virtiofs_opendal/
buffer.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::cell::RefCell;
19use std::cmp::min;
20use std::ptr;
21
22use vm_memory::bitmap::BitmapSlice;
23use vm_memory::VolatileSlice;
24
25use crate::error::*;
26
27/// ReadWriteAtVolatile is a trait that allows reading and writing from a slice of VolatileSlice.
28pub trait ReadWriteAtVolatile<B: BitmapSlice> {
29    fn read_vectored_at_volatile(&self, bufs: &[&VolatileSlice<B>]) -> Result<usize>;
30    fn write_vectored_at_volatile(&self, bufs: &[&VolatileSlice<B>]) -> Result<usize>;
31}
32
33impl<B: BitmapSlice, T: ReadWriteAtVolatile<B> + ?Sized> ReadWriteAtVolatile<B> for &T {
34    fn read_vectored_at_volatile(&self, bufs: &[&VolatileSlice<B>]) -> Result<usize> {
35        (**self).read_vectored_at_volatile(bufs)
36    }
37
38    fn write_vectored_at_volatile(&self, bufs: &[&VolatileSlice<B>]) -> Result<usize> {
39        (**self).write_vectored_at_volatile(bufs)
40    }
41}
42
43/// BufferWrapper is a wrapper around opendal::Buffer that implements ReadWriteAtVolatile.
44pub struct BufferWrapper {
45    buffer: RefCell<opendal::Buffer>,
46}
47
48impl BufferWrapper {
49    pub fn new(buffer: opendal::Buffer) -> BufferWrapper {
50        BufferWrapper {
51            buffer: RefCell::new(buffer),
52        }
53    }
54
55    pub fn get_buffer(&self) -> opendal::Buffer {
56        return self.buffer.borrow().clone();
57    }
58}
59
60impl<B: BitmapSlice> ReadWriteAtVolatile<B> for BufferWrapper {
61    fn read_vectored_at_volatile(&self, bufs: &[&VolatileSlice<B>]) -> Result<usize> {
62        let slice_guards: Vec<_> = bufs.iter().map(|s| s.ptr_guard_mut()).collect();
63        let iovecs: Vec<_> = slice_guards
64            .iter()
65            .map(|s| libc::iovec {
66                iov_base: s.as_ptr() as *mut libc::c_void,
67                iov_len: s.len() as libc::size_t,
68            })
69            .collect();
70        if iovecs.is_empty() {
71            return Ok(0);
72        }
73        let data = self.buffer.borrow().to_vec();
74        let mut result = 0;
75        for (index, iovec) in iovecs.iter().enumerate() {
76            let num = min(data.len() - result, iovec.iov_len);
77            if num == 0 {
78                break;
79            }
80            unsafe {
81                ptr::copy_nonoverlapping(data[result..].as_ptr(), iovec.iov_base as *mut u8, num)
82            }
83            bufs[index].bitmap().mark_dirty(0, num);
84            result += num;
85        }
86        Ok(result)
87    }
88
89    fn write_vectored_at_volatile(&self, bufs: &[&VolatileSlice<B>]) -> Result<usize> {
90        let slice_guards: Vec<_> = bufs.iter().map(|s| s.ptr_guard()).collect();
91        let iovecs: Vec<_> = slice_guards
92            .iter()
93            .map(|s| libc::iovec {
94                iov_base: s.as_ptr() as *mut libc::c_void,
95                iov_len: s.len() as libc::size_t,
96            })
97            .collect();
98        if iovecs.is_empty() {
99            return Ok(0);
100        }
101        let len = iovecs.iter().map(|iov| iov.iov_len).sum();
102        let mut data = vec![0; len];
103        let mut offset = 0;
104        for iov in iovecs.iter() {
105            unsafe {
106                ptr::copy_nonoverlapping(
107                    iov.iov_base as *const u8,
108                    data.as_mut_ptr().add(offset),
109                    iov.iov_len,
110                );
111            }
112            offset += iov.iov_len;
113        }
114        *self.buffer.borrow_mut() = opendal::Buffer::from(data);
115        Ok(len)
116    }
117}
virtiofs_opendal/buffer.rs

virtiofs_opendal/
buffer.rs
