tests/test-newcgi.t

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 tests if CGI files from after d0db3462d568 but
before d74fc8dec2b4 still work.

  $ hg init test
  $ cat >hgweb.cgi <<HGWEB
  > #!$PYTHON
  > #
  > # An example CGI script to use hgweb, edit as necessary
  > 
  > import cgitb
  > cgitb.enable()
  > 
  > from mercurial import demandimport; demandimport.enable()
  > from mercurial.hgweb import hgweb
  > from mercurial.hgweb import wsgicgi
  > from mercurial.hgweb.request import wsgiapplication
  > 
  > def make_web_app():
  >     return hgweb("test", "Empty test repository")
  > 
  > wsgicgi.launch(wsgiapplication(make_web_app))
  > HGWEB

  $ chmod 755 hgweb.cgi

  $ cat >hgweb.config <<HGWEBDIRCONF
  > [paths]
  > test = test
  > HGWEBDIRCONF

  $ cat >hgwebdir.cgi <<HGWEBDIR
  > #!$PYTHON
  > #
  > # An example CGI script to export multiple hgweb repos, edit as necessary
  > 
  > import cgitb
  > cgitb.enable()
  > 
  > from mercurial import demandimport; demandimport.enable()
  > from mercurial.hgweb import hgwebdir
  > from mercurial.hgweb import wsgicgi
  > from mercurial.hgweb.request import wsgiapplication
  > 
  > def make_web_app():
  >     return hgwebdir("hgweb.config")
  > 
  > wsgicgi.launch(wsgiapplication(make_web_app))
  > HGWEBDIR

  $ chmod 755 hgwebdir.cgi

  $ . "$TESTDIR/cgienv"
  $ "$PYTHON" hgweb.cgi > page1
  $ "$PYTHON" hgwebdir.cgi > page2

  $ PATH_INFO="/test/"
  $ PATH_TRANSLATED="/var/something/test.cgi"
  $ REQUEST_URI="/test/test/"
  $ SCRIPT_URI="http://hg.omnifarious.org/test/test/"
  $ SCRIPT_URL="/test/test/"
  $ "$PYTHON" hgwebdir.cgi > page3

  $ grep -i error page1 page2 page3
  [1]