view tests/test-merge-subrepos.t @ 44363:f7459da77f23

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

  $ hg init

  $ echo a > a
  $ hg ci -qAm 'add a'

  $ hg init subrepo
  $ echo 'subrepo = http://example.net/libfoo' > .hgsub
  $ hg ci -qAm 'added subrepo'

  $ hg up -qC 0
  $ echo ax > a
  $ hg ci -m 'changed a'
  created new head

  $ hg up -qC 1
  $ cd subrepo
  $ echo b > b
  $ hg add b
  $ cd ..

Should fail, since there are added files to subrepo:

  $ hg merge
  abort: uncommitted changes in subrepository "subrepo"
  [255]

Deleted files trigger a '+' marker in top level repos.  Deleted files are also
noticed by `update --check` in the top level repo.

  $ hg ci -Sqm 'add b'
  $ echo change > subrepo/b

  $ hg ci -Sm 'change b'
  committing subrepository subrepo

  $ rm a
  $ hg id
  9bfe45a197d7+ tip
  $ hg sum
  parent: 4:9bfe45a197d7 tip
   change b
  branch: default
  commit: 1 deleted (clean)
  update: 1 new changesets, 2 branch heads (merge)
  phases: 5 draft

  $ hg up --check -r '.^'
  abort: uncommitted changes
  [255]
  $ hg st -S
  ! a
  $ hg up -Cq .

Test that dirty is consistent through subrepos

  $ rm subrepo/b

A deleted subrepo file is flagged as dirty, like the top level repo

  $ hg id --config extensions.blackbox= --config blackbox.dirty=True \
  > --config blackbox.track='command commandfinish'
  9bfe45a197d7+ tip
  $ cat .hg/blackbox.log
  * @9bfe45a197d7b0ab09bf287729dd57e9619c9da5+ (*)> serve --cmdserver chgunix * (glob) (chg !)
  * @9bfe45a197d7b0ab09bf287729dd57e9619c9da5+ (*)> id --config *extensions.blackbox=* --config *blackbox.dirty=True* (glob)
  * @9bfe45a197d7b0ab09bf287729dd57e9619c9da5+ (*)> id --config *extensions.blackbox=* --config *blackbox.dirty=True* exited 0 * (glob)

TODO: a deleted file should be listed as such, like the top level repo

  $ hg sum
  parent: 4:9bfe45a197d7 tip
   change b
  branch: default
  commit: (clean)
  update: 1 new changesets, 2 branch heads (merge)
  phases: 5 draft

Modified subrepo files are noticed by `update --check` and `summary`

  $ echo mod > subrepo/b
  $ hg st -S
  M subrepo/b

  $ hg up -r '.^' --check
  abort: uncommitted changes in subrepository "subrepo"
  [255]

  $ hg sum
  parent: 4:9bfe45a197d7 tip
   change b
  branch: default
  commit: 1 subrepos
  update: 1 new changesets, 2 branch heads (merge)
  phases: 5 draft

TODO: why is -R needed here?  If it's because the subrepo is treated as a
discrete unit, then this should probably warn or something.
  $ hg revert -R subrepo --no-backup subrepo/b -r .

  $ rm subrepo/b
  $ hg st -S
  ! subrepo/b

`hg update --check` notices a subrepo with a missing file, like it notices a
missing file in the top level repo.

  $ hg up -r '.^' --check
  abort: uncommitted changes in subrepository "subrepo"
  [255]

  $ hg up -r '.^' --config ui.interactive=True << EOF
  > d
  > EOF
  file 'b' was deleted in local [working copy] but was modified in other [destination].
  You can use (c)hanged version, leave (d)eleted, or leave (u)nresolved.
  What do you want to do? d
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

XXX: There's a difference between wdir() and '.', so there should be a status.
`hg files -S` from the top is also missing 'subrepo/b'.

  $ hg st -S
  $ hg st -R subrepo
  $ hg files -R subrepo
  [1]
  $ hg files -R subrepo -r '.'
  subrepo/b

  $ hg bookmark -r tip @other
  $ echo xyz > subrepo/c
  $ hg ci -SAm 'add c'
  adding subrepo/c
  committing subrepository subrepo
  created new head
  $ rm subrepo/c

Merge sees deleted subrepo files as an uncommitted change

  $ hg merge @other
  abort: uncommitted changes in subrepository "subrepo"
  [255]