cborutil: change buffering strategy
Profiling revealed that we were spending a lot of time on the
line that was concatenating the old buffer with the incoming data
when attempting to decode long byte strings, such as manifest
revisions.
Essentially, we were feeding N chunks of size len(X) << len(Y) into
decode() and continuously allocating a new, larger buffer to hold
the undecoded input. This created substantial memory churn and
slowed down execution.
Changing the code to aggregate pending chunks in a list until we
have enough data to fully decode the next atom makes things much
more efficient.
I don't have exact data, but I recall the old code spending >1s
on manifest fulltexts from the mozilla-unified repo. The new code
doesn't significantly appear in profile output.
Differential Revision: https://phab.mercurial-scm.org/D4854
#require no-msys # MSYS will translate web paths as if they were file paths
This is a test of the push wire protocol over CGI-based hgweb.
initialize repository
$ hg init r
$ cd r
$ echo a > a
$ hg ci -A -m "0"
adding a
$ echo '[web]' > .hg/hgrc
$ echo 'allow_push = *' >> .hg/hgrc
$ echo 'push_ssl = false' >> .hg/hgrc
create hgweb invocation script
$ cat >hgweb.cgi <<HGWEB
> import cgitb
> cgitb.enable()
> from mercurial import demandimport; demandimport.enable()
> from mercurial.hgweb import hgweb
> from mercurial.hgweb import wsgicgi
> application = hgweb(b'.', b'test repository')
> wsgicgi.launch(application)
> HGWEB
$ chmod 755 hgweb.cgi
test preparation
$ . "$TESTDIR/cgienv"
$ REQUEST_METHOD="POST"; export REQUEST_METHOD
$ CONTENT_TYPE="application/octet-stream"; export CONTENT_TYPE
$ hg bundle --type v1 --all bundle.hg
1 changesets found
$ CONTENT_LENGTH=279; export CONTENT_LENGTH;
expect failure because heads doesn't match (formerly known as 'unsynced changes')
$ QUERY_STRING="cmd=unbundle&heads=0000000000000000000000000000000000000000"; export QUERY_STRING
$ "$PYTHON" hgweb.cgi <bundle.hg >page1 2>&1
$ cat page1
Status: 200 Script output follows\r (esc)
Content-Type: application/mercurial-0.1\r (esc)
Content-Length: 64\r (esc)
\r (esc)
0
repository changed while preparing changes - please try again
successful force push
$ QUERY_STRING="cmd=unbundle&heads=666f726365"; export QUERY_STRING
$ "$PYTHON" hgweb.cgi <bundle.hg >page2 2>&1
$ cat page2
Status: 200 Script output follows\r (esc)
Content-Type: application/mercurial-0.1\r (esc)
Content-Length: 102\r (esc)
\r (esc)
1
adding changesets
adding manifests
adding file changes
added 0 changesets with 0 changes to 1 files
successful push, list of heads
$ QUERY_STRING="cmd=unbundle&heads=f7b1eb17ad24730a1651fccd46c43826d1bbc2ac"; export QUERY_STRING
$ "$PYTHON" hgweb.cgi <bundle.hg >page3 2>&1
$ cat page3
Status: 200 Script output follows\r (esc)
Content-Type: application/mercurial-0.1\r (esc)
Content-Length: 102\r (esc)
\r (esc)
1
adding changesets
adding manifests
adding file changes
added 0 changesets with 0 changes to 1 files
successful push, SHA1 hash of heads (unbundlehash capability)
$ QUERY_STRING="cmd=unbundle&heads=686173686564 5a785a5f9e0d433b88ed862b206b011b0c3a9d13"; export QUERY_STRING
$ "$PYTHON" hgweb.cgi <bundle.hg >page4 2>&1
$ cat page4
Status: 200 Script output follows\r (esc)
Content-Type: application/mercurial-0.1\r (esc)
Content-Length: 102\r (esc)
\r (esc)
1
adding changesets
adding manifests
adding file changes
added 0 changesets with 0 changes to 1 files
$ cd ..