view tests/test-merge-commit.t @ 26379:39d643252b9f

revlog: use existing file handle when reading during _addrevision

_addrevision() may need to read from revlogs as part of computing
deltas. Previously, we would flush existing file handles and open
a new, short-lived file handle to perform the reading.

If we have an existing file handle, it seems logical to reuse it
for reading instead of opening a new file handle. This patch
makes that the new behavior.

After this patch, revlog files are only reopened when adding
revisions if the revlog is switched from inline to non-inline.

On Linux when unbundling a bundle of the mozilla-central repo, this
patch has the following impact on system call counts:

Call     Before     After       Delta
write    827,639    673,390   -154,249
open     700,103    684,089    -16,014
read      74,489     74,489          0
fstat    493,924    461,896    -32,028
close    249,131    233,117    -16,014
stat     242,001    242,001          0
lstat     18,676     18,676          0
lseek     20,268     20,268          0
ioctl     14,652     13,173     -1,479
TOTAL  3,180,758  2,930,679   -250,079

It's worth noting that many of the open() calls fail due to missing
files. That's why there are many more open() calls than close().

Despite the significant system call reduction, this change does not
seem to have a significant performance impact on Linux.

On Windows 10 (not a VM, on a SSD), this patch appears to reduce
unbundle time for mozilla-central from ~960s to ~920s. This isn't
as significant as I was hoping. But a decrease it is nonetheless.
Still, Windows unbundle performance is still >2x slower than Linux.

Despite the lack of significant gains, fewer system calls is fewer
system calls. If nothing else, this will narrow the focus of potential
areas to optimize in the future.

Check that renames are correctly saved by a commit after a merge

Test with the merge on 3 having the rename on the local parent

  $ hg init a
  $ cd a

  $ echo line1 > foo
  $ hg add foo
  $ hg ci -m '0: add foo'

  $ echo line2 >> foo
  $ hg ci -m '1: change foo'

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

  $ hg mv foo bar
  $ rm bar
  $ echo line0 > bar
  $ echo line1 >> bar
  $ hg ci -m '2: mv foo bar; change bar'
  created new head

  $ hg merge 1
  merging bar and foo to bar
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cat bar
  line0
  line1
  line2

  $ hg ci -m '3: merge with local rename'

  $ hg debugindex bar
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0      77  .....       2 d35118874825 000000000000 000000000000 (re)
       1        77      76  .....       3 5345f5ab8abd 000000000000 d35118874825 (re)

  $ hg debugrename bar
  bar renamed from foo:9e25c27b87571a1edee5ae4dddee5687746cc8e2

  $ hg debugindex foo
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       7  .....       0 690b295714ae 000000000000 000000000000 (re)
       1         7      13  .....       1 9e25c27b8757 690b295714ae 000000000000 (re)


Revert the content change from rev 2:

  $ hg up -C 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ rm bar
  $ echo line1 > bar
  $ hg ci -m '4: revert content change from rev 2'
  created new head

  $ hg log --template '{rev}:{node|short} {parents}\n'
  4:2263c1be0967 2:0f2ff26688b9 
  3:0555950ead28 2:0f2ff26688b9 1:5cd961e4045d 
  2:0f2ff26688b9 0:2665aaee66e9 
  1:5cd961e4045d 
  0:2665aaee66e9 

This should use bar@rev2 as the ancestor:

  $ hg --debug merge 3
    searching for copies back to rev 1
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 0f2ff26688b9, local: 2263c1be0967+, remote: 0555950ead28
   preserving bar for resolve of bar
   bar: versions differ -> m
  picked tool 'internal:merge' for bar (binary False symlink False)
  merging bar
  my bar@2263c1be0967+ other bar@0555950ead28 ancestor bar@0f2ff26688b9
   premerge successful
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cat bar
  line1
  line2

  $ hg ci -m '5: merge'

  $ hg debugindex bar
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0      77  .....       2 d35118874825 000000000000 000000000000 (re)
       1        77      76  .....       3 5345f5ab8abd 000000000000 d35118874825 (re)
       2       153       7  .....       4 ff4b45017382 d35118874825 000000000000 (re)
       3       160      13  .....       5 3701b4893544 ff4b45017382 5345f5ab8abd (re)


Same thing, but with the merge on 3 having the rename
on the remote parent:

  $ cd ..
  $ hg clone -U -r 1 -r 2 a b
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 2 files (+1 heads)
  $ cd b

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

  $ hg merge 2
  merging foo and bar to bar
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cat bar
  line0
  line1
  line2

  $ hg ci -m '3: merge with remote rename'

  $ hg debugindex bar
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0      77  .....       2 d35118874825 000000000000 000000000000 (re)
       1        77      76  .....       3 5345f5ab8abd 000000000000 d35118874825 (re)

  $ hg debugrename bar
  bar renamed from foo:9e25c27b87571a1edee5ae4dddee5687746cc8e2

  $ hg debugindex foo
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       7  .....       0 690b295714ae 000000000000 000000000000 (re)
       1         7      13  .....       1 9e25c27b8757 690b295714ae 000000000000 (re)


Revert the content change from rev 2:

  $ hg up -C 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ rm bar
  $ echo line1 > bar
  $ hg ci -m '4: revert content change from rev 2'
  created new head

  $ hg log --template '{rev}:{node|short} {parents}\n'
  4:2263c1be0967 2:0f2ff26688b9 
  3:3ffa6b9e35f0 1:5cd961e4045d 2:0f2ff26688b9 
  2:0f2ff26688b9 0:2665aaee66e9 
  1:5cd961e4045d 
  0:2665aaee66e9 

This should use bar@rev2 as the ancestor:

  $ hg --debug merge 3
    searching for copies back to rev 1
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 0f2ff26688b9, local: 2263c1be0967+, remote: 3ffa6b9e35f0
   preserving bar for resolve of bar
   bar: versions differ -> m
  picked tool 'internal:merge' for bar (binary False symlink False)
  merging bar
  my bar@2263c1be0967+ other bar@3ffa6b9e35f0 ancestor bar@0f2ff26688b9
   premerge successful
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cat bar
  line1
  line2

  $ hg ci -m '5: merge'

  $ hg debugindex bar
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0      77  .....       2 d35118874825 000000000000 000000000000 (re)
       1        77      76  .....       3 5345f5ab8abd 000000000000 d35118874825 (re)
       2       153       7  .....       4 ff4b45017382 d35118874825 000000000000 (re)
       3       160      13  .....       5 3701b4893544 ff4b45017382 5345f5ab8abd (re)

  $ cd ..