proxmox-backup/src/backup/index.rs
2019-10-26 11:42:05 +02:00

157 lines
4.3 KiB
Rust

use std::collections::HashMap;
use std::pin::Pin;
use std::task::{Context, Poll};
use bytes::{Bytes, BytesMut};
use failure::*;
use futures::*;
/// Trait to get digest list from index files
///
/// To allow easy iteration over all used chunks.
pub trait IndexFile {
fn index_count(&self) -> usize;
fn index_digest(&self, pos: usize) -> Option<&[u8; 32]>;
fn index_bytes(&self) -> u64;
/// Returns most often used chunks
fn find_most_used_chunks(&self, max: usize) -> HashMap<[u8; 32], usize> {
let mut map = HashMap::new();
for pos in 0..self.index_count() {
let digest = self.index_digest(pos).unwrap();
let count = map.entry(*digest).or_insert(0);
*count += 1;
}
let mut most_used = Vec::new();
for (digest, count) in map {
if count <= 1 { continue; }
match most_used.binary_search_by_key(&count, |&(_digest, count)| count) {
Ok(p) => most_used.insert(p, (digest, count)),
Err(p) => most_used.insert(p, (digest, count)),
}
if most_used.len() > max { let _ = most_used.pop(); }
}
let mut map = HashMap::new();
for data in most_used {
map.insert(data.0, data.1);
}
map
}
}
/// Encode digest list from an `IndexFile` into a binary stream
///
/// The reader simply returns a birary stream of 32 byte digest values.
pub struct DigestListEncoder {
index: Box<dyn IndexFile + Send + Sync>,
pos: usize,
count: usize,
}
impl DigestListEncoder {
pub fn new(index: Box<dyn IndexFile + Send + Sync>) -> Self {
let count = index.index_count();
Self { index, pos: 0, count }
}
}
impl std::io::Read for DigestListEncoder {
fn read(&mut self, buf: &mut [u8]) -> Result<usize, std::io::Error> {
if buf.len() < 32 {
panic!("read buffer too small");
}
if self.pos < self.count {
let mut written = 0;
loop {
let digest = self.index.index_digest(self.pos).unwrap();
buf[written..(written + 32)].copy_from_slice(digest);
self.pos += 1;
written += 32;
if self.pos >= self.count {
break;
}
if (written + 32) >= buf.len() {
break;
}
}
Ok(written)
} else {
Ok(0)
}
}
}
/// Decodes a Stream<Item=Bytes> into Stream<Item=<[u8;32]>
///
/// The reader simply returns a birary stream of 32 byte digest values.
pub struct DigestListDecoder<S: Unpin> {
input: S,
buffer: BytesMut,
}
impl<S: Unpin> DigestListDecoder<S> {
pub fn new(input: S) -> Self {
Self { input, buffer: BytesMut::new() }
}
}
impl<S: Unpin> Unpin for DigestListDecoder<S> {}
impl<S: Unpin, E> Stream for DigestListDecoder<S>
where
S: Stream<Item=Result<Bytes, E>>,
E: Into<Error>,
{
type Item = Result<[u8; 32], Error>;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> {
let this = self.get_mut();
loop {
if this.buffer.len() >= 32 {
let left = this.buffer.split_to(32);
let mut digest = std::mem::MaybeUninit::<[u8; 32]>::uninit();
unsafe {
(*digest.as_mut_ptr()).copy_from_slice(&left[..]);
return Poll::Ready(Some(Ok(digest.assume_init())));
}
}
match Pin::new(&mut this.input).poll_next(cx) {
Poll::Pending => {
return Poll::Pending;
}
Poll::Ready(Some(Err(err))) => {
return Poll::Ready(Some(Err(err.into())));
}
Poll::Ready(Some(Ok(data))) => {
this.buffer.extend_from_slice(&data);
// continue
}
Poll::Ready(None) => {
let rest = this.buffer.len();
if rest == 0 {
return Poll::Ready(None);
}
return Poll::Ready(Some(Err(format_err!(
"got small digest ({} != 32).",
rest,
))));
}
}
}
}
}