Large allocation in CipherSuites.

[Xuelei Fan]

Hi Clive,

It’s a good point to me!  Did you have the numbers about the performance impact?

Considering the size of CipherSuites, I think it is good to make an improvement.  As we are already here, may be we could consider if we could make further performance improvement for searching as well.

Thanks,
Xuelei

> On Jul 9, 2021, at 10:52 AM, Verghese, Clive <verghese at amazon.com> wrote:
> 
> Hi 
> 
> We have identified large number of allocations in CipherSuites[1]. The root cause for the allocations is that in the `CipherSuite.values` call in `nameof` and `valueof` functions. These functions are called by the SSLAlgorithmDecomposer and in SSLEngineImpl. The enumeration values functions clones the array before returning. A previous discussion on the compiler-dev channel[2] describes why the values function returns a clone. We would like to propose that the CipherSuite.values be stored in a `private static final` field [3]. This would prevent the need to clone the array for each lookup across the enum. 
> 
> The proposed change stores the ciphers as an array itself. The other alternative would be to store the values as a HashMap. However, I feel that this would not be optimal due to the ordering of the Enumeration. 
> 
> Looking for your feedback and recommendations. If the proposal look good, I can go ahead and create a JBS issue and submit a PR for the same. 
> 
> Regards,
> Clive Verghese 
> 
> 1 : https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/sun/security/ssl/CipherSuite.java
> 2 : http://mail.openjdk.java.net/pipermail/compiler-dev/2018-July/012242.html
> 3 : https://github.com/cliveverghese/jdk/commit/8b34c06d8305ef9cb6a790e4cc8ca169c2fc9d79
> 
>