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view tests/test-contrib.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 | 567bddcb4271 |
children | 5abc47d4ca6b |
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Set vars: $ CONTRIBDIR="$TESTDIR/../contrib" 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]