manifestmerge: use dicthelpers.diff and join This patch improves manifestmerge performance significantly. In a repository with 170,000 files, the following results were observed on a clean working directory. Revision '.' adds one file. hg perfmergecalculate -r . - before: 0.41 seconds - after: 0.13 seconds hg perfmergecalculate -r .^ - before: 0.53 seconds - after: 0.24 seconds Comparing against '.' is much faster than comparing against '.^' because with '.', the wctx and p2 manifest strings have the same identity, so comparisons are simply pointer equality. With '.^', the strings have different identities so we need to perform memcmps. Any operation that uses manifestmerge benefits. - hg update . goes from 2.04 seconds to 1.75 - hg update .^ goes from 2.52 seconds to 2.25 - hg rebase -r . -d .~6 (involves 4 merges) goes from 11.8 seconds to 10.8

manifestdict: add a method to diff _flags This will be used in an upcoming patch.

mercurial: implement diff and join for dicts Given two dicts, diff returns a dict containing all the keys that are present in one dict but not the other, or whose values are different between the dicts. The values are pairs of the values from the dicts, with missing values being represented as an optional argument, defaulting to None. Given two dicts, join performs what is known as an outer join in relational database land: it returns a dict containing all the keys across both dicts. The values are pairs as above, except they aren't compared to see if they're the same.