wireproto: implement batching on peer executor interface
This is a bit more complicated than non-batch requests because we
need to buffer sends until the last request arrives *and* we need
to support resolving futures as data arrives from the remote.
In a classical concurrent.futures executor model, the future
"starts" as soon as it is submitted. However, we have nothing to
start until the last command is submitted.
If we did nothing, calling result() would deadlock, since the future
hasn't "started." So in the case where we queue the command, we return
a special future type whose result() will trigger sendcommands().
This eliminates the deadlock potential. It also serves as a check
against callers who may be calling result() prematurely, as it will
prevent any subsequent callcommands() from working. This behavior
is slightly annoying and a bit restrictive. But it's the world
that half duplex connections forces on us.
In order to support streaming responses, we were previously using
a generator. But with a futures-based API, we're using futures
and not generators. So in order to get streaming, we need a
background thread to read data from the server.
The approach taken in this patch is to leverage the ThreadPoolExecutor
from concurrent.futures for managing a background thread. We create
an executor and future that resolves when all response data is
processed (or an error occurs). When exiting the context manager,
we wait on that background reading before returning.
I was hoping we could manually spin up a threading.Thread and this
would be simple. But I ran into a few deadlocks when implementing.
After looking at the source code to concurrent.futures, I figured
it would just be easier to use a ThreadPoolExecutor than implement
all the code needed to manually manage a thread.
To prove this works, a use of the batch API in discovery has been
updated.
Differential Revision: https://phab.mercurial-scm.org/D3269
Use hgrc within $TESTTMP
$ HGRCPATH=`pwd`/hgrc
$ export HGRCPATH
hide outer repo
$ hg init
Use an alternate var for scribbling on hgrc to keep check-code from
complaining about the important settings we may be overwriting:
$ HGRC=`pwd`/hgrc
$ export HGRC
Basic syntax error
$ echo "invalid" > $HGRC
$ hg version
hg: parse error at $TESTTMP/hgrc:1: invalid
[255]
$ echo "" > $HGRC
Issue1199: Can't use '%' in hgrc (eg url encoded username)
$ hg init "foo%bar"
$ hg clone "foo%bar" foobar
updating to branch default
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd foobar
$ cat .hg/hgrc
# example repository config (see 'hg help config' for more info)
[paths]
default = $TESTTMP/foo%bar
# path aliases to other clones of this repo in URLs or filesystem paths
# (see 'hg help config.paths' for more info)
#
# default:pushurl = ssh://jdoe@example.net/hg/jdoes-fork
# my-fork = ssh://jdoe@example.net/hg/jdoes-fork
# my-clone = /home/jdoe/jdoes-clone
[ui]
# name and email (local to this repository, optional), e.g.
# username = Jane Doe <jdoe@example.com>
$ hg paths
default = $TESTTMP/foo%bar
$ hg showconfig
bundle.mainreporoot=$TESTTMP/foobar
paths.default=$TESTTMP/foo%bar
$ cd ..
issue1829: wrong indentation
$ echo '[foo]' > $HGRC
$ echo ' x = y' >> $HGRC
$ hg version
hg: parse error at $TESTTMP/hgrc:2: x = y
unexpected leading whitespace
[255]
$ $PYTHON -c "from __future__ import print_function; print('[foo]\nbar = a\n b\n c \n de\n fg \nbaz = bif cb \n')" \
> > $HGRC
$ hg showconfig foo
foo.bar=a\nb\nc\nde\nfg
foo.baz=bif cb
$ FAKEPATH=/path/to/nowhere
$ export FAKEPATH
$ echo '%include $FAKEPATH/no-such-file' > $HGRC
$ hg version
Mercurial Distributed SCM (version *) (glob)
(see https://mercurial-scm.org for more information)
Copyright (C) 2005-* Matt Mackall and others (glob)
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$ unset FAKEPATH
make sure global options given on the cmdline take precedence
$ hg showconfig --config ui.verbose=True --quiet
bundle.mainreporoot=$TESTTMP
ui.verbose=False
ui.debug=False
ui.quiet=True
$ touch foobar/untracked
$ cat >> foobar/.hg/hgrc <<EOF
> [ui]
> verbose=True
> EOF
$ hg -R foobar st -q
username expansion
$ olduser=$HGUSER
$ unset HGUSER
$ FAKEUSER='John Doe'
$ export FAKEUSER
$ echo '[ui]' > $HGRC
$ echo 'username = $FAKEUSER' >> $HGRC
$ hg init usertest
$ cd usertest
$ touch bar
$ hg commit --addremove --quiet -m "added bar"
$ hg log --template "{author}\n"
John Doe
$ cd ..
