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).
# init
$ hg init
$ echo a > a
$ hg add a
$ hg commit -m'a'
$ echo b > b
$ hg add b
$ hg commit -m'b'
$ hg up -C 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo c > c
$ hg add c
$ hg commit -m'c'
created new head
# test merging of diverged bookmarks
$ hg bookmark -r 1 "c@diverge"
$ hg bookmark -r 1 b
$ hg bookmark c
$ hg bookmarks
b 1:d2ae7f538514
* c 2:d36c0562f908
c@diverge 1:d2ae7f538514
$ hg merge "c@diverge"
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg commit -m'merge'
$ hg bookmarks
b 1:d2ae7f538514
* c 3:b8f96cf4688b
$ hg up -C 3
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
(leaving bookmark c)
$ echo d > d
$ hg add d
$ hg commit -m'd'
$ hg up -C 3
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo e > e
$ hg add e
$ hg commit -m'e'
created new head
$ hg up -C 5
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg bookmark e
$ hg bookmarks
b 1:d2ae7f538514
c 3:b8f96cf4688b
* e 5:26bee9c5bcf3
# the picked side is bookmarked
$ hg up -C 4
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
(leaving bookmark e)
$ hg merge
abort: heads are bookmarked - please merge with an explicit rev
(run 'hg heads' to see all heads)
[255]
# our revision is bookmarked
$ hg up -C e
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
(activating bookmark e)
$ hg merge
abort: no matching bookmark to merge - please merge with an explicit rev or bookmark
(run 'hg heads' to see all heads)
[255]
# merge bookmark heads
$ hg up -C 4
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
(leaving bookmark e)
$ echo f > f
$ hg commit -Am "f"
adding f
$ hg bookmarks -r 4 "e@diverged"
$ hg up -q -C "e@diverged"
$ hg merge
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg parents
changeset: 4:a0546fcfe0fb
bookmark: e@diverged
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: d
changeset: 5:26bee9c5bcf3
bookmark: e
parent: 3:b8f96cf4688b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: e
$ hg up -C e
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
(activating bookmark e)
$ hg bookmarks
b 1:d2ae7f538514
c 3:b8f96cf4688b
* e 5:26bee9c5bcf3
e@diverged 4:a0546fcfe0fb
$ hg merge
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg commit -m'merge'
$ hg bookmarks
b 1:d2ae7f538514
c 3:b8f96cf4688b
* e 7:ca784329f0ba
# test warning when all heads are inactive bookmarks
$ hg up -C 6
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
(leaving bookmark e)
$ echo g > g
$ hg commit -Am 'g'
adding g
$ hg bookmark -i g
$ hg bookmarks
b 1:d2ae7f538514
c 3:b8f96cf4688b
e 7:ca784329f0ba
g 8:04dd21731d95
$ hg heads
changeset: 8:04dd21731d95
bookmark: g
tag: tip
parent: 6:be381d1126a0
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: g
changeset: 7:ca784329f0ba
bookmark: e
parent: 5:26bee9c5bcf3
parent: 4:a0546fcfe0fb
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: merge
$ hg merge
abort: heads are bookmarked - please merge with an explicit rev
(run 'hg heads' to see all heads)
[255]