Cleanup logger (#4653)

A step towards #3603. For now
just doing relatively shallow cleanups, but hopefully that paves the way
to bigger refactorings


The main external-facing change is renaming
`inStream`/`outputStream`/`errorStream` to `streams.in`/`out`/`err`,
though the internal refactorings are more substantial

bsp/src/mill/bsp/BSP.scala

@@ -50,9 +50,9 @@ object BSP extends ExternalModule with CoursierModule {
    */
   def startSession(allBootstrapEvaluators: Evaluator.AllBootstrapEvaluators)
       : Command[BspServerResult] = Task.Command(exclusive = true) {
-    Task.log.errorStream.println("BSP/startSession: Starting BSP session")
+    Task.log.streams.err.println("BSP/startSession: Starting BSP session")
     val res = BspContext.bspServerHandle.runSession(allBootstrapEvaluators.value)
-    Task.log.errorStream.println(s"BSP/startSession: Finished BSP session, result: ${res}")
+    Task.log.streams.err.println(s"BSP/startSession: Finished BSP session, result: ${res}")
     res
   }
 

bsp/src/mill/bsp/BspContext.scala

@@ -24,7 +24,7 @@ private[mill] class BspContext(
   BspContext.bspServerHandle =
     try {
       startBspServer(
-        streams = streams,
+        streams0 = streams,
         logStream = bspLogStream,
         canReload = true
       ).get
@@ -37,27 +37,26 @@ private[mill] class BspContext(
   streams.err.println("BSP server started")
 
   def startBspServer(
-      streams: SystemStreams,
+      streams0: SystemStreams,
       logStream: Option[PrintStream],
       canReload: Boolean
   ): Result[BspServerHandle] = {
     val log: Logger = new Logger {
       override def colored: Boolean = false
-      override def systemStreams: SystemStreams = new SystemStreams(
-        out = streams.out,
-        err = streams.err,
+      override def streams: SystemStreams = new SystemStreams(
+        out = streams0.out,
+        err = streams0.err,
         in = DummyInputStream
       )
+      def prompt = new Logger.Prompt.NoOp {
+        override def setPromptDetail(key: Seq[String], s: String): Unit = streams.err.println(s)
+      }
 
       override def info(s: String): Unit = streams.err.println(s)
       override def error(s: String): Unit = streams.err.println(s)
       override def ticker(s: String): Unit = streams.err.println(s)
-      override def setPromptDetail(key: Seq[String], s: String): Unit = streams.err.println(s)
-      override def debug(s: String): Unit = streams.err.println(s)
-
-      override def debugEnabled: Boolean = true
 
-      override def rawOutputStream: PrintStream = systemStreams.out
+      override def debug(s: String): Unit = streams.err.println(s)
     }
 
     BspWorker(mill.api.WorkspaceRoot.workspaceRoot, home, log).flatMap { worker =>

bsp/worker/src/mill/bsp/worker/MillBspLogger.scala

@@ -1,7 +1,7 @@
 package mill.bsp.worker
 
 import ch.epfl.scala.bsp4j._
-import mill.api.{ColorLogger, Logger}
+import mill.api.{Logger}
 import mill.internal.ProxyLogger
 
 /**
@@ -19,7 +19,7 @@ import mill.internal.ProxyLogger
  */
 private class MillBspLogger(client: BuildClient, taskId: Int, logger: Logger)
     extends ProxyLogger(logger)
-    with ColorLogger {
+    with Logger {
   override def infoColor = fansi.Color.Blue
   override def errorColor = fansi.Color.Red
 

