Mercurial > hg
view tests/test-mq-qqueue.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 | 4f2f0f367ef6 |
children |
line wrap: on
line source
$ echo "[extensions]" >> $HGRCPATH $ echo "mq=" >> $HGRCPATH $ hg init foo $ cd foo $ echo a > a $ hg ci -qAm a Default queue: $ hg qqueue patches (active) $ echo b > a $ hg qnew -fgDU somestuff Applied patches in default queue: $ hg qap somestuff Try to change patch (create succeeds, switch fails): $ hg qqueue foo --create abort: new queue created, but cannot make active as patches are applied [255] $ hg qqueue foo patches (active) Empty default queue: $ hg qpop popping somestuff patch queue now empty Switch queue: $ hg qqueue foo $ hg qqueue foo (active) patches List queues, quiet: $ hg qqueue --quiet foo patches Fail creating queue with already existing name: $ hg qqueue --create foo abort: queue "foo" already exists [255] $ hg qqueue foo (active) patches Create new queue for rename: $ hg qqueue --create bar $ hg qqueue bar (active) foo patches Rename queue, same name: $ hg qqueue --rename bar abort: can't rename "bar" to its current name [255] Rename queue to existing: $ hg qqueue --rename foo abort: queue "foo" already exists [255] Rename queue: $ hg qqueue --rename buz $ hg qqueue buz (active) foo patches Switch back to previous queue: $ hg qqueue foo $ hg qqueue --delete buz $ hg qqueue foo (active) patches Create queue for purge: $ hg qqueue --create purge-me $ hg qqueue foo patches purge-me (active) Create patch for purge: $ hg qnew patch-purge-me $ ls -1d .hg/patches-purge-me 2>/dev/null || true .hg/patches-purge-me $ hg qpop -a popping patch-purge-me patch queue now empty Purge queue: $ hg qqueue foo $ hg qqueue --purge purge-me $ hg qqueue foo (active) patches $ ls -1d .hg/patches-purge-me 2>/dev/null || true Unapplied patches: $ hg qun $ echo c > a $ hg qnew -fgDU otherstuff Fail switching back: $ hg qqueue patches abort: new queue created, but cannot make active as patches are applied [255] Fail deleting current: $ hg qqueue foo --delete abort: cannot delete currently active queue [255] Switch back and delete foo: $ hg qpop -a popping otherstuff patch queue now empty $ hg qqueue patches $ hg qqueue foo --delete $ hg qqueue patches (active) Tricky cases: $ hg qqueue store --create $ hg qnew journal $ hg qqueue patches store (active) $ hg qpop -a popping journal patch queue now empty $ hg qqueue patches $ hg qun somestuff Invalid names: $ hg qqueue test/../../bar --create abort: invalid queue name, may not contain the characters ":\/." [255] $ hg qqueue . --create abort: invalid queue name, may not contain the characters ":\/." [255] $ cd ..