procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
================================
Test corner case around bookmark
================================
This test file is meant to gather test around bookmark that are specific
enough to not find a place elsewhere.
Test bookmark/changelog race condition
======================================
The data from the bookmark file are filtered to only contains bookmark with
node known to the changelog. If the cache invalidation between these two bits
goes wrong, bookmark can be dropped.
Setup
-----
initial repository setup
$ hg init bookrace-server
$ cd bookrace-server
$ echo a > a
$ hg add a
$ hg commit -m root
$ echo a >> a
$ hg bookmark book-A
$ hg commit -m A0
$ hg up 'desc(root)'
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(leaving bookmark book-A)
$ echo b > b
$ hg add b
$ hg bookmark book-B
$ hg commit -m B0
created new head
$ hg up null
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
(leaving bookmark book-B)
$ hg phase --public --rev 'all()'
$ hg log -G
o changeset: 2:c79985706978
| bookmark: book-B
| tag: tip
| parent: 0:6569b5a81c7e
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: B0
|
| o changeset: 1:39c28d785860
|/ bookmark: book-A
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: A0
|
o changeset: 0:6569b5a81c7e
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: root
$ hg book
book-A 1:39c28d785860
book-B 2:c79985706978
$ cd ..
Add new changeset on each bookmark in distinct clones
$ hg clone ssh://user@dummy/bookrace-server client-A
requesting all changes
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 2 files (+1 heads)
new changesets 6569b5a81c7e:c79985706978
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg -R client-A update book-A
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
(activating bookmark book-A)
$ echo a >> client-A/a
$ hg -R client-A commit -m A1
$ hg clone ssh://user@dummy/bookrace-server client-B
requesting all changes
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 2 files (+1 heads)
new changesets 6569b5a81c7e:c79985706978
updating to branch default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg -R client-B update book-B
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
(activating bookmark book-B)
$ echo b >> client-B/b
$ hg -R client-B commit -m B1
extension to reproduce the race
-------------------------------
If two process are pushing we want to make sure the following happens:
* process A read changelog
* process B to its full push
* process A read bookmarks
* process A proceed with rest of the push
We build a server side extension for this purpose
$ cat > bookrace.py << EOF
> import atexit
> import os
> import time
> from mercurial import bookmarks, error, extensions
>
> def wait(repo):
> if not os.path.exists('push-A-started'):
> assert repo._currentlock(repo._lockref) is None
> assert repo._currentlock(repo._wlockref) is None
> repo.ui.status(b'setting raced push up\n')
> with open('push-A-started', 'w'):
> pass
> clock = 300
> while not os.path.exists('push-B-done'):
> clock -= 1
> if clock <= 0:
> raise error.Abort("race scenario timed out")
> time.sleep(0.1)
>
> def reposetup(ui, repo):
> class racedrepo(repo.__class__):
> @property
> def _bookmarks(self):
> wait(self)
> return super(racedrepo, self)._bookmarks
> repo.__class__ = racedrepo
>
> def e():
> with open('push-A-done', 'w'):
> pass
> atexit.register(e)
> EOF
Actual test
-----------
Start the raced push.
$ cat >> bookrace-server/.hg/hgrc << EOF
> [extensions]
> bookrace=$TESTTMP/bookrace.py
> EOF
$ hg push -R client-A -r book-A >push-output.txt 2>&1 &
Wait up to 30 seconds for that push to start.
$ clock=30
$ while [ ! -f push-A-started ] && [ $clock -gt 0 ] ; do
> clock=`expr $clock - 1`
> sleep 1
> done
Do the other push.
$ cat >> bookrace-server/.hg/hgrc << EOF
> [extensions]
> bookrace=!
> EOF
$ hg push -R client-B -r book-B
pushing to ssh://user@dummy/bookrace-server
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
updating bookmark book-B
Signal the raced put that we are done (it waits up to 30 seconds).
$ touch push-B-done
Wait for the raced push to finish (with the remaning of the initial 30 seconds).
$ while [ ! -f push-A-done ] && [ $clock -gt 0 ] ; do
> clock=`expr $clock - 1`
> sleep 1
> done
Check raced push output.
$ cat push-output.txt
pushing to ssh://user@dummy/bookrace-server
searching for changes
remote: setting raced push up
remote has heads on branch 'default' that are not known locally: f26c3b5167d1
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
updating bookmark book-A
Check result of the push.
$ hg -R bookrace-server log -G
o changeset: 4:9ce3b28c16de
| bookmark: book-A
| tag: tip
| parent: 1:39c28d785860
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: A1
|
| o changeset: 3:f26c3b5167d1
| | bookmark: book-B
| | user: test
| | date: Thu Jan 01 00:00:00 1970 +0000
| | summary: B1
| |
| o changeset: 2:c79985706978
| | parent: 0:6569b5a81c7e
| | user: test
| | date: Thu Jan 01 00:00:00 1970 +0000
| | summary: B0
| |
o | changeset: 1:39c28d785860
|/ user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: A0
|
o changeset: 0:6569b5a81c7e
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: root
$ hg -R bookrace-server book
book-A 4:9ce3b28c16de
book-B 3:f26c3b5167d1