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).
$ cat <<EOF >> $HGRCPATH
> [extensions]
> mq =
> [mq]
> git = keep
> EOF
$ hg init a
$ cd a
$ echo 'base' > base
$ hg ci -Ambase
adding base
$ hg qnew -mmqbase mqbase
$ echo 'patched' > base
$ hg qrefresh
qdiff:
$ hg qdiff
diff -r d20a80d4def3 base
--- a/base Thu Jan 01 00:00:00 1970 +0000
+++ b/base* (glob)
@@ -1,1 +1,1 @@
-base
+patched
qdiff dirname:
$ hg qdiff --nodates .
diff -r d20a80d4def3 base
--- a/base
+++ b/base
@@ -1,1 +1,1 @@
-base
+patched
qdiff filename:
$ hg qdiff --nodates base
diff -r d20a80d4def3 base
--- a/base
+++ b/base
@@ -1,1 +1,1 @@
-base
+patched
$ hg revert -a
$ hg qpop
popping mqbase
patch queue now empty
$ hg qdelete mqbase
$ printf '1\n2\n3\n4\nhello world\ngoodbye world\n7\n8\n9\n' > lines
$ hg ci -Amlines -d '2 0'
adding lines
$ hg qnew -mmqbase2 mqbase2
$ printf '\n\n1\n2\n3\n4\nhello world\n goodbye world\n7\n8\n9\n' > lines
$ hg qdiff --nodates -U 1
diff -r b0c220e1cf43 lines
--- a/lines
+++ b/lines
@@ -1,1 +1,3 @@
+
+
1
@@ -4,4 +6,4 @@
4
-hello world
-goodbye world
+hello world
+ goodbye world
7
$ hg qdiff --nodates -b
diff -r b0c220e1cf43 lines
--- a/lines
+++ b/lines
@@ -1,9 +1,11 @@
+
+
1
2
3
4
hello world
-goodbye world
+ goodbye world
7
8
9
$ hg qdiff --nodates -U 1 -B
diff -r b0c220e1cf43 lines
--- a/lines
+++ b/lines
@@ -4,4 +4,4 @@
4
-hello world
-goodbye world
+hello world
+ goodbye world
7
$ hg qdiff --nodates -w
diff -r b0c220e1cf43 lines
--- a/lines
+++ b/lines
@@ -1,3 +1,5 @@
+
+
1
2
3
$ hg qdiff --nodates --reverse
diff -r b0c220e1cf43 lines
--- a/lines
+++ b/lines
@@ -1,11 +1,9 @@
-
-
1
2
3
4
-hello world
- goodbye world
+hello world
+goodbye world
7
8
9
qdiff preserve existing git flag:
$ hg qrefresh --git
$ echo a >> lines
$ hg qdiff
diff --git a/lines b/lines
--- a/lines
+++ b/lines
@@ -1,9 +1,12 @@
+
+
1
2
3
4
-hello world
-goodbye world
+hello world
+ goodbye world
7
8
9
+a
$ hg qdiff --stat
lines | 7 +++++--
1 files changed, 5 insertions(+), 2 deletions(-)
$ hg qrefresh
qdiff when file deleted (but not removed) in working dir:
$ hg qnew deleted-file
$ echo a > newfile
$ hg add newfile
$ hg qrefresh
$ rm newfile
$ hg qdiff
$ cd ..