tests/test-copies-unrelated.t

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

#testcases filelog compatibility changeset sidedata

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > rebase=
  > [alias]
  > l = log -G -T '{rev} {desc}\n{files}\n'
  > EOF

#if compatibility
  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > copies.read-from = compatibility
  > EOF
#endif

#if changeset
  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > copies.read-from = changeset-only
  > copies.write-to = changeset-only
  > EOF
#endif

#if sidedata
  $ cat >> $HGRCPATH << EOF
  > [format]
  > exp-use-copies-side-data-changeset = yes
  > EOF
#endif

  $ REPONUM=0
  $ newrepo() {
  >     cd $TESTTMP
  >     REPONUM=`expr $REPONUM + 1`
  >     hg init repo-$REPONUM
  >     cd repo-$REPONUM
  > }

Copy a file, then delete destination, then copy again. This does not create a new filelog entry.
  $ newrepo
  $ echo x > x
  $ hg ci -Aqm 'add x'
  $ echo x2 > x
  $ hg ci -m 'modify x'
  $ hg co -q 0
  $ hg cp x y
  $ hg ci -qm 'copy x to y'
  $ hg rm y
  $ hg ci -m 'remove y'
  $ hg cp -f x y
  $ hg ci -m 'copy x onto y (again)'
  $ hg l
  @  4 copy x onto y (again)
  |  y
  o  3 remove y
  |  y
  o  2 copy x to y
  |  y
  | o  1 modify x
  |/   x
  o  0 add x
     x
  $ hg debugp1copies -r 4
  x -> y
  $ hg debugpathcopies 0 4
  x -> y
  $ hg graft -r 1
  grafting 1:* "modify x" (glob)
  merging y and x to y
  $ hg co -qC 1
  $ hg graft -r 4
  grafting 4:* "copy x onto y (again)" (glob)
  merging x and y to y

Copy x to y, then remove y, then add back y. With copy metadata in the
changeset, this could easily end up reporting y as copied from x (if we don't
unmark it as a copy when it's removed). Despite x and y not being related, we
want grafts to propagate across the rename.
  $ newrepo
  $ echo x > x
  $ hg ci -Aqm 'add x'
  $ echo x2 > x
  $ hg ci -m 'modify x'
  $ hg co -q 0
  $ hg mv x y
  $ hg ci -qm 'rename x to y'
  $ hg rm y
  $ hg ci -qm 'remove y'
  $ echo x > y
  $ hg ci -Aqm 'add back y'
  $ hg l
  @  4 add back y
  |  y
  o  3 remove y
  |  y
  o  2 rename x to y
  |  x y
  | o  1 modify x
  |/   x
  o  0 add x
     x
  $ hg debugpathcopies 0 4
BROKEN: This should succeed and merge the changes from x into y
  $ hg graft -r 1
  grafting 1:* "modify x" (glob)
  file 'x' was deleted in local [local] but was modified in other [graft].
  You can use (c)hanged version, leave (d)eleted, or leave (u)nresolved.
  What do you want to do? u
  abort: unresolved conflicts, can't continue
  (use 'hg resolve' and 'hg graft --continue')
  [255]

Add x, remove it, then add it back, then rename x to y. Similar to the case
above, but here the break in history is before the rename.
  $ newrepo
  $ echo x > x
  $ hg ci -Aqm 'add x'
  $ echo x2 > x
  $ hg ci -m 'modify x'
  $ hg co -q 0
  $ hg rm x
  $ hg ci -qm 'remove x'
  $ echo x > x
  $ hg ci -Aqm 'add x again'
  $ hg mv x y
  $ hg ci -m 'rename x to y'
  $ hg l
  @  4 rename x to y
  |  x y
  o  3 add x again
  |  x
  o  2 remove x
  |  x
  | o  1 modify x
  |/   x
  o  0 add x
     x
  $ hg debugpathcopies 0 4
  x -> y
  $ hg graft -r 1
  grafting 1:* "modify x" (glob)
  merging y and x to y
  $ hg co -qC 1
  $ hg graft -r 4
  grafting 4:* "rename x to y" (glob)
  merging x and y to y

Add x, modify it, remove it, then add it back, then rename x to y. Similar to
the case above, but here the re-added file's nodeid is different from before
the break.

