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).
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init a
$ cd a
$ echo 'base' > base
$ hg ci -Ambase
adding base
$ hg qnew -mmqbase mqbase
$ hg qrename mqbase renamed
$ mkdir .hg/patches/foo
$ hg qrename renamed foo
$ hg qseries
foo/renamed
$ ls .hg/patches/foo
renamed
$ mkdir .hg/patches/bar
$ hg qrename foo/renamed bar
$ hg qseries
bar/renamed
$ ls .hg/patches/bar
renamed
$ hg qrename bar/renamed baz
$ hg qseries
baz
$ ls .hg/patches/baz
.hg/patches/baz
$ hg qrename baz new/dir
$ hg qseries
new/dir
$ ls .hg/patches/new/dir
.hg/patches/new/dir
$ cd ..
Test patch being renamed before committed:
$ hg init b
$ cd b
$ hg qinit -c
$ hg qnew x
$ hg qrename y
$ hg qcommit -m rename
$ cd ..
Test overlapping renames (issue2388)
$ hg init c
$ cd c
$ hg qinit -c
$ echo a > a
$ hg add
adding a
$ hg qnew patcha
$ echo b > b
$ hg add
adding b
$ hg qnew patchb
$ hg ci --mq -m c1
$ hg qrename patchb patchc
$ hg qrename patcha patchb
$ hg st --mq
M patchb
M series
A patchc
R patcha
$ cd ..
Test renames with mq repo (issue2097)
$ hg init issue2097
$ cd issue2097
$ hg qnew p0
$ (cd .hg/patches && hg init)
$ hg qren p0 p1
$ hg debugstate --mq
$ hg ci --mq -mq0
nothing changed
[1]
$ cd ..
Test renaming to a folded patch (issue3058)
$ hg init issue3058
$ cd issue3058
$ hg init --mq
$ echo a > a
$ hg add a
$ hg qnew adda
$ echo b >> a
$ hg qnew addb
$ hg qpop
popping addb
now at: adda
$ hg ci --mq -m "save mq"
$ hg qfold addb
$ hg qmv addb
$ cat .hg/patches/addb
# HG changeset patch
# Parent 0000000000000000000000000000000000000000
diff -r 000000000000 a
--- /dev/null * (glob)
+++ b/a * (glob)
@@ -0,0 +1,2 @@
+a
+b
$ cd ..