RFR 8153674: Expected SocketException not thrown when calling bind() with setReuseAddress(false)

[Mark Sheppard]

Hi Chris,
      I don't fully understand your objections to the approach taken.
Is there a compatibility issue with the addition of the additional 
methods to MulticastSocket?

I don't see Datagram.setReuseAddress(...) handling the SO_REUSEPORT 
option, this has to be done explicitly via setOption at this level of 
abstraction.

MulticastSocket is a subclass of DatagramSocket (that in itself is a 
questionable structuring), and as such
has specialized behaviour, and part  of that specialization is the 
setting of  the setting SO_REUSEADDR and SO_REUSEPORT
in its constructors, to enable address reuse semantics, prior to binding 
an address.
As part of that specialization, it would seem appropriate that 
MulticastSocket manipulate the SO_REUSEPORT
option in a consistent way. Adding an overridden setReuseAddress(...) 
method provides that consistency and
encapsulates the specialized behaviour.

Is alternatively proposal to NOT do anything to MulticastSocket, BUT 
document clearly how to handle the failing scenario, that an MulticastSocket
requires both setReuseAddress() and a setOption call to disable 
reuseaddress semantics on an unbound MulticastSocket ?


This then raises the question of why have a convenience method, such as 
setReuseAddress() in the first place, when it can be handled
adequately via the setOption

regards
Mark

On 14/09/2016 13:34, Chris Hegarty wrote:
> Mark,
>
> On 14/09/16 13:23, Mark Sheppard wrote:
>>
>> Hi Chris,
>>     so are you accepting that it is correct to add the overridden
>> methods in MulticastSocket and that these need
>> appropriate javadoc ?
>
> I think we need these, but they should just call their super
> equivalents, i.e. no implicit setting of SO_REUSEPORT. They would
> exist solely as a place to locate guidance, or a note, that one
> will likely want to set SO_REUSEPORT too.
>
>> or are you advocating pushing the handing of the SO_REUSEPORT into the
>> base DatagramSocket class ?
>
> It is already there. I am not proposing to change this.
>
>> It is not clear how your code changes fit in the proposed fix i.e. the
>> explicit setting of the option to false?
>
> My proposal is an alternative. It is not related to the current
> webrev.
>
>> With the current proposed changes then I think it would be sufficient to
>> invoke setReuseAddress(true) in MulticastSocket constructors
>> rather than
>>
>>         // Enable SO_REUSEADDR before binding
>>         setReuseAddress
>> <https://java.se.oracle.com/source/s?defs=setReuseAddress&project=jdk9-dev>(*true*); 
>>
>>
>>         // Enable SO_REUSEPORT if supported before binding
>>         *if* (supportedOptions
>> <https://java.se.oracle.com/source/xref/jdk9-dev/jdk/src/java.base/share/classes/java/net/MulticastSocket.java#supportedOptions>().contains 
>>
>> <https://java.se.oracle.com/source/s?defs=contains&project=jdk9-dev>(StandardSocketOptions 
>>
>> <https://java.se.oracle.com/source/s?defs=StandardSocketOptions&project=jdk9-dev>.SO_REUSEPORT 
>>
>> <https://java.se.oracle.com/source/s?defs=SO_REUSEPORT&project=jdk9-dev>)) 
>> {
>>             *this*.setOption
>> <https://java.se.oracle.com/source/s?defs=setOption&project=jdk9-dev>(StandardSocketOptions 
>>
>> <https://java.se.oracle.com/source/s?defs=StandardSocketOptions&project=jdk9-dev>.SO_REUSEPORT 
>>
>> <https://java.se.oracle.com/source/s?defs=SO_REUSEPORT&project=jdk9-dev>, 
>> *true*);
>>         }
>>
>>
>> as the overridden setReuseAddress takes care of SO_REUSEPORT
>
> Yes, this is what Vyom has proposed, in the webrev.
>
> I would like to explore an alternative, so see what it would look like.
>
> -Chris.
>
>
>> regards
>> Mark
>>
>> On 14/09/2016 11:43, Chris Hegarty wrote:
>>> Vyom,
>>>
>>> On 11/09/16 08:01, Vyom Tewari wrote:
>>>> Hi All,
>>>>
>>>> Please review the below code change.
>>>>
>>>> Bug        : https://bugs.openjdk.java.net/browse/JDK-8153674
>>>>
>>>> Webrev  :
>>>> http://cr.openjdk.java.net/~vtewari/8153674/webrev0.0/index.html
>>>> <http://cr.openjdk.java.net/%7Evtewari/8153674/webrev0.0/index.html>
>>>>
>>>> This change override the "get/setReuseAddress"  for MulticaseSocket 
>>>> and
>>>> will abstract with both reuse attributes(SO_REUSEADDR & SO_REUSEPORT).
>>>
>>> This issue arises since the changes for 6432031 "Add support for
>>> SO_REUSEPORT" [1], which sets SO_REUSEPORT on MulticastSocket, if
>>> the available. So setting setReuseAddress(false) alone is no longer
>>> sufficient to disable address/port reuse, one must also set
>>> SO_REUSEPORT to false.
>>>
>>> I would be really nervous about changing set/getReuseAddress, without
>>> at least updating the javadoc to indicate that it is now, for MS,
>>> operating on two socket options.  Although, I do have sympathy
>>> here since SO_REUSEPORT and SO_REUSEADDR are almost identical when
>>> dealing with multicasting.
>>>
>>> An alternative, maybe; Since the MS constructors document that
>>> SO_REUSEPORT will be set, where available, maybe a javadoc note
>>> on the set/getReuseAddress methods would be sufficient, that
>>> indicates that StandardSocketOptions#SO_REUSEPORT may also need
>>> to be set to have the desired effect?
>>>
>>> If so, then code would have to:
>>>
>>>     setReuseAddress(false);
>>>
>>>     if 
>>> (supportedOptions().contains(StandardSocketOptions.SO_REUSEPORT))
>>>         this.setOption(StandardSocketOptions.SO_REUSEPORT, false);
>>>
>>>   , but at least it is explicit.
>>>
>>> Q: not all MS constructors document that SO_REUSEPORT is set, but
>>> they should, right? This seems to have slipped past during 6432031 [1].
>>>
>>> -Chris.
>>>
>>> [1] https://bugs.openjdk.java.net/browse/JDK-6432031
>>