[twisted] add request error handler to avoid finishing it twice And avoid stack traces like:: Traceback (most recent call last): File "/usr/lib/python2.7/threading.py", line 783, in __bootstrap self.__bootstrap_inner() File "/usr/lib/python2.7/threading.py", line 810, in __bootstrap_inner self.run() File "/usr/lib/python2.7/threading.py", line 763, in run self.__target(*self.__args, **self.__kwargs) --- <exception caught here> --- [...] File "/usr/lib/python2.7/dist-packages/twisted/python/threadpool.py", line 196, in _worker result = context.call(ctx, function, *args, **kwargs) File "/usr/lib/python2.7/dist-packages/twisted/python/context.py", line 118, in callWithContext return self.currentContext().callWithContext(ctx, func, *args, **kw) File "/usr/lib/python2.7/dist-packages/twisted/python/context.py", line 81, in callWithContext return func(*args,**kw) File "/home/me/envs/grshell-cw/cubicweb/statsd_logger.py", line 121, in __call__ return self.callable(*args, **kw) File "/home/me/envs/grshell-cw/cubicweb/etwist/server.py", line 131, in render_request code=500, twisted_request=request) File "/home/me/envs/grshell-cw/cubicweb/etwist/http.py", line 22, in __init__ self._finalize() File "/home/me/envs/grshell-cw/cubicweb/etwist/http.py", line 46, in _finalize self._twreq.finish() File "/usr/lib/python2.7/dist-packages/twisted/web/server.py", line 228, in finish return http.Request.finish(self) File "/usr/lib/python2.7/dist-packages/twisted/web/http.py", line 931, in finish "Request.finish called on a request after its connection was lost; " exceptions.RuntimeError: Request.finish called on a request after its connection was lost; use Request.notifyFinish to keep track of this.

"""twisted server for CubicWeb web instances

:organization: Logilab
:copyright: 2001-2011 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""




class HTTPResponse(object):
    """An object representing an HTTP Response to be sent to the client.
    """
    def __init__(self, twisted_request, code=None, headers=None, stream=None):
        self._headers_out = headers
        self._twreq = twisted_request
        self._stream = stream
        self._code = code

        self._init_headers()
        self._finalize()

    def _init_headers(self):
        if self._headers_out is None:
            return
        # initialize headers
        for k, values in self._headers_out.getAllRawHeaders():
            self._twreq.responseHeaders.setRawHeaders(k, values)
        # add content-length if not present
        if (self._headers_out.getHeader('content-length') is None
            and self._stream is not None):
            self._twreq.setHeader('content-length', len(self._stream))

    def _finalize(self):
        # cw_failed is set on errors such as "connection aborted by client". In
        # such cases, req.finish() was already called and calling it a twice
        # would crash
        if getattr(self._twreq, 'cw_failed', False):
            return
        # we must set code before writing anything, else it's too late
        if self._code is not None:
            self._twreq.setResponseCode(self._code)
        if self._stream is not None:
            self._twreq.write(str(self._stream))
        self._twreq.finish()

    def __repr__(self):
        return "<%s.%s code=%d>" % (self.__module__, self.__class__.__name__, self._code)