TOMEE-4662 - Speed up annotation processing during WAR deploy

[tandraschko]

Speed up annotation processing during WAR deploy

OpenEJBContextConfig.isIncluded() resolves the canonical path of the module
roots and of the web resource on every call, and Tomcat calls
processAnnotationsWebResource() once per web resource. On a WAR with a few
hundred classes under WEB-INF/classes that is thousands of filesystem
syscalls, most of them resolving the same handful of paths again and again.
Three changes, no behaviour change:

• Memoise File.getCanonicalFile() and the URL to File conversion. Both
  mappings are stable for the lifetime of a deploy and the config instance is
  per context.
• Return early from processAnnotationsWebResource() once every module has
  been processed. There is nothing left to match the resource against, and that
  branch never delegates to super, so resolving the resource is wasted work.
• Reuse the path from FileResource.getCanonicalPath() instead of letting
  isIncluded() resolve the same, already canonical, path a second time.
  Measured on a synthetic WAR (40 jars, 513 classes in WEB-INF/classes) with
  tomee-embedded: isIncluded() accounted for 165 of 468 deploy-phase profiler
  samples before the change and 1 after, and deploy wall time dropped ~25%.
  Note this was measured on Windows, where getCanonicalPath() is considerably
  more expensive than on Linux, so expect a smaller gain there.

Also see apache/tomcat#1030

[jungm]

https://ci-builds.apache.org/job/Tomee/view/tomee-11.x/job/pull-request-manual-with-tck/52/

[jungm]

Nice speedup, logic checks out. Two changes I'd make before merge:

1. Use ConcurrentHashMap for both caches. With parallelAnnotationScanning="true", Tomcat runs processAnnotationsUrl on multiple utility-executor threads, which reaches the maps via internalProcessAnnotations → isIncludedIn. Concurrent puts into a plain HashMap can lose entries or corrupt the table.

2. Clear both maps in configureStop(), like webInfClassesAnnotationsProcessed. The listener survives context stop/start, so after a reload canonicalFiles can hold stale resolutions (symlinks/paths may have changed), and both maps otherwise retain ~one entry per class file for the life of the context.

Also: please file a TOMEE JIRA and reference it in the title/commit, per project convention.

[tandraschko]

both done: https://issues.apache.org/jira/browse/TOMEE-4662