util-eval: Reset reporter between checks

Problem

When you want to use the util-eval for validating the correctness of a small
chunk of code, you have to reset whole state between invocations (flag
resetState=true), which is expensive when you already have a bunch of compiled
and loaded classes. Without this, if one check fails, all subsequent checks
will fail as well, since some errors has been reported previously.

Solution

Scala compiler API allows for resetting just the reporter, so that compiled and
loaded classes can remain for re-usage for next checks.

Result

Public API remains the same, however the internal API has one new synchronized
method resetReporter() which does what is explained in the "Solution" section.

Signed-off-by: Ryan O'Neill <ryano@twitter.com>

RB_ID=859878

1 files changed, 11 insertions, 0 deletions

diff --git a/libraries/eval/Eval.scala b/libraries/eval/Eval.scala
index 92329d3..abd1836 100644
--- a/libraries/eval/Eval.scala
+++ b/libraries/eval/Eval.scala
@@ -242,6 +242,7 @@ class Eval(target: Option[File]) {
     val id = uniqueId(sourceForString(code))
     val className = "Evaluator__" + id
     val wrappedCode = wrapCodeInClass(className, code)
+    resetReporter()
     compile(wrappedCode) // may throw CompilerException
   }
 
@@ -266,6 +267,10 @@ class Eval(target: Option[File]) {
     compiler.findClass(className).getOrElse { throw new ClassNotFoundException("no such class: " + className) }
   }
 
+  private[util] def resetReporter(): Unit = {
+    compiler.resetReporter()
+  }
+
   private[util] def uniqueId(code: String, idOpt: Option[Int] = Some(jvmId)): String = {
     val digest = MessageDigest.getInstance("SHA-1").digest(code.getBytes())
     val sha = new BigInteger(1, digest).toString(16)
@@ -533,6 +538,12 @@ class Eval(target: Option[File]) {
       classLoader = new AbstractFileClassLoader(target, this.getClass.getClassLoader)
     }
 
+    def resetReporter(): Unit = {
+      synchronized {
+        reporter.reset()
+      }
+    }
+
     object Debug {
       val enabled =
         System.getProperty("eval.debug") != null