view tests/test-issue612.t @ 25222:0de132d5328a

treemanifest: lazily load manifests

Most operations on treemanifests already visit only relevant
submanifests. Notable examples include __getitem__, __contains__,
walk/matches with matcher, diff. By making submanifests lazily loaded,
we speed up all these operations.

The lazy loading is achieved by adding a _load() method that gets
defined where we currently eagerly parse the manifest. We make sure to
call it before any access to _dirs, _files or _flags.

Some timings on the Mozilla repo (with flat manifest timings for
reference):

hg cat -r . README.txt: 1.644s -> 0.096s (0.255s)
hg diff -r .^ -r .    : 1.746s -> 0.137s (0.431s)
hg files -r . python  : 1.508s -> 0.146s (0.335s)
hg files -r .         : 2.125s -> 2.203s (0.712s)

http://mercurial.selenic.com/bts/issue612

  $ hg init
  $ mkdir src
  $ echo a > src/a.c
  $ hg ci -Ama
  adding src/a.c

  $ hg mv src source
  moving src/a.c to source/a.c (glob)

  $ hg ci -Ammove

  $ hg co -C 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ echo new > src/a.c
  $ echo compiled > src/a.o
  $ hg ci -mupdate
  created new head

  $ hg status
  ? src/a.o

  $ hg merge
  merging src/a.c and source/a.c to source/a.c
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg status
  M source/a.c
  R src/a.c
  ? src/a.o