$ hg showconfig
bundle.mainreporoot=$TESTTMP
ui.username=$FAKEUSER
$ unset FAKEUSER
$ HGUSER=$olduser
$ export HGUSER
showconfig with multiple arguments
$ echo "[alias]" > $HGRC
$ echo "log = log -g" >> $HGRC
$ echo "[defaults]" >> $HGRC
$ echo "identify = -n" >> $HGRC
$ hg showconfig alias defaults
alias.log=log -g
defaults.identify=-n
$ hg showconfig alias alias
alias.log=log -g
$ hg showconfig alias.log alias.log
alias.log=log -g
$ hg showconfig alias defaults.identify
alias.log=log -g
defaults.identify=-n
$ hg showconfig alias.log defaults.identify
alias.log=log -g
defaults.identify=-n
HGPLAIN
$ echo "[ui]" > $HGRC
$ echo "debug=true" >> $HGRC
$ echo "fallbackencoding=ASCII" >> $HGRC
$ echo "quiet=true" >> $HGRC
$ echo "slash=true" >> $HGRC
$ echo "traceback=true" >> $HGRC
$ echo "verbose=true" >> $HGRC
$ echo "style=~/.hgstyle" >> $HGRC
$ echo "logtemplate={node}" >> $HGRC
$ echo "[defaults]" >> $HGRC
$ echo "identify=-n" >> $HGRC
$ echo "[alias]" >> $HGRC
$ echo "log=log -g" >> $HGRC
customized hgrc
$ hg showconfig
read config from: $TESTTMP/hgrc
$TESTTMP/hgrc:13: alias.log=log -g
repo: bundle.mainreporoot=$TESTTMP
$TESTTMP/hgrc:11: defaults.identify=-n
$TESTTMP/hgrc:2: ui.debug=true
$TESTTMP/hgrc:3: ui.fallbackencoding=ASCII
$TESTTMP/hgrc:4: ui.quiet=true
$TESTTMP/hgrc:5: ui.slash=true
$TESTTMP/hgrc:6: ui.traceback=true
$TESTTMP/hgrc:7: ui.verbose=true
$TESTTMP/hgrc:8: ui.style=~/.hgstyle
$TESTTMP/hgrc:9: ui.logtemplate={node}
plain hgrc
$ HGPLAIN=; export HGPLAIN
$ hg showconfig --config ui.traceback=True --debug
read config from: $TESTTMP/hgrc
repo: bundle.mainreporoot=$TESTTMP
--config: ui.traceback=True
--verbose: ui.verbose=False
--debug: ui.debug=True
--quiet: ui.quiet=False
with environment variables
$ PAGER=p1 EDITOR=e1 VISUAL=e2 hg showconfig --debug
set config by: $EDITOR
set config by: $VISUAL
set config by: $PAGER
read config from: $TESTTMP/hgrc
repo: bundle.mainreporoot=$TESTTMP
$PAGER: pager.pager=p1
$VISUAL: ui.editor=e2
--verbose: ui.verbose=False
--debug: ui.debug=True
--quiet: ui.quiet=False
plain mode with exceptions
$ cat > plain.py <<EOF
> from mercurial import commands, extensions
> def _config(orig, ui, repo, *values, **opts):
> ui.write('plain: %r\n' % ui.plain())
> return orig(ui, repo, *values, **opts)
> def uisetup(ui):
> extensions.wrapcommand(commands.table, 'config', _config)
> EOF
$ echo "[extensions]" >> $HGRC
$ echo "plain=./plain.py" >> $HGRC
$ HGPLAINEXCEPT=; export HGPLAINEXCEPT
$ hg showconfig --config ui.traceback=True --debug
plain: True
read config from: $TESTTMP/hgrc
repo: bundle.mainreporoot=$TESTTMP
$TESTTMP/hgrc:15: extensions.plain=./plain.py
--config: ui.traceback=True
--verbose: ui.verbose=False
--debug: ui.debug=True
--quiet: ui.quiet=False
$ unset HGPLAIN
$ hg showconfig --config ui.traceback=True --debug
plain: True
read config from: $TESTTMP/hgrc
repo: bundle.mainreporoot=$TESTTMP
$TESTTMP/hgrc:15: extensions.plain=./plain.py
--config: ui.traceback=True
--verbose: ui.verbose=False
--debug: ui.debug=True
--quiet: ui.quiet=False
$ HGPLAINEXCEPT=i18n; export HGPLAINEXCEPT
$ hg showconfig --config ui.traceback=True --debug
plain: True
read config from: $TESTTMP/hgrc
repo: bundle.mainreporoot=$TESTTMP
$TESTTMP/hgrc:15: extensions.plain=./plain.py
--config: ui.traceback=True
--verbose: ui.verbose=False
--debug: ui.debug=True
--quiet: ui.quiet=False
source of paths is not mangled
$ cat >> $HGRCPATH <<EOF
> [paths]
> foo = bar
> EOF
$ hg showconfig --debug paths
plain: True
read config from: $TESTTMP/hgrc
$TESTTMP/hgrc:17: paths.foo=$TESTTMP/bar