view README @ 20895:f52e4ca93529

revset: improve roots revset performance

Previously we would iterate over every item in the subset, checking if it was in
the provided args. This often meant iterating over every rev in the repo.

Now we iterate over the args provided, checking if they exist in the subset.
On a large repo this brings setting phase boundaries (which use this revset
roots(X:: - X::Y)) down from 0.8 seconds to 0.4 seconds.

The "roots((tip~100::) - (tip~100::tip))" revset in revsetbenchmarks shows it
going from 0.12s to 0.10s, so we should be able to catch regressions here in the
future.

This actually introduces a regression in 'roots(all())' (0.2s to 0.26s) since
we're now using spansets, which are slightly slower to do containment checks on.
I believe this trade off is worth it, since it makes the revset O(number of
args) instead of O(size of repo).

Mercurial
=========

Mercurial is a fast, easy to use, distributed revision control tool
for software developers.

Basic install:

 $ make            # see install targets
 $ make install    # do a system-wide install
 $ hg debuginstall # sanity-check setup
 $ hg              # see help

Running without installing:

 $ make local      # build for inplace usage
 $ ./hg --version  # should show the latest version

See http://mercurial.selenic.com/ for detailed installation
instructions, platform-specific notes, and Mercurial user information.