aspectj dependency scope [was: version update to 1.8.x]

[Andrei-Pozolotin]

kamon depends on aspect version 1.7.4 which seems abandoned
http://search.maven.org/#search%7Cgav%7C1%7Cg%3A%22org.aspectj%22%20AND%20a%3A%22aspectjweaver%22

while 1.8.x is in development; would it be appropriate to do aspectj version update to 1.8.x ?

[ivantopo]

Hello Andrei, as of 290a3c9 we moved to AspectJ 1.8.1 and probably will take it to 1.8.4 that was released a few hours ago. In practice we never found any problem in using the 1.8.1 weaver with previous versions of Kamon, but the upgrade is there anyway, our next release will come with the upgraded versions. Also, note that we no longer have a compile dependency on the weaver, just on aspectjrt.

[Andrei-Pozolotin]

Ivan:

1. re: "next release will come with the upgraded versions"

• great, thank you

2. re: "no longer have a compile dependency on the weaver, just on aspectjrt"

• it still seems like a mistake. I mean, from reading the following
  https://github.com/eclipse/org.aspectj/tree/master/build
  it looks like, in terms of classes included in the jar content:

aspectjrt.jar < [is part of] < aspectjweaver.jar < [is part of] < aspectjtools.jar

and since aspectjweaver is provided to the system class loader as an agent,
then additional dependency to aspectjrt will lead to class duplication
and class loader conflicts

I verified that when I remove aspectjrt form the class path
and when jvm is started with -javaagent:aspectjweaver.jar
or when aspectjweaver is loaded via jvm attach api,
kamon still works fine.

so the kamon-core dependency should be either to aspectjrt or to aspectjweaver,
but only in scope=provided (or as a not-transitive dependency).

I would prefer aspectjweaver, to have people think
only about single artifact they must provide on class path,
eliminate confusion aspectjrt vs aspectjweaver as well as version mismatch.

this affects both sbt and maven

pom.xml should look like

        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <scope>provided</scope>
        </dependency>

[ivantopo]

@Andrei-Pozolotin thanks a lot for the detailed explanation, totally agree with the proposal and made the changes already!

[Andrei-Pozolotin]

thank you.