cheroot.server: procedure `serve()` has detached from `start()` #98

polymorphm · 2018-05-27T20:37:54Z

What is the related issue number (starting with #)

it is release with issues #68 ("is there any right way to interrupt a started server?")

What is the current behavior? (You can also link to an open issue here)

see my next simple example:

# -*- mode: python; coding: utf-8 -*-

from cheroot.wsgi import Server
import signal
import threading

def helloAAA_wsgi(environ, start_response):
    start_response('200 OK', [('Content-type','text/plain;charset=utf-8')])
    
    yield 'Hello world! #AAA\n'.encode()

def helloBBB_wsgi(environ, start_response):
    start_response('200 OK', [('Content-type','text/plain;charset=utf-8')])
    
    yield 'Hello world! #BBB\n'.encode()

def helloCCC_wsgi(environ, start_response):
    start_response('200 OK', [('Content-type','text/plain;charset=utf-8')])
    
    yield 'Hello world! #CCC\n'.encode()

def main():
    signal.pthread_sigmask(signal.SIG_BLOCK, {signal.SIGINT, signal.SIGTERM})
    
    serverAAA = Server(('127.0.0.1', 8081), helloAAA_wsgi)
    serverBBB = Server(('127.0.0.1', 8082), helloBBB_wsgi)
    serverCCC = Server(('127.0.0.1', 8083), helloCCC_wsgi)
    
    t1 = threading.Thread(target=serverAAA.start) # THERE IS AN ERROR
    t2 = threading.Thread(target=serverBBB.start) # THERE IS AN ERROR
    t3 = threading.Thread(target=serverCCC.start) # THERE IS AN ERROR
    
    t1.start()
    t2.start()
    t3.start()
    
    print('*** all servers have started! *** (we are lying here right now :))')
    
    # XXX   IT IS WRONG!
    #       we can't really say about finishing start-procedure.
    #       and we can't be sure about ability to invoke ``stop()`` (see below).
    #       if ``start()`` hadn't done ready status yet, we couldn't invoke ``stop()``
    
    print('*** serving requests is in process... ***')
    
    signal.sigwaitinfo({signal.SIGINT, signal.SIGTERM})
    
    print('*** terminating... ***')
    
    serverAAA.stop()
    serverBBB.stop()
    serverCCC.stop()
    
    t1.join()
    t2.join()
    t3.join()
    
    # XXX
    #       we won't be here, if any ``stop()`` has invoked too early
    
    print('*** gracefully terminated! ***')

if __name__ == '__main__':
    main()

What is the new behavior (if this is a feature change)?

please, see my next another example:

# -*- mode: python; coding: utf-8 -*-

from cheroot.wsgi import Server
import signal
import threading

def helloAAA_wsgi(environ, start_response):
    start_response('200 OK', [('Content-type','text/plain;charset=utf-8')])
    
    yield 'Hello world! #AAA\n'.encode()

def helloBBB_wsgi(environ, start_response):
    start_response('200 OK', [('Content-type','text/plain;charset=utf-8')])
    
    yield 'Hello world! #BBB\n'.encode()

def helloCCC_wsgi(environ, start_response):
    start_response('200 OK', [('Content-type','text/plain;charset=utf-8')])
    
    yield 'Hello world! #CCC\n'.encode()

def main():
    signal.pthread_sigmask(signal.SIG_BLOCK, {signal.SIGINT, signal.SIGTERM})
    
    serverAAA = Server(('127.0.0.1', 8081), helloAAA_wsgi)
    serverBBB = Server(('127.0.0.1', 8082), helloBBB_wsgi)
    serverCCC = Server(('127.0.0.1', 8083), helloCCC_wsgi)
    
    serverAAA.start(dont_serve=True)
    serverBBB.start(dont_serve=True)
    serverCCC.start(dont_serve=True)
    
    print('*** all servers have started! ***')
    
    t1 = threading.Thread(target=serverAAA.serve)
    t2 = threading.Thread(target=serverBBB.serve)
    t3 = threading.Thread(target=serverCCC.serve)
    
    t1.start()
    t2.start()
    t3.start()
    
    print('*** serving requests is in process... ***')
    
    signal.sigwaitinfo({signal.SIGINT, signal.SIGTERM})
    
    print('*** terminating... ***')
    
