JDK10 RFR: 8165437 Evaluate the use of gettimeofday in Networking code

[Chris Hegarty]

> On Tue, Apr 18, 2017 at 7:08 AM, Vyom Tewari <vyom.tewari at oracle.com> wrote:
> ...
> 
> Thanks for review, please find the updated webrev(http://cr.openjdk.java.net/~vtewari/8165437/webrev0.6/index.html) 

The changes mainly look good to me, just a few comments:

1) src/java.base/unix/native/libnet/PlainSocketImpl.c

   L235     jlong nanoTimeout = timeout * NET_NSEC_PER_MSEC;

   Can you please move this to the latest block of code that requires it, i.e..
   just after L327 if (connect_rv != 0) { …

2) src/java.base/share/native/libnet/net_util.h

   Should these definitions be moved to src/java.base/unix/native/libnet/net_util_md.h?


Regarding JVM_NanoTime being a JVM_LEAF and/or taking a JNIEnv (
both of which are, in todays hotspot VM, effectively ignored ), this is a
separate issue. I have raised it off list with others from the VM team,
without much interest. I will refrain from filing a JIRA issue to track potential
changes in the VM for this. Others are welcome to do so, if they wish. I 
suggest that we simply continue to pass a valid JNIEnv, since it is not
much extra effort to do so. ( this can be refactored later, if the VM interface
is ever updated ).


> On 24 Apr 2017, at 12:07, Thomas Stüfe <thomas.stuefe at gmail.com> wrote:
> 
> ...
> That aside, I am not a big fan of the removal of the old NET_Timeout. Before, there were two functions, "NET_Timeout" just taking the timeout value, "NET_Timeout0" taking a timeout and a start value. You removed the first variant and therefore added the many additional JVM_NanoTime() calls at NET_Timeout callsites. This makes the code harder to read and also kind of exposes the internal implementation of NET_Timeout (namely the fact that NET_Timeout uses JVM_NanoTime for time measurement). Could you please let both variants live, optionally with better names?

I think that it may not be worth added back the simpler variant. It
would only be used by PlainDatagramSocketImpl, correct? All other
usages would use the variant that accepts the current nano time.

-Chris.