[issue-39] add logging output to file (#53)

3 files changed, 72 insertions, 19 deletions

diff --git a/core/src/main/scala/mill/Main.scala b/core/src/main/scala/mill/Main.scala
index df9e0dc6..afc59e33 100644
--- a/core/src/main/scala/mill/Main.scala
+++ b/core/src/main/scala/mill/Main.scala
@@ -93,7 +93,7 @@ object Main {
         case _ => Nil
       }
       target <- mill.main.Resolve.resolve(sel, disc.mirror, obj, rest, crossSelectors, Nil)
-      evaluator = new Evaluator(pwd / 'out, Discovered.mapping(obj)(disc), log)
+      evaluator = new Evaluator(pwd / 'out, Discovered.mapping(obj)(disc), log, sel)
       _ <- evaluate(evaluator, target, watch).toLeft(())
     } yield ()
 
diff --git a/core/src/main/scala/mill/eval/Evaluator.scala b/core/src/main/scala/mill/eval/Evaluator.scala
index 96c868e9..b4f4413f 100644
--- a/core/src/main/scala/mill/eval/Evaluator.scala
+++ b/core/src/main/scala/mill/eval/Evaluator.scala
@@ -1,12 +1,11 @@
 package mill.eval
 
-import java.io.PrintStream
-
 import ammonite.ops._
 import ammonite.runtime.SpecialClassLoader
 import mill.define.{Graph, Target, Task}
 import mill.discover.Mirror
 import mill.discover.Mirror.LabelledTarget
+import mill.discover.Mirror.Segment.{Cross, Label}
 import mill.util
 import mill.util._
 
@@ -14,7 +13,8 @@ import scala.collection.mutable
 
 class Evaluator(workspacePath: Path,
                 labeling: Map[Target[_], LabelledTarget[_]],
-                log: Logger){
+                log: Logger,
+                sel: List[Mirror.Segment] = List()){
 
   def evaluate(goals: OSet[Task[_]]): Evaluator.Results = {
     mkdir(workspacePath)
@@ -155,6 +155,8 @@ class Evaluator(workspacePath: Path,
       if(logRun) { log.info("Running " + targetLabel) }
     }
 
+    val multiLogger = resolveLogger(targetDestPath)
+
     for (target <- nonEvaluatedTargets) {
 
       newEvaluated.append(target)
@@ -168,15 +170,16 @@ class Evaluator(workspacePath: Path,
           val args = new Ctx(
             targetInputValues.toArray[Any],
             targetDestPath.orNull,
-            log
+            multiLogger
           )
+
           val out = System.out
           val err = System.err
           try{
-            System.setErr(log.outputStream)
-            System.setOut(log.outputStream)
-            Console.withOut(log.outputStream){
-              Console.withErr(log.outputStream){
+            System.setErr(multiLogger.outputStream)
+            System.setOut(multiLogger.outputStream)
+            Console.withOut(multiLogger.outputStream){
+              Console.withErr(multiLogger.outputStream){
                 target.evaluate(args)
               }
             }
@@ -189,9 +192,29 @@ class Evaluator(workspacePath: Path,
       newResults(target) = res
     }
 
+    multiLogger.close()
+
     (newResults, newEvaluated)
   }
 
+  def resolveLogger(targetDestPath: Option[Path]): Logger = {
+    if (targetDestPath.isEmpty && sel.isEmpty)
+      log
+    else {
+      val path = targetDestPath.getOrElse(
+        sel.foldLeft[Path](pwd / 'out) {
+          case (d, Label(s)) => d / s
+          case (d, Cross(args)) => d / args.map(_.toString)
+        }
+      )
+      val dir = path / up
+      mkdir(dir)
+      val file = dir / (path.last + ".log")
+      rm(file)
+      MultiLogger(log, FileLogger(file))
+    }
+  }
+
 }
 
 
diff --git a/core/src/main/scala/mill/util/Logger.scala b/core/src/main/scala/mill/util/Logger.scala
index ba8aa95f..d988c1fc 100644
--- a/core/src/main/scala/mill/util/Logger.scala
+++ b/core/src/main/scala/mill/util/Logger.scala
@@ -1,29 +1,59 @@
 package mill.util
 
-import java.io.{OutputStream, PrintStream}
+import java.io.{FileOutputStream, PrintStream}
 
+import ammonite.ops.Path
 import ammonite.util.Colors
 
 
-trait Logger{
+trait Logger {
   val outputStream: PrintStream
   def info(s: String): Unit
   def error(s: String): Unit
+  def close(): Unit = ()
 }
 
-object DummyLogger extends Logger{
-  object outputStream extends PrintStream(new OutputStream {
-    def write(b: Int) = ()
-  })
+object DummyLogger extends Logger {
+  object outputStream extends PrintStream(_ => ())
   def info(s: String) = ()
   def error(s: String) = ()
 }
-class PrintLogger(coloredOutput: Boolean) extends Logger{
-  val outputStream = System.err
+
+case class PrintLogger(coloredOutput: Boolean) extends Logger {
+  val outputStream: PrintStream = System.err
+
   val colors =
     if(coloredOutput) Colors.Default
     else Colors.BlackWhite
 
-  def info(s: String) = System.err.println(colors.info()(s))
-  def error(s: String) = System.err.println(colors.error()(s))
+  def info(s: String) = outputStream.println(colors.info()(s))
+  def error(s: String) = outputStream.println(colors.error()(s))
+}
+
+case class FileLogger(file: Path) extends Logger {
+  private[this] var outputStreamUsed: Boolean = false
+
+  lazy val outputStream = {
+    outputStreamUsed = true
+    new PrintStream(new FileOutputStream(file.toIO.getAbsolutePath))
+  }
+
+  def info(s: String) = outputStream.println(s)
+  def error(s: String) = outputStream.println(s)
+  override def close() = {
+    if (outputStreamUsed)
+      outputStream.close()
+  }
+}
+
+case class MultiLogger(streams: Logger*) extends Logger {
+  lazy val outputStream: PrintStream =
+    new PrintStream(b => streams.foreach(_.outputStream.write(b))) {
+      override def flush() = streams.foreach(_.outputStream.flush())
+      override def close() = streams.foreach(_.outputStream.close())
+    }
+
+  def info(s: String) = streams.foreach(_.info(s))
+  def error(s: String) = streams.foreach(_.error(s))
+  override def close() = streams.foreach(_.close())
 }
\ No newline at end of file