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 >
