RFR : 8195857 : Posix platforms : move os::is_headless_jre check coding to os::Posix and remove test for libmawt

[Bob Vandette]

If we are going to preserve this functionality and make alterations, I suggest that
we try to move this into the desktop module and remove it from the hotspot sources.
Other than finding an appropriate path at startup to initialize the property, there is
no reason why this check can’t be written in Java.   This functionality has nothing to
do with Hotspot or VMs.  (I should have probably done this when I first added this check).

Bob.

> On Jan 23, 2018, at 5:57 AM, Baesken, Matthias <matthias.baesken at sap.com> wrote:
> 
> Hi David, thanks for the comments.
> 
>> I'd need to do some checking but I think this may all be effectively
>> dead code.
> 
> Please do the checking, maybe we can completely remove it.
> 
> Best Regards, Matthias
> 
> 
>> -----Original Message-----
>> From: David Holmes [mailto:david.holmes at oracle.com]
>> Sent: Dienstag, 23. Januar 2018 11:30
>> To: Baesken, Matthias <matthias.baesken at sap.com>; 'hotspot-
>> dev at openjdk.java.net' <hotspot-dev at openjdk.java.net>
>> Subject: Re: RFR : 8195857 : Posix platforms : move os::is_headless_jre check
>> coding to os::Posix and remove test for libmawt
>> 
>> Hi Matthias,
>> 
>> Some preliminary comments ...
>> 
>> On 23/01/2018 6:24 PM, Baesken, Matthias wrote:
>>> Hello,  I  noticed that  os::is_headless_jre()  still checks  on the Posix
>> platforms  for libmawt  which is not present any longer.
>> 
>> I wonder why that comment was put in but the code not changed ...
>> 
>>> Additionally the  os::is_headless_jre()   function could be  put in a central
>> place at os_posix  to avoid code duplication.
>> 
>> I think you could simplify further and just define in os.cpp with three
>> cases: windows, OS X, posix. I normally wouldn't suggest that but given
>> Windows and OS X are always false, it's quite trivial.
>> 
>> That said this may simplify even further because I don't know if the
>> concept of a headless JRE is even meaningful anymore. This what put in
>> place in 2010 to support Java SE Embedded. We had a special build
>> process that would remove the library from the JRE image, then a runtime
>> check os::is_headless_jre() run during argument processing, that if
>> true, caused the java.awt.headless property to be set to true (unless
>> already set). I don't think we can even build a "headless JRE" any more.
>> 
>> I'd need to do some checking but I think this may all be effectively
>> dead code.
>> 
>> Thanks,
>> David
>> -------
>> 
>>> Could you please review my change .
>>> 
>>> Webrev :
>>> 
>>> http://cr.openjdk.java.net/~mbaesken/webrevs/8195857/
>>> 
>>> Bug :
>>> 
>>> https://bugs.openjdk.java.net/browse/JDK-8195857
>>> 
>>> 
>>> 
>>> Thanks, Matthias
>>>