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
workingfilectx.date = (1000, 0)
ASCII : Gr?ezi!
Latin-1 : Grüezi!
UTF-8 : Grüezi!
<status modified=['foo'], added=[], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
diff --git a/foo b/foo
--- a/foo
+++ b/foo
@@ -1,1 +1,2 @@
foo
+bar
= checking context.status():
== checking workingctx.status:
wctx._status=<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=[]>
=== with "pattern match":
<status modified=['bar-m'], added=[], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
wctx._status=<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=[]>
<status modified=[], added=['bar-m'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
wctx._status=<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=[]>
=== with "always match" and "listclean=True":
<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=['foo']>
wctx._status=<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=[]>
<status modified=[], added=['bar-a', 'bar-m'], removed=[], deleted=[], unknown=[], ignored=[], clean=['foo']>
wctx._status=<status modified=['bar-m'], added=['bar-a'], removed=['bar-r'], deleted=[], unknown=[], ignored=[], clean=[]>
== checking workingcommitctx.status:
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
=== with "always match":
<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
<status modified=[], added=['bar-a', 'bar-m', 'bar-r'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
=== with "always match" and "listclean=True":
<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=['bar-r', 'foo']>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
<status modified=[], added=['bar-a', 'bar-m', 'bar-r'], removed=[], deleted=[], unknown=[], ignored=[], clean=['foo']>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
=== with "pattern match":
<status modified=['bar-m'], added=[], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
<status modified=[], added=['bar-m'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
=== with "pattern match" and "listclean=True":
<status modified=[], added=[], removed=[], deleted=[], unknown=[], ignored=[], clean=['bar-r', 'foo']>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>
<status modified=[], added=['bar-r'], removed=[], deleted=[], unknown=[], ignored=[], clean=['foo']>
wcctx._status=<status modified=['bar-m'], added=['bar-a'], removed=[], deleted=[], unknown=[], ignored=[], clean=[]>