adding rsockets support into JDK

[Lu, Yingqi]

Rename the sample code filenames:

For connect/accept occur in the same thread: http://cr.openjdk.java.net/~ylu/testNonBlocking_rconnect_modified.c

For connect/accept occur in two different threads: http://cr.openjdk.java.net/~ylu/testNonBlocking_rconnect_modified_2threads.c

Thanks,
Lucy

>-----Original Message-----
>From: Lu, Yingqi
>Sent: Monday, December 10, 2018 4:36 PM
>To: 'Alan Bateman' <Alan.Bateman at oracle.com>; Chris Hegarty
><chris.hegarty at oracle.com>; nio-dev at openjdk.java.net
>Cc: Viswanathan, Sandhya <sandhya.viswanathan at intel.com>; Aundhe,
>Shirish <shirish.aundhe at intel.com>; Kaczmarek, Eric
><eric.kaczmarek at intel.com>
>Subject: RE: adding rsockets support into JDK
>
>Hi Alan/Chris,
>
>I was able to confirm that connecting on non-blocking socket causes issues. It
>happens when connect/accept occurs in the same thread or different threads
>in the same process.
>
>Then, I did a small tweak in Chris's sample application by spawning a thread
>doing rpoll on the connection_fd. Now, the connect/accept works in both of
>the cases above. Please let me know if this is a valid workaround for the issue.
>
>Performance wise, this workaround should not impact send/receive at all. It
>might only add a small overhead to the connection setup phase only with non-
>blocking RDMA socket.
>
>The modified app code is available at
>
>For connect/accept occur in the same thread:
>https://cr.openjdk.java.net/~ylu/testNonBlocking_raccept_modified.c
>
>For connect/accept occur in two different threads:
>https://cr.openjdk.java.net/~ylu/testNonBlocking_raccept_modified_2threa
>ds.c
>
>Thanks,
>Lucy
>
>>-----Original Message-----
>>From: Alan Bateman [mailto:Alan.Bateman at oracle.com]
>>Sent: Saturday, December 8, 2018 8:10 AM
>>To: Chris Hegarty <chris.hegarty at oracle.com>; Lu, Yingqi
>><yingqi.lu at intel.com>; nio-dev at openjdk.java.net
>>Cc: Viswanathan, Sandhya <sandhya.viswanathan at intel.com>; Aundhe,
>>Shirish <shirish.aundhe at intel.com>; Kaczmarek, Eric
>><eric.kaczmarek at intel.com>
>>Subject: Re: adding rsockets support into JDK
>>
>>On 08/12/2018 09:39, Chris Hegarty wrote:
>>> :
>>>
>>> - It has become apparent that mixing blocking and non-blocking
>>>   connect/accept operations, in the same thread, may cause issues.
>>> For
>>>   example, attempting to setup a connected-socket on the same host by
>>>   issuing a non-blocking connect followed by a blocking accept, will
>>>   just hang and not make progress [3]. Upon further enquiries it
>>> appears
>>>   that the programming model for rsocket is a subtly different than
>>> that
>>>   of the regular Berkeley sockets ( at least for the connection
>>>   handshake ). It is not immediately clear how to reasonably
>>> workaround
>>>   this issue ( it's not a bug in rdma-core, but more a fundamental
>>> part
>>>   of its thread-less operation ).
>>>
>>Would it be possible to expand on this to say whether the same issues
>>arises when the non-blocking connect is initiated on a different
>>thread, or in a different process, or even a different machine on the fabric.
>>That is, if the socket is non-blocking and I do a rconnect and then
>>delay before doing anything else on the socket then will the peer doing
>>accept be blocked/hung in the mean-time?
>>
>>-Alan