  $ newrepo
  $ echo x > x
  $ hg ci -Aqm 'add x'
  $ echo x2 > x
  $ hg ci -m 'modify x'
  $ echo x3 > x
  $ hg ci -qm 'modify x again'
  $ hg co -q 1
  $ hg rm x
  $ hg ci -qm 'remove x'
# Same content to avoid conflicts
  $ hg revert -r 1 x
  $ hg ci -Aqm 'add x again'
  $ hg mv x y
  $ hg ci -m 'rename x to y'
  $ hg l
  @  5 rename x to y
  |  x y
  o  4 add x again
  |  x
  o  3 remove x
  |  x
  | o  2 modify x again
  |/   x
  o  1 modify x
  |  x
  o  0 add x
     x
  $ hg debugpathcopies 0 5
  x -> y (no-filelog !)
#if no-filelog
  $ hg graft -r 2
  grafting 2:* "modify x again" (glob)
  merging y and x to y
#else
BROKEN: This should succeed and merge the changes from x into y
  $ hg graft -r 2
  grafting 2:* "modify x again" (glob)
  file 'x' was deleted in local [local] but was modified in other [graft].
  You can use (c)hanged version, leave (d)eleted, or leave (u)nresolved.
  What do you want to do? u
  abort: unresolved conflicts, can't continue
  (use 'hg resolve' and 'hg graft --continue')
  [255]
#endif
  $ hg co -qC 2
BROKEN: This should succeed and merge the changes from x into y
  $ hg graft -r 5
  grafting 5:* "rename x to y"* (glob)
  file 'x' was deleted in other [graft] but was modified in local [local].
  You can use (c)hanged version, (d)elete, or leave (u)nresolved.
  What do you want to do? u
  abort: unresolved conflicts, can't continue
  (use 'hg resolve' and 'hg graft --continue')
  [255]

Add x, remove it, then add it back, rename x to y from the first commit.
Similar to the case above, but here the break in history is parallel to the
rename.
  $ newrepo
  $ echo x > x
  $ hg ci -Aqm 'add x'
  $ hg rm x
  $ hg ci -qm 'remove x'
  $ echo x > x
  $ hg ci -Aqm 'add x again'
  $ echo x2 > x
  $ hg ci -m 'modify x'
  $ hg co -q 0
  $ hg mv x y
  $ hg ci -qm 'rename x to y'
  $ hg l
  @  4 rename x to y
  |  x y
  | o  3 modify x
  | |  x
  | o  2 add x again
  | |  x
  | o  1 remove x
  |/   x
  o  0 add x
     x
  $ hg debugpathcopies 2 4
  x -> y
  $ hg graft -r 3
  grafting 3:* "modify x" (glob)
  merging y and x to y
  $ hg co -qC 3
  $ hg graft -r 4
  grafting 4:* "rename x to y" (glob)
  merging x and y to y

Add x, remove it, then add it back, rename x to y from the first commit.
Similar to the case above, but here the re-added file's nodeid is different
from the base.
  $ newrepo
  $ echo x > x
  $ hg ci -Aqm 'add x'
  $ hg rm x
  $ hg ci -qm 'remove x'
  $ echo x2 > x
  $ hg ci -Aqm 'add x again with different content'
  $ hg co -q 0
  $ hg mv x y
  $ hg ci -qm 'rename x to y'
  $ hg l
  @  3 rename x to y
  |  x y
  | o  2 add x again with different content
  | |  x
  | o  1 remove x
  |/   x
  o  0 add x
     x
  $ hg debugpathcopies 2 3
  x -> y
BROKEN: This should merge the changes from x into y
  $ hg graft -r 2
  grafting 2:* "add x again with different content" (glob)
  $ hg co -qC 2
BROKEN: This should succeed and merge the changes from x into y
  $ hg graft -r 3
  grafting 3:* "rename x to y" (glob)
  file 'x' was deleted in other [graft] but was modified in local [local].
  You can use (c)hanged version, (d)elete, or leave (u)nresolved.
  What do you want to do? u
  abort: unresolved conflicts, can't continue
  (use 'hg resolve' and 'hg graft --continue')
  [255]

