tests/hgweberror.py

revset: make generatorset.__nonzero__ lazy

The 'for r in self:' call could trigger full consumption of the generator while
we only need a single value. We also fast path if a single value got already
computed. See inline comment for more details.

This provide massive speedup for lazy operation using boolean testing.

max(::tip)
e5b507efb36e) wall 0.055609 comb 0.060000 user 0.060000 sys 0.000000 (best of 100)
after change) wall 0.000109 comb 0.000000 user 0.000000 sys 0.000000 (best of 19146)

# A dummy extension that installs an hgweb command that throws an Exception.

from mercurial.hgweb import webcommands

def raiseerror(web, req, tmpl):
    '''Dummy web command that raises an uncaught Exception.'''

    # Simulate an error after partial response.
    if 'partialresponse' in req.form:
        req.respond(200, 'text/plain')
        req.write('partial content\n')

    raise AttributeError('I am an uncaught error!')

def extsetup(ui):
    setattr(webcommands, 'raiseerror', raiseerror)
    webcommands.__all__.append('raiseerror')