test_put_snapshot_local_filesystem seems to be flaky

[tillrohrmann]

The test test_put_snapshot_local_filesystem seems to be flaky: https://github.com/restatedev/restate/actions/runs/12356871562/job/34483774350#step:11:459.

It failed with

──── STDOUT:             restate-worker partition::snapshots::repository::tests::test_put_snapshot_local_filesystem

running 1 test
test partition::snapshots::repository::tests::test_put_snapshot_local_filesystem ... 2024-12-16T16:26:59.261752Z ERROR restate_worker::partition::snapshots::repository: error=Downloaded snapshot file Path { raw: "tmp/.tmpeWowbT/0/lsn_00000001734366419253-snap_14MqSnfDPgswhfdOH5MrdiF/data.sst" } has unexpected size: expected 13, got 0
FAILED

failures:

failures:
    partition::snapshots::repository::tests::test_put_snapshot_local_filesystem

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 64 filtered out; finished in 0.03s

cc @pcholakov

[pcholakov]

Interesting, I'd seen this during development but I thought it was just a bug that I had fixed. Looking into it.

[pcholakov]

Have we seen more occurrences of this, @tillrohrmann? I did a quick scan of recent GHA failures and didn't find any but it is hard to filter for. I ran 1000 iterations of the test on macOS and Ubuntu/x64 and got zero failures.

I added a simple check to verify the size post-upload; I'd like to also add explicit checksums to the metadata for added paranoia at some point soon.

[tillrohrmann]

I've seen this test failure occur for the first time.

[pcholakov]

Not 100% related but at least it might catch whether the issue happens on put, or on get - I created a draft PR that outlines what I was thinking with snapshot SST file checksums: #2436.