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Don't compute md5sums as much in the updater. #326

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This commit is contained in:
Dustin Carlino 2021-05-11 11:39:54 -07:00
parent 1e5771897f
commit e02a1c17f2
1 changed files with 16 additions and 14 deletions
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30
updater/src/main.rs
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@ -306,22 +306,24 @@ fn generate_manifest(truth: &Manifest) -> Manifest {
Parallelism::Fastest,
paths,
|(orig_path, path)| {
let uncompressed_size_bytes = std::fs::metadata(&orig_path).unwrap().len();
// Always calculate the md5sum for files under 1GB.
let checksum = if uncompressed_size_bytes < 1024 * 1024 * 1024 {
md5sum(&orig_path)
} else if truth
.entries
.get(&path)
.map(|entry| entry.uncompressed_size_bytes == uncompressed_size_bytes)
.unwrap_or(false)
// If the file's modtime is newer than 3 hours or the uncompressed size has changed,
// calculate md5sum. Otherwise assume no change. This heuristic saves lots of time and
// doesn't stress my poor SSD as much.
let metadata = std::fs::metadata(&orig_path).unwrap();
let uncompressed_size_bytes = metadata.len();
let recent_modtime = metadata.modified().unwrap().elapsed().unwrap()
< std::time::Duration::from_secs(60 * 60 * 3);
let checksum = if recent_modtime
|| truth
.entries
.get(&path)
.map(|entry| entry.uncompressed_size_bytes != uncompressed_size_bytes)
.unwrap_or(true)
{
// For files larger than 1GB, don't recalculate the md5sum if the size hasn't
// changed. This saves substantial time for a few gigantic files in data/input that
// rarely change.
truth.entries[&path].checksum.clone()
} else {
md5sum(&orig_path)
} else {
truth.entries[&path].checksum.clone()
};
(
path,