Jeremy Soller
98 lines
2.5 KiB
Rust
98 lines
2.5 KiB
Rust
use std::{cmp, ptr};
|
|
|
|
use redoxfs::Disk;
|
|
|
|
use syscall::error::Result;
|
|
|
|
use self::lru_cache::LruCache;
|
|
|
|
mod linked_hash_map;
|
|
mod lru_cache;
|
|
|
|
fn copy_memory(src: &[u8], dest: &mut [u8]) -> usize {
|
|
let len = cmp::min(src.len(), dest.len());
|
|
unsafe { ptr::copy(src.as_ptr(), dest.as_mut_ptr(), len) };
|
|
len
|
|
}
|
|
|
|
pub struct Cache<T> {
|
|
inner: T,
|
|
cache: LruCache<u64, [u8; 512]>,
|
|
}
|
|
|
|
impl<T: Disk> Cache<T> {
|
|
pub fn new(inner: T) -> Self {
|
|
Cache {
|
|
inner: inner,
|
|
cache: LruCache::new(65536) // 32 MB cache
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<T: Disk> Disk for Cache<T> {
|
|
fn read_at(&mut self, block: u64, buffer: &mut [u8]) -> Result<usize> {
|
|
// println!("Cache read at {}", block);
|
|
|
|
let mut read = 0;
|
|
let mut failed = false;
|
|
for i in 0..(buffer.len() + 511)/512 {
|
|
let block_i = block + i as u64;
|
|
|
|
let buffer_i = i * 512;
|
|
let buffer_j = cmp::min(buffer_i + 512, buffer.len());
|
|
let buffer_slice = &mut buffer[buffer_i .. buffer_j];
|
|
|
|
if let Some(cache_buf) = self.cache.get_mut(&block_i) {
|
|
read += copy_memory(cache_buf, buffer_slice);
|
|
}else{
|
|
failed = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
if failed {
|
|
try!(self.inner.read_at(block, buffer));
|
|
|
|
read = 0;
|
|
for i in 0..(buffer.len() + 511)/512 {
|
|
let block_i = block + i as u64;
|
|
|
|
let buffer_i = i * 512;
|
|
let buffer_j = cmp::min(buffer_i + 512, buffer.len());
|
|
let buffer_slice = &buffer[buffer_i .. buffer_j];
|
|
|
|
let mut cache_buf = [0; 512];
|
|
read += copy_memory(buffer_slice, &mut cache_buf);
|
|
self.cache.insert(block_i, cache_buf);
|
|
}
|
|
}
|
|
|
|
Ok(read)
|
|
}
|
|
|
|
fn write_at(&mut self, block: u64, buffer: &[u8]) -> Result<usize> {
|
|
// println!("Cache write at {}", block);
|
|
|
|
try!(self.inner.write_at(block, buffer));
|
|
|
|
let mut written = 0;
|
|
for i in 0..(buffer.len() + 511)/512 {
|
|
let block_i = block + i as u64;
|
|
|
|
let buffer_i = i * 512;
|
|
let buffer_j = cmp::min(buffer_i + 512, buffer.len());
|
|
let buffer_slice = &buffer[buffer_i .. buffer_j];
|
|
|
|
let mut cache_buf = [0; 512];
|
|
written += copy_memory(buffer_slice, &mut cache_buf);
|
|
self.cache.insert(block_i, cache_buf);
|
|
}
|
|
|
|
Ok(written)
|
|
}
|
|
|
|
fn size(&mut self) -> Result<u64> {
|
|
self.inner.size()
|
|
}
|
|
}
|