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.
Enable obsolete markers
$ cat >> $HGRCPATH << EOF
> [experimental]
> evolution=createmarkers
> [phases]
> publish=False
> EOF
Build a repo with some cacheable bits:
$ hg init a
$ cd a
$ echo a > a
$ hg ci -qAm0
$ hg tag t1
$ hg book -i bk1
$ hg branch -q b2
$ hg ci -Am1
$ hg tag t2
$ echo dumb > dumb
$ hg ci -qAmdumb
$ hg debugobsolete b1174d11b69e63cb0c5726621a43c859f0858d7f
$ hg phase -pr t1
$ hg phase -fsr t2
Make a helper function to check cache damage invariants:
- command output shouldn't change
- cache should be present after first use
- corruption/repair should be silent (no exceptions or warnings)
- cache should survive deletion, overwrite, and append
- unreadable / unwriteable caches should be ignored
- cache should be rebuilt after corruption
$ damage() {
> CMD=$1
> CACHE=.hg/cache/$2
> CLEAN=$3
> hg $CMD > before
> test -f $CACHE || echo "not present"
> echo bad > $CACHE
> test -z "$CLEAN" || $CLEAN
> hg $CMD > after
> diff -u before after || echo "*** overwrite corruption"
> echo corruption >> $CACHE
> test -z "$CLEAN" || $CLEAN
> hg $CMD > after
> diff -u before after || echo "*** append corruption"
> rm $CACHE
> mkdir $CACHE
> test -z "$CLEAN" || $CLEAN
> hg $CMD > after
> diff -u before after || echo "*** read-only corruption"
> test -d $CACHE || echo "*** directory clobbered"
> rmdir $CACHE
> test -z "$CLEAN" || $CLEAN
> hg $CMD > after
> diff -u before after || echo "*** missing corruption"
> test -f $CACHE || echo "not rebuilt"
> }
Beat up tags caches:
$ damage "tags --hidden" tags2
$ damage tags tags2-visible
$ damage "tag -f t3" hgtagsfnodes1
Beat up hidden cache:
$ damage log hidden
Beat up branch caches:
$ damage branches branch2-base "rm .hg/cache/branch2-[vs]*"
$ damage branches branch2-served "rm .hg/cache/branch2-[bv]*"
$ damage branches branch2-visible
$ damage "log -r branch(.)" rbc-names-v1
$ damage "log -r branch(default)" rbc-names-v1
$ damage "log -r branch(b2)" rbc-revs-v1
We currently can't detect an rbc cache with unknown names:
$ damage "log -qr branch(b2)" rbc-names-v1
--- before * (glob)
+++ after * (glob)
@@ -1,8 +?,0 @@ (glob)
-2:5fb7d38b9dc4
-3:60b597ffdafa
-4:b1174d11b69e
-5:6354685872c0
-6:5ebc725f1bef
-7:7b76eec2f273
-8:ef3428d9d644
-9:ba7a936bc03c
*** append corruption