RFR: 8000975: (process) Merge UNIXProcess.java.bsd & UNIXProcess.java.linux (& .solaris & .aix)

roger riggs roger.riggs at oracle.com
Tue Apr 1 19:47:22 UTC 2014


A minor point, but the Enum for LaunchMechanism can be simpler; the 
defined enum values (1,2,3)
are never used and can be removed along with the extra constructor.

With the refactoring so f0ar, this seems more complex and harder to 
At least in the non-merged version all (and only) the code for a 
platform was in a single class.
The static UNIXProcess subclasses for the various platforms are always 
kept around.

Other alternatives would have been to factor the common code (Streams 
into a utilities class or ProcessImpl and retain the 1st class 
subclasses (with different names)
for each platform or merge more up into ProcessImpl.

Maybe it will be clearer with additional refactoring.

$.02, Roger

On 4/1/2014 1:04 PM, Peter Levart wrote:
> On 04/01/2014 05:43 PM, Peter Levart wrote:
>> On 04/01/2014 03:49 PM, roger riggs wrote:
>>> Hi Peter,
>>> The design using enum for the os dependencies does not make it possible
>>> to include only the support needed for a particular platform at 
>>> build time.
>>> Every implementation will be carrying around the support for all the 
>>> other platforms.
>>> A build time binding would be more efficient.
>>> Roger
>> That's true. A trade-off between maintainability and efficiency. The 
>> efficiency has two categories here. One is the size of the 
>> distributable and the other is run-time efficiency. I've been 
>> thinking to improve both efficiencies (the run-time in particular) 
>> with a little re-design. Since nearly each OS platform requires a 
>> sub-class of UNIXProcess to implement the differences, I can move the 
>> implementations of various methods now in Os enum to the UNIXProcess 
>> subclasses and get rid of Os enum per-instance subclasses.
>> Let me try this and see what comes out.
> Hi Roger,
> Well, it turns out the methods would like to stay in Os (renamed to 
> Platform), but there is no need for per-enum-instance subclasses. 
> Using enum constructor parameters and switch statements makes code 
> even more compact and easy to follow...
> http://cr.openjdk.java.net/~plevart/jdk9-dev/UNIXProcess/webrev.04/
> I belive there is still room for consolidating logic in various 
> Input/OutputStream wrappers used in UNIXProcess variants. But in the 
> first round I tried to preserve the exact behaviour. If the wrapping 
> of streams could be made more-or-less equal in all UNIX platforms, 
> then the need for UNIXProcess subclasses and/or overhead of support 
> classes included but not used goes away...
> Regards, Peter
>>> On 4/1/2014 9:16 AM, Peter Levart wrote:
>>>> Hi Alan, Volker,
>>>> Thanks for sharing the info and for testing on AIX. Here's the 
>>>> updated webrev that hopefully includes the correct "dispatch on 
>>>> os.name" logic. I included "Solaris" as an alternative to "SunOS" 
>>>> since I saw this in some documents on Internet. If this is 
>>>> superfluous, I can remove it:
>>>> http://cr.openjdk.java.net/~plevart/jdk9-dev/UNIXProcess/webrev.03/
>>>> I tested this on Linux and Solaris and the java/lang/ProcessBuilder 
>>>> jtreg tests pass. So with Volker's test on AIX, the only OS 
>>>> platform left for testing is Mac OS X. Would someone volunteer?
>>>> Regards, Peter
>>>> On 03/27/2014 11:18 AM, Volker Simonis wrote:
>>>>> Hi Peter,
>>>>> thanks for applying these changes to the AIX files as well.
>>>>> With the additional line:
>>>>>              if (osName.equals("AIX")) { return AIX; }
>>>>> in Os.get() your change compiles cleanly on AIX and runs the
>>>>> java/lang/ProcessBuilder tests without any errors.
>>>>> So from an AIX perspective, thumbs up.
>>>>> Regards,
>>>>> Volker
>>>>> On Wed, Mar 26, 2014 at 5:18 PM, Alan Bateman 
>>>>> <Alan.Bateman at oracle.com> wrote:
>>>>>> On 26/03/2014 15:19, Peter Levart wrote:
>>>>>>> I couldn't find any official document about possible os.name 
>>>>>>> values for
>>>>>>> different supported OSes. Does anyone have a pointer?
>>>>>> I don't know if there is a definite list but I assume we don't 
>>>>>> need to be
>>>>>> concerned with anything beyond the 4 that we have in OpenJDK, 
>>>>>> which is
>>>>>> "Linux", "SunOS", "AIX" and contains("OS X").
>>>>>> If we get to the point in JDK 9 where src/solaris is renamed to 
>>>>>> src/unix (or
>>>>>> something equivalent) then it could mean that the Os enum can be 
>>>>>> replaced
>>>>>> with an OS specific class in src/linux, src/solaris, ... and this 
>>>>>> would
>>>>>> avoid the need for an os.name check at runtime.
>>>>>> -Alan.

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