dirstate: use a presized dict for the dirstate
This uses a simple heuristic to avoid expensive resizes.
On a real-world repo with around 400,000 files, perfdirstate:
before: ! wall 0.155562 comb 0.160000 user 0.150000 sys 0.010000 (best of 64)
after: ! wall 0.132638 comb 0.130000 user 0.120000 sys 0.010000 (best of 75)
On another real-world repo with around 250,000 files:
before: ! wall 0.098459 comb 0.100000 user 0.090000 sys 0.010000 (best of 100)
after: ! wall 0.089084 comb 0.090000 user 0.080000 sys 0.010000 (best of 100)
$ hg init t
$ cd t
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ rm b
$ hg update 0
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo This is file b2 > b
$ hg add b
$ hg commit -m "commit #2"
created new head
$ cd ..; rm -r t
$ mkdir t
$ cd t
$ hg init
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ rm b
$ hg update 0
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo This is file b2 > b
$ hg commit -A -m "commit #2"
adding b
created new head
$ cd ..; rm -r t
$ hg init t
$ cd t
$ echo This is file a1 > a
$ hg add a
$ hg commit -m "commit #0"
$ echo This is file b1 > b
$ hg add b
$ hg commit -m "commit #1"
$ rm b
$ hg remove b
$ hg update 0
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo This is file b2 > b
$ hg commit -A -m "commit #2"
adding b
created new head
$ cd ..