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 serve
$ hgserve()
> {
> hg serve -a localhost -d --pid-file=hg.pid -E errors.log -v $@ \
> | sed -e "s/:$HGPORT1\\([^0-9]\\)/:HGPORT1\1/g" \
> -e "s/:$HGPORT2\\([^0-9]\\)/:HGPORT2\1/g" \
> -e 's/http:\/\/[^/]*\//http:\/\/localhost\//'
> if [ -f hg.pid ]; then
> killdaemons.py hg.pid
> fi
> echo % errors
> cat errors.log
> }
$ hg init test
$ cd test
$ echo '[web]' > .hg/hgrc
$ echo 'accesslog = access.log' >> .hg/hgrc
$ echo "port = $HGPORT1" >> .hg/hgrc
Without -v
$ hg serve -a localhost -p $HGPORT -d --pid-file=hg.pid -E errors.log
$ cat hg.pid >> "$DAEMON_PIDS"
$ if [ -f access.log ]; then
> echo 'access log created - .hg/hgrc respected'
> fi
access log created - .hg/hgrc respected
errors
$ cat errors.log
With -v
$ hgserve
listening at http://localhost/ (bound to *$LOCALIP*:HGPORT1) (glob) (?)
% errors
With -v and -p HGPORT2
$ hgserve -p "$HGPORT2"
listening at http://localhost/ (bound to *$LOCALIP*:HGPORT2) (glob) (?)
% errors
With -v and -p daytime (should fail because low port)
#if no-root no-windows
$ KILLQUIETLY=Y
$ hgserve -p daytime
abort: cannot start server at 'localhost:13': Permission denied
abort: child process failed to start
% errors
$ KILLQUIETLY=N
#endif
With --prefix foo
$ hgserve --prefix foo
listening at http://localhost/foo/ (bound to *$LOCALIP*:HGPORT1) (glob) (?)
% errors
With --prefix /foo
$ hgserve --prefix /foo
listening at http://localhost/foo/ (bound to *$LOCALIP*:HGPORT1) (glob) (?)
% errors
With --prefix foo/
$ hgserve --prefix foo/
listening at http://localhost/foo/ (bound to *$LOCALIP*:HGPORT1) (glob) (?)
% errors
With --prefix /foo/
$ hgserve --prefix /foo/
listening at http://localhost/foo/ (bound to *$LOCALIP*:HGPORT1) (glob) (?)
% errors
$ "$PYTHON" $RUNTESTDIR/killdaemons.py $DAEMON_PIDS
With out of bounds accesses
$ rm access.log
$ hg serve -a localhost -p $HGPORT -d --prefix some/dir \
> --pid-file=hg.pid -E errors.log
$ cat hg.pid >> "$DAEMON_PIDS"
$ hg id http://localhost:$HGPORT/some/dir7
abort: HTTP Error 404: Not Found
[255]
$ hg id http://localhost:$HGPORT/some
abort: HTTP Error 404: Not Found
[255]
$ cat access.log errors.log
$LOCALIP - - [$LOGDATE$] "GET /some/dir7?cmd=capabilities HTTP/1.1" 404 - (glob)
$LOCALIP - - [$LOGDATE$] "GET /some?cmd=capabilities HTTP/1.1" 404 - (glob)
$ cd ..