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use std::fs::File;
use std::io;
use std::io::Write;
#[cfg(windows)]
use std::io::{Seek, SeekFrom};
use std::path::Path;
#[cfg(unix)]
use std::os::unix::fs::FileExt;
#[cfg(windows)]
use std::os::windows::fs::FileExt;
use super::{ReadAt, WriteAt};
#[derive(Debug)]
pub struct RandomAccessFile {
file: File,
#[cfg(not(unix))]
pos: u64,
}
impl RandomAccessFile {
pub fn open<P: AsRef<Path>>(path: P) -> io::Result<RandomAccessFile> {
RandomAccessFile::try_new(File::open(path)?)
}
pub fn try_new(file: File) -> io::Result<RandomAccessFile> {
RandomAccessFile::try_new_impl(file)
}
#[cfg(unix)]
fn try_new_impl(file: File) -> io::Result<RandomAccessFile> {
unsafe {
use std::os::unix::io::AsRawFd;
libc::posix_fadvise(file.as_raw_fd(), 0, file.metadata()?.len() as i64, libc::POSIX_FADV_RANDOM);
}
Ok(RandomAccessFile { file })
}
#[cfg(not(unix))]
fn try_new_impl(mut file: File) -> io::Result<RandomAccessFile> {
let pos = file.seek(SeekFrom::Current(0))?;
Ok(RandomAccessFile { file, pos })
}
pub fn try_into_inner(self) -> Result<File, (RandomAccessFile, io::Error)> {
RandomAccessFile::try_into_inner_impl(self)
}
#[cfg(unix)]
fn try_into_inner_impl(self) -> Result<File, (RandomAccessFile, io::Error)> {
Ok(self.file)
}
#[cfg(not(unix))]
fn try_into_inner_impl(mut self) -> Result<File, (RandomAccessFile, io::Error)> {
match self.file.seek(SeekFrom::Start(self.pos)) {
Ok(_) => Ok(self.file),
Err(err) => Err((self, err)),
}
}
}
#[cfg(unix)]
impl ReadAt for RandomAccessFile {
#[inline]
fn read_at(&self, pos: u64, buf: &mut [u8]) -> io::Result<usize> {
FileExt::read_at(&self.file, buf, pos)
}
}
#[cfg(unix)]
impl WriteAt for RandomAccessFile {
fn write_at(&mut self, pos: u64, buf: &[u8]) -> io::Result<usize> {
FileExt::write_at(&self.file, buf, pos)
}
fn flush(&mut self) -> io::Result<()> {
Write::flush(&mut self.file)
}
}
#[cfg(windows)]
impl ReadAt for RandomAccessFile {
#[inline]
fn read_at(&self, pos: u64, buf: &mut [u8]) -> io::Result<usize> {
FileExt::seek_read(&self.file, buf, pos)
}
}
#[cfg(windows)]
impl WriteAt for RandomAccessFile {
fn write_at(&mut self, pos: u64, buf: &[u8]) -> io::Result<usize> {
FileExt::seek_write(&self.file, buf, pos)
}
fn flush(&mut self) -> io::Result<()> {
Write::flush(&mut self.file)
}
}