## oplog.mark_progress()


Record that one action of a running operation completed.


Usage

``` python
oplog.mark_progress(
    root,
    op_id,
    action,
    **detail,
)
```


A multi-action operation (a [new](vcs.VcsAdapter.md#tether.vcs.VcsAdapter.new) forking five branches, a `gc` releasing twenty pins) that dies half-way leaves a started entry; these records say which of its actions had already taken effect, so `repair` can list them and a re-run knows what is left.