https://www.baeldung.com/lombok-custom-annotation seems to imply that we could add this support by extending Lombok.
Ralph > On Jul 10, 2022, at 1:58 PM, Ralph Goers <ralph.go...@dslextreme.com> wrote: > > Because I don’t see how it can work. > > A ThreadLocal is a run time construct. If you are saving location information > in > a ThreadLocal then it is only good for the life of the request and/or thread. > But > the location information will never change. It is fixed even before the Class > is loaded. > So I simply don’t see the point of using a ThreadLocal. > > Furthermore, I am ONLY interested in injecting location information at > compile > time. That means there will always be zero run time cost. Using an agent or > some > other technique requires modifying the class as it is loaded or other runtime > manipulations. > > I’ve looked at the HandleLog method in Lombok. It actually isn’t very > complicated. > It uses JCTree and the util package from javac and adds the logger field > directly > to the class the compiler is constructing. From what I can tell it should > also be > possible to scan the source and modify the appropriate lines in the same way, > but it would require a POC. > > Ralph > >> On Jul 10, 2022, at 1:09 PM, Volkan Yazıcı <vol...@yazi.ci> wrote: >> >> Why do you prefer `withLocation()` compared to the thread-local approach? >> >> On Sun, Jul 10, 2022 at 9:55 PM Ralph Goers <ralph.go...@dslextreme.com> >> wrote: >> >>> This is exactly why I believe we should only support LogBuilder as it >>> already >>> has withLocation(). I see no point in adding the parameter to all the >>> non-fluent >>> variations. >>> >>> To work, the location must be passed as a parameter on the logging API >>> call. >>> Thus it won’t work for Log4j 1 or SLF4J. >>> >>> Ralph >>> >>>> On Jul 10, 2022, at 12:47 PM, Volkan Yazıcı <vol...@yazi.ci> wrote: >>>> >>>> Indeed supporting both static and dynamic weaving seems like the ideal >>>> approach. (SPI-Fly is an interesting one. My OSGi illiteracy blocked me >>>> from wrapping my mind around all of its details. Nevertheless, I think I >>>> get the gist of it.) For both functionalities, we need to receive a >>> package >>>> list to scan for, right? >>>> >>>> Translating logger calls to the ones that receive the source location >>>> information as arguments is also a valid direction. Though note that this >>>> requires doubling the size of the API surface, AFAIC. That is, for every >>>> `info(String)`, we need to introduce `info(String, SourceLocation)`, etc. >>>> Hence, I am inclined to go this route unless I am missing something. >>>> >>>> Piotr, what is your take on my claim that this optimization won't work >>> for >>>> bridges (SLF4J, log4j-1.2-api, etc.)? >>>> >>>> On Sat, Jul 9, 2022 at 5:02 PM Piotr P. Karwasz <piotr.karw...@gmail.com >>>> >>>> wrote: >>>> >>>>> Hi Volkan, >>>>> >>>>> On Sat, 9 Jul 2022 at 12:05, Volkan Yazıcı <vol...@yazi.ci> wrote: >>>>>> I think we can extend this experiment to implement zero-cost source >>>>>> location capture for Log4j. Though I will appreciate your help on some >>>>>> loose ends. Assuming we have a bullet-proof mechanism to inline source >>>>>> location capture given a class, what is the right way to ship this? As >>> a >>>>>> Maven plugin that kicks in at compile time? Wouldn't that make this >>>>> feature >>>>>> impossible to use without recompiling user sources? As a runtime >>> utility? >>>>>> If so, what about the cost of classpath scanning & weaving? If the >>>>> bytecode >>>>>> weaving only intercepts at Log4j API calls, this won't work for Log4j 1 >>>>>> bridge, SLF4J, or any other indirect access to the Log4j API. What do >>> you >>>>>> think? I have used a thread-local to pass the source location to the >>>>>> caller, is there a better alternative? (Putting aside the >>> dynamic-scoped >>>>>> variables to be shipped with Loom.) >>>>> >>>>> Great idea. I think that we can provide both a static and dynamic >>>>> weaver from the same code (cf. SPI-Fly: >>>>> https://github.com/apache/aries/tree/trunk/spi-fly). Developers would >>>>> be advised to statically weave their artifacts, while system >>>>> administrators could do it during runtime. >>>>> >>>>> The usage of a `ThreadLocal` seems Ok to me. Alternatively we could >>>>> add some parameters to the `Logger.log` calls, but this would mean 4 >>>>> additional parameters on each simple call and we'll end up using the >>>>> `Logger.log` method with an Object array. >>>>> >>>>> Piotr >>>>> >>> >>> >
