49 lines
1.6 KiB
Rust
49 lines
1.6 KiB
Rust
use std::path::PathBuf;
|
|
|
|
#[derive(Debug, Clone)]
|
|
pub struct FileInfo {
|
|
pub relative_filename: PathBuf,
|
|
pub offset_in_torrent: u64,
|
|
pub piece_range: std::ops::Range<u32>,
|
|
pub len: u64,
|
|
}
|
|
|
|
// Iterate file pieces in the following order: first, last, everything else from start to end.
|
|
fn iter_piece_priorities(range: std::ops::Range<usize>) -> impl Iterator<Item = usize> {
|
|
// First and last of each file first, then the rest of pieces in that file.
|
|
let r = range;
|
|
use std::iter::once;
|
|
|
|
let first = once(r.start);
|
|
let last = once(r.start + r.len().overflowing_sub(1).0); // it's ok if it repeats, doesn't matter
|
|
let mid = r.clone().skip(1).take(r.len().overflowing_sub(2).0);
|
|
|
|
// The take(r.len()) is to not yield start/end pieces in case of 0 and 1 lengths.
|
|
first.chain(last).chain(mid).take(r.len())
|
|
}
|
|
|
|
impl FileInfo {
|
|
pub fn piece_range_usize(&self) -> std::ops::Range<usize> {
|
|
self.piece_range.start as usize..self.piece_range.end as usize
|
|
}
|
|
|
|
pub fn iter_piece_priorities(&self) -> impl Iterator<Item = usize> {
|
|
iter_piece_priorities(self.piece_range_usize())
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use super::iter_piece_priorities;
|
|
|
|
#[test]
|
|
fn test_iter_piece_priorities() {
|
|
let it = |r: std::ops::Range<usize>| -> Vec<usize> { iter_piece_priorities(r).collect() };
|
|
assert_eq!(it(0..0), Vec::<usize>::new());
|
|
|
|
assert_eq!(it(0..1), vec![0]);
|
|
assert_eq!(it(0..2), vec![0, 1]);
|
|
assert_eq!(it(0..3), vec![0, 2, 1]);
|
|
assert_eq!(it(0..4), vec![0, 3, 1, 2]);
|
|
}
|
|
}
|