ui: add special-purpose atexit functionality
In spite of its longstanding use, Python's built-in atexit code is
not suitable for Mercurial's purposes, for several reasons:
* Handlers run after application code has finished.
* Because of this, the code that runs handlers swallows exceptions
(since there's no possible stacktrace to associate errors with).
If we're lucky, we'll get something spat out to stderr (if stderr
still works), which of course isn't any use in a big deployment
where it's important that exceptions get logged and aggregated.
* Mercurial's current atexit handlers make unfortunate assumptions
about process state (specifically stdio) that, coupled with the
above problems, make it impossible to deal with certain categories
of error (try "hg status > /dev/full" on a Linux box).
* In Python 3, the atexit implementation is completely hidden, so
we can't hijack the platform's atexit code to run handlers at a
time of our choosing.
As a result, here's a perfectly cromulent atexit-like implementation
over which we have control. This lets us decide exactly when the
handlers run (after each request has completed), and control what
the process state is when that occurs (and afterwards).
# Create server
$ hg init server
$ cd server
$ cat >> .hg/hgrc << EOF
> [extensions]
> extension=$TESTDIR/flagprocessorext.py
> EOF
$ cd ../
# Clone server and enable extensions
$ hg clone -q server client
$ cd client
$ cat >> .hg/hgrc << EOF
> [extensions]
> extension=$TESTDIR/flagprocessorext.py
> EOF
# Commit file that will trigger the noop extension
$ echo '[NOOP]' > noop
$ hg commit -Aqm "noop"
# Commit file that will trigger the base64 extension
$ echo '[BASE64]' > base64
$ hg commit -Aqm 'base64'
# Commit file that will trigger the gzip extension
$ echo '[GZIP]' > gzip
$ hg commit -Aqm 'gzip'
# Commit file that will trigger noop and base64
$ echo '[NOOP][BASE64]' > noop-base64
$ hg commit -Aqm 'noop+base64'
# Commit file that will trigger noop and gzip
$ echo '[NOOP][GZIP]' > noop-gzip
$ hg commit -Aqm 'noop+gzip'
# Commit file that will trigger base64 and gzip
$ echo '[BASE64][GZIP]' > base64-gzip
$ hg commit -Aqm 'base64+gzip'
# Commit file that will trigger base64, gzip and noop
$ echo '[BASE64][GZIP][NOOP]' > base64-gzip-noop
$ hg commit -Aqm 'base64+gzip+noop'
# TEST: ensure the revision data is consistent
$ hg cat noop
[NOOP]
$ hg debugdata noop 0
[NOOP]
$ hg cat -r . base64
[BASE64]
$ hg debugdata base64 0
W0JBU0U2NF0K (no-eol)
$ hg cat -r . gzip
[GZIP]
$ hg debugdata gzip 0
x\x9c\x8bv\x8f\xf2\x0c\x88\xe5\x02\x00\x08\xc8\x01\xfd (no-eol) (esc)
$ hg cat -r . noop-base64
[NOOP][BASE64]
$ hg debugdata noop-base64 0
W05PT1BdW0JBU0U2NF0K (no-eol)
$ hg cat -r . noop-gzip
[NOOP][GZIP]
$ hg debugdata noop-gzip 0
x\x9c\x8b\xf6\xf3\xf7\x0f\x88\x8dv\x8f\xf2\x0c\x88\xe5\x02\x00\x1dH\x03\xf1 (no-eol) (esc)
$ hg cat -r . base64-gzip
[BASE64][GZIP]
$ hg debugdata base64-gzip 0
eJyLdnIMdjUziY12j/IMiOUCACLBBDo= (no-eol)
$ hg cat -r . base64-gzip-noop
[BASE64][GZIP][NOOP]
$ hg debugdata base64-gzip-noop 0
eJyLdnIMdjUziY12j/IMiI328/cPiOUCAESjBi4= (no-eol)
# Push to the server
$ hg push
pushing to $TESTTMP/server (glob)
searching for changes
adding changesets
adding manifests
adding file changes
added 7 changesets with 7 changes to 7 files
# Initialize new client (not cloning) and setup extension
$ cd ..
