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view tests/test-logtoprocess.t @ 37631:2f626233859b
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
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 13 Apr 2018 11:02:34 -0700 |
parents | af43cb56af4e |
children | dfca83594145 |
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#require no-windows ATTENTION: logtoprocess runs commands asynchronously. Be sure to append "| cat" to hg commands, to wait for the output, if you want to test its output. Otherwise the test will be flaky. Test if logtoprocess correctly captures command-related log calls. $ hg init $ cat > $TESTTMP/foocommand.py << EOF > from __future__ import absolute_import > from mercurial import registrar > cmdtable = {} > command = registrar.command(cmdtable) > configtable = {} > configitem = registrar.configitem(configtable) > configitem('logtoprocess', 'foo', > default=None, > ) > @command(b'foo', []) > def foo(ui, repo): > ui.log('foo', 'a message: %(bar)s\n', bar='spam') > EOF $ cp $HGRCPATH $HGRCPATH.bak $ cat >> $HGRCPATH << EOF > [extensions] > logtoprocess= > foocommand=$TESTTMP/foocommand.py > [logtoprocess] > command=echo 'logtoprocess command output:'; > echo "\$EVENT"; > echo "\$MSG1"; > echo "\$MSG2" > commandfinish=echo 'logtoprocess commandfinish output:'; > echo "\$EVENT"; > echo "\$MSG1"; > echo "\$MSG2"; > echo "\$MSG3" > foo=echo 'logtoprocess foo output:'; > echo "\$EVENT"; > echo "\$MSG1"; > echo "\$OPT_BAR" > EOF Running a command triggers both a ui.log('command') and a ui.log('commandfinish') call. The foo command also uses ui.log. Use sort to avoid ordering issues between the various processes we spawn: $ hg foo | cat | sort (chg !) 0 a message: spam command command (chg !) commandfinish foo foo foo foo foo exited 0 after * seconds (glob) logtoprocess command output: logtoprocess command output: (chg !) logtoprocess commandfinish output: logtoprocess foo output: serve --cmdserver chgunix * (glob) (chg !) serve --cmdserver chgunix * (glob) (chg !) spam Confirm that logging blocked time catches stdio properly: $ cp $HGRCPATH.bak $HGRCPATH $ cat >> $HGRCPATH << EOF > [extensions] > logtoprocess= > pager= > [logtoprocess] > uiblocked=echo "\$EVENT stdio \$OPT_STDIO_BLOCKED ms command \$OPT_COMMAND_DURATION ms" > [ui] > logblockedtimes=True > EOF $ hg log | cat uiblocked stdio [0-9]+.[0-9]* ms command [0-9]+.[0-9]* ms (re)