corda/experimental/quasar-hook

What is this?

This is a javaagent that may be used while running applications using quasar. It hooks into quasar to track what methods are scanned, instrumented and used at runtime, and generates an exclude pattern that may be passed in to quasar to stop it from scanning classes unnecessarily.

Arguments

expand, alwaysExcluded and truncate tweak the output exclude pattern. expand is a list of packages to always expand (for example instead of generating com.* generate com.google.*,com.typesafe.* etc.), alwaysExcluded is a list of packages under which all classes are considered excluded irregardless of instrumentation, truncate is a list of packages that should not be included in the exclude pattern. Truncating net.corda means nothing should be excluded from instrumentation in Corda.

How to generate an exclude pattern for Corda

In order to generate a good exclude pattern we need to exercise the Corda code so that most classes get loaded and inspected by quasar and quasar-hook. For this we can run tests using the 'Quasar exclude pattern extraction (...)' intellij run configuration, which includes the hook. In addition we should run the tool on a bare corda.jar, as some additional classes are used when the jar is invoked directly. To do this we'll use a node in samples:

./gradlew experimental:quasar-hook:jar
./gradlew samples:irs-demo:deployNodes
cd samples/irs-demo/build/nodes/NotaryService
java -javaagent:../../../../../experimental/quasar-hook/build/libs/quasar-hook.jar=expand=com,de,org,co,io;truncate=net.corda;alwaysExcluded=com.opengamma,io.atomix -jar corda.jar

Once the node is started just exit the node.

We can take the union of the two generated exclude patterns to get a final one.