call close() on compiler in scalacWorker after each job (#1504)

* call close() on compiler in scalacworker

Author: crt-31

src/java/io/bazel/rulesscala/scalac/ReportableMainClass.java

@@ -11,15 +11,28 @@
 import scala.tools.nsc.MainClass;
 import scala.tools.nsc.Settings;
 import scala.tools.nsc.reporters.Reporter;
+import java.lang.AutoCloseable;
 
 public class ReportableMainClass extends MainClass {
   private Reporter reporter;
   private final CompileOptions ops;
+  private Global compiler = null;
 
   public ReportableMainClass(CompileOptions ops) {
     this.ops = ops;
   }
 
+  public void close() throws Exception{
+    if(compiler != null){
+
+      //nsc.Global didn't inherit from Closeable until 2.12.9.
+      if(compiler instanceof AutoCloseable){
+        ((AutoCloseable)compiler).close();
+      }
+      compiler = null;
+    }
+  }
+
   @Override
   public Global newCompiler() {
     createDiagnosticsFile();
@@ -31,7 +44,8 @@ public Global newCompiler() {
 
     reporter = new DepsTrackingReporter(settings, ops, reporter);
 
-    return new Global(settings, reporter);
+    compiler = new Global(settings, reporter);
+    return compiler;
   }
 
   private void createDiagnosticsFile() {

src/java/io/bazel/rulesscala/scalac/ScalacWorker.java

@@ -258,7 +258,7 @@ private static boolean isMacroException(Throwable ex) {
   }
 
   private static void compileScalaSources(CompileOptions ops, String[] scalaSources, Path classes)
-      throws IOException {
+      throws IOException, Exception {
 
     String[] pluginArgs = buildPluginArgs(ops.plugins);
     String[] pluginParams = getPluginParamsFrom(ops);
@@ -285,7 +285,11 @@ private static void compileScalaSources(CompileOptions ops, String[] scalaSource
       } else {
         throw ex;
       }
+    }finally {
+      comp.close();
     }
+
+
     long stop = System.currentTimeMillis();
     if (ops.printCompileTime) {
       System.err.println("Compiler runtime: " + (stop - start) + "ms.");