wireproto: implement basic frame reading and processing
We just implemented support for writing frames. Now let's implement
support for reading them.
The bulk of the new code is for a class that maintains the state of
a server. Essentially, you construct an instance, feed frames to it,
and it tells you what you should do next. The design is inspired by
the "sans I/O" movement and the reactor pattern. We don't want to
perform I/O or any major blocking event during frame ingestion because
this arbitrarily limits ways that server pieces can be implemented.
For example, it makes it much harder to swap in an alternate
implementation based on asyncio or do crazy things like have requests
dispatch to other processes.
We do still implement readframe() which does I/O. But it is decoupled
from the server reactor. And important parsing of frame headers is
a standalone function. So I/O is only needed to obtain frame data.
Because testing server-side ingest is useful and difficult on running
servers, we create a new "debugreflect" endpoint that will echo back
to the client what was received and how it was interpreted. This could
be useful for a server admin, someone implementing a client. But
immediately, it is useful for testing: we're able to demonstrate that
frames are parsed correctly and turned into requests to run commands
without having to implement command dispatch on the server!
In addition, we implement Python level unit tests for the reactor.
This is vastly more efficient than sending requests to the
"debugreflect" endpoint and vastly more powerful for advanced
testing.
Differential Revision: https://phab.mercurial-scm.org/D2852
$ cat <<EOF >> $HGRCPATH
> [extensions]
> mq =
> [mq]
> git = keep
> [diff]
> nodates = 1
> EOF
init:
$ hg init repo
$ cd repo
$ echo a > a
$ hg ci -Am adda
adding a
$ echo a >> a
$ hg qnew -f p1
$ echo b >> a
$ hg qnew -f p2
$ echo c >> a
$ hg qnew -f p3
Fold in the middle of the queue:
(this tests also that editor is not invoked if '--edit' is not
specified)
$ hg qpop p1
popping p3
popping p2
now at: p1
$ hg qdiff
diff -r 07f494440405 a
--- a/a
+++ b/a
@@ -1,1 +1,2 @@
a
+a
$ HGEDITOR=cat hg qfold p2
$ grep git .hg/patches/p1 && echo 'git patch found!'
[1]
$ hg qser
p1
p3
$ hg qdiff
diff -r 07f494440405 a
--- a/a
+++ b/a
@@ -1,1 +1,3 @@
a
+a
+b
Fold with local changes:
$ echo d >> a
$ hg qfold p3
abort: local changes found, qrefresh first
[255]
$ hg diff -c .
diff -r 07f494440405 -r ???????????? a (glob)
--- a/a
+++ b/a
@@ -1,1 +1,3 @@
a
+a
+b
$ hg revert -a --no-backup
reverting a
Fold git patch into a regular patch, expect git patch:
$ echo a >> a
$ hg qnew -f regular
$ hg cp a aa
$ hg qnew --git -f git
$ hg qpop
popping git
now at: regular
$ hg qfold git
$ cat .hg/patches/regular
# HG changeset patch
# Parent ???????????????????????????????????????? (glob)
diff --git a/a b/a
--- a/a
+++ b/a
@@ -1,3 +1,4 @@
a
a
b
+a
diff --git a/a b/aa
copy from a
copy to aa
--- a/a
+++ b/aa
@@ -1,3 +1,4 @@
a
a
b
+a
$ hg qpop
popping regular
now at: p1
$ hg qdel regular
Fold regular patch into a git patch, expect git patch:
$ hg cp a aa
$ hg qnew --git -f git
$ echo b >> aa
$ hg qnew -f regular
$ hg qpop
popping regular
now at: git
$ hg qfold regular
$ cat .hg/patches/git
# HG changeset patch
# Parent ???????????????????????????????????????? (glob)
diff --git a/a b/aa
copy from a
copy to aa
--- a/a
+++ b/aa
@@ -1,3 +1,4 @@
a
a
b
+b
Test saving last-message.txt:
$ hg qrefresh -m "original message"
$ cat > $TESTTMP/commitfailure.py <<EOF
> from mercurial import error
> def reposetup(ui, repo):
> class commitfailure(repo.__class__):
> def commit(self, *args, **kwargs):
> raise error.Abort('emulating unexpected abort')
> repo.__class__ = commitfailure
> EOF
$ cat >> .hg/hgrc <<EOF
> [extensions]
> # this failure occurs before editor invocation
> commitfailure = $TESTTMP/commitfailure.py
> EOF
$ cat > $TESTTMP/editor.sh << EOF
> echo "==== before editing"
> cat \$1
> echo "===="
> (echo; echo "test saving last-message.txt") >> \$1
> EOF
$ hg qapplied
p1
git
$ hg tip --template "{files}\n"
aa
(test that editor is not invoked before transaction starting,
and that combination of '--edit' and '--message' doesn't abort execution)
$ rm -f .hg/last-message.txt
$ HGEDITOR="sh $TESTTMP/editor.sh" hg qfold -e -m MESSAGE p3
qrefresh interrupted while patch was popped! (revert --all, qpush to recover)
abort: emulating unexpected abort
[255]
$ test -f .hg/last-message.txt
[1]
(reset applied patches and directory status)
$ cat >> .hg/hgrc <<EOF
> [extensions]
> # this failure occurs after editor invocation
> commitfailure = !
> EOF
$ hg qapplied
p1
$ hg status -A aa
? aa
$ rm aa
$ hg status -m
M a
$ hg revert --no-backup -q a
$ hg qpush -q git
now at: git
(test that editor is invoked and commit message is saved into
"last-message.txt")
$ cat >> .hg/hgrc <<EOF
> [hooks]
> # this failure occurs after editor invocation
> pretxncommit.unexpectedabort = false
> EOF
$ rm -f .hg/last-message.txt
$ HGEDITOR="sh $TESTTMP/editor.sh" hg qfold -e p3
==== before editing
original message
HG: Enter commit message. Lines beginning with 'HG:' are removed.
HG: Leave message empty to use default message.
HG: --
HG: user: test
HG: branch 'default'
HG: added aa
HG: changed a
====
note: commit message saved in .hg/last-message.txt
transaction abort!
rollback completed
qrefresh interrupted while patch was popped! (revert --all, qpush to recover)
abort: pretxncommit.unexpectedabort hook exited with status 1
[255]
$ cat .hg/last-message.txt
original message
test saving last-message.txt
(confirm whether files listed up in the commit message editing are correct)
$ cat >> .hg/hgrc <<EOF
> [hooks]
> pretxncommit.unexpectedabort =
> EOF
$ hg status -u | while read f; do rm ${f}; done
$ hg revert --no-backup -q --all
$ hg qpush -q git
now at: git
$ hg qpush -q --move p3
now at: p3
$ hg status --rev "git^1" --rev . -arm
M a
A aa
$ cd ..