opendal/services/compfs/
reader.rs

1// Licensed to the Apache Software Foundation (ASF) under one
2// or more contributor license agreements.  See the NOTICE file
3// distributed with this work for additional information
4// regarding copyright ownership.  The ASF licenses this file
5// to you under the Apache License, Version 2.0 (the
6// "License"); you may not use this file except in compliance
7// with the License.  You may obtain a copy of the License at
8//
9//   http://www.apache.org/licenses/LICENSE-2.0
10//
11// Unless required by applicable law or agreed to in writing,
12// software distributed under the License is distributed on an
13// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
14// KIND, either express or implied.  See the License for the
15// specific language governing permissions and limitations
16// under the License.
17
18use std::sync::Arc;
19
20use compio::buf::{buf_try, IntoInner, IoBuf};
21use compio::io::AsyncReadAt;
22
23use super::core::CompfsCore;
24use crate::raw::*;
25use crate::*;
26
27#[derive(Debug)]
28pub struct CompfsReader {
29    core: Arc<CompfsCore>,
30    file: compio::fs::File,
31    offset: u64,
32    end: Option<u64>,
33}
34
35impl CompfsReader {
36    pub(super) fn new(core: Arc<CompfsCore>, file: compio::fs::File, range: BytesRange) -> Self {
37        Self {
38            core,
39            file,
40            offset: range.offset(),
41            end: range.size().map(|v| v + range.offset()),
42        }
43    }
44}
45
46impl oio::Read for CompfsReader {
47    async fn read(&mut self) -> Result<Buffer> {
48        let pos = self.offset;
49        if let Some(end) = self.end {
50            if end <= pos {
51                return Ok(Buffer::new());
52            }
53        }
54
55        let mut bs = self.core.buf_pool.get();
56        // reserve 64KB buffer by default, we should allow user to configure this or make it adaptive.
57        let max_len = if let Some(end) = self.end {
58            (end - pos) as usize
59        } else {
60            64 * 1024
61        };
62        bs.reserve(max_len);
63        let f = self.file.clone();
64        let (n, mut bs) = self
65            .core
66            .exec(move || async move {
67                // reserve doesn't guarantee the exact size
68                let (n, bs) = buf_try!(@try f.read_at(bs.slice(..max_len), pos).await);
69                Ok((n, bs.into_inner()))
70            })
71            .await?;
72        let frozen = bs.split_to(n).freeze();
73        self.offset += frozen.len() as u64;
74        self.core.buf_pool.put(bs);
75        Ok(Buffer::from(frozen))
76    }
77}
opendal/services/compfs/reader.rs

opendal/services/compfs/
reader.rs