Add x on two branches, then rename x to y on one side. Similar to the case
above, but here the break in history is via the base commit.
  $ newrepo
  $ echo a > a
  $ hg ci -Aqm 'base'
  $ echo x > x
  $ hg ci -Aqm 'add x'
  $ echo x2 > x
  $ hg ci -m 'modify x'
  $ hg co -q 0
  $ echo x > x
  $ hg ci -Aqm 'add x again'
  $ hg mv x y
  $ hg ci -qm 'rename x to y'
  $ hg l
  @  4 rename x to y
  |  x y
  o  3 add x again
  |  x
  | o  2 modify x
  | |  x
  | o  1 add x
  |/   x
  o  0 base
     a
  $ hg debugpathcopies 1 4
  x -> y
  $ hg graft -r 2
  grafting 2:* "modify x" (glob)
  merging y and x to y
  $ hg co -qC 2
  $ hg graft -r 4
  grafting 4:* "rename x to y"* (glob)
  merging x and y to y

Add x on two branches, with same content but different history, then rename x
to y on one side. Similar to the case above, here the file's nodeid is
different between the branches.
  $ newrepo
  $ echo a > a
  $ hg ci -Aqm 'base'
  $ echo x > x
  $ hg ci -Aqm 'add x'
  $ echo x2 > x
  $ hg ci -m 'modify x'
  $ hg co -q 0
  $ touch x
  $ hg ci -Aqm 'add empty x'
# Same content to avoid conflicts
  $ hg revert -r 1 x
  $ hg ci -m 'modify x to match commit 1'
  $ hg mv x y
  $ hg ci -qm 'rename x to y'
  $ hg l
  @  5 rename x to y
  |  x y
  o  4 modify x to match commit 1
  |  x
  o  3 add empty x
  |  x
  | o  2 modify x
  | |  x
  | o  1 add x
  |/   x
  o  0 base
     a
  $ hg debugpathcopies 1 5
  x -> y (no-filelog !)
#if no-filelog
  $ hg graft -r 2
  grafting 2:* "modify x" (glob)
  merging y and x to y
#else
BROKEN: This should succeed and merge the changes from x into y
  $ hg graft -r 2
  grafting 2:* "modify x" (glob)
  file 'x' was deleted in local [local] but was modified in other [graft].
  You can use (c)hanged version, leave (d)eleted, or leave (u)nresolved.
  What do you want to do? u
  abort: unresolved conflicts, can't continue
  (use 'hg resolve' and 'hg graft --continue')
  [255]
#endif
  $ hg co -qC 2
BROKEN: This should succeed and merge the changes from x into y
  $ hg graft -r 5
  grafting 5:* "rename x to y"* (glob)
  file 'x' was deleted in other [graft] but was modified in local [local].
  You can use (c)hanged version, (d)elete, or leave (u)nresolved.
  What do you want to do? u
  abort: unresolved conflicts, can't continue
  (use 'hg resolve' and 'hg graft --continue')
  [255]

Copies via null revision (there shouldn't be any)
  $ newrepo
  $ echo x > x
  $ hg ci -Aqm 'add x'
  $ hg cp x y
  $ hg ci -m 'copy x to y'
  $ hg co -q null
  $ echo x > x
  $ hg ci -Aqm 'add x (again)'
  $ hg l
  @  2 add x (again)
     x
  o  1 copy x to y
  |  y
  o  0 add x
     x
  $ hg debugpathcopies 1 2
  $ hg debugpathcopies 2 1
  $ hg graft -r 1
  grafting 1:* "copy x to y" (glob)

Copies involving a merge of multiple roots.

  $ newrepo
  $ echo a > a
  $ hg ci -Aqm 'add a'
  $ echo a >> a
  $ hg ci -Aqm 'update a'
  $ echo a >> a
  $ hg ci -Aqm 'update a'

  $ hg up null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo b > a
  $ hg ci -Aqm 'add a'
  $ hg mv a b
  $ hg ci -Aqm 'move a to b'
  $ echo b >> b
  $ hg ci -Aqm 'update b'
  $ hg merge 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg ci -m "merge with other branch"
  $ echo a >> a
  $ echo a >> a
  $ echo b >> b
  $ hg ci -Aqm 'update a and b'
  $ hg l
  @  7 update a and b
  |  a b
  o    6 merge with other branch
  |\
  | o  5 update b
  | |  b
  | o  4 move a to b
  | |  a b
  | o  3 add a
  |    a
  | o  2 update a
  | |  a
  | o  1 update a
  |/   a
  o  0 add a
     a
  $ hg cat a -r 7
  a
  a
  a
  $ hg cat a -r 2
  a
  a
  a
  $ hg cat a -r 0
  a
  $ hg debugpathcopies 7 2
  $ hg debugpathcopies 2 7
  $ hg merge 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)