$ hg init client2
$ cd client2
$ cat >> .hg/hgrc << EOF
> [paths]
> default = $TESTTMP/server
> [extensions]
> extension=$TESTDIR/flagprocessorext.py
> EOF
# Pull from server and update to latest revision
$ hg pull default
pulling from $TESTTMP/server (glob)
requesting all changes
adding changesets
adding manifests
adding file changes
added 7 changesets with 7 changes to 7 files
(run 'hg update' to get a working copy)
$ hg update
7 files updated, 0 files merged, 0 files removed, 0 files unresolved
# TEST: ensure the revision data is consistent
$ hg cat noop
[NOOP]
$ hg debugdata noop 0
[NOOP]
$ hg cat -r . base64
[BASE64]
$ hg debugdata base64 0
W0JBU0U2NF0K (no-eol)
$ hg cat -r . gzip
[GZIP]
$ hg debugdata gzip 0
x\x9c\x8bv\x8f\xf2\x0c\x88\xe5\x02\x00\x08\xc8\x01\xfd (no-eol) (esc)
$ hg cat -r . noop-base64
[NOOP][BASE64]
$ hg debugdata noop-base64 0
W05PT1BdW0JBU0U2NF0K (no-eol)
$ hg cat -r . noop-gzip
[NOOP][GZIP]
$ hg debugdata noop-gzip 0
x\x9c\x8b\xf6\xf3\xf7\x0f\x88\x8dv\x8f\xf2\x0c\x88\xe5\x02\x00\x1dH\x03\xf1 (no-eol) (esc)
$ hg cat -r . base64-gzip
[BASE64][GZIP]
$ hg debugdata base64-gzip 0
eJyLdnIMdjUziY12j/IMiOUCACLBBDo= (no-eol)
$ hg cat -r . base64-gzip-noop
[BASE64][GZIP][NOOP]
$ hg debugdata base64-gzip-noop 0
eJyLdnIMdjUziY12j/IMiI328/cPiOUCAESjBi4= (no-eol)
# TEST: ensure a missing processor is handled
$ echo '[FAIL][BASE64][GZIP][NOOP]' > fail-base64-gzip-noop
$ hg commit -Aqm 'fail+base64+gzip+noop'
abort: missing processor for flag '0x1'!
[255]
# TEST: ensure we cannot register several flag processors on the same flag
$ cat >> .hg/hgrc << EOF
> [extensions]
> extension=$TESTDIR/flagprocessorext.py
> duplicate=$TESTDIR/flagprocessorext.py
> EOF
$ echo 'this should fail' > file
$ hg commit -Aqm 'add file'
abort: cannot register multiple processors on flag '0x8'.
[255]
$ cd ..
# TEST: bundle repo
$ hg init bundletest
$ cd bundletest
$ cat >> .hg/hgrc << EOF
> [extensions]
> flagprocessor=$TESTDIR/flagprocessorext.py
> EOF
$ for i in 0 single two three 4; do
> echo '[BASE64]a-bit-longer-'$i > base64
> hg commit -m base64-$i -A base64
> done
$ hg update 2 -q
$ echo '[BASE64]a-bit-longer-branching' > base64
$ hg commit -q -m branching
$ hg bundle --base 1 bundle.hg
4 changesets found
$ hg --config extensions.strip= strip -r 2 --no-backup --force -q
$ hg -R bundle.hg log --stat -T '{rev} {desc}\n' base64
5 branching
base64 | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
4 base64-4
base64 | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
3 base64-three
base64 | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
2 base64-two
base64 | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
1 base64-single
base64 | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
0 base64-0
base64 | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
$ hg bundle -R bundle.hg --base 1 bundle-again.hg -q
$ hg -R bundle-again.hg log --stat -T '{rev} {desc}\n' base64
5 branching
base64 | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
4 base64-4
base64 | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
3 base64-three
base64 | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
2 base64-two
base64 | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
1 base64-single
base64 | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
0 base64-0
base64 | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)
$ rm bundle.hg bundle-again.hg
# TEST: hg status
$ hg status
$ hg diff