[mod_python] requests are blocking when using req.sendfile

Graham Dumpleton graham.dumpleton at gmail.com
Fri Sep 26 05:51:39 EDT 2008


What does your handler actually do? The following works for me no problems.

from mod_python import apache

def handler(req):
    req.filename = '/etc/services'
    req.finfo = apache.stat(req.filename, apache.APR_FINFO_MIN)
    return apache.DECLINED

Does the file exist prior to calling apr.stat()?

Apache even sets the output headers okay:

HTTP/1.1 200 OK
Date: Fri, 26 Sep 2008 09:50:33 GMT
Server: Apache/2.2.8 (Unix) mod_python/3.3.2-dev-20080311 Python/2.5.1
mod_ssl/2.2.8 OpenSSL/0.9.7l DAV/2 mod_wsgi/3.0-TRUNK
Last-Modified: Sun, 23 Sep 2007 21:37:31 GMT
ETag: "535d-a5847-43ad44fac1cc0"
Accept-Ranges: bytes
Content-Length: 677959
Connection: close
Content-Type: text/plain

Ie., ETag and length etc.

Graham

2008/9/26 Matt Barnicle <mattb at wageslavery.org>:
> nope  :-(
>
>> One last thing to add then. If this doesn't work, I'll have to just
>> try it myself. :-)
>>
>>   req.handler = 'default-handler'
>>
>> Graham
>>
>> 2008/9/26 Matt Barnicle <mattb at wageslavery.org>:
>>> ok, that worked..  but unfortunately the blocking issue is still
>>> happening.  i've verified that the download controller is
>>> returning
>>> apache.DECLINED and the file downloads ok.
>>>
>>> - [email protected]
>>>
>>>> Try adding:
>>>>
>>>>   req.path_info = ''
>>>>
>>>> Graham
>>>>
>>>> 2008/9/26 Matt Barnicle <mattb at wageslavery.org>:
>>>>>> 2008/9/25 Matt Barnicle <mattb at wageslavery.org>:
>>>>>>>> 2008/9/24 Matt Barnicle <mattb at wageslavery.org>:
>>>>>>>>>> Are you setting a content length on the response before
>>>>>>>>>> calling
>>>>>>>>>> req.sendfile()?
>>>>>>>>>>
>>>>>>>>>> How many concurrent requests for these files are you
>>>>>>>>>> receiving
>>>>> and
>>>>>>>>>> how long does it take to download a file?
>>>>>>>>>>
>>>>>>>>>> Graham
>>>>>>>>>
>>>>>>>>> yes, i believe so..  now that you mention it, i haven't
>>>>>>>>> verified
>>>>>>>>> the file size from the code below, i will do that to be
>>>>>>>>> sure.
>>>>> here
>>>>>>>>> is the code:
>>>>>>>>>
>>>>>>>>> file_path = self.conf.run.app_folder + 'public' +
>>>>>>>>> download.path
>>>>>>>>> file_stat = os.stat(file_path)
>>>>>>>>> file_size = str(file_stat.st_size)
>>>>>>>>>
>>>>>>>>> self.req.headers_out['Content-Length'] = file_size
>>>>>>>>> self.req.headers_out['Content-Disposition'] = 'attachment;
>>>>>>>>> filename=%s' % os.path.basename(file_path)
>>>>>>>>>
>>>>>>>>> bytes_sent = self.req.sendfile(file_path)
>>>>>>>>
>>>>>>>> BTW, now that you are using mod_python 3.3.1, instead of
>>>>>>>> using
>>>>>>>> req.sendfile(), you could possibly delegate serving of the
>>>>> static file
>>>>>>>> back to Apache. From memory this can be done using:
>>>>>>>>
>>>>>>>>   req.filename = self.conf.run.app_folder + 'public' +
>>>>>>>> download.path
>>>>>>>>   req.finfo = apache.stat(req.filename, apache.APR_FINFO_MIN)
>>>>>>>>   return apache.DECLINED
>>>>>>>>
>>>>>>>> By returning apache.DECLINED you say mod_python handler will
>>>>>>>> not
>>>>>>>> actually handle it, and by having updated req.filename and
>>>>>>>> req.fileinfo updated to new file, when it falls through to
>>>>>>>> default-handler it should serve it as static file.
>>>>>>>>
>>>>>>>> Doing it this way should bypass prior Apache access control
>>>>>>>> checks.
>>>>>>>> Thus file doesn't need to be in Apache document tree or
>>>>>>>> anywhere
>>>>> else
>>>>>>>> that is accessible.
>>>>>>>>
>>>>>>>> I believe doing it this way also has benefit that Apache will
>>>>>>>> automatically set various headers that you probably wouldn't
>>>>>>>> be.
>>>>>>>>
>>>>>>>> Please let us know if this alternate method works.
>>>>>>>>
>>>>>>>> Graham
>>>>>>> i tried the following but it doesn't seem to do what i want:
>>>>>>>
>>>>>>> DocumentRoot /var/www/my/application/public
>>>>>>> <Directory /var/www/my/application/public>
>>>>>>>  AddHandler python-program .py
>>>>>>>  PythonHandler myhandler
>>>>>>> </Directory>
>>>>>>
>>>>>> Use SetHandler instead of AddHandler.
>>>>>>
>>>>>>   DocumentRoot /var/www/my/application/public
>>>>>>   <Directory /var/www/my/application/public>
>>>>>>    SetHandler python-program
>>>>>>    PythonHandler myhandler
>>>>>>   </Directory>
>>>>>>
>>>>>> Graham
>>>>>
>>>>> ok, getting closer..  now i get a 404 error in the browser
>>>>> saying
>>>>> 'The requested URL /download/file/3 was not found on this
>>>>> server.'
>>>>> and in the apache logs:
>>>>>
>>>>> File does not exist:
>>>>> /var/www/application/public/downloads/music/music.zip/file/3
>>>>>
>>>>> so it looks like it's taking the last part of the URI and
>>>>> appending
>>>>> it to the physical filename and looking for that...  the request
>>>>> URI
>>>>> is 'http://example.com/download/file/3'.  the 'download'
>>>>> controller
>>>>> is what manages the music downloads.
>>>>>
>>>>> - [email protected]
>>>>>
>>>>>
>>>>
>>>
>>>
>>>
>>
>
>
>


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