RFR (XS) : 8141641: Runtime: implement range for ErrorLogTimeout

[David Holmes]

On 17/11/2015 1:59 AM, gerard ziemski wrote:
> Thank you David and Dmitry for reviews. Please see my response in-line:
>
>
>>> 3) Also, David suggested to wrap constants in multiplication in
>>> src/share/vm/runtime/thread.cpp into CONST64 to avoid possible
>>> overflows, i.e.:
>>> os::sleep(this, ErrorLogTimeout * CONST64(1000), false);
>
> I must have missed something - where/when did David suggest doing this?
>
>
>> I'm making a bit of a hash of this review - sorry.
>>
>> I agree with Dmitry that the os::sleep call should be changed as above:
>>
>> os::sleep(this, ErrorLogTimeout * CONST64(1000), false);
>>
>> but as the sleep arg is a jlong we need to limit ErrorLogTimeout to
>> (MAX_JLONG/1000) _but_ that's too big for uintx on
>> 32-bit. Which means the true range is different on 32-bit versus
>> 64-bit. So if I finally get this right we should have
>> the range as:
>>
>> range(0, LP64_ONLY(MAX_JLONG/1000) NOT_LP64(UINTX_MAX))
>>
>> Not sure we have MAX_JLONG defined as a constant. I don't agree with
>> just selecting the 32-bit range as that again
>> becomes an arbitrary constraint on 64-bit.
>
> Since os:sleep() takes jlong (8 bytes long on both 32 and 64 bit), them
> it would appear that the most straightforward solution is to change
> ErrorLogTimeout type from "uintx" to "uint64_t" (also 8 bytes on both 32
> and 64 bit) and then we can have the range simply defined as:
>
> range(0, max_jlong/1000)
 >
> And then we can have:
>
> os::sleep(this, ErrorLogTimeout * CONST64(1000), false); // in seconds
>
> Do we agree?

Not quite. First if ErrorLogTimeout is 64-bit then we don't need to 
apply CONST64 to 1000 as integer promotion will take care of it. But we 
then pass an unsigned 64-bit value where a signed 64-bit value is 
expected and that will need a cast to avoid a conversion warning.

So perhaps ErrorLogTimeout should be int64_t instead - even though only 
positive values are valid?

Thanks,
David

>
> cheers