[9] RFR 8177969: Faster FilePermission::implies by avoiding the use of Path::relativize

[Weijun Wang]

Webrev updated at

   http://cr.openjdk.java.net/~weijun/8177969/webrev.02/

Changes since webrev.01:

1. Comments.

2. Another enhancement when I am writing comments. Since we can be sure 
that a path has no ".." by only looking at its head, we can also be sure 
that a path is all ".." by only looking at its tail.

JPRT core+jaxp runs fine. JCK tests run fine.

Now benchmark result (after adjusting the granted permission to 
"../../../../-") is:

Benchmark                         Mode  Cnt       Score       Error  Units
checkReadNewUnfixed  thrpt   15  174963.698 ±  5952.239  ops/s
checkReadNewFixed00  thrpt   15  417692.698 ± 24994.735  ops/s
checkReadNewFixed02  thrpt   15  447824.218 ± 20199.194  ops/s
checkReadOld200      thrpt   15  425353.705 ±  3546.411  ops/s
checkReadOld201      thrpt   15    2045.070 ±    57.287  ops/s

This time checkReadNewFixed02 looks even better than checkReadOld200 
running on jdk8u131. I dare not run it again. :-)

Thanks
Max

On 04/08/2017 04:48 AM, Sean Mullan wrote:
> This fix looks good to me. However, I would suggest adding some
> additional comments to the body of the containsPath method explaining
> what it is doing so that it is easier to understand.
>
> --Sean
>
> On 4/7/17 10:50 AM, Weijun Wang wrote:
>> Webrev updated at
>>
>>    http://cr.openjdk.java.net/~weijun/8177969/webrev.01/
>>
>> Changes since webrev.00 [1]
>>
>> 1. Copyright years.
>>
>> 2. Test fix. check() should include Windows drive tests like contains()
>> does.
>>
>> Thanks
>> Max
>>
>> [1]
>> http://cr.openjdk.java.net/~weijun/8177969/webrev.01/interdiff.patch.html
>>
>> On 04/05/2017 10:13 PM, Roger Riggs wrote:
>>> Hi Max,
>>>
>>> The code looks ok.
>>>
>>> How much faster does it make FilePermission compares?
>>>
>>> I assume if it is not accepted to be fixed in JDK 9, you will push it to
>>> JDK 10.
>>>
>>> Roger
>>>
>>>
>>> On 4/3/2017 11:30 AM, Weijun Wang wrote:
>>>> http://cr.openjdk.java.net/~weijun/8177969/webrev.00/
>>>>
>>>> This new implementation of containsPath(Path,Path) uses the logic of
>>>> Path::relativize without directly calling it, which is much faster now.
>>>>
>>>> Thanks
>>>> Max
>>>