view tests/test-flags.t @ 27430:e240e914d226 stable

revlog: seek to end of file before writing (issue4943)

Revlogs were recently refactored to open file handles in "a+" and use a
persistent file handle for reading and writing. This drastically
reduced the number of file handles being opened.

Unfortunately, it appears that some versions of Solaris lose the file
offset when performing a write after the handle has been seeked.

The simplest workaround is to seek to EOF on files opened in a+ mode
before writing to them, which is what this patch does.

Ideally, this code would exist in the vfs layer. However, this would
require creating a proxy class for file objects in order to provide a
custom implementation of write(). This would add overhead. Since
revlogs are the only files we open in a+ mode, the one-off workaround
in revlog.py should be sufficient.

This patch appears to have little to no impact on performance on my
Linux machine.

#require execbit

  $ umask 027

  $ hg init test1
  $ cd test1
  $ touch a b
  $ hg add a b
  $ hg ci -m "added a b"

  $ cd ..
  $ hg clone test1 test3
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg init test2
  $ cd test2
  $ hg pull ../test1
  pulling from ../test1
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 2 changes to 2 files
  (run 'hg update' to get a working copy)
  $ hg co
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ chmod +x a
  $ hg ci -m "chmod +x a"

the changelog should mention file a:

  $ hg tip --template '{files}\n'
  a

  $ cd ../test1
  $ echo 123 >>a
  $ hg ci -m "a updated"

  $ hg pull ../test2
  pulling from ../test2
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 0 files (+1 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg heads
  changeset:   2:7f4313b42a34
  tag:         tip
  parent:      0:22a449e20da5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     chmod +x a
  
  changeset:   1:c6ecefc45368
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a updated
  
  $ hg history
  changeset:   2:7f4313b42a34
  tag:         tip
  parent:      0:22a449e20da5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     chmod +x a
  
  changeset:   1:c6ecefc45368
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a updated
  
  changeset:   0:22a449e20da5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     added a b
  

  $ hg -v merge
  resolving manifests
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ cat a
  123
  $ [ -x a ]

  $ cd ../test3
  $ echo 123 >>b
  $ hg ci -m "b updated"

  $ hg pull ../test2
  pulling from ../test2
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 0 files (+1 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg heads
  changeset:   2:7f4313b42a34
  tag:         tip
  parent:      0:22a449e20da5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     chmod +x a
  
  changeset:   1:dc57ead75f79
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     b updated
  
  $ hg history
  changeset:   2:7f4313b42a34
  tag:         tip
  parent:      0:22a449e20da5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     chmod +x a
  
  changeset:   1:dc57ead75f79
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     b updated
  
  changeset:   0:22a449e20da5
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     added a b
  

  $ hg -v merge
  resolving manifests
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ ls -l ../test[123]/a > foo
  $ cut -b 1-10 < foo
  -rwxr-x---
  -rwxr-x---
  -rwxr-x---

  $ hg debugindex a
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       0  .....       0 b80de5d13875 000000000000 000000000000 (re)
  $ hg debugindex -R ../test2 a
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       0  .....       0 b80de5d13875 000000000000 000000000000 (re)
  $ hg debugindex -R ../test1 a
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       0  .....       0 b80de5d13875 000000000000 000000000000 (re)
       1         0       5  .....       1 7fe919cc0336 b80de5d13875 000000000000 (re)

  $ cd ..