RFR: 8238566: java.security.Provider$Service.supportsParameter() is racy

[Daniel Fuchs]

Hi Valerie,

Given that hasKeyAttributes is already decelared as volatile,
may I suggest the following change that uses double locking?
It will  avoid synchronizing in the happy case where `hasKeyAttributes`
has already been computed.

1924         private boolean hasKeyAttributes() {
1925             Boolean b = hasKeyAttributes;
                  if (b != null) return b;
                  synchronized (this) {
                      b = hasKeyAttributes;
1926                 if (b != null) return b;
1927                 String s;
1928                 s = getAttribute("SupportedKeyFormats");

                      ...

1948                 hasKeyAttributes = b;
1949             }
1950             return b;
1951         }


best regards,

-- daniel

On 11/03/2020 20:31, Valerie Peng wrote:
> 
> Anyone can help reviewing this?
> 
> I addressed this by applying the double-checked-locking pattern for lazy 
> initialization of instance fields.
> 
> Existing code already have most of the code structured for the pattern 
> but misses the second check.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8238566
> 
> Webrev: http://cr.openjdk.java.net/~valeriep/8238566/webrev.00/
> 
> Thanks,
> 
> Valerie