bsp/worker/src/mill/bsp/worker/MillBuildServer.scala

@@ -4,7 +4,7 @@ import ch.epfl.scala.bsp4j
 import ch.epfl.scala.bsp4j.*
 import com.google.gson.JsonObject
 import mill.api.ExecResult
-import mill.api.{ColorLogger, CompileProblemReporter, DummyTestReporter, Result, TestReporter}
+import mill.api.{Logger, CompileProblemReporter, DummyTestReporter, Result, TestReporter}
 import mill.bsp.{BspServerResult, Constants}
 import mill.bsp.worker.Utils.{makeBuildTarget, outputPaths, sanitizeUri}
 import mill.define.Segment.Label
@@ -801,7 +801,7 @@ private class MillBuildServer(
       goals: Seq[Task[?]],
       reporter: Int => Option[CompileProblemReporter] = _ => Option.empty[CompileProblemReporter],
       testReporter: TestReporter = DummyTestReporter,
-      logger: ColorLogger = null
+      logger: Logger = null
   ): ExecutionResults = {
     val logger0 = Option(logger).getOrElse(evaluator.baseLogger)
     mill.runner.MillMain.withOutLock(
@@ -812,7 +812,7 @@ private class MillBuildServer(
         case n: NamedTask[_] => n.label
         case t => t.toString
       },
-      streams = logger0.systemStreams
+      streams = logger0.streams
     ) {
       evaluator.execute(
         goals,

ci/mill-bootstrap.patch

@@ -1,5 +1,5 @@
 diff --git a/build.mill b/build.mill
-index 5c48e1e4e43..538e4b86e0c 100644
+index 42be8622781..ecb84c31089 100644
 --- a/build.mill
 +++ b/build.mill
 @@ -1,16 +1,16 @@
@@ -189,7 +189,7 @@ index e49f218f4be..9d03aa073f3 100644
        def ivyDeps = Task {
          if (!caseName.contains("realistic") && !caseName.contains("sourcecode")) super.ivyDeps()
 diff --git a/dist/package.mill b/dist/package.mill
-index fbbeacbc843..fb06c486273 100644
+index fbbeacbc843..b3e00f8db5f 100644
 --- a/dist/package.mill
 +++ b/dist/package.mill
 @@ -2,15 +2,14 @@ package build.dist
@@ -210,6 +210,15 @@ index fbbeacbc843..fb06c486273 100644
      case m: PublishModule if (m ne build.dist) && (m ne build.dist.native) => m
    }
    def moduleDeps = Seq(build.runner, build.idea, build.main.init)
+@@ -44,7 +43,7 @@ trait InstallModule extends build.MillPublishJavaModule {
+         (os.home / ".cache/mill/download" / (build.millVersion() + batExt)).toString()
+       )
+     )()
+-    Task.log.outputStream.println(path.toString())
++    Task.log.streams.out.println(path.toString())
+     PathRef(path)
+   }
+
 @@ -185,10 +184,10 @@ object `package` extends RootModule with InstallModule {
          val wd = os.Path(wd0, Task.workspace)
          os.makeDir.all(wd)
@@ -650,7 +659,7 @@ index 3b577e29c65..7f45dcaeab6 100644
    def forkEnv =
      super.forkEnv() ++ Map("MILL_EXECUTABLE_PATH" -> build.dist.launcher().path.toString())
 diff --git a/website/package.mill b/website/package.mill
-index f88dc3fe8f6..eb1916dae76 100644
+index f88dc3fe8f6..2e2d2be3716 100644
 --- a/website/package.mill
 +++ b/website/package.mill
 @@ -26,7 +26,7 @@ object `package` extends RootModule {
@@ -753,3 +762,52 @@ index f88dc3fe8f6..eb1916dae76 100644
    def blogFolder = Task {
      os.copy(blogFolder0().path, Task.dest, mergeFolders = true)
      expandDiagramsInDirectoryAdocFile(Task.dest, mill.main.VisualizeModule.classpath().map(_.path))
+@@ -332,21 +332,21 @@ object `package` extends RootModule {
+
+   def localPages: T[PathRef] = Task {
+     val pages = generatePages(authorMode = true).apply().apply(oldDocSources().map(_.path))
+-    Task.log.outputStream.println(
++    Task.log.streams.out.println(
+       s"You can browse the pages at: ${(pages.path / "index.html").toNIO.toUri()}"
+     )
+     pages
+   }
+   def fastPages: T[PathRef] = Task {
+     val pages = generatePages(authorMode = true).apply().apply(Nil)
+-    Task.log.outputStream.println(
++    Task.log.streams.out.println(
+       s"You can browse the pages at: ${(pages.path / "index.html").toNIO.toUri()}"
+     )
+     pages
+   }
+
+   def generatePages(authorMode: Boolean) = Task.Anon { (extraSources: Seq[os.Path]) =>
+-    Task.log.errorStream.println("Creating Antora playbook ...")
++    Task.log.streams.err.println("Creating Antora playbook ...")
+     // dependency to sources
+     source()
+     val docSite = Task.dest
+@@ -357,7 +357,7 @@ object `package` extends RootModule {
+       data = githubPagesPlaybookText(authorMode).apply().apply(extraSources),
+       createFolders = true
+     )
+-    Task.log.errorStream.println("Running Antora ...")
++    Task.log.streams.err.println("Running Antora ...")
+     runAntora(
+       npmDir = npmBase(),
+       workDir = docSite,
+@@ -373,12 +373,12 @@ object `package` extends RootModule {
+     os.write(siteDir / ".nojekyll", "")
+
+     // sanitize devAntora source URLs
+-    Task.log.errorStream.println("Sanitizing links ...")
++    Task.log.streams.err.println("Sanitizing links ...")
+     sanitizeDevUrls(siteDir, devAntoraSources().path, build.baseDir / "docs", build.baseDir)
+
+     // only copy the "api" sub-dir; api docs contains a top-level index.html with we don't want
+     val unidocSrc = if (authorMode) site.unidocLocal().path else site.unidocSite().path
+-    Task.log.errorStream.println(s"Copying API docs from ${unidocSrc} ...")
++    Task.log.streams.err.println(s"Copying API docs from ${unidocSrc} ...")
+     os.copy(unidocSrc, siteDir / "api/latest", createFolders = true)
+
+     PathRef(siteDir)

