Pin,
task::{Context, Poll},
};
use n0_future::StreamExt;
use crate::{
api::{
blobs::{Blobs, ReaderOptions},
proto::ExportRangesItem,
},
Hash,
};
/// A reader for blobs that implements `AsyncRead` and `AsyncSeek`.
#[derive(Debug)]
pub struct BlobReader {
blobs: Blobs,
options: ReaderOptions,
state: ReaderState,
}
#[derive(Default, derive_more::Debug)]
enum ReaderState {
Idle {
position: u64,
},
Seeking {
position: u64,
},
Reading {
position: u64,
#[debug(skip)]
op: n0_future::boxed::BoxStream<ExportRangesItem>,
},
#[default]
Poisoned,
}
impl BlobReader {
pub(super) fn new(blobs: Blobs, options: ReaderOptions) -> Self {
Self {
blobs,
options,
state: ReaderState::Idle { position: 0 },
}
}
pub fn hash(&self) -> &Hash {
&self.options.hash
}
}
impl tokio::io::AsyncRead for BlobReader {
fn poll_read(
self: Pin<&mut Self>,
cx: &mut Context<'_>,
buf: &mut tokio::io::ReadBuf<'_>,
) -> Poll<io::Result<()>> {
let this = self.get_mut();
let mut position1 = None;
loop {
let guard = &mut this.state;
match std::mem::take(guard) {
ReaderState::Idle { position } => {
// todo: read until next page boundary instead of fixed size
let len = buf.remaining() as u64;
let end = position.checked_add(len).ok_or_else(|| {
io::Error::new(ErrorKind::InvalidInput, "Position overflow when reading")
})?;
// start the export op for the entire size of the buffer, and convert to a stream
let stream = this
.blobs
.export_ranges(this.options.hash, position..end)
.stream();
position1 = Some(position);
*guard = ReaderState::Reading {
position,
op: Box::pin(stream),
};
}
ReaderState::Reading { position, mut op } => {
let position1 = position1.get_or_insert(position);
match op.poll_next(cx) {
Poll::Ready(Some(ExportRangesItem::Size(_))) => {
*guard = ReaderState::Reading { position, op };
}
Poll::Ready(Some(ExportRangesItem::Data(data))) => {
if data.offset != *position1 {
break Poll::Ready(Err(io::Error::other(
"Data offset does not match expected position",
)));
}
buf.put_slice(&data.data);
// update just local position1, not the position in the state.
*position1 =
position1
.checked_add(data.data.len() as u64)
.ok_or_else(|| {
io::Error::new(ErrorKind::InvalidInput, "Position overflow")
})?;
*guard = ReaderState::Reading { position, op };
}
Poll::Ready(Some(ExportRangesItem::Error(err))) => {
*guard = ReaderState::Idle { position };
break Poll::Ready(Err(io::Error::other(format!(
"Error reading data: {err}"
))));
}
Poll::Ready(None) => {
// done with the stream, go back in idle.
*guard = ReaderState::Idle {
position: *position1,
};
break Poll::Ready(Ok(()));
}
Poll::Pending => {
break if position != *position1 {
// we read some data so we need to abort the op.
//
// we can't be sure we won't be called with the same buf size next time.
*guard = ReaderState::Idle {
position: *position1,
};
Poll::Ready(Ok(()))
} else {
// nothing was read yet, we remain in the reading state
//
// we make an assumption here that the next call will be with the same buf size.
*guard = ReaderState::Reading {
position: *position1,
op,
};
Poll::Pending
};
}
}
}
state @ ReaderState::Seeking { .. } => {
// should I try to recover from this or just keep it poisoned?
this.state = state;
break Poll::Ready(Err(io::Error::other("Can't read while seeking")));
}
ReaderState::Poisoned => {
break Poll::Ready(Err(io::Error::other("Reader is poisoned")));
}
};
}
}
}
impl tokio::io::AsyncSeek for BlobReader {
fn start_seek(
self: std::pin::Pin<&mut Self>,
seek_from: tokio::io::SeekFrom,
) -> io::Result<()> {
let this = self.get_mut();
let guard = &mut this.state;
match std::mem::take(guard) {
ReaderState::Idle { position } => {
let position1 = match seek_from {
SeekFrom::Start(pos) => pos,
SeekFrom::Current(offset) => {
position.checked_add_signed(offset).ok_or_else(|| {
io::Error::new(
ErrorKind::InvalidInput,
"Position overflow when seeking",
)
})?
