tests/test-unionrepo.t

osutil: implement setprocname to set process title for some platforms

This patch adds a simple setprocname method to osutil. The operation is not
defined by any standard and is platform-specific, the current implementation
tries to cover some major platforms (ex. Linux, OS X, FreeBSD) that is
relatively easy to support. Other platforms (Windows [4], other BSDs, ...)
can be added in the future.

The current implementation supports two methods to change process title:
  a. setproctitle if available (works in FreeBSD).
  b. rewrite argv in place (works in Linux [1] and Mac OS X). [2] [3]

[1]: Linux has "prctl(PR_SET_NAME, ...)" but 1) it has 16-byte limit, which
is too small; 2) it is not quite equivalent to what we want - it changes
"/proc/self/comm", not "/proc/self/cmdline" - "comm" change won't show up
in "ps" output unless "-o comm" is used.

[2]: The implementation does not rewrite the **environ buffer like some
other implementations do, just to make the code simpler and safer. However,
this also means the buffer size we can rewrite is significantly shorter. If
we are really greedy and want the "environ" space, we can change the
implementation later.

[3]: It requires a CPython private API: Py_GetArgcArgv to get the original
argv. Unfortunately Python 3 makes a copy of argv and returns the wchar_t
version, so it is not supported for now. (if we really want to, we could
count backwards from "char **environ", given known argc and argv, not sure
if that's a good idea - probably not)

[4]: The feature is aimed to make it easier for forked command server
processes to show what they are doing. Since Windows does not support
fork(), despite it's a major platform, its support is not added in this
patch.

Test unionrepo functionality

Create one repository

  $ hg init repo1
  $ cd repo1
  $ touch repo1-0
  $ echo repo1-0 > f
  $ hg ci -Aqmrepo1-0
  $ touch repo1-1
  $ echo repo1-1 >> f
  $ hg ci -Aqmrepo1-1
  $ touch repo1-2
  $ echo repo1-2 >> f
  $ hg ci -Aqmrepo1-2
  $ hg log --template '{rev}:{node|short}  {desc|firstline}\n'
  2:68c0685446a3  repo1-2
  1:8a58db72e69d  repo1-1
  0:f093fec0529b  repo1-0
  $ tip1=`hg id -q`
  $ cd ..

- and a clone with a not-completely-trivial history

  $ hg clone -q repo1 --rev 0 repo2
  $ cd repo2
  $ touch repo2-1
  $ sed '1i\
  > repo2-1 at top
  > ' f > f.tmp
  $ mv f.tmp f
  $ hg ci -Aqmrepo2-1
  $ touch repo2-2
  $ hg pull -q ../repo1 -r 1
  $ hg merge -q
  $ hg ci -Aqmrepo2-2-merge
  $ touch repo2-3
  $ echo repo2-3 >> f
  $ hg ci -mrepo2-3
  $ hg log --template '{rev}:{node|short}  {desc|firstline}\n'
  4:2f0d178c469c  repo2-3
  3:9e6fb3e0b9da  repo2-2-merge
  2:8a58db72e69d  repo1-1
  1:c337dba826e7  repo2-1
  0:f093fec0529b  repo1-0
  $ cd ..

revisions from repo2 appear as appended / pulled to repo1

  $ hg -R union:repo1+repo2 log --template '{rev}:{node|short}  {desc|firstline}\n'
  5:2f0d178c469c  repo2-3
  4:9e6fb3e0b9da  repo2-2-merge
  3:c337dba826e7  repo2-1
  2:68c0685446a3  repo1-2
  1:8a58db72e69d  repo1-1
  0:f093fec0529b  repo1-0

manifest can be retrieved for revisions in both repos

  $ hg -R union:repo1+repo2 mani -r $tip1
  f
  repo1-0
  repo1-1
  repo1-2
  $ hg -R union:repo1+repo2 mani -r 4
  f
  repo1-0
  repo1-1
  repo2-1
  repo2-2

files can be retrieved form both repos

  $ hg -R repo1 cat repo1/f -r2
  repo1-0
  repo1-1
  repo1-2

  $ hg -R union:repo1+repo2 cat -r$tip1 repo1/f
  repo1-0
  repo1-1
  repo1-2

  $ hg -R union:repo1+repo2 cat -r4 $TESTTMP/repo1/f
  repo2-1 at top
  repo1-0
  repo1-1

files can be compared across repos

  $ hg -R union:repo1+repo2 diff -r$tip1 -rtip
  diff -r 68c0685446a3 -r 2f0d178c469c f
  --- a/f	Thu Jan 01 00:00:00 1970 +0000
  +++ b/f	Thu Jan 01 00:00:00 1970 +0000
  @@ -1,3 +1,4 @@
  +repo2-1 at top
   repo1-0
   repo1-1
  -repo1-2
  +repo2-3

heads from both repos are found correctly

  $ hg -R union:repo1+repo2 heads --template '{rev}:{node|short}  {desc|firstline}\n'
  5:2f0d178c469c  repo2-3
  2:68c0685446a3  repo1-2

revsets works across repos

  $ hg -R union:repo1+repo2 id -r "ancestor($tip1, 5)"
  8a58db72e69d

annotate works - an indication that linkrevs works

  $ hg --cwd repo1 -Runion:../repo2 annotate $TESTTMP/repo1/f -r tip
  3: repo2-1 at top
  0: repo1-0
  1: repo1-1
  5: repo2-3

union repos can be cloned ... and clones works correctly

  $ hg clone -U union:repo1+repo2 repo3
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 6 changesets with 11 changes to 6 files (+1 heads)

  $ hg -R repo3 paths
  default = union:repo1+repo2

  $ hg -R repo3 verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  6 files, 6 changesets, 11 total revisions

  $ hg -R repo3 heads --template '{rev}:{node|short}  {desc|firstline}\n'
  5:2f0d178c469c  repo2-3
  2:68c0685446a3  repo1-2

  $ hg -R repo3 log --template '{rev}:{node|short}  {desc|firstline}\n'
  5:2f0d178c469c  repo2-3
  4:9e6fb3e0b9da  repo2-2-merge
  3:c337dba826e7  repo2-1
  2:68c0685446a3  repo1-2
  1:8a58db72e69d  repo1-1
  0:f093fec0529b  repo1-0

union repos should use the correct rev number (issue5024)

  $ hg init a
  $ cd a
  $ echo a0 >> f
  $ hg ci -Aqm a0
  $ cd ..
  $ hg init b
  $ cd b
  $ echo b0 >> f
  $ hg ci -Aqm b0
  $ echo b1 >> f
  $ hg ci -qm b1
  $ cd ..

"hg files -v" to call fctx.size() -> fctx.iscensored()
  $ hg files -R union:b+a -r2 -v
           3   b/f (glob)