worker: rewrite error handling so os._exit covers all cases
Previously the worker error handling is like:
pid = os.fork() --+
if pid == 0: |
.... | problematic
.... --+
try: --+
.... | worker error handling
--+
If a signal arrives when Python is executing the "problematic" lines, an
external error handling (dispatch.py) will take over the control flow and
it's no longer guaranteed "os._exit" is called (see
86cd09bc13ba for why it
is necessary).
This patch rewrites the error handling so it covers all possible code paths
for a worker even during fork.
Note: "os.getpid() == parentpid" is used to test if the process is parent or
not intentionally, instead of checking "pid", because "pid = os.fork()" may
be not atomic - it's possible that that a signal hits the worker before the
assignment completes [1]. The newly added test replaces "os.fork" to
exercise that extreme case.
[1]: CPython compiles "pid = os.fork()" to 2 byte codes: "CALL_FUNCTION" and
"STORE_FAST", so it's probably not atomic:
def f():
pid = os.fork()
dis.dis(f)
2 0 LOAD_GLOBAL 0 (os)
3 LOAD_ATTR 1 (fork)
6 CALL_FUNCTION 0
9 STORE_FAST 0 (pid)
12 LOAD_CONST 0 (None)
15 RETURN_VALUE
Environment setup for MQ
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ cat >> $HGRCPATH <<EOF
> [defaults]
> # explicit date to commit with fixed hashid
> qnew = -d "0 0"
> qrefresh = -d "0 0"
> qfold = -d "0 0"
> EOF
$ hg init
$ hg qinit
Should fail if no patches applied
(this tests also that editor is not invoked if '--edit' is not
specified)
$ hg qrefresh
no patches applied
[1]
$ hg qrefresh -e
no patches applied
[1]
$ hg qnew -m "First commit message" first-patch
$ echo aaaa > file
$ hg add file
$ HGEDITOR=cat hg qrefresh
Should display 'First commit message'
$ hg log -l1 --template "{desc}\n"
First commit message
Testing changing message with -m
(this tests also that '--edit' can be used with '--message', and
that '[committemplate] changeset' definition and commit log specific
template keyword 'extramsg' work well)
$ cat >> .hg/hgrc <<EOF
> [committemplate]
> listupfiles = {file_adds %
> "HG: added {file}\n" }{file_mods %
> "HG: changed {file}\n" }{file_dels %
> "HG: removed {file}\n" }{if(files, "",
> "HG: no files changed\n")}
>
> changeset = HG: this is customized commit template
> {desc}\n\n
> HG: Enter commit message. Lines beginning with 'HG:' are removed.
> HG: {extramsg}
> HG: --
> HG: user: {author}
> HG: branch '{branch}'\n{listupfiles}
> EOF
$ echo bbbb > file
$ HGEDITOR=cat hg qrefresh -m "Second commit message" -e
HG: this is customized commit template
Second commit message
HG: Enter commit message. Lines beginning with 'HG:' are removed.
HG: Leave message empty to use default message.
HG: --
HG: user: test
HG: branch 'default'
HG: added file
$ cat >> .hg/hgrc <<EOF
> # disable customizing for subsequent tests
> [committemplate]
> changeset =
> EOF
Should display 'Second commit message'
$ hg log -l1 --template "{desc}\n"
Second commit message
Testing changing message with -l
$ echo "Third commit message" > logfile
$ echo " This is the 3rd log message" >> logfile
$ echo bbbb > file
$ hg qrefresh -l logfile
Should display 'Third commit message\\\n This is the 3rd log message'
$ hg log -l1 --template "{desc}\n"
Third commit message
This is the 3rd log message
Testing changing message with -l-
$ hg qnew -m "First commit message" second-patch
$ echo aaaa > file2
$ hg add file2
$ echo bbbb > file2
$ (echo "Fifth commit message"; echo " This is the 5th log message") | hg qrefresh -l-
Should display 'Fifth commit message\\\n This is the 5th log message'
$ hg log -l1 --template "{desc}\n"
Fifth commit message
This is the 5th log message
Test saving last-message.txt:
$ cat > $TESTTMP/editor.sh << EOF
> echo "==== before editing"
> cat \$1
> echo "===="
> (echo; echo "test saving last-message.txt") >> \$1
> EOF
$ cat > $TESTTMP/commitfailure.py <<EOF
> from mercurial import error
> def reposetup(ui, repo):
> class commitfailure(repo.__class__):
> def commit(self, *args, **kwargs):
> raise error.Abort('emulating unexpected abort')
> repo.__class__ = commitfailure
> EOF
$ cat >> .hg/hgrc <<EOF
> [extensions]
> # this failure occurs before editor invocation
> commitfailure = $TESTTMP/commitfailure.py
> EOF
$ hg qapplied
first-patch
second-patch
$ hg tip --template "{files}\n"
file2
(test that editor is not invoked before transaction starting)
$ rm -f .hg/last-message.txt
$ HGEDITOR="sh $TESTTMP/editor.sh" hg qrefresh -e
qrefresh interrupted while patch was popped! (revert --all, qpush to recover)
abort: emulating unexpected abort
[255]
$ test -f .hg/last-message.txt
[1]
(reset applied patches and directory status)
$ cat >> .hg/hgrc <<EOF
> [extensions]
> commitfailure = !
