comparison mercurial/scmutil.py @ 45515:89f0d9f87701

branchmap: add a cache validation cache, avoid expensive re-hash on every use

In a pathological `hg log` case, we end up executing the branchmap validity
checking twice per commit displayed. Or maybe we always do, and I just noticed
because it's really slow in this repo for some reason.

Before:
```
  Time (mean ± σ):      9.816 s ±  0.071 s    [User: 9.435 s, System: 0.392 s]

  Range (min … max):    9.709 s …  9.920 s
```

After:
```
  Time (mean ± σ):      8.671 s ±  0.078 s    [User: 8.309 s, System: 0.392 s]

  Range (min … max):    8.594 s …  8.816 s
```

Differential Revision: https://phab.mercurial-scm.org/D9023

45514:93a0f3ba36bb

    that SHA-1 digest.
    """
    cl = repo.changelog
    if not cl.filteredrevs:
        return None
    key = None
    revs = sorted(r for r in cl.filteredrevs if r <= maxrev)
    if revs:
        s = hashutil.sha1()
        for rev in revs:
            s.update(b'%d;' % rev)
        key = s.digest()
    return key


def walkrepos(path, followsym=False, seen_dirs=None, recurse=False):
    '''yield every hg repository under path, always recursively.

45515:89f0d9f87701

    that SHA-1 digest.
    """
    cl = repo.changelog
    if not cl.filteredrevs:
        return None
    key = cl._filteredrevs_hashcache.get(maxrev)
    if not key:
        revs = sorted(r for r in cl.filteredrevs if r <= maxrev)
        if revs:
            s = hashutil.sha1()
            for rev in revs:
                s.update(b'%d;' % rev)
            key = s.digest()
            cl._filteredrevs_hashcache[maxrev] = key
    return key


def walkrepos(path, followsym=False, seen_dirs=None, recurse=False):
    '''yield every hg repository under path, always recursively.