[9] RFR: 8177136: Caller sensitive method System.getLogger should specify what happens if there is no caller on the stack.

[Daniel Fuchs]

On 21/03/2017 18:21, Brent Christian wrote:
> Hi, Daniel
>
> I think the new @throws tag gives a good explanation of the situation,
> with instructions for someone wanting to get a System.Logger from JNI.
>
> To nitpick on style, it's maybe on the long side for an @throws -
> perhaps consider a slightly more concise version:
>
>      * @throws IllegalCallerException if there is no {@linkplain
>      *         StackWalker#getCallerClass() caller} frame, i.e.
>      *         this method is called from JNI
>      *         and there is no Java frame on the stack.<br>
>      *         To obtain a logger in such a context, the caller
>      *         should either use an auxiliary class that will implicitly
>      *         be identified as the caller, or use the system {@link
>      *         LoggerFinder#getLoggerFinder() LoggerFinder} to
>      *         obtain a logger. Note that doing the latter
>      *         may eagerly initialize the underlying logging
>      *         system.

Thanks Brent. What about deleting *the caller should either* and
adding ...to obtain a logger *instead*:

      * @throws IllegalCallerException if there is no {@linkplain
      *         StackWalker#getCallerClass() caller} frame, i.e. this method
      *         is called from JNI and there is no Java frame on the 
stack.<br>
      *         Note: To obtain a logger in such a context, use an auxiliary
      *         class that will implicitly be identified as the caller, 
or use
      *         the system {@link LoggerFinder#getLoggerFinder() 
LoggerFinder}
      *         to obtain a logger instead. Note however that doing the 
latter
      *         may force the eager initialization of the underlying logging
      *         system.


best regards,

-- daniel

>
> Thanks,
> -Brent
>
> On 3/21/17 5:44 AM, Daniel Fuchs wrote:
>> Hi,
>>
>> Please find below an updated patch for:
>>
>> 8177136: Caller sensitive method System.getLogger should  specify
>>          what happens if there is no caller on the stack.
>> https://bugs.openjdk.java.net/browse/JDK-8177136
>>
>> webrev:
>> http://cr.openjdk.java.net/~dfuchs/webrev_8177136/webrev.01
>>
>> System.getLogger(name) and System.getLogger(name, resourceBundle)
>> are specified to call LoggerFinder to obtain a logger, which requires
>> the module of the caller class.
>> When there is no java frame on the stack, then the caller information
>> cannot be obtained and there is not enough context to know which module
>> would be appropriate.
>> The proposal is to throw IllegalCallerException - which is the exception
>> that StackWalker::getCallerClass will throw if called by
>> System::getLogger in this case.
>>
>> This RFR follows the discussion started here:
>> http://mail.openjdk.java.net/pipermail/core-libs-dev/2017-March/046868.html
>>
>>
>> best regards,
>>
>> -- daniel