idempotent change propagation

using lastModified instead of a non-idempotent needsUpdate flag
this fixes a bug where dependees would not be rebuilt if cbt exited
or was killed after dependencies were already rebuilt.

9 files changed, 56 insertions, 55 deletions

diff --git a/stage2/BasicBuild.scala b/stage2/BasicBuild.scala
index 2fd34c7..ef5411a 100644
--- a/stage2/BasicBuild.scala
+++ b/stage2/BasicBuild.scala
@@ -98,7 +98,7 @@ trait BaseBuild extends BuildInterface with DependencyImplementation with Trigge
   }
   logEmptySourceDirectories()
 
-  def Resolver( urls: URL* ) = MavenResolver( context.cbtHasChanged, context.paths.mavenCache, urls: _* )
+  def Resolver( urls: URL* ) = MavenResolver( context.cbtLastModified, context.paths.mavenCache, urls: _* )
 
   def ScalaDependency(
     groupId: String, artifactId: String, version: String, classifier: Classifier = Classifier.none,
@@ -126,7 +126,7 @@ trait BaseBuild extends BuildInterface with DependencyImplementation with Trigge
     val resourcesDirectory = projectDirectory ++ "/resources"
       ClassPath( if(resourcesDirectory.exists) Seq(resourcesDirectory) else Nil )
   }
-  def exportedClasspath   : ClassPath = ClassPath(compile.toSeq) ++ resourceClasspath
+  def exportedClasspath   : ClassPath = ClassPath(compileFile.toSeq) ++ resourceClasspath
   def targetClasspath = ClassPath(Seq(compileTarget))
   // ========== compile, run, test ==========
 
@@ -137,23 +137,20 @@ trait BaseBuild extends BuildInterface with DependencyImplementation with Trigge
     "-unchecked"
   )
 
-  def needsUpdate: Boolean = taskCache[BaseBuild]("needsUpdate").memoize[java.lang.Boolean](
-    context.cbtHasChanged
-    || lib.needsUpdate( sourceFiles, compileStatusFile )
-    || transitiveDependencies.filterNot(_ == context.parentBuild).exists(_.needsUpdate)
-  )
+  final def lastModified: Long = compile.getOrElse(0L)
+
+  final def compileFile: Option[File] = compile.map(_ => compileTarget)
 
-  def compile: Option[File] = taskCache[BaseBuild]("compile").memoize{
+  def compile: Option[Long] = taskCache[BaseBuild]("_compile").memoize{
     lib.compile(
-      context.cbtHasChanged,
-      needsUpdate || context.parentBuild.map(_.needsUpdate).getOrElse(false),
+      context.cbtLastModified,
       sourceFiles, compileTarget, compileStatusFile, compileDependencies,
       context.paths.mavenCache, scalacOptions, context.classLoaderCache,
       zincVersion = zincVersion, scalaVersion = scalaVersion
     )
   }
 
-  def mainClasses: Seq[Class[_]] = compile.toSeq.flatMap( lib.mainClasses( _, classLoader(classLoaderCache) ) )
+  def mainClasses: Seq[Class[_]] = compileFile.toSeq.flatMap( lib.mainClasses( _, classLoader(classLoaderCache) ) )
 
   def runClass: Option[String] = lib.runClass( mainClasses ).map( _.getName )
 
@@ -181,7 +178,7 @@ trait BaseBuild extends BuildInterface with DependencyImplementation with Trigge
       System.setProperty(colorized, "true")
     }
 
-    val scalac = new ScalaCompilerDependency(context.cbtHasChanged, context.paths.mavenCache, scalaVersion)
+    val scalac = new ScalaCompilerDependency(context.cbtLastModified, context.paths.mavenCache, scalaVersion)
     lib.runMain(
       "scala.tools.nsc.MainGenericRunner",
       Seq(
diff --git a/stage2/BuildDependency.scala b/stage2/BuildDependency.scala
index 4b4fdc1..236f958 100644
--- a/stage2/BuildDependency.scala
+++ b/stage2/BuildDependency.scala
@@ -27,7 +27,7 @@ final case class DirectoryDependency(context: Context) extends TriggerLoop{
   def exportedClasspath = ClassPath()
   def dependencies = Seq(build)
   def triggerLoopFiles = root.triggerLoopFiles
-  def needsUpdate = build.needsUpdate
+  def lastModified = build.lastModified
   def targetClasspath = ClassPath()
 }
 /*
diff --git a/stage2/GitDependency.scala b/stage2/GitDependency.scala
index e27eff9..059d650 100644
--- a/stage2/GitDependency.scala
+++ b/stage2/GitDependency.scala
@@ -76,5 +76,5 @@ case class GitDependency(
 
