tests/test-copy.t

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.

  $ mkdir part1
  $ cd part1

  $ hg init
  $ echo a > a
  $ hg add a
  $ hg commit -m "1"
  $ hg status
  $ hg copy a b
  $ hg --config ui.portablefilenames=abort copy a con.xml
  abort: filename contains 'con', which is reserved on Windows: 'con.xml'
  [255]
  $ hg status
  A b
  $ hg sum
  parent: 0:c19d34741b0a tip
   1
  branch: default
  commit: 1 copied
  update: (current)
  phases: 1 draft
  $ hg --debug commit -m "2"
  committing files:
  b
   b: copy a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3
  committing manifest
  committing changelog
  committed changeset 1:93580a2c28a50a56f63526fb305067e6fbf739c4

we should see two history entries

  $ hg history -v
  changeset:   1:93580a2c28a5
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       b
  description:
  2
  
  
  changeset:   0:c19d34741b0a
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       a
  description:
  1
  
  

we should see one log entry for a

  $ hg log a
  changeset:   0:c19d34741b0a
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     1
  

this should show a revision linked to changeset 0

  $ hg debugindex a
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       3  .....       0 b789fdd96dc2 000000000000 000000000000 (re)

we should see one log entry for b

  $ hg log b
  changeset:   1:93580a2c28a5
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     2
  

this should show a revision linked to changeset 1

  $ hg debugindex b
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0      65  .....       1 37d9b5d994ea 000000000000 000000000000 (re)

this should show the rename information in the metadata

  $ hg debugdata b 0 | head -3 | tail -2
  copy: a
  copyrev: b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3

  $ md5sum.py .hg/store/data/b.i
  4999f120a3b88713bbefddd195cf5133  .hg/store/data/b.i
  $ hg cat b > bsum
  $ md5sum.py bsum
  60b725f10c9c85c70d97880dfe8191b3  bsum
  $ hg cat a > asum
  $ md5sum.py asum
  60b725f10c9c85c70d97880dfe8191b3  asum
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  2 files, 2 changesets, 2 total revisions

  $ cd ..


  $ mkdir part2
  $ cd part2

  $ hg init
  $ echo foo > foo
should fail - foo is not managed
  $ hg mv foo bar
  foo: not copying - file is not managed
  abort: no files to copy
  [255]
  $ hg st -A
  ? foo
  $ hg add foo
dry-run; print a warning that this is not a real copy; foo is added
  $ hg mv --dry-run foo bar
  foo has not been committed yet, so no copy data will be stored for bar.
  $ hg st -A
  A foo
should print a warning that this is not a real copy; bar is added
  $ hg mv foo bar
  foo has not been committed yet, so no copy data will be stored for bar.
  $ hg st -A
  A bar
should print a warning that this is not a real copy; foo is added
  $ hg cp bar foo
  bar has not been committed yet, so no copy data will be stored for foo.
  $ hg rm -f bar
  $ rm bar
  $ hg st -A
  A foo
  $ hg commit -m1

moving a missing file
  $ rm foo
  $ hg mv foo foo3
  foo: deleted in working directory
  foo3 does not exist!
  $ hg up -qC .

copy --after to a nonexistent target filename
  $ hg cp -A foo dummy
  foo: not recording copy - dummy does not exist

dry-run; should show that foo is clean
  $ hg copy --dry-run foo bar
  $ hg st -A
  C foo
should show copy
  $ hg copy foo bar
  $ hg st -C
  A bar
    foo

shouldn't show copy
  $ hg commit -m2
  $ hg st -C

should match
  $ hg debugindex foo
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       5  .....       0 2ed2a3912a0b 000000000000 000000000000 (re)
  $ hg debugrename bar
  bar renamed from foo:2ed2a3912a0b24502043eae84ee4b279c18b90dd

  $ echo bleah > foo
  $ echo quux > bar
  $ hg commit -m3

should not be renamed
  $ hg debugrename bar
  bar not renamed

  $ hg copy -f foo bar
should show copy
  $ hg st -C
  M bar
    foo

XXX: filtering lfilesrepo.status() in 3.3-rc causes the copy source to not be
displayed.
  $ hg st -C --config extensions.largefiles=
  M bar
    foo

  $ hg commit -m3

should show no parents for tip
  $ hg debugindex bar
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0      69  .....       1 7711d36246cc 000000000000 000000000000 (re)
       1        69       6  .....       2 bdf70a2b8d03 7711d36246cc 000000000000 (re)
       2        75      71  .....       3 b2558327ea8d 000000000000 000000000000 (re)
should match
  $ hg debugindex foo
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       5  .....       0 2ed2a3912a0b 000000000000 000000000000 (re)
       1         5       7  .....       2 dd12c926cf16 2ed2a3912a0b 000000000000 (re)
  $ hg debugrename bar
  bar renamed from foo:dd12c926cf165e3eb4cf87b084955cb617221c17

should show no copies
  $ hg st -C

copy --after on an added file
  $ cp bar baz
  $ hg add baz
  $ hg cp -A bar baz
  $ hg st -C
  A baz
    bar

foo was clean:
  $ hg st -AC foo
  C foo
but it's considered modified after a copy --after --force
  $ hg copy -Af bar foo
  $ hg st -AC foo
  M foo
    bar

  $ cd ..