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
// 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.
use std::cmp;
use std::future::Future;
use std::pin::Pin;
use std::task::ready;
use std::task::Context;
use std::task::Poll;
use flagset::FlagSet;
use futures::Stream;
use futures::StreamExt;
use crate::raw::*;
use crate::*;
/// Lister is designed to list entries at given path in an asynchronous
/// manner.
///
/// Users can construct Lister by [`Operator::lister`] or [`Operator::lister_with`], and can use `metakey` along with list.
/// For example, suppose you need to access `content_length`, you can bring the corresponding field in metakey when listing:
/// `op.list_with("dir/").metakey(Metakey::ContentLength).await?;`.
///
/// - Lister implements `Stream<Item = Result<Entry>>`.
/// - Lister will return `None` if there is no more entries or error has been returned.
pub struct Lister {
acc: FusedAccessor,
lister: Option<oio::Lister>,
/// required_metakey is the metakey required by users.
required_metakey: FlagSet<Metakey>,
fut: Option<BoxedStaticFuture<(oio::Lister, Result<Option<oio::Entry>>)>>,
/// tasks is used to store tasks that are run in concurrent.
///
/// TODO: maybe we should move logic inside?
tasks: ConcurrentFutures<StatTask>,
errored: bool,
}
/// StatTask is used to store the task that is run in concurrent.
///
/// # Note for clippy
///
/// Clippy will raise error for this enum like the following:
///
/// ```shell
/// error: large size difference between variants
/// --> core/src/types/list.rs:64:1
/// |
/// 64 | / enum StatTask {
/// 65 | | /// BoxFuture is used to store the join handle of spawned task.
/// 66 | | Handle(BoxFuture<(String, Result<RpStat>)>),
/// | | -------------------------------------------- the second-largest variant contains at least 0 bytes
/// 67 | | /// KnownEntry is used to store the entry that already contains the required metakey.
/// 68 | | KnownEntry(Option<Entry>),
/// | | ------------------------- the largest variant contains at least 264 bytes
/// 69 | | }
/// | |_^ the entire enum is at least 0 bytes
/// |
/// = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#large_enum_variant
/// = note: `-D clippy::large-enum-variant` implied by `-D warnings`
/// = help: to override `-D warnings` add `#[allow(clippy::large_enum_variant)]`
/// help: consider boxing the large fields to reduce the total size of the enum
/// |
/// 68 | KnownEntry(Box<Option<Entry>>),
/// | ~~~~~~~~~~~~~~~~~~
/// ```
/// But this lint is wrong since it doesn't take the generic param JoinHandle into account. In fact, they have exactly
/// the same size:
///
/// ```rust
/// use std::mem::size_of;
///
/// use opendal::Entry;
/// use opendal::Result;
///
/// assert_eq!(256, size_of::<(String, Result<opendal::raw::RpStat>)>());
/// assert_eq!(256, size_of::<Option<Entry>>());
/// ```
///
/// So let's ignore this lint:
#[allow(clippy::large_enum_variant)]
enum StatTask {
/// Stating is used to store the join handle of spawned task.
///
/// TODO: Replace with static future type after rust supported.
Stating(BoxedStaticFuture<(String, Result<Metadata>)>),
/// Known is used to store the entry that already contains the required metakey.
Known(Option<(String, Metadata)>),
}
impl Future for StatTask {
type Output = (String, Result<Metadata>);
fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Self::Output> {
match self.get_mut() {
StatTask::Stating(fut) => Pin::new(fut).poll(cx),
StatTask::Known(entry) => {
let (path, metadata) = entry.take().expect("entry should not be None");
Poll::Ready((path, Ok(metadata)))
}
}
}
}
/// # Safety
///
/// Lister will only be accessed by `&mut Self`
unsafe impl Sync for Lister {}
impl Lister {
/// Create a new lister.
pub(crate) async fn create(acc: FusedAccessor, path: &str, args: OpList) -> Result<Self> {
let required_metakey = args.metakey();
let concurrent = cmp::max(1, args.concurrent());
let (_, lister) = acc.list(path, args).await?;
Ok(Self {
acc,
lister: Some(lister),
required_metakey,
fut: None,
tasks: ConcurrentFutures::new(concurrent),
errored: false,
})
}
}
impl Stream for Lister {
type Item = Result<Entry>;
fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
// Returns `None` if we have errored.
