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use super::{Chunker, ChunkerError};
use fastcdc;
use std::io::Read;
#[derive(Clone, Copy)]
pub struct FastCDC {
pub min_size: usize,
pub max_size: usize,
pub avg_size: usize,
}
impl Chunker for FastCDC {
type Chunks = FastCDCChunker;
fn chunk_boxed(&self, read: Box<dyn Read + Send + 'static>) -> Self::Chunks {
FastCDCChunker {
settings: *self,
buffer: vec![0_u8; self.max_size],
length: 0,
read,
eof: false,
}
}
}
impl Default for FastCDC {
fn default() -> Self {
FastCDC {
min_size: 32_768,
avg_size: 65_536,
max_size: 131_072,
}
}
}
pub struct FastCDCChunker {
settings: FastCDC,
buffer: Vec<u8>,
length: usize,
read: Box<dyn Read + Send + 'static>,
eof: bool,
}
impl FastCDCChunker {
fn drain_bytes(&mut self, count: usize) -> Result<Vec<u8>, ChunkerError> {
assert!(self.buffer.len() == self.settings.max_size);
if count > self.length {
Err(ChunkerError::InternalError(format!(
"Invalid count given to FastCDCChunker::drain_bytes. Count: {}, Length: {}",
count, self.length
)))
} else {
let output = self.buffer.drain(..count).collect::<Vec<_>>();
self.length -= count;
self.buffer.resize(self.settings.max_size, 0_u8);
Ok(output)
}
}
fn is_empty(&self) -> bool {
self.length == 0
}
fn read_bytes(&mut self) -> Result<usize, ChunkerError> {
assert!(self.buffer.len() == self.settings.max_size);
if self.eof {
Ok(0)
} else {
let mut total_bytes = 0;
while !self.eof && self.length < self.settings.max_size {
let bytes_read = self.read.read(&mut self.buffer[self.length..])?;
self.length += bytes_read;
if bytes_read == 0 {
self.eof = true;
}
total_bytes += bytes_read;
}
Ok(total_bytes)
}
}
fn next_chunk(&mut self) -> Result<Vec<u8>, ChunkerError> {
assert_eq!(self.buffer.len(), self.settings.max_size);
self.read_bytes()?;
if self.is_empty() {
Err(ChunkerError::Empty)
} else {
let mut slicer = fastcdc::FastCDC::new(
&self.buffer[..self.length],
self.settings.min_size,
self.settings.avg_size,
self.settings.max_size,
);
if let Some(chunk) = slicer.next() {
let result = self.drain_bytes(chunk.length)?;
Ok(result)
} else {
Err(ChunkerError::Empty)
}
}
}
}
impl Iterator for FastCDCChunker {
type Item = Result<Vec<u8>, ChunkerError>;
fn next(&mut self) -> Option<Result<Vec<u8>, ChunkerError>> {
let slice = self.next_chunk();
if let Err(ChunkerError::Empty) = slice {
None
} else {
Some(slice)
}
}
}
#[cfg(test)]
mod tests {
use super::*;
use rand::prelude::*;
use std::io::Cursor;
fn get_test_data() -> Vec<u8> {
let size = FastCDC::default().max_size * 10;
let mut vec = vec![0_u8; size];
rand::thread_rng().fill_bytes(&mut vec);
vec
}
#[test]
fn one_or_more_chunks() {
let data = get_test_data();
let cursor = Cursor::new(data);
let chunker = FastCDC::default();
let chunks = chunker
.chunk(cursor)
.map(|x| x.unwrap())
.collect::<Vec<_>>();
assert!(chunks.len() > 1);
}
#[test]
fn reassemble_data() {
let data = get_test_data();
let cursor = Cursor::new(data.clone());
let chunks = FastCDC::default()
.chunk(cursor)
.map(|x| x.unwrap())
.collect::<Vec<_>>();
let rebuilt: Vec<u8> = chunks.concat();
assert_eq!(data, rebuilt);
}
#[test]
fn identical_chunks() {
let data = get_test_data();
let cursor1 = Cursor::new(data.clone());
let chunks1 = FastCDC::default()
.chunk(cursor1)
.map(|x| x.unwrap())
.collect::<Vec<_>>();
let cursor2 = Cursor::new(data);
let chunks2 = FastCDC::default()
.chunk(cursor2)
.map(|x| x.unwrap())
.collect::<Vec<_>>();
assert_eq!(chunks1, chunks2);
}
#[test]
fn max_size() {
let data = get_test_data();
let max_size = FastCDC::default().max_size;
let chunks = FastCDC::default()
.chunk(Cursor::new(data))
.map(|x| x.unwrap())
.collect::<Vec<_>>();
for chunk in chunks {
assert!(chunk.len() <= max_size);
}
}
#[test]
fn min_size() {
let data = get_test_data();
let min_size = FastCDC::default().min_size;
let chunks = FastCDC::default()
.chunk(Cursor::new(data))
.map(|x| x.unwrap())
.collect::<Vec<_>>();
let mut undersized_count = 0;
for chunk in chunks {
if chunk.len() < min_size {
undersized_count += 1;
}
}
assert!(undersized_count <= 1);
}
}