prune: size the artifacts concurrently, drop the per-path info lines

The dry run still spammed one info line per artifact before the
grouped digest, and the size walk was serial: tens of seconds of pure
readdir/stat over the records' hundreds of thousands of files.

The per-path lines drop to debug (the grouped report is the
user-facing output), and the size pass now fans out over a shared
work queue with scoped threads — directory-level parallelism, same
du -x mount-crossing rule. 16s to 6.4s wall on a 440 GiB sessions
tree, totals unchanged.
This commit is contained in:
2026-10-02 23:29:21 +02:00
parent 2991237c91
commit 74c74f0a61
+84 -35
View File
@@ -135,42 +135,89 @@ pub fn format_bytes(bytes: u64) -> String {
}
}
/// Total size of `path` in bytes: a file's length, or the recursive walk
/// of a directory. Unreadable entries count as zero — prune removes them
/// all the same. The walk never crosses a mount point (`du -x`): residual
/// chroots hold bind-mounted `/proc` and overlay filesystems whose virtual
/// files (`/proc/kcore` alone reports 128 TiB) would poison the total.
fn path_bytes(path: &Path) -> u64 {
/// Total size of every artifact in bytes, measured concurrently: the
/// records hold hundreds of thousands of files (a single kernel build
/// tree is ~100 GB of objects), and a serial walk costs tens of seconds.
///
/// Directory walks never cross a mount point (`du -x`): residual chroots
/// hold bind-mounted `/proc` and overlay filesystems whose virtual files
/// (`/proc/kcore` alone reports 128 TiB) would poison the totals.
/// Unreadable entries count as zero — prune removes them all the same.
fn size_artifacts(artifacts: &[&Artifact]) -> Vec<u64> {
use std::collections::VecDeque;
use std::os::unix::fs::MetadataExt;
use std::sync::Mutex;
use std::sync::atomic::{AtomicU64, AtomicUsize, Ordering};
let Ok(meta) = fs::symlink_metadata(path) else {
return 0;
};
if !meta.is_dir() {
return meta.len();
}
let root_dev = meta.dev();
let mut total = 0;
let mut stack = vec![path.to_path_buf()];
while let Some(dir) = stack.pop() {
let Ok(entries) = fs::read_dir(&dir) else {
continue;
};
for entry in entries.flatten() {
let path = entry.path();
let Ok(meta) = fs::symlink_metadata(&path) else {
continue;
};
if meta.is_dir() {
if meta.dev() == root_dev {
stack.push(path);
// The device each artifact lives on: the walk descends only into
// directories on the same device.
let root_devs: Vec<u64> = artifacts
.iter()
.map(|a| fs::symlink_metadata(a.path()).map_or(0, |meta| meta.dev()))
.collect();
let totals: Vec<AtomicU64> = (0..artifacts.len()).map(|_| AtomicU64::new(0)).collect();
let queue: Mutex<VecDeque<(usize, PathBuf)>> = Mutex::new(
artifacts
.iter()
.enumerate()
.map(|(idx, artifact)| (idx, artifact.path().to_path_buf()))
.collect(),
);
// Every queued-but-unfinished item: the workers stop when the queue
// is empty and nothing is in flight.
let pending = AtomicUsize::new(artifacts.len());
let workers = std::thread::available_parallelism()
.map(|n| n.get())
.unwrap_or(4)
.min(16);
std::thread::scope(|scope| {
for _ in 0..workers {
scope.spawn(|| {
loop {
let item = queue.lock().unwrap().pop_front();
let Some((idx, path)) = item else {
if pending.load(Ordering::Acquire) == 0 {
return;
}
std::thread::yield_now();
continue;
};
let Ok(meta) = fs::symlink_metadata(&path) else {
pending.fetch_sub(1, Ordering::AcqRel);
continue;
};
if !meta.is_dir() {
totals[idx].fetch_add(meta.len(), Ordering::Relaxed);
pending.fetch_sub(1, Ordering::AcqRel);
continue;
}
let Ok(entries) = fs::read_dir(&path) else {
pending.fetch_sub(1, Ordering::AcqRel);
continue;
};
for entry in entries.flatten() {
let child = entry.path();
let Ok(meta) = fs::symlink_metadata(&child) else {
continue;
};
let same_device = meta.dev() == root_devs[idx];
if meta.is_dir() && same_device {
pending.fetch_add(1, Ordering::AcqRel);
queue.lock().unwrap().push_back((idx, child));
} else if !meta.is_dir() && same_device {
totals[idx].fetch_add(meta.len(), Ordering::Relaxed);
}
}
pending.fetch_sub(1, Ordering::AcqRel);
}
} else {
total += meta.len();
}
});
}
}
total
});
totals.into_iter().map(|total| total.into_inner()).collect()
}
/// Number of newest build logs kept when `--all` is not passed.
@@ -759,7 +806,7 @@ pub fn prune_in_roots(
// The actionable subset with sizes measured BEFORE anything is
// removed: a removed tree has no size left to report.
let mut actionable: Vec<(&Artifact, u64)> = Vec::new();
let mut filtered: Vec<&Artifact> = Vec::new();
for artifact in &artifacts {
// Cached tarballs are only removed when --all is requested: they are
// expensive to re-download.
@@ -774,12 +821,14 @@ pub fn prune_in_roots(
continue;
}
actionable.push((artifact, path_bytes(artifact.path())));
filtered.push(artifact);
}
let sizes = size_artifacts(&filtered);
let actionable: Vec<(&Artifact, u64)> = filtered.iter().copied().zip(sizes).collect();
for (artifact, _) in &actionable {
let path = artifact.path();
log::info!("{}: {}", artifact.kind(), path.display());
log::debug!("{}: {}", artifact.kind(), path.display());
if options.dry_run {
report.removed.push(path.to_path_buf());