A few attempts at micro-optimizing the current hot spots

5 files changed, 45 insertions, 25 deletions

diff --git a/main/src/mill/main/MainRunner.scala b/main/src/mill/main/MainRunner.scala
index a4a54df8..4205b6dc 100644
--- a/main/src/mill/main/MainRunner.scala
+++ b/main/src/mill/main/MainRunner.scala
@@ -1,13 +1,15 @@
 package mill.main
 import java.io.{InputStream, OutputStream, PrintStream}
 
+import ammonite.Main
 import ammonite.interp.{Interpreter, Preprocessor}
 import ammonite.ops.Path
 import ammonite.util._
 import mill.eval.{Evaluator, PathRef}
-
 import mill.util.PrintLogger
 
+import scala.annotation.tailrec
+
 
 /**
   * Customized version of [[ammonite.MainRunner]], allowing us to run Mill
@@ -35,8 +37,27 @@ class MainRunner(val config: ammonite.main.Cli.Config,
     while(statAll()) Thread.sleep(100)
   }
 
+  /**
+    * Custom version of [[watchLoop]] that lets us generate the watched-file
+    * signature only on demand, so if we don't have config.watch enabled we do
+    * not pay the cost of generating it
+    */
+  @tailrec final def watchLoop2[T](isRepl: Boolean,
+                                   printing: Boolean,
+                                   run: Main => (Res[T], () => Seq[(Path, Long)])): Boolean = {
+    val (result, watched) = run(initMain(isRepl))
+
+    val success = handleWatchRes(result, printing)
+    if (!config.watch) success
+    else{
+      watchAndWait(watched())
+      watchLoop2(isRepl, printing, run)
+    }
+  }
+
+
   override def runScript(scriptPath: Path, scriptArgs: List[String]) =
-    watchLoop(
+    watchLoop2(
       isRepl = false,
       printing = true,
       mainCfg => {
@@ -58,12 +79,22 @@ class MainRunner(val config: ammonite.main.Cli.Config,
 
         result match{
           case Res.Success(data) =>
-            val (eval, evaluationWatches, res) = data
+            val (eval, evalWatches, res) = data
 
             stateCache = Some(Evaluator.State(eval.rootModule, eval.classLoaderSig, eval.workerCache, interpWatched))
-
-            (Res(res), interpWatched ++ evaluationWatches)
-          case _ => (result, interpWatched)
+            val watched = () => {
+              val alreadyStale = evalWatches.exists(p => p.sig != PathRef(p.path, p.quick).sig)
+              // If the file changed between the creation of the original
+              // `PathRef` and the current moment, use random junk .sig values
+              // to force an immediate re-run. Otherwise calculate the
+              // pathSignatures the same way Ammonite would and hand over the
+              // values, so Ammonite can watch them and only re-run if they
+              // subsequently change
+              if (alreadyStale) evalWatches.map(_.path -> util.Random.nextLong())
+              else evalWatches.map(p => p.path -> Interpreter.pathSignature(p.path))
+            }
+            (Res(res), () => interpWatched ++ watched())
+          case _ => (result, () => interpWatched)
         }
       }
     )
@@ -104,7 +135,7 @@ class MainRunner(val config: ammonite.main.Cli.Config,
          |  // doesn't get picked up during reflective child-module discovery
          |  def millSelf = Some(this)
          |
-         |  implicit def millDiscover: mill.define.Discover[this.type] = mill.define.Discover[this.type]
+         |  implicit lazy val millDiscover: mill.define.Discover[this.type] = mill.define.Discover[this.type]
          |}
          |
          |sealed trait $wrapName extends mill.main.MainModule{
diff --git a/main/src/mill/main/RunScript.scala b/main/src/mill/main/RunScript.scala
index 85930e9b..553f5b69 100644
--- a/main/src/mill/main/RunScript.scala
+++ b/main/src/mill/main/RunScript.scala
@@ -29,7 +29,7 @@ object RunScript{
                 scriptArgs: Seq[String],
                 stateCache: Option[Evaluator.State],
                 log: Logger)
-  : (Res[(Evaluator[Any], Seq[(Path, Long)], Either[String, Seq[Js.Value]])], Seq[(Path, Long)]) = {
+  : (Res[(Evaluator[Any], Seq[PathRef], Either[String, Seq[Js.Value]])], Seq[(Path, Long)]) = {
 
