##// END OF EJS Templates
dirstate-tree: Skip readdir() in `hg status -mard`...
dirstate-tree: Skip readdir() in `hg status -mard` When running the status algorithm in a mode where we don’t list unknown or ignored files, all we care about are files that are listed in the dirstate. We can there for skip making expensive calls to readdir() to list the contents of filesystem directories, and instead only run stat() to get the filesystem state of files listed in the dirstate. (This state may be an error for files that don’t exist anymore on the filesystem.) On 16 CPU threads, this reduces the time spent in the `status()` function for `hg status -mard` on an old snapshot of mozilla-central from ~70ms to ~50ms. Differential Revision: https://phab.mercurial-scm.org/D10752

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index.rs
95 lines | 2.4 KiB | application/rls-services+xml | RustLexer
// Copyright 2019-2020 Georges Racinet <georges.racinet@octobus.net>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.
//! Minimal `RevlogIndex`, readable from standard Mercurial file format
use hg::*;
use memmap::*;
use std::fs::File;
use std::ops::Deref;
use std::path::Path;
use std::slice;
pub struct Index {
data: Box<dyn Deref<Target = [IndexEntry]> + Send>,
}
/// A fixed sized index entry. All numbers are big endian
#[repr(C)]
pub struct IndexEntry {
not_used_yet: [u8; 24],
p1: Revision,
p2: Revision,
node: Node,
unused_node: [u8; 12],
}
pub const INDEX_ENTRY_SIZE: usize = 64;
impl IndexEntry {
fn parents(&self) -> [Revision; 2] {
[Revision::from_be(self.p1), Revision::from_be(self.p1)]
}
}
impl RevlogIndex for Index {
fn len(&self) -> usize {
self.data.len()
}
fn node(&self, rev: Revision) -> Option<&Node> {
if rev == NULL_REVISION {
return None;
}
let i = rev as usize;
if i >= self.len() {
None
} else {
Some(&self.data[i].node)
}
}
}
impl Graph for &Index {
fn parents(&self, rev: Revision) -> Result<[Revision; 2], GraphError> {
let [p1, p2] = (*self).data[rev as usize].parents();
let len = (*self).len();
if p1 < NULL_REVISION
|| p2 < NULL_REVISION
|| p1 as usize >= len
|| p2 as usize >= len
{
return Err(GraphError::ParentOutOfRange(rev));
}
Ok([p1, p2])
}
}
struct IndexMmap(Mmap);
impl Deref for IndexMmap {
type Target = [IndexEntry];
fn deref(&self) -> &[IndexEntry] {
let ptr = self.0.as_ptr() as *const IndexEntry;
// Any misaligned data will be ignored.
debug_assert_eq!(
self.0.len() % std::mem::align_of::<IndexEntry>(),
0,
"Misaligned data in mmap"
);
unsafe { slice::from_raw_parts(ptr, self.0.len() / INDEX_ENTRY_SIZE) }
}
}
impl Index {
pub fn load_mmap(path: impl AsRef<Path>) -> Self {
let file = File::open(path).unwrap();
let msg = "Index file is missing, or missing permission";
let mmap = unsafe { MmapOptions::new().map(&file) }.expect(msg);
Self {
data: Box::new(IndexMmap(mmap)),
}
}
}