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
============================================
Testing obsolescence markers push: Cases A.6
============================================
Mercurial pushes obsolescences markers relevant to the "pushed-set", the set of
all changesets that requested to be "in sync" after the push (even if they are
already on both side).
This test belongs to a series of tests checking such set is properly computed
and applied. This does not tests "obsmarkers" discovery capabilities.
Category A: simple cases
TestCase 6: new markers between changesets already known on both side
Variants:
# a: explicit push
# b: bare push
A.6 new markers between changesets already known on both side
==============================================================
.. {{{
.. A ◕⇠● B
.. |/
.. ● O
.. }}}
..
.. Marker exist from:
..
.. * `A◕⇠● B`
..
.. Command runs:
..
.. * hg push -r B
.. * hg push
..
.. Expected exchange:
..
.. * `A◕⇠● B`
Setup
-----
$ . $TESTDIR/testlib/exchange-obsmarker-util.sh
initial
$ setuprepos A.6
creating test repo for test case A.6
- pulldest
- main
- pushdest
cd into `main` and proceed with env setup
$ cd main
$ mkcommit A0
$ hg update -q 0
$ mkcommit A1
created new head
make both changeset known in remote
$ hg push -qf ../pushdest
$ hg push -qf ../pulldest
create a marker after this
$ hg debugobsolete `getid 'desc(A0)'` `getid 'desc(A1)'`
$ hg log -G --hidden
@ e5ea8f9c7314 (draft): A1
|
| x 28b51eb45704 (draft): A0
|/
o a9bdc8b26820 (public): O
$ inspect_obsmarkers
obsstore content
================
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
$ cd ..
$ cd ..
$ cp -R A.6 A.6.a
$ cp -R A.6 A.6.b
Actual Test (explicit push version)
-----------------------------------
$ dotest A.6.a A1
## Running testcase A.6.a
# testing echange of "A1" (e5ea8f9c7314)
## initial state
# obstore: main
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
# obstore: pulldest
## pushing "A1" from main to pushdest
pushing to pushdest
searching for changes
no changes found
remote: 1 new obsolescence markers
## post push state
# obstore: main
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pulldest
## pulling "e5ea8f9c7314" from main into pulldest
pulling from main
no changes found
1 new obsolescence markers
## post pull state
# obstore: main
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pulldest
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
Actual Test (bare push version)
-------------------------------
$ dotest A.6.b
## Running testcase A.6.b
## initial state
# obstore: main
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
# obstore: pulldest
## pushing from main to pushdest
pushing to pushdest
searching for changes
no changes found
remote: 1 new obsolescence markers
## post push state
# obstore: main
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pulldest
## pulling from main into pulldest
pulling from main
searching for changes
no changes found
1 new obsolescence markers
## post pull state
# obstore: main
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pushdest
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}
# obstore: pulldest
28b51eb45704506b5c603decd6bf7ac5e0f6a52f e5ea8f9c73143125d36658e90ef70c6d2027a5b7 0 (Thu Jan 01 00:00:00 1970 +0000) {'user': 'test'}