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
Test EOL patching
$ cat >> $HGRCPATH <<EOF
> [diff]
> git = 1
> EOF
Set up helpers
$ seteol () {
> if [ $1 = "LF" ]; then
> EOL='\n'
> else
> EOL='\r\n'
> fi
> }
$ makerepo () {
> seteol $1
> echo
> echo "# ==== setup $1 repository ===="
> echo '% hg init'
> hg init repo
> cd repo
> cat > .hgeol <<EOF
> [repository]
> native = $1
> [patterns]
> unix.txt = LF
> win.txt = CRLF
> **.txt = native
> EOF
> printf "first\r\nsecond\r\nthird\r\n" > win.txt
> printf "first\nsecond\nthird\n" > unix.txt
> printf "first${EOL}second${EOL}third${EOL}" > native.txt
> hg commit --addremove -m 'checkin'
> cd ..
> }
$ dotest () {
> seteol $1
> echo
> echo "% hg clone repo repo-$1"
> hg clone --noupdate repo repo-$1
> cd repo-$1
> cat > .hg/hgrc <<EOF
> [extensions]
> eol =
> [eol]
> native = $1
> EOF
> hg update
> echo '% native.txt'
> cat native.txt
> echo '% unix.txt'
> cat unix.txt
> echo '% win.txt'
> cat win.txt
> printf "first${EOL}third${EOL}" > native.txt
> printf "first\r\nthird\r\n" > win.txt
> printf "first\nthird\n" > unix.txt
> echo '% hg diff'
> hg diff > p
> cat p
> echo '% hg revert'
> hg revert --all
> echo '% hg import'
> hg import -m 'patch' p
> echo '% native.txt'
> cat native.txt
> echo '% unix.txt'
> cat unix.txt
> echo '% win.txt'
> cat win.txt
> echo '% hg diff -c tip'
> hg diff -c tip
> cd ..
> rm -r repo-$1
> }
Run tests
$ makerepo LF
# ==== setup LF repository ====
% hg init
adding .hgeol
adding native.txt
adding unix.txt
adding win.txt
$ dotest LF
% hg clone repo repo-LF
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
% native.txt
first
second
third
% unix.txt
first
second
third
% win.txt
first\r (esc)
second\r (esc)
third\r (esc)
% hg diff
diff --git a/native.txt b/native.txt
--- a/native.txt
+++ b/native.txt
@@ -1,3 +1,2 @@
first
-second
third
diff --git a/unix.txt b/unix.txt
--- a/unix.txt
+++ b/unix.txt
@@ -1,3 +1,2 @@
first
-second
third
diff --git a/win.txt b/win.txt
--- a/win.txt
+++ b/win.txt
@@ -1,3 +1,2 @@
first\r (esc)
-second\r (esc)
third\r (esc)
% hg revert
reverting native.txt
reverting unix.txt
reverting win.txt
% hg import
applying p
% native.txt
first
third
% unix.txt
first
third
% win.txt
first\r (esc)
third\r (esc)
% hg diff -c tip
diff --git a/native.txt b/native.txt
--- a/native.txt
+++ b/native.txt
@@ -1,3 +1,2 @@
first
-second
third
diff --git a/unix.txt b/unix.txt
--- a/unix.txt
+++ b/unix.txt
@@ -1,3 +1,2 @@
first
-second
third
diff --git a/win.txt b/win.txt
--- a/win.txt
+++ b/win.txt
@@ -1,3 +1,2 @@
first\r (esc)
-second\r (esc)
third\r (esc)
$ dotest CRLF
% hg clone repo repo-CRLF
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
% native.txt
first\r (esc)
second\r (esc)
third\r (esc)
% unix.txt
first
second
third
% win.txt
first\r (esc)
second\r (esc)
third\r (esc)
% hg diff
diff --git a/native.txt b/native.txt
--- a/native.txt
+++ b/native.txt
@@ -1,3 +1,2 @@
first
-second
third
diff --git a/unix.txt b/unix.txt
--- a/unix.txt
+++ b/unix.txt
@@ -1,3 +1,2 @@
first
-second
third
diff --git a/win.txt b/win.txt
