view tests/test-rename-merge1.t @ 30212:260af19891f2

changegroup: increase write buffer size to 128k

By default, Python defers to the operating system for choosing the
default buffer size on opened files. On my Linux machine, the default
is 4k, which is really small for 2016.

This patch bumps the write buffer size when writing
changegroups/bundles to 128k. This matches the 128k read buffer
we already use on revlogs.

It's worth noting that this only impacts when writing to an explicit
file (such as during `hg bundle`). Buffers when writing to bundle
files via the repo vfs or to a temporary file are not impacted.

When producing a none-v2 bundle file of the mozilla-unified repository,
this change caused the number of write() system calls to drop from
952,449 to 29,788. After this change, the most frequent system
calls are fstat(), read(), lseek(), and open(). There were
2,523,672 system calls after this patch (so a net decrease of
~950k is statistically significant).

This change shows no performance change on my system. But I have a
high-end system with a fast SSD. It is quite possible this change
will have a significant impact on network file systems, where
extra network round trips due to excessive I/O system calls could
introduce significant latency.

  $ hg init

  $ echo "[merge]" >> .hg/hgrc
  $ echo "followcopies = 1" >> .hg/hgrc

  $ echo foo > a
  $ echo foo > a2
  $ hg add a a2
  $ hg ci -m "start"

  $ hg mv a b
  $ hg mv a2 b2
  $ hg ci -m "rename"

  $ hg co 0
  2 files updated, 0 files merged, 2 files removed, 0 files unresolved

  $ echo blahblah > a
  $ echo blahblah > a2
  $ hg mv a2 c2
  $ hg ci -m "modify"
  created new head

  $ hg merge -y --debug
    searching for copies back to rev 1
    unmatched files in local:
     c2
    unmatched files in other:
     b
     b2
    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
     src: 'a' -> dst: 'b' *
     src: 'a2' -> dst: 'b2' !
     src: 'a2' -> dst: 'c2' !
    checking for directory renames
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: af1939970a1c, local: 044f8520aeeb+, remote: 85c198ef2f6c
  note: possible conflict - a2 was renamed multiple times to:
   c2
   b2
   preserving a for resolve of b
  removing a
   b2: remote created -> g
  getting b2
   b: remote moved from a -> m (premerge)
  picked tool ':merge' for b (binary False symlink False changedelete False)
  merging a and b to b
  my b@044f8520aeeb+ other b@85c198ef2f6c ancestor a@af1939970a1c
   premerge successful
  1 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg status -AC
  M b
    a
  M b2
  R a
  C c2

  $ cat b
  blahblah

  $ hg ci -m "merge"

  $ hg debugindex b
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0      67  .....       1 57eacc201a7f 000000000000 000000000000 (re)
       1        67      72  .....       3 4727ba907962 000000000000 57eacc201a7f (re)

  $ hg debugrename b
  b renamed from a:dd03b83622e78778b403775d0d074b9ac7387a66

This used to trigger a "divergent renames" warning, despite no renames

  $ hg cp b b3
  $ hg cp b b4
  $ hg ci -A -m 'copy b twice'
  $ hg up eb92d88a9712
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ hg up
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg rm b3 b4
  $ hg ci -m 'clean up a bit of our mess'

We'd rather not warn on divergent renames done in the same changeset (issue2113)

  $ hg cp b b3
  $ hg mv b b4
  $ hg ci -A -m 'divergent renames in same changeset'
  $ hg up c761c6948de0
  1 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ hg up
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved

Check for issue2642

  $ hg init t
  $ cd t

  $ echo c0 > f1
  $ hg ci -Aqm0

  $ hg up null -q
  $ echo c1 > f1 # backport
  $ hg ci -Aqm1
  $ hg mv f1 f2
  $ hg ci -qm2

  $ hg up 0 -q
  $ hg merge 1 -q --tool internal:local
  $ hg ci -qm3

  $ hg merge 2
  merging f1 and f2 to f2
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cat f2
  c0

  $ cd ..

Check for issue2089

  $ hg init repo2089
  $ cd repo2089

  $ echo c0 > f1
  $ hg ci -Aqm0

  $ hg up null -q
  $ echo c1 > f1
  $ hg ci -Aqm1

  $ hg up 0 -q
  $ hg merge 1 -q --tool internal:local
  $ echo c2 > f1
  $ hg ci -qm2

  $ hg up 1 -q
  $ hg mv f1 f2
  $ hg ci -Aqm3

  $ hg up 2 -q
  $ hg merge 3
  merging f1 and f2 to f2
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ cat f2
  c2

  $ cd ..

Check for issue3074

  $ hg init repo3074
  $ cd repo3074
  $ echo foo > file
  $ hg add file
  $ hg commit -m "added file"
  $ hg mv file newfile
  $ hg commit -m "renamed file"
  $ hg update 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg rm file
  $ hg commit -m "deleted file"
  created new head
  $ hg merge --debug
    searching for copies back to rev 1
    unmatched files in other:
     newfile
    all copies found (* = to merge, ! = divergent, % = renamed and deleted):
     src: 'file' -> dst: 'newfile' %
    checking for directory renames
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 19d7f95df299, local: 0084274f6b67+, remote: 5d32493049f0
  note: possible conflict - file was deleted and renamed to:
   newfile
   newfile: remote created -> g
  getting newfile
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg status
  M newfile
  $ cd ..