}
SeekFrom::End(_offset) => {
// todo: support seeking from end if we know the size
return Err(io::Error::new(
ErrorKind::InvalidInput,
"Seeking from end is not supported yet",
))?;
}
};
*guard = ReaderState::Seeking {
position: position1,
};
Ok(())
}
ReaderState::Reading { .. } => Err(io::Error::other("Can't seek while reading")),
ReaderState::Seeking { .. } => Err(io::Error::other("Already seeking")),
ReaderState::Poisoned => Err(io::Error::other("Reader is poisoned")),
}
}
fn poll_complete(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<io::Result<u64>> {
let this = self.get_mut();
let guard = &mut this.state;
Poll::Ready(match std::mem::take(guard) {
ReaderState::Seeking { position } => {
*guard = ReaderState::Idle { position };
Ok(position)
}
ReaderState::Idle { position } => {
// seek calls poll_complete just in case, to finish a pending seek operation
// before the next seek operation. So it is poll_complete/start_seek/poll_complete
*guard = ReaderState::Idle { position };
Ok(position)
}
state @ ReaderState::Reading { .. } => {
// should I try to recover from this or just keep it poisoned?
*guard = state;
Err(io::Error::other("Can't seek while reading"))
}
ReaderState::Poisoned => Err(io::Error::other("Reader is poisoned")),
})
}
}
#[cfg(test)]
mod tests {
use bao_tree::ChunkRanges;
use testresult::TestResult;
use tokio::io::{AsyncReadExt, AsyncSeekExt};
use super::*;
use crate::{
store::{
fs::{
tests::{create_n0_bao, test_data, INTERESTING_SIZES},
FsStore,
},
mem::MemStore,
},
util::ChunkRangesExt,
};
async fn reader_smoke(blobs: &Blobs) -> TestResult<()> {
for size in INTERESTING_SIZES {
let data = test_data(size);
let tag = blobs.add_bytes(data.clone()).await?;
// read all
{
let mut reader = blobs.reader(tag.hash);
let mut buf = Vec::new();
reader.read_to_end(&mut buf).await?;
assert_eq!(buf, data);
let pos = reader.stream_position().await?;
assert_eq!(pos, data.len() as u64);
}
// seek to mid and read all
{
let mut reader = blobs.reader(tag.hash);
let mid = size / 2;
reader.seek(SeekFrom::Start(mid as u64)).await?;
let mut buf = Vec::new();
reader.read_to_end(&mut buf).await?;
assert_eq!(buf, data[mid..].to_vec());
let pos = reader.stream_position().await?;
assert_eq!(pos, data.len() as u64);
}
}
Ok(())
}
async fn reader_partial(blobs: &Blobs) -> TestResult<()> {
for size in INTERESTING_SIZES {
let data = test_data(size);
let ranges = ChunkRanges::chunk(0);
let (hash, bao) = create_n0_bao(&data, &ranges)?;
println!("importing {} bytes", bao.len());
blobs.import_bao_bytes(hash, ranges.clone(), bao).await?;
// read the first chunk or the entire blob, whatever is smaller
// this should work!
{
let mut reader = blobs.reader(hash);
let valid = size.min(1024);
let mut buf = vec![0u8; valid];
reader.read_exact(&mut buf).await?;
assert_eq!(buf, data[..valid]);
let pos = reader.stream_position().await?;
assert_eq!(pos, valid as u64);
}
if size > 1024 {
// read the part we don't have - should immediately return an error
{
let mut reader = blobs.reader(hash);
let mut rest = vec![0u8; size - 1024];
reader.seek(SeekFrom::Start(1024)).await?;
let res = reader.read_exact(&mut rest).await;
assert!(res.is_err());
}
// read crossing the end of the blob - should return an error despite
// the first bytes being valid.
// A read that fails should not update the stream position.
{
let mut reader = blobs.reader(hash);
let mut buf = vec![0u8; size];
let res = reader.read(&mut buf).await;
assert!(res.is_err());
let pos = reader.stream_position().await?;
assert_eq!(pos, 0);
}
}
}
Ok(())
}
#[tokio::test]
async fn reader_partial_fs() -> TestResult<()> {
let testdir = tempfile::tempdir()?;
let store = FsStore::load(testdir.path().to_owned()).await?;
reader_partial(store.blobs()).await?;
Ok(())
}
#[tokio::test]
async fn reader_partial_memory() -> TestResult<()> {
let store = MemStore::new();
reader_partial(store.blobs()).await?;
Ok(())
}
#[tokio::test]
async fn reader_smoke_fs() -> TestResult<()> {
let testdir = tempfile::tempdir()?;
let store = FsStore::load(testdir.path().to_owned()).await?;
reader_smoke(store.blobs()).await?;
Ok(())
}
#[tokio::test]
async fn reader_smoke_memory() -> TestResult<()> {
let store = MemStore::new();
reader_smoke(store.blobs()).await?;
Ok(())
}
}