if self.errored {
return Poll::Ready(None);
}
// Trying to pull more tasks if there are more space.
if self.tasks.has_remaining() {
// Building future is we have a lister available.
if let Some(mut lister) = self.lister.take() {
let fut = async move {
let res = lister.next_dyn().await;
(lister, res)
};
self.fut = Some(Box::pin(fut));
}
if let Some(fut) = self.fut.as_mut() {
if let Poll::Ready((lister, entry)) = fut.as_mut().poll(cx) {
self.lister = Some(lister);
self.fut = None;
match entry {
Ok(Some(oe)) => {
let (path, metadata) = oe.into_entry().into_parts();
if metadata.contains_metakey(self.required_metakey) {
self.tasks
.push_back(StatTask::Known(Some((path, metadata))));
} else {
let acc = self.acc.clone();
let fut = async move {
let res = acc.stat(&path, OpStat::default()).await;
(path, res.map(|rp| rp.into_metadata()))
};
self.tasks.push_back(StatTask::Stating(Box::pin(fut)));
}
}
Ok(None) => {
self.lister = None;
}
Err(err) => {
self.errored = true;
return Poll::Ready(Some(Err(err)));
}
}
}
}
}
// Try to poll tasks
if let Some((path, rp)) = ready!(self.tasks.poll_next_unpin(cx)) {
let metadata = rp?;
return Poll::Ready(Some(Ok(Entry::new(path, metadata))));
}
if self.lister.is_some() || self.fut.is_some() {
Poll::Pending
} else {
Poll::Ready(None)
}
}
}
/// BlockingLister is designed to list entries at given path in a blocking
/// manner.
///
/// Users can construct Lister by [`BlockingOperator::lister`] or [`BlockingOperator::lister_with`].
///
/// - Lister implements `Iterator<Item = Result<Entry>>`.
/// - Lister will return `None` if there is no more entries or error has been returned.
pub struct BlockingLister {
acc: FusedAccessor,
/// required_metakey is the metakey required by users.
required_metakey: FlagSet<Metakey>,
lister: oio::BlockingLister,
errored: bool,
}
/// # Safety
///
/// BlockingLister will only be accessed by `&mut Self`
unsafe impl Sync for BlockingLister {}
impl BlockingLister {
/// Create a new lister.
pub(crate) fn create(acc: FusedAccessor, path: &str, args: OpList) -> Result<Self> {
let required_metakey = args.metakey();
let (_, lister) = acc.blocking_list(path, args)?;
Ok(Self {
acc,
required_metakey,
lister,
errored: false,
})
}
}
/// TODO: we can implement next_chunk.
impl Iterator for BlockingLister {
type Item = Result<Entry>;
fn next(&mut self) -> Option<Self::Item> {
// Returns `None` if we have errored.
if self.errored {
return None;
}
let entry = match self.lister.next() {
Ok(Some(entry)) => entry,
Ok(None) => return None,
Err(err) => {
self.errored = true;
return Some(Err(err));
}
};
let (path, metadata) = entry.into_entry().into_parts();
if metadata.contains_metakey(self.required_metakey) {
return Some(Ok(Entry::new(path, metadata)));
}
let metadata = match self.acc.blocking_stat(&path, OpStat::default()) {
Ok(rp) => rp.into_metadata(),
Err(err) => {
self.errored = true;
return Some(Err(err));
}
};
Some(Ok(Entry::new(path, metadata)))
}
}
#[cfg(test)]
#[cfg(feature = "services-azblob")]
mod tests {
use futures::future;
use futures::StreamExt;
use super::*;
use crate::services::Azblob;
/// Inspired by <https://gist.github.com/kyle-mccarthy/1e6ae89cc34495d731b91ebf5eb5a3d9>
///
/// Invalid lister should not panic nor endless loop.
#[tokio::test]
async fn test_invalid_lister() -> Result<()> {
let _ = tracing_subscriber::fmt().try_init();
let mut builder = Azblob::default();
builder
.container("container")
.account_name("account_name")
.account_key("account_key")
.endpoint("https://account_name.blob.core.windows.net");
let operator = Operator::new(builder)?.finish();
let lister = operator.lister("/").await?;
lister
.filter_map(|entry| {
dbg!(&entry);
future::ready(entry.ok())
})
.for_each(|entry| {
println!("{:?}", entry);
future::ready(())
})
.await;
Ok(())
}
}