use crate::{DatabaseError, Result, StorageBackend};
use std::fs::File;
use std::io;
use std::io::{Read, Seek, SeekFrom, Write};
use std::sync::Mutex;
#[derive(Debug)]
pub struct FileBackend {
file: Mutex<File>,
}
impl FileBackend {
pub fn new(file: File) -> Result<Self, DatabaseError> {
Ok(Self {
file: Mutex::new(file),
})
}
}
impl StorageBackend for FileBackend {
fn len(&self) -> Result<u64, io::Error> {
Ok(self.file.lock().unwrap().metadata()?.len())
}
fn read(&self, offset: u64, len: usize) -> Result<Vec<u8>, io::Error> {
let mut result = vec![0; len];
let mut file = self.file.lock().unwrap();
file.seek(SeekFrom::Start(offset))?;
file.read_exact(&mut result)?;
Ok(result)
}
fn set_len(&self, len: u64) -> Result<(), io::Error> {
self.file.lock().unwrap().set_len(len)
}
fn sync_data(&self, _eventual: bool) -> Result<(), io::Error> {
self.file.lock().unwrap().sync_data()
}
fn write(&self, offset: u64, data: &[u8]) -> Result<(), io::Error> {
let mut file = self.file.lock().unwrap();
file.seek(SeekFrom::Start(offset))?;
file.write_all(data)
}
}