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
Set vars:
$ CONTRIBDIR="$TESTDIR/../contrib"
Prepare repo-a:
$ hg init repo-a
$ cd repo-a
$ echo this is file a > a
$ hg add a
$ hg commit -m first
$ echo adding to file a >> a
$ hg commit -m second
$ echo adding more to file a >> a
$ hg commit -m third
$ hg verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 3 changesets, 3 total revisions
Dumping revlog of file a to stdout:
$ $PYTHON "$CONTRIBDIR/dumprevlog" .hg/store/data/a.i
file: .hg/store/data/a.i
node: 183d2312b35066fb6b3b449b84efc370d50993d0
linkrev: 0
parents: 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000
length: 15
-start-
this is file a
-end-
node: b1047953b6e6b633c0d8197eaa5116fbdfd3095b
linkrev: 1
parents: 183d2312b35066fb6b3b449b84efc370d50993d0 0000000000000000000000000000000000000000
length: 32
-start-
this is file a
adding to file a
-end-
node: 8c4fd1f7129b8cdec6c7f58bf48fb5237a4030c1
linkrev: 2
parents: b1047953b6e6b633c0d8197eaa5116fbdfd3095b 0000000000000000000000000000000000000000
length: 54
-start-
this is file a
adding to file a
adding more to file a
-end-
Dump all revlogs to file repo.dump:
$ find .hg/store -name "*.i" | sort | xargs $PYTHON "$CONTRIBDIR/dumprevlog" > ../repo.dump
$ cd ..
Undumping into repo-b:
$ hg init repo-b
$ cd repo-b
$ $PYTHON "$CONTRIBDIR/undumprevlog" < ../repo.dump
.hg/store/00changelog.i
.hg/store/00manifest.i
.hg/store/data/a.i
$ cd ..
Rebuild fncache with clone --pull:
$ hg clone --pull -U repo-b repo-c
requesting all changes
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 1 files
new changesets de1da620e7d8:46946d278c50
Verify:
$ hg -R repo-c verify
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 3 changesets, 3 total revisions
Compare repos:
$ hg -R repo-c incoming repo-a
comparing with repo-a
searching for changes
no changes found
[1]
$ hg -R repo-a incoming repo-c
comparing with repo-c
searching for changes
no changes found
[1]
Test simplemerge command:
$ cp "$CONTRIBDIR/simplemerge" .
$ echo base > base
$ echo local > local
$ cat base >> local
$ cp local orig
$ cat base > other
$ echo other >> other
changing local directly
$ $PYTHON simplemerge local base other && echo "merge succeeded"
merge succeeded
$ cat local
local
base
other
$ cp orig local
printing to stdout
$ $PYTHON simplemerge -p local base other
local
base
other
local:
$ cat local
local
base
conflicts
$ cp base conflict-local
$ cp other conflict-other
$ echo not other >> conflict-local
$ echo end >> conflict-local
$ echo end >> conflict-other
$ $PYTHON simplemerge -p conflict-local base conflict-other
base
<<<<<<< conflict-local
not other
=======
other
>>>>>>> conflict-other
end
[1]
1 label
$ $PYTHON simplemerge -p -L foo conflict-local base conflict-other
base
<<<<<<< foo
not other
=======
other
>>>>>>> conflict-other
end
[1]
2 labels
$ $PYTHON simplemerge -p -L foo -L bar conflict-local base conflict-other
base
<<<<<<< foo
not other
=======
other
>>>>>>> bar
end
[1]
3 labels
$ $PYTHON simplemerge -p -L foo -L bar -L base conflict-local base conflict-other
base
<<<<<<< foo
not other
end
||||||| base
=======
other
end
>>>>>>> bar
[1]
too many labels
$ $PYTHON simplemerge -p -L foo -L bar -L baz -L buz conflict-local base conflict-other
abort: can only specify three labels.
[255]
binary file
$ $PYTHON -c "f = open('binary-local', 'w'); f.write('\x00'); f.close()"
$ cat orig >> binary-local
$ $PYTHON simplemerge -p binary-local base other
warning: binary-local looks like a binary file.
[1]
binary file --text
$ $PYTHON simplemerge -a -p binary-local base other 2>&1
warning: binary-local looks like a binary file.
\x00local (esc)
base
other
help
$ $PYTHON simplemerge --help
simplemerge [OPTS] LOCAL BASE OTHER
Simple three-way file merge utility with a minimal feature set.
Apply to LOCAL the changes necessary to go from BASE to OTHER.
By default, LOCAL is overwritten with the results of this operation.
options:
-L --label labels to use on conflict markers
-a --text treat all files as text
-p --print print results instead of overwriting LOCAL
--no-minimal no effect (DEPRECATED)
-h --help display help and exit
-q --quiet suppress output
wrong number of arguments
$ $PYTHON simplemerge
simplemerge: wrong number of arguments
simplemerge [OPTS] LOCAL BASE OTHER
Simple three-way file merge utility with a minimal feature set.
Apply to LOCAL the changes necessary to go from BASE to OTHER.
By default, LOCAL is overwritten with the results of this operation.
options:
-L --label labels to use on conflict markers
-a --text treat all files as text
-p --print print results instead of overwriting LOCAL
--no-minimal no effect (DEPRECATED)
-h --help display help and exit
-q --quiet suppress output
[1]
bad option
$ $PYTHON simplemerge --foo -p local base other
simplemerge: option --foo not recognized
simplemerge [OPTS] LOCAL BASE OTHER
Simple three-way file merge utility with a minimal feature set.
Apply to LOCAL the changes necessary to go from BASE to OTHER.
By default, LOCAL is overwritten with the results of this operation.
options:
-L --label labels to use on conflict markers
-a --text treat all files as text
-p --print print results instead of overwriting LOCAL
--no-minimal no effect (DEPRECATED)
-h --help display help and exit
-q --quiet suppress output
[1]