   def exportedClasspath = ClassPath()
   private[cbt] def targetClasspath = exportedClasspath
-  def needsUpdate: Boolean = false
+  def lastModified: Long = dependency.lastModified
 }
diff --git a/stage2/Lib.scala b/stage2/Lib.scala
index c570ca3..a76e281 100644
--- a/stage2/Lib.scala
+++ b/stage2/Lib.scala
@@ -15,7 +15,7 @@ import scala.util._
 case class Developer(id: String, name: String, timezone: String, url: URL)
 
 /** Don't extend. Create your own libs :). */
-final class Lib(logger: Logger) extends Stage1Lib(logger) with Scaffold{
+final class Lib(val logger: Logger) extends Stage1Lib(logger) with Scaffold{
   lib =>
 
   val buildClassName = "Build"
@@ -74,7 +74,7 @@ final class Lib(logger: Logger) extends Stage1Lib(logger) with Scaffold{
   }
 
   def docJar(
-    cbtHasChanged: Boolean,
+    cbtLastModified: Long,
     scalaVersion: String,
     sourceFiles: Seq[File],
     dependencyClasspath: ClassPath,
@@ -101,7 +101,7 @@ final class Lib(logger: Logger) extends Stage1Lib(logger) with Scaffold{
         runMain(
           "scala.tools.nsc.ScalaDoc",
           args,
-          new ScalaDependencies(cbtHasChanged,mavenCache,scalaVersion).classLoader(classLoaderCache)
+          new ScalaDependencies(cbtLastModified,mavenCache,scalaVersion).classLoader(classLoaderCache)
         )
       }
       lib.jarFile(
diff --git a/stage2/PackageJars.scala b/stage2/PackageJars.scala
index 3ecceb2..7079786 100644
--- a/stage2/PackageJars.scala
+++ b/stage2/PackageJars.scala
@@ -11,7 +11,7 @@ trait PackageJars extends BaseBuild with ArtifactInfo{
   )( _() ).flatten
 
   def jar: Option[File] = taskCache[PackageJars]("jar").memoize{
-    compile.flatMap( lib.jar( artifactId, scalaMajorVersion, version, _, jarTarget ) )
+    compileFile.flatMap( lib.jar( artifactId, scalaMajorVersion, version, _, jarTarget ) )
   }
 
   def srcJar: Option[File] = taskCache[PackageJars]("srcJar").memoize{
@@ -20,7 +20,7 @@ trait PackageJars extends BaseBuild with ArtifactInfo{
 
