RFR 7004967: SecureRandom should be more explicit about threading

[Xuelei Fan]

1.  More specific

    "A SecureRandom service provider can advertise that it is
     thread-safe by setting the service provider attribute
     "ThreadSafe" to "true" when registering the provider."

A service provider may contains many services implementations.  May need 
to be more specific to set "ThreadSafe" for SecureRandom only, rather 
the full provider is thread safe.  For example:

     map.put("SecureRandom.SHA1PRNG ThreadSafe", "true");

Otherwise, a service provider need to make sure all services are thread 
safe, or all services implementation are not thread safe.

2. "true" is the only true property value.
     "If this attribute is not set or is "false", this class will
      instead ..."

If the attribute is set to "yes" or "hello, world!", I think it is the 
same as set to "false" per your current implementation.

     "Otherwise, this class will ... "

May need to update the implementation accordingly if you accept the 
comments.

Xuelei


On 11/2/2016 3:27 PM, Wang Weijun wrote:
> Ping again.
>
> There is an updated version at http://cr.openjdk.java.net/~weijun/7004967/webrev.01/ with doc-only changes.
>
> Thanks
> Max
>
>> On Aug 25, 2016, at 10:00 AM, Weijun Wang <weijun.wang at oracle.com> wrote:
>>
>> Please review the enhancement at
>>
>>  http://cr.openjdk.java.net/~weijun/7004967/webrev.00/
>>
>> Basically, we want SecureRandom to be more efficient by removing all synchronized keywords from its public methods and let an implementation to take care of thread-safety (We already did some in JDK-8098581). On the other hand, we need to make sure that existing implementations that have not synchronized correctly to behave just as good as before.
>>
>> Therefore a new Service Attribute "ThreadSafe" is introduced. If you think your implementation is already thread-safe, set it to "true" and SecureRandom will be happy. Otherwise, don't set it and SecureRandom will continuously call your SecureRandomSpi engine methods in synchronized blocks.
>>
>> Thanks
>> Max
>