    # now it is SAFE to invoke ``stop()`` here
    
    serverAAA.stop()
    serverBBB.stop()
    serverCCC.stop()
    
    t1.join()
    t2.join()
    t3.join()
    
    print('*** gracefully terminated! ***')

if __name__ == '__main__':
    main()

Other information:
Checklist:
- I think the code is well written
- I wrote good commit messages
- I have squashed related commits together after the changes have been approved
- Unit tests for the changes exist
- Integration tests for the changes exist (if applicable)
- I used the same coding conventions as the rest of the project
- The new code doesn't generate linter offenses
- Documentation reflects the changes
- The PR relates to only one subject with a clear title
  and description in grammatically correct, complete sentences

This change is

codecov · 2018-05-27T20:47:33Z

Codecov Report

Merging #98 into master will increase coverage by 1.38%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #98      +/-   ##
==========================================
+ Coverage   66.05%   67.44%   +1.38%     
==========================================
  Files          19       19              
  Lines        3067     3781     +714     
==========================================
+ Hits         2026     2550     +524     
- Misses       1041     1231     +190

jaraco

Without understanding the user's underlying complaint, the change this PR attempts to make seems perfectly reasonable.

I would make one request, though - don't use a boolean parameter to a function to select what that function does. Instead, just call the functions you need. i.e.:

def start(self):
    self.prepare()
    self.serve()

def prepare(self):
    # do the prep

This simpler refactoring provides the necessary hook that prepares the server without starting, but also to start the server, but more clearly and simply.

…d from ``start()``

polymorphm · 2018-07-14T16:11:22Z

@jaraco I agree with your code suggestion. (I thought about it early, but at that time I was afraid doing it, cause it is more big change)

I've just changed my branch to your suggestion.

polymorphm · 2018-07-14T16:13:10Z

the example of using now is

    # -*- mode: python; coding: utf-8 -*-

    from cheroot.wsgi import Server
    import signal
    import threading

    def helloAAA_wsgi(environ, start_response):
        start_response('200 OK', [('Content-type','text/plain;charset=utf-8')])
        
        yield 'Hello world! #AAA\n'.encode()

    def helloBBB_wsgi(environ, start_response):
        start_response('200 OK', [('Content-type','text/plain;charset=utf-8')])
        
        yield 'Hello world! #BBB\n'.encode()

    def helloCCC_wsgi(environ, start_response):
        start_response('200 OK', [('Content-type','text/plain;charset=utf-8')])
        
        yield 'Hello world! #CCC\n'.encode()

    def main():
        signal.pthread_sigmask(signal.SIG_BLOCK, {signal.SIGINT, signal.SIGTERM})
        
        serverAAA = Server(('127.0.0.1', 8081), helloAAA_wsgi)
        serverBBB = Server(('127.0.0.1', 8082), helloBBB_wsgi)
        serverCCC = Server(('127.0.0.1', 8083), helloCCC_wsgi)
        
        serverAAA.prepare()
        serverBBB.prepare()
        serverCCC.prepare()
        
        print('*** all servers have started! ***')
        
        t1 = threading.Thread(target=serverAAA.serve)
        t2 = threading.Thread(target=serverBBB.serve)
        t3 = threading.Thread(target=serverCCC.serve)
        
        t1.start()
        t2.start()
        t3.start()
        
        print('*** serving requests is in process... ***')
        
        signal.sigwaitinfo({signal.SIGINT, signal.SIGTERM})
        
        print('*** terminating... ***')
        
        # now it is SAFE to invoke ``stop()`` here
        
        serverAAA.stop()
        serverBBB.stop()
        serverCCC.stop()
        
        t1.join()
        t2.join()
        t3.join()
        
        print('*** gracefully terminated! ***')

    if __name__ == '__main__':
        main()

webknjaz

LGTM.
@polymorphm would you mind adding tests/docs as well?

Resolved.

polymorphm · 2018-07-28T13:50:37Z

@webknjaz > would you mind adding tests/docs as well?

I added two tests, with hoping them are useful :-) .