     val (evalState, interpWatched) = stateCache match{
       case Some(s) if watchedSigUnchanged(s.watched) => Res.Success(s) -> s.watched
@@ -58,18 +58,7 @@ object RunScript{
       evaluator <- evalRes
       (evalWatches, res) <- Res(evaluateTasks(evaluator, scriptArgs, multiSelect = false))
     } yield {
-      val alreadyStale = evalWatches.exists(p => p.sig != PathRef(p.path, p.quick).sig)
-      // If the file changed between the creation of the original
-      // `PathRef` and the current moment, use random junk .sig values
-      // to force an immediate re-run. Otherwise calculate the
-      // pathSignatures the same way Ammonite would and hand over the
-      // values, so Ammonite can watch them and only re-run if they
-      // subsequently change
-      val evaluationWatches =
-        if (alreadyStale) evalWatches.map(_.path -> util.Random.nextLong())
-        else evalWatches.map(p => p.path -> Interpreter.pathSignature(p.path))
-
-      (evaluator, evaluationWatches, res.map(_.flatMap(_._2)))
+      (evaluator, evalWatches, res.map(_.flatMap(_._2)))
     }
     (evaluated, interpWatched)
   }
diff --git a/main/test/src/mill/eval/ModuleTests.scala b/main/test/src/mill/eval/ModuleTests.scala
index d2fa7184..f089a251 100644
--- a/main/test/src/mill/eval/ModuleTests.scala
+++ b/main/test/src/mill/eval/ModuleTests.scala
@@ -13,7 +13,7 @@ object ModuleTests extends TestSuite{
     object inner extends mill.Module{
       def y = T{17}
     }
-    def millDiscover = Discover[this.type]
+    lazy val millDiscover = Discover[this.type]
   }
   object Build extends TestUtil.BaseModule{
     def z = T{ ExternalModule.x() + ExternalModule.inner.y() }
@@ -36,7 +36,7 @@ object ModuleTests extends TestSuite{
       object Build extends mill.define.ExternalModule {
 
         def z = T{ ExternalModule.x() + ExternalModule.inner.y() }
-        def millDiscover = Discover[this.type]
+        lazy val millDiscover = Discover[this.type]
       }
 
       intercept[java.lang.AssertionError]{ Build }
diff --git a/main/test/src/mill/util/TestGraphs.scala b/main/test/src/mill/util/TestGraphs.scala
index 750ef015..11f72d02 100644
--- a/main/test/src/mill/util/TestGraphs.scala
+++ b/main/test/src/mill/util/TestGraphs.scala
@@ -180,7 +180,7 @@ object TestGraphs{
   object canOverrideSuper extends TestUtil.BaseModule with BaseModule {
     override def foo = T{ super.foo() ++ Seq("object") }
     override def cmd(i: Int) = T.command{ super.cmd(i)() ++ Seq("object" + i) }
-    def millDiscover: Discover[this.type] = Discover[this.type]
+    override lazy val millDiscover: Discover[this.type] = Discover[this.type]
   }
 
   trait TraitWithModule extends Module{ outer =>
@@ -193,7 +193,7 @@ object TestGraphs{
 
   // Make sure nested objects inherited from traits work
   object TraitWithModuleObject extends TestUtil.BaseModule with TraitWithModule{
-    def millDiscover: Discover[this.type] = Discover[this.type]
+    override lazy val millDiscover: Discover[this.type] = Discover[this.type]
   }
 
 
diff --git a/main/test/src/mill/util/TestUtil.scala b/main/test/src/mill/util/TestUtil.scala
index b30d5d51..d06c7f6a 100644
--- a/main/test/src/mill/util/TestUtil.scala
+++ b/main/test/src/mill/util/TestUtil.scala
@@ -32,7 +32,7 @@ object TestUtil {
                    millName0: sourcecode.Name,
                    overrides: Overrides)
     extends mill.define.BaseModule(getSrcPathBase() / millModuleEnclosing0.value.split("\\.| |#")){
-    def millDiscover: Discover[this.type] = Discover[this.type]
+    lazy val millDiscover: Discover[this.type] = Discover[this.type]
   }
 
   object test{