opendal/services/hdfs_native/
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 bytes::Bytes;
19use futures::StreamExt;
20use hdfs_native::file::FileReader;
21use hdfs_native::HdfsError;
22
23use crate::raw::*;
24use crate::services::hdfs_native::error::parse_hdfs_error;
25use crate::*;
26
27pub struct HdfsNativeReader {
28    read: usize,
29    size: usize,
30    stream: futures::stream::BoxStream<'static, Result<Bytes, HdfsError>>,
31}
32
33unsafe impl Sync for HdfsNativeReader {}
34
35impl HdfsNativeReader {
36    pub fn new(f: FileReader, offset: usize, size: usize) -> Self {
37        let size = size.min(f.file_length() - offset);
38        HdfsNativeReader {
39            read: 0,
40            size,
41            stream: Box::pin(f.read_range_stream(offset, size)),
42        }
43    }
44}
45
46impl oio::Read for HdfsNativeReader {
47    async fn read(&mut self) -> Result<Buffer> {
48        if self.read >= self.size {
49            return Ok(Buffer::new());
50        }
51
52        if let Some(bytes) = self.stream.as_mut().next().await {
53            let bytes = bytes.map_err(parse_hdfs_error)?;
54            let buf = Buffer::from(bytes);
55            self.read += buf.len();
56
57            Ok(buf)
58        } else {
59            Ok(Buffer::new())
60        }
61    }
62}
opendal/services/hdfs_native/reader.rs

opendal/services/hdfs_native/
reader.rs
