Mercurial > hg
view tests/test-children.t @ 37711:65a23cc8e75b
cborutil: implement support for streaming encoding, bytestring decoding
The vendored cbor2 package is... a bit disappointing.
On the encoding side, it insists that you pass it something with
a write() to send data to. That means if you want to emit data to
a generator, you have to construct an e.g. io.BytesIO(), write()
to it, then get the data back out. There can be non-trivial overhead
involved.
The encoder also doesn't support indefinite types - bytestrings, arrays,
and maps that don't have a known length. Again, this is really
unfortunate because it requires you to buffer the entire source and
destination in memory to encode large things.
On the decoding side, it supports reading indefinite length types.
But it buffers them completely before returning. More sadness.
This commit implements "streaming" encoders for various CBOR types.
Encoding emits a generator of hunks. So you can efficiently stream
encoded data elsewhere.
It also implements support for emitting indefinite length bytestrings,
arrays, and maps.
On the decoding side, we only implement support for decoding an
indefinite length bytestring from a file object. It will emit a
generator of raw chunks from the source.
I didn't want to reinvent so many wheels. But profiling the wire
protocol revealed that the overhead of constructing io.BytesIO()
instances to temporarily hold results has a non-trivial overhead.
We're talking >15% of execution time for operations like
"transfer the fulltexts of all files in a revision." So I can
justify this effort.
Fortunately, CBOR is a relatively straightforward format. And we have
a reference implementation in the repo we can test against.
Differential Revision: https://phab.mercurial-scm.org/D3303
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sat, 14 Apr 2018 16:36:15 -0700 |
parents | 7c8524efd847 |
children |
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test children command $ cat <<EOF >> $HGRCPATH > [extensions] > children = > EOF init $ hg init t $ cd t no working directory $ hg children setup $ echo 0 > file0 $ hg ci -qAm 0 -d '0 0' $ echo 1 > file1 $ hg ci -qAm 1 -d '1 0' $ echo 2 >> file0 $ hg ci -qAm 2 -d '2 0' $ hg co null 0 files updated, 0 files merged, 2 files removed, 0 files unresolved $ echo 3 > file3 $ hg ci -qAm 3 -d '3 0' hg children at revision 3 (tip) $ hg children $ hg co null 0 files updated, 0 files merged, 1 files removed, 0 files unresolved hg children at nullrev (should be 0 and 3) $ hg children changeset: 0:4df8521a7374 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: 0 changeset: 3:e2962852269d tag: tip parent: -1:000000000000 user: test date: Thu Jan 01 00:00:03 1970 +0000 summary: 3 $ hg co 1 2 files updated, 0 files merged, 0 files removed, 0 files unresolved hg children at revision 1 (should be 2) $ hg children changeset: 2:8f5eea5023c2 user: test date: Thu Jan 01 00:00:02 1970 +0000 summary: 2 $ hg co 2 1 files updated, 0 files merged, 0 files removed, 0 files unresolved hg children at revision 2 (other head) $ hg children $ for i in null 0 1 2 3 '2^'; do > echo "hg children -r '$i'" > hg children -r $i > done hg children -r 'null' changeset: 0:4df8521a7374 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: 0 changeset: 3:e2962852269d tag: tip parent: -1:000000000000 user: test date: Thu Jan 01 00:00:03 1970 +0000 summary: 3 hg children -r '0' changeset: 1:708c093edef0 user: test date: Thu Jan 01 00:00:01 1970 +0000 summary: 1 hg children -r '1' changeset: 2:8f5eea5023c2 user: test date: Thu Jan 01 00:00:02 1970 +0000 summary: 2 hg children -r '2' hg children -r '3' hg children -r '2^' changeset: 2:8f5eea5023c2 user: test date: Thu Jan 01 00:00:02 1970 +0000 summary: 2 hg children -r 0 file0 (should be 2) $ hg children -r 0 file0 changeset: 2:8f5eea5023c2 user: test date: Thu Jan 01 00:00:02 1970 +0000 summary: 2 hg children -r 1 file0 (should be 2) $ hg children -r 1 file0 changeset: 2:8f5eea5023c2 user: test date: Thu Jan 01 00:00:02 1970 +0000 summary: 2 $ hg co 0 1 files updated, 0 files merged, 1 files removed, 0 files unresolved hg children file0 at revision 0 (should be 2) $ hg children file0 changeset: 2:8f5eea5023c2 user: test date: Thu Jan 01 00:00:02 1970 +0000 summary: 2 should be compatible with templater (don't pass fctx to displayer) $ hg children file0 -Tdefault changeset: 2:8f5eea5023c2 user: test date: Thu Jan 01 00:00:02 1970 +0000 summary: 2 $ cd ..