contrib/flyway/src/mill/contrib/flyway/FlywayModule.scala

@@ -74,7 +74,7 @@ trait FlywayModule extends JavaModule {
     val out =
       s"""Schema version: ${currentSchemaVersion}
          |${MigrationInfoDumper.dumpToAsciiTable(info.all)}""".stripMargin
-    Task.log.outputStream.println(out)
+    Task.log.streams.out.println(out)
     out
   }
 }

core/api/src/mill/api/Logger.scala

@@ -1,6 +1,6 @@
 package mill.api
 
-import java.io.{InputStream, PrintStream}
+import java.io.PrintStream
 
 /**
  * The standard logging interface of the Mill build tool.
@@ -24,66 +24,73 @@ import java.io.{InputStream, PrintStream}
  * but when `show` is used both are forwarded to stderr and stdout is only
  * used to display the final `show` output for easy piping.
  */
-trait Logger extends AutoCloseable {
+trait Logger {
   def infoColor: fansi.Attrs = fansi.Attrs.Empty
   def errorColor: fansi.Attrs = fansi.Attrs.Empty
   def colored: Boolean
 
-  private[mill] def unprefixedSystemStreams: SystemStreams = systemStreams
-  def systemStreams: SystemStreams
-
-  def errorStream: PrintStream = systemStreams.err
-  def outputStream: PrintStream = systemStreams.out
-
-  /**
-   * [[rawOutputStream]] is intended to be a version of [[outputStream]]
-   * without decoration: colors, prefixes, timestamps, etc. It is intended
-   * for the use of tasks like `show` which output data in a way that is
-   * easily readable by downstream programs.
-   */
-  def rawOutputStream: PrintStream = systemStreams.out
-  def inStream: InputStream = systemStreams.in
+  private[mill] def unprefixedStreams: SystemStreams = streams
+  def streams: SystemStreams
 
   def info(s: String): Unit
   def debug(s: String): Unit
   def error(s: String): Unit
   def ticker(s: String): Unit
 
-  private[mill] def setPromptDetail(key: Seq[String], s: String): Unit = ticker(s)
-  private[mill] def reportKey(key: Seq[String]): Unit = ()
-  private[mill] def setPromptLine(
-      key: Seq[String],
-      verboseKeySuffix: String,
-      message: String
-  ): Unit =
-    ticker(s"${key.mkString("-")} $message")
-  private[mill] def setPromptLine(): Unit = ()
-  private[mill] def setPromptHeaderPrefix(s: String): Unit = ()
-  private[mill] def clearPromptStatuses(): Unit = ()
-  private[mill] def removePromptLine(key: Seq[String]): Unit = ()
-  private[mill] def removePromptLine(): Unit = ()
-  private[mill] def withPromptPaused[T](t: => T): T = t
-  private[mill] def withPromptUnpaused[T](t: => T): T = t
-
-  /**
-   * @since Mill 0.10.5
-   */
-  // We only default-implement it to keep binary compatibility in 0.10.x
-  def debugEnabled: Boolean = false
-
-  def close(): Unit = ()
+  private[mill] def prompt: Logger.Prompt
 
