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

[David Holmes]

On 22/03/2017 10:09 AM, David Holmes wrote:
> Hi Daniel,
>
> On 22/03/2017 4:41 AM, Daniel Fuchs wrote:
>> Hi Brent,
>>
>> Here is an updated webrev that incorporates your feedback:
>>
>> http://cr.openjdk.java.net/~dfuchs/webrev_8177136/webrev.02
>
> You could move all the detail to the @implSpec method as a clarification

@implSpec section

David

> on the use of the caller e.g.:
>
>      * @implSpec
>      * Instances returned by this method route messages to loggers
>      * obtained by calling {@link LoggerFinder#getLogger(java.lang.String,
>      * java.lang.reflect.Module) LoggerFinder.getLogger(name, module)},
> where
>      * {@code module} is the caller's module. In cases where there is
>      * no Java caller on the stack (e.g when called directly from a JNI
>      * attached thread) an IllegalCallerException is thrown. To obtain
>      * a logger in such a context ...
>
> then just:
>
>    * @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.
>
> Up to you.
>
> Thanks,
> David
>
>> Thanks!
>>
>> -- daniel
>>
>> 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
>>>
>>> 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
>>