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;
21use compio::buf::IntoInner;
22use compio::buf::IoBuf;
23use compio::io::AsyncReadAt;
24
25use super::core::CompfsCore;
26use crate::raw::*;
27use crate::*;
28
29#[derive(Debug)]
30pub struct CompfsReader {
31    core: Arc<CompfsCore>,
32    file: compio::fs::File,
33    offset: u64,
34    end: Option<u64>,
35}
36
37impl CompfsReader {
38    pub(super) fn new(core: Arc<CompfsCore>, file: compio::fs::File, range: BytesRange) -> Self {
39        Self {
40            core,
41            file,
42            offset: range.offset(),
43            end: range.size().map(|v| v + range.offset()),
44        }
45    }
46}
47
48impl oio::Read for CompfsReader {
49    async fn read(&mut self) -> Result<Buffer> {
50        let pos = self.offset;
51        if let Some(end) = self.end {
52            if end <= pos {
53                return Ok(Buffer::new());
54            }
55        }
56
57        let mut bs = self.core.buf_pool.get();
58        // reserve 64KB buffer by default, we should allow user to configure this or make it adaptive.
59        let max_len = if let Some(end) = self.end {
60            (end - pos) as usize
61        } else {
62            64 * 1024
63        };
64        bs.reserve(max_len);
65        let f = self.file.clone();
66        let (n, mut bs) = self
67            .core
68            .exec(move || async move {
69                // reserve doesn't guarantee the exact size
70                let (n, bs) = buf_try!(@try f.read_at(bs.slice(..max_len), pos).await);
71                Ok((n, bs.into_inner()))
72            })
73            .await?;
74        let frozen = bs.split_to(n).freeze();
75        self.offset += frozen.len() as u64;
76        self.core.buf_pool.put(bs);
77        Ok(Buffer::from(frozen))
78    }
79}
opendal/services/compfs/reader.rs

opendal/services/compfs/
reader.rs