--- a/win.txt
+++ b/win.txt
@@ -1,3 +1,2 @@
first\r (esc)
-second\r (esc)
third\r (esc)
% hg revert
reverting native.txt
reverting unix.txt
reverting win.txt
% hg import
applying p
% native.txt
first\r (esc)
third\r (esc)
% unix.txt
first
third
% win.txt
first\r (esc)
third\r (esc)
% hg diff -c tip
diff --git a/native.txt b/native.txt
--- a/native.txt
+++ b/native.txt
@@ -1,3 +1,2 @@
first
-second
third
diff --git a/unix.txt b/unix.txt
--- a/unix.txt
+++ b/unix.txt
@@ -1,3 +1,2 @@
first
-second
third
diff --git a/win.txt b/win.txt
--- a/win.txt
+++ b/win.txt
@@ -1,3 +1,2 @@
first\r (esc)
-second\r (esc)
third\r (esc)
$ rm -r repo
$ makerepo CRLF
# ==== setup CRLF repository ====
% hg init
adding .hgeol
adding native.txt
adding unix.txt
adding win.txt
$ dotest LF
% hg clone repo repo-LF
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
% native.txt
first
second
third
% unix.txt
first
second
third
% win.txt
first\r (esc)
second\r (esc)
third\r (esc)
% hg diff
diff --git a/native.txt b/native.txt
--- a/native.txt
+++ b/native.txt
@@ -1,3 +1,2 @@
first\r (esc)
-second\r (esc)
third\r (esc)
diff --git a/unix.txt b/unix.txt
--- a/unix.txt
+++ b/unix.txt
@@ -1,3 +1,2 @@
first
-second
third
diff --git a/win.txt b/win.txt
--- a/win.txt
+++ b/win.txt
@@ -1,3 +1,2 @@
first\r (esc)
-second\r (esc)
third\r (esc)
% hg revert
reverting native.txt
reverting unix.txt
reverting win.txt
% hg import
applying p
% native.txt
first
third
% unix.txt
first
third
% win.txt
first\r (esc)
third\r (esc)
% hg diff -c tip
diff --git a/native.txt b/native.txt
--- a/native.txt
+++ b/native.txt
@@ -1,3 +1,2 @@
first\r (esc)
-second\r (esc)
third\r (esc)
diff --git a/unix.txt b/unix.txt
--- a/unix.txt
+++ b/unix.txt
@@ -1,3 +1,2 @@
first
-second
third
diff --git a/win.txt b/win.txt
--- a/win.txt
+++ b/win.txt
@@ -1,3 +1,2 @@
first\r (esc)
-second\r (esc)
third\r (esc)
$ dotest CRLF
% hg clone repo repo-CRLF
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
% native.txt
first\r (esc)
second\r (esc)
third\r (esc)
% unix.txt
first
second
third
% win.txt
first\r (esc)
second\r (esc)
third\r (esc)
% hg diff
diff --git a/native.txt b/native.txt
--- a/native.txt
+++ b/native.txt
@@ -1,3 +1,2 @@
first\r (esc)
-second\r (esc)
third\r (esc)
diff --git a/unix.txt b/unix.txt
--- a/unix.txt
+++ b/unix.txt
@@ -1,3 +1,2 @@
first
-second
third
diff --git a/win.txt b/win.txt
--- a/win.txt
+++ b/win.txt
@@ -1,3 +1,2 @@
first\r (esc)
-second\r (esc)
third\r (esc)
% hg revert
reverting native.txt
reverting unix.txt
reverting win.txt
% hg import
applying p
% native.txt
first\r (esc)
third\r (esc)
% unix.txt
first
third
% win.txt
first\r (esc)
third\r (esc)
% hg diff -c tip
diff --git a/native.txt b/native.txt
--- a/native.txt
+++ b/native.txt
@@ -1,3 +1,2 @@
first\r (esc)
-second\r (esc)
third\r (esc)
diff --git a/unix.txt b/unix.txt
--- a/unix.txt
+++ b/unix.txt
@@ -1,3 +1,2 @@
first
-second
third
diff --git a/win.txt b/win.txt
--- a/win.txt
+++ b/win.txt
@@ -1,3 +1,2 @@
first\r (esc)
-second\r (esc)
third\r (esc)
$ rm -r repo