Is there documentation only in cheroot/cheroot/server.py header doc-string?

webknjaz · 2018-07-28T14:11:12Z

@polymorphm you may create an .rst file under docs/, it should work.

webknjaz · 2018-07-28T14:45:41Z

cheroot/test/test_server.py

+def test_prepare_makes_server_ready():
+    """Check that prepare() makes the server ready, and stop() clears it."""
+    httpserver = HTTPServer(
+        bind_addr=(ANY_INTERFACE_IPV6, EPHEMERAL_PORT),


This might be unstable in case of missing IPv6.

you're right

polymorphm · 2018-07-29T22:22:26Z

I've added some words about starting and stopping a server and made links-to-functions "clickable". It looks ready enough in my humble opinion :-) .

I apologize for delays from my side

webknjaz · 2018-08-01T09:56:35Z

cheroot/server.py

                if req.close_connection:
                    return

+For running a server you can invoke :func:`start() <HTTPServer.start()>` (it


Have you tried rendering it? I think it's a broken reference.

I rendered via

pip install '.[docs]' && sphinx-build docs docs/_build

it did this HTML:

For running a server you can invoke <a class="reference internal" href="#cheroot.server.HTTPServer.start" title="cheroot.server.HTTPServer.start"><code class="xref py py-func docutils literal notranslate">start()</code></a> (it will run the server forever) or use invoking <a class="reference internal" href="#cheroot.server.HTTPServer.prepare" title="cheroot.server.HTTPServer.prepare"><code class="xref py py-func docutils literal notranslate">prepare()</code></a> and <a class="reference internal" href="#cheroot.server.HTTPServer.serve" title="cheroot.server.HTTPServer.serve"><code class="xref py py-func docutils literal notranslate">serve()</code></a> like this:

where the reference is

<dl class="method"> <dt id="cheroot.server.HTTPServer.start"> <code class="descname">start</code>()<a class="headerlink" href="#cheroot.server.HTTPServer.start" title="Permalink to this definition">¶</a></dt> <dd>Run the server forever. It is shortcut for invoking <a class="reference internal" href="#cheroot.server.HTTPServer.prepare" title="cheroot.server.HTTPServer.prepare"><code class="xref py py-func docutils literal notranslate">prepare()</code></a> then <a class="reference internal" href="#cheroot.server.HTTPServer.serve" title="cheroot.server.HTTPServer.serve"><code class="xref py py-func docutils literal notranslate">serve()</code></a>. </dd></dl>

It looks correct for me.

may be I should use some other command for rendering? could you write it to me please?

No, looks fine. It's just that normally you don't need to put braces there.

webknjaz · 2018-08-01T11:52:19Z

@polymorphm thanks!
Release of v6.4.0 is on its way to PYPI: https://travis-ci.org/cherrypy/cheroot/builds/410767541.
It will be available @ https://pypi.org/p/Cheroot/6.4.0 (ETA 30 min).

webknjaz · 2018-08-01T12:26:11Z

Testing under osx/3.7 env failed because of missing virtualenv-init there, I've manually triggered deployment job.

cc: @jaraco

webknjaz · 2018-08-01T12:29:25Z

Upload successful: https://pypi.org/project/Cheroot/6.4.0/

polymorphm mentioned this pull request May 27, 2018

is there any right way to interrupt a started server? #68

Closed

webknjaz requested review from jaraco and webknjaz May 31, 2018 09:39

jaraco previously requested changes Jul 10, 2018

View reviewed changes

cheroot.server: procedures prepare() and serve() have detache…

7138bc2

…d from ``start()``

Fix typo in comment

aa9fa70

webknjaz approved these changes Jul 16, 2018

View reviewed changes

webknjaz requested a review from jaraco July 16, 2018 11:16

Fix docstring for prepare()

8089c84

webknjaz reviewed Jul 28, 2018

View reviewed changes

polymorphm added 3 commits July 28, 2018 23:47

added two tests for server functions: prepare(), serve(), stop()

18e89b1

cheroot.server: fixed pseudo code in doc-string of module

28b340a

some words about starting and stopping a server in docs

f6423ee

webknjaz reviewed Aug 1, 2018

View reviewed changes

webknjaz merged commit b7fea72 into cherrypy:master Aug 1, 2018

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cheroot.server: procedure serve() has detached from start() #98

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cheroot.server: procedure `serve()` has detached from `start()` #98

cheroot.server: procedure `serve()` has detached from `start()` #98

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