nodemap: introduce an option to use mmap to read the nodemap mapping
The performance and memory benefit is much greater if we don't have to copy all
the data in memory for each information. So we introduce an option (on by
default) to read the data using mmap.
This changeset is the last one definition the API for index support nodemap
data. (they have to be able to use the mmaping).
Below are some benchmark comparing the best we currently have in 5.3 with the
final step of this series (using the persistent nodemap implementation in
Rust). The benchmark run `hg perfindex` with various revset and the following
variants:
Before:
* do not use the persistent nodemap
* use the CPython implementation of the index for nodemap
* use mmapping of the changelog index
After:
* use the MixedIndex Rust code, with the NodeTree object for nodemap access
(still in review)
* use the persistent nodemap data from disk
* access the persistent nodemap data through mmap
* use mmapping of the changelog index
The persistent nodemap greatly speed up most operation on very large
repositories. Some of the previously very fast lookup end up a bit slower because
the persistent nodemap has to be setup. However the absolute slowdown is very
small and won't matters in the big picture.
Here are some numbers (in seconds) for the reference copy of mozilla-try:
Revset Before After abs-change speedup
-10000: 0.004622 0.005532 0.000910 × 0.83
-10: 0.000050 0.000132 0.000082 × 0.37
tip 0.000052 0.000085 0.000033 × 0.61
0 + (-10000:) 0.028222 0.005337 -0.022885 × 5.29
0 0.023521 0.000084 -0.023437 × 280.01
(-10000:) + 0 0.235539 0.005308 -0.230231 × 44.37
(-10:) + :9 0.232883 0.000180 -0.232703 ×1293.79
(-10000:) + (:99) 0.238735 0.005358 -0.233377 × 44.55
:99 + (-10000:) 0.317942 0.005593 -0.312349 × 56.84
:9 + (-10:) 0.313372 0.000179 -0.313193 ×1750.68
:9 0.316450 0.000143 -0.316307 ×2212.93
On smaller repositories, the cost of nodemap related operation is not as big, so
the win is much more modest. Yet it helps shaving a handful of millisecond here
and there.
Here are some numbers (in seconds) for the reference copy of mercurial:
Revset Before After abs-change speedup
-10: 0.000065 0.000097 0.000032 × 0.67
tip 0.000063 0.000078 0.000015 × 0.80
0 0.000561 0.000079 -0.000482 × 7.10
-10000: 0.004609 0.003648 -0.000961 × 1.26
0 + (-10000:) 0.005023 0.003715 -0.001307 × 1.35
(-10:) + :9 0.002187 0.000108 -0.002079 ×20.25
(-10000:) + 0 0.006252 0.003716 -0.002536 × 1.68
(-10000:) + (:99) 0.006367 0.003707 -0.002660 × 1.71
:9 + (-10:) 0.003846 0.000110 -0.003736 ×34.96
:9 0.003854 0.000099 -0.003755 ×38.92
:99 + (-10000:) 0.007644 0.003778 -0.003866 × 2.02
Differential Revision: https://phab.mercurial-scm.org/D7894
Testing interaction of sparse and narrow when both are enabled on the client
side and we do a non-ellipsis clone
#testcases tree flat
$ . "$TESTDIR/narrow-library.sh"
$ cat << EOF >> $HGRCPATH
> [extensions]
> sparse =
> EOF
#if tree
$ cat << EOF >> $HGRCPATH
> [experimental]
> treemanifest = 1
> EOF
#endif
$ hg init master
$ cd master
$ mkdir inside
$ echo 'inside' > inside/f
$ hg add inside/f
$ hg commit -m 'add inside'
$ mkdir widest
$ echo 'widest' > widest/f
$ hg add widest/f
$ hg commit -m 'add widest'
$ mkdir outside
$ echo 'outside' > outside/f
$ hg add outside/f
$ hg commit -m 'add outside'
$ cd ..
narrow clone the inside file
$ hg clone --narrow ssh://user@dummy/master narrow --include inside/f
requesting all changes
adding changesets
adding manifests
adding file changes
added 3 changesets with 1 changes to 1 files
new changesets *:* (glob)
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd narrow
$ hg tracked
I path:inside/f
$ hg files
inside/f
XXX: we should have a flag in `hg debugsparse` to list the sparse profile
$ test -f .hg/sparse
[1]
$ cat .hg/requires
dotencode
fncache
generaldelta
narrowhg-experimental
revlogv1
sparserevlog
store
treemanifest (tree !)
$ hg debugrebuilddirstate