-  def enableTicker: Boolean = false
-
-  private[mill] def subLogger(path: os.Path, verboseKeySuffix: String, message: String): Logger =
+  private[mill] def subLogger(path: os.Path, keySuffix: String, message: String): Logger =
     this
 
-  private[mill] def withPrompt[T](t: => T): T = {
-    setPromptLine()
+  private[mill] def withPromptLine[T](t: => T): T = {
+    prompt.setPromptLine(logPrefixKey, keySuffix, message)
     try t
-    finally removePromptLine()
+    finally prompt.removePromptLine(logPrefixKey)
   }
 
   def withOutStream(outStream: PrintStream): Logger = this
+  private[mill] def message: String = ""
+  private[mill] def keySuffix: String = ""
   private[mill] def logPrefixKey: Seq[String] = Nil
+  final def debugEnabled = prompt.debugEnabled
+}
+
+object Logger {
+
+  /**
+   * APIs that allow a logger to interact with the global prompt: setting and unsetting
+   * lines, enabling or disabling the prompt, etc. Normally passed through from logger
+   * to logger unchanged without any customization.
+   */
+  trait Prompt {
+    private[mill] def setPromptDetail(key: Seq[String], s: String): Unit
+    private[mill] def reportKey(key: Seq[String]): Unit
+    private[mill] def setPromptLine(key: Seq[String], keySuffix: String, message: String): Unit
+    private[mill] def setPromptHeaderPrefix(s: String): Unit
+    private[mill] def clearPromptStatuses(): Unit
+    private[mill] def removePromptLine(key: Seq[String]): Unit
+    private[mill] def withPromptPaused[T](t: => T): T
+    private[mill] def withPromptUnpaused[T](t: => T): T
+
+    def debugEnabled: Boolean
+
+    def enableTicker: Boolean
+  }
+  object Prompt {
+    class NoOp extends Prompt {
+      private[mill] def setPromptDetail(key: Seq[String], s: String): Unit = ()
+      private[mill] def reportKey(key: Seq[String]): Unit = ()
+      private[mill] def setPromptLine(key: Seq[String], keySuffix: String, message: String): Unit =
+        ()
+      private[mill] def setPromptHeaderPrefix(s: String): Unit = ()
+      private[mill] def clearPromptStatuses(): Unit = ()
+      private[mill] def removePromptLine(key: Seq[String]): Unit = ()
+      private[mill] def withPromptPaused[T](t: => T): T = t
+      private[mill] def withPromptUnpaused[T](t: => T): T = t
+
+      def debugEnabled: Boolean = false
+
+      def enableTicker: Boolean = false
+    }
+  }
 }

core/define/src/mill/define/Evaluator.scala

@@ -10,14 +10,14 @@ trait Evaluator extends AutoCloseable {
   private[mill] def allowPositionalCommandArgs: Boolean
   private[mill] def selectiveExecution: Boolean
   private[mill] def workspace: os.Path
-  private[mill] def baseLogger: ColorLogger
+  private[mill] def baseLogger: Logger
   private[mill] def outPath: os.Path
   private[mill] def codeSignatures: Map[String, Int]
   private[mill] def rootModule: BaseModule
   private[mill] def workerCache: mutable.Map[Segments, (Int, Val)]
   private[mill] def env: Map[String, String]
 
-  def withBaseLogger(newBaseLogger: ColorLogger): Evaluator
+  def withBaseLogger(newBaseLogger: Logger): Evaluator
 
   def resolveSegments(
       scriptArgs: Seq[String],
@@ -38,7 +38,7 @@ trait Evaluator extends AutoCloseable {
       targets: Seq[Task[T]],
       reporter: Int => Option[CompileProblemReporter] = _ => Option.empty[CompileProblemReporter],
       testReporter: TestReporter = DummyTestReporter,
-      logger: ColorLogger = baseLogger,
+      logger: Logger = baseLogger,
       serialCommandExec: Boolean = false,
       selectiveExecution: Boolean = false
   ): Evaluator.Result[T]