Demian Brecht added the comment:
> socket.setdefaulttimeout([timeout]) -- it is bad practice
I'm not really arguing this. It solves the problem, but definitely not in the
best of ways. My point in referencing setdefaulttimeout is that if /all/ you
care about is the timeout and you're horribly opposed to using an API as I
suggested, you still have the option of using setdefaulttimeout. To be clear,
it's not something that I'd advocate.
> because setting this global varible we may spoil other cases. example "TCP
> keepalive" [s.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, true) ]
I'm afraid you've somewhat lost me here. Calling setdefaulttimeout simply sets
the value of defaulttimeout in socketmodule.c, which newly created sockets use
as their default value until explicitly overridden via settimeout().
> and again -- compare what shorter (and what more clear):
Sure, your example is clear for this /specific/ use case. To illustrate my
point about ambiguity though, it's unclear what the behaviour should be here
based on your patch:
proxy = ServerProxy('http://example.com/gateway/', timeout=42,
transport=Transport(2))
Should the value in the Transport instance be used or the one in the
ServerProxy parameter list? It's not obvious and therefore not a sound decision
from an API design standpoint.
Ignoring my suggestion of a connection_factory altogether, limiting the timeout
to the Transport class is a little more sane and doesn't risk ambiguity:
proxy = ServerProxy('http://example.com/gateway/',
transport=Transport(timeout=2))
Should my suggestion be tossed out, I do think that this is the most sane path
to go down.
Now, re-introducing my thoughts on a connection factory (which I still believe
is /much/ more flexible and extensible than simply passing in a timeout
parameter for the reasons I previously mentioned), should the timeout parameter
still be accepted at the Transport level, you run into the same level of
ambiguity:
transport = Transport(timeout=2, connection_factory=lambda h:
HTTPConnection(h, timeout=42))
So now the argument in my mind becomes: Should the connection attributes be
assignable through Transport instantiation or should the user have
accessibility to create their own instance of a connection class that adheres
to the expected API and pass that in? To me, the flexibility and benefits of
the latter far outweighs the additional complexity:
transport = Transport(timeout=2)
transport = Transport(connection_factory=lambda h: HTTPConnection(h,
timeout=42))
> if you NOT point timeout in "RPC-client" -- you program will freeze or will
> maked resource leak (with small probability).
Assuming a lack of concurrency, your program will indeed freeze until the
system timeout has been reached. I'm not sure about a leak. If you have an
example of such a case, it would likely be a good candidate for a new issue.
> answer: because *unknown* which value need to using by default.
No, the default should be set to socket._GLOBAL_DEFAULT_TIMEOUT (the same
default used by HTTPConnection). When unset, the timeout on the socket is
unspecified resulting in a value of -1, which then defaults to the
system-specific timeout.
Hopefully I've clarified things a little better. Of course, that doesn't mean
that you'll agree, in which case we'll just have to agree to disagree :)
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<http://bugs.python.org/issue14134>
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