   def docJar: Option[File] = taskCache[PackageJars]("docJar").memoize{
     lib.docJar(
-      context.cbtHasChanged,
+      context.cbtLastModified,
       scalaVersion, sourceFiles, compileClasspath, docTarget,
       jarTarget, artifactId, scalaMajorVersion, version,
       scalacOptions, context.classLoaderCache, context.paths.mavenCache
diff --git a/stage2/Stage2.scala b/stage2/Stage2.scala
index 2884ddb..542a982 100644
--- a/stage2/Stage2.scala
+++ b/stage2/Stage2.scala
@@ -30,9 +30,9 @@ object Stage2 extends Stage2Base{
       args.args.drop( taskIndex +1 ).toArray,
       logger.enabledLoggers.toArray,
       logger.start,
-      args.cbtHasChanged,
+      args.stage2LastModified,
       null,
-      args.persistentCache,
+      args.classLoaderCache.hashMap,
       args.transientCache,
       args.cache,
       args.cbtHome,
diff --git a/stage2/ToolsStage2.scala b/stage2/ToolsStage2.scala
index df615fc..2b5e092 100644
--- a/stage2/ToolsStage2.scala
+++ b/stage2/ToolsStage2.scala
@@ -4,7 +4,7 @@ object ToolsStage2 extends Stage2Base{
   def run( _args: Stage2Args ): Unit = {
     val args = _args.args.dropWhile(Seq("tools","direct") contains _)
     val lib = new Lib(_args.logger)
-    val toolsTasks = new ToolsTasks(lib, args, _args.cwd, _args.classLoaderCache, _args.cache, _args.cbtHome, _args.cbtHasChanged)
+    val toolsTasks = new ToolsTasks(lib, args, _args.cwd, _args.classLoaderCache, _args.cache, _args.cbtHome, _args.stage2LastModified)
     new lib.ReflectObject(toolsTasks){
       def usage: String = "Available methods: " ++ lib.taskNames(toolsTasks.getClass).mkString("  ")
     }.callNullary(args.lift(0))
diff --git a/stage2/ToolsTasks.scala b/stage2/ToolsTasks.scala
index 839780a..6acf72c 100644
--- a/stage2/ToolsTasks.scala
+++ b/stage2/ToolsTasks.scala
@@ -9,11 +9,11 @@ class ToolsTasks(
   classLoaderCache: ClassLoaderCache,
   cache: File,
   cbtHome: File,
-  cbtHasChanged: Boolean
+  cbtLastModified: Long
 ){
   private val paths = CbtPaths(cbtHome, cache)
   import paths._
-  private def Resolver( urls: URL* ) = MavenResolver(cbtHasChanged,mavenCache,urls: _*)
+  private def Resolver( urls: URL* ) = MavenResolver(cbtLastModified,mavenCache,urls: _*)
   implicit val logger: Logger = lib.logger
   implicit val transientCache: java.util.Map[AnyRef,AnyRef] = new java.util.HashMap
   def createMain: Unit = lib.createMain( cwd )
@@ -56,7 +56,7 @@ class ToolsTasks(
   }
   def scala = {
     val version = args.lift(1).getOrElse(constants.scalaVersion)
-    val scalac = new ScalaCompilerDependency( cbtHasChanged, mavenCache, version )
+    val scalac = new ScalaCompilerDependency( cbtLastModified, mavenCache, version )
     val _args = Seq("-cp", scalac.classpath.string) ++ args.drop(2)
     lib.runMain(
       "scala.tools.nsc.MainGenericRunner", _args, scalac.classLoader(classLoaderCache)
@@ -97,14 +97,15 @@ class ToolsTasks(
           val n = valName(d)
           s"""
     // ${d.groupId}:${d.artifactId}:${d.version}
-    download(new URL(mavenUrl + "${d.basePath(true)}.jar"), Paths.get(${n}File), "${d.jarSha1}");
-
     String[] ${n}ClasspathArray = new String[]{${deps.sortBy(_.jar).map(valName(_)+"File").mkString(", ")}};
-    String ${n}Classpath = classpath( ${n}ClasspathArray );
-    ClassLoader $n =
-      classLoaderCache.contains( ${n}Classpath )
-      ? classLoaderCache.get( ${n}Classpath )
-      : classLoaderCache.put( classLoader( ${n}File, $parentString ), ${n}Classpath );"""
+    ClassLoader $n = loadDependency(
+      mavenUrl + "${d.basePath(true)}.jar",
+      ${n}File,
+      "${d.jarSha1}",
+      classLoaderCache,
+      $parentString,
+      ${n}ClasspathArray
+    );"""
       }
     }
     val assignments = codeEach(zinc) ++ codeEach(scalaXml)
@@ -116,6 +117,7 @@ import java.io.*;
 import java.nio.file.*;
 import java.net.*;
 import java.security.*;
+import java.util.*;
 import static cbt.Stage0Lib.*;
 import static cbt.NailgunLauncher.*;
 
@@ -130,13 +132,13 @@ class EarlyDependencies{
 ${files.map(d => s"""  String ${valName(d)}File;""").mkString("\n")}
 
   public EarlyDependencies(
-    String mavenCache, String mavenUrl, JavaCache<ClassLoader> classLoaderCache, ClassLoader rootClassLoader
+    String mavenCache, String mavenUrl, ClassLoaderCache classLoaderCache, ClassLoader rootClassLoader
   ) throws Throwable {
 ${files.map(d => s"""    ${valName(d)}File = mavenCache + "${d.basePath(true)}.jar";""").mkString("\n")}
 
 ${scalaDeps.map(d => s"""    download(new URL(mavenUrl + "${d.basePath(true)}.jar"), Paths.get(${valName(d)}File