view .editorconfig @ 42237:9f45d3d526f9

hgtagsfnodescache: inherit fnode from parent when possible

If a changeset does not update the content of `.hgtags`, it means it will use
the same file-node (for `.hgtags`) as its parents. In this case we can
directly reuse the parent's file-node.

We use this property when updating the `hgtagsfnodescache` taking a faster path
if we already have a cached value for the parents of the node we are looking
at.

Doing so provides a large performance boost when looking at a lot of fnodes,
especially on repository with very large manifest:

timing for `tagsmod.fnoderevs(ui, repo, repo.changelog.revs())`

mercurial: (41907 revisions, 1923 files)

    before: 6.9 seconds
    after:  2.7 seconds (-54%)

pypy: (96266 revisions, 5198 files)

    before: 80 seconds
    after:  20 seconds (-75%)

mozilla-central: (463411 revisions, 272080 files)

    before: 7166.4 seconds
    after:    47.8 seconds (-99%, x150 speedup)

On a copy of mozilla-try with about 35K heads ans 1.7M changesets, this moves
the computation from many hours to a couple of minutes, making it more
interesting to do a full warm up of this cache before computing tags (from a
cold cache).

There seems to be other performance low hanging fruits, like avoiding the use of
changectx or a more revision centric logic. However, the new code is fast enough
for my needs right now.

# See http://EditorConfig.org for the specification

root = true

[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true

[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true

[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false