> EOF
$ hg qapplied
first-patch
$ hg status -A file2
? file2
$ rm file2
$ hg qpush -q second-patch
now at: second-patch
(test that editor is invoked and commit message is saved into
"last-message.txt")
$ cat >> .hg/hgrc <<EOF
> [hooks]
> # this failure occurs after editor invocation
> pretxncommit.unexpectedabort = false
> EOF
$ rm -f .hg/last-message.txt
$ hg status --rev "second-patch^1" -arm
A file2
$ HGEDITOR="sh $TESTTMP/editor.sh" hg qrefresh -e
==== before editing
Fifth commit message
This is the 5th log message
HG: Enter commit message. Lines beginning with 'HG:' are removed.
HG: Leave message empty to use default message.
HG: --
HG: user: test
HG: branch 'default'
HG: added file2
====
note: commit message saved in .hg/last-message.txt
transaction abort!
rollback completed
qrefresh interrupted while patch was popped! (revert --all, qpush to recover)
abort: pretxncommit.unexpectedabort hook exited with status 1
[255]
$ cat .hg/last-message.txt
Fifth commit message
This is the 5th log message
test saving last-message.txt
Test visibility of in-memory dirstate changes outside transaction to
external process
$ cat > $TESTTMP/checkvisibility.sh <<EOF
> echo "===="
> hg parents --template "{rev}:{node|short}\n"
> hg status -arm
> echo "===="
> EOF
== test visibility to external editor
$ hg update -C -q first-patch
$ rm -f file2
$ hg qpush -q second-patch --config hooks.pretxncommit.unexpectedabort=
now at: second-patch
$ echo bbbb >> file2
$ sh "$TESTTMP/checkvisibility.sh"
====
1:e30108269082
M file2
====
$ HGEDITOR="sh \"$TESTTMP/checkvisibility.sh\"" hg qrefresh -e
====
0:25e397dabed2
A file2
====
note: commit message saved in .hg/last-message.txt
transaction abort!
rollback completed
qrefresh interrupted while patch was popped! (revert --all, qpush to recover)
abort: pretxncommit.unexpectedabort hook exited with status 1
[255]
(rebuilding at failure of qrefresh bases on rev #0, and it causes
dropping status of "file2")
$ sh "$TESTTMP/checkvisibility.sh"
====
0:25e397dabed2
====
== test visibility to precommit external hook
$ hg update -C -q
$ rm -f file2
$ hg qpush -q second-patch --config hooks.pretxncommit.unexpectedabort=
now at: second-patch
$ echo bbbb >> file2
$ cat >> .hg/hgrc <<EOF
> [hooks]
> precommit.checkvisibility = sh "$TESTTMP/checkvisibility.sh"
> EOF
$ sh "$TESTTMP/checkvisibility.sh"
====
1:e30108269082
M file2
====
$ hg qrefresh
====
0:25e397dabed2
A file2
====
transaction abort!
rollback completed
qrefresh interrupted while patch was popped! (revert --all, qpush to recover)
abort: pretxncommit.unexpectedabort hook exited with status 1
[255]
$ sh "$TESTTMP/checkvisibility.sh"
====
0:25e397dabed2
====
$ cat >> .hg/hgrc <<EOF
> [hooks]
> precommit.checkvisibility =
> EOF
== test visibility to pretxncommit external hook
$ hg update -C -q
$ rm -f file2
$ hg qpush -q second-patch --config hooks.pretxncommit.unexpectedabort=
now at: second-patch
$ echo bbbb >> file2
$ cat >> .hg/hgrc <<EOF
> [hooks]
> pretxncommit.checkvisibility = sh "$TESTTMP/checkvisibility.sh"
> # make checkvisibility run before unexpectedabort
> priority.pretxncommit.checkvisibility = 10
> EOF
$ sh "$TESTTMP/checkvisibility.sh"
====
1:e30108269082
M file2
====
$ hg qrefresh
====
0:25e397dabed2
A file2
====
transaction abort!
rollback completed
qrefresh interrupted while patch was popped! (revert --all, qpush to recover)
abort: pretxncommit.unexpectedabort hook exited with status 1
[255]
$ sh "$TESTTMP/checkvisibility.sh"
====
0:25e397dabed2
====
$ cat >> .hg/hgrc <<EOF
> [hooks]
> pretxncommit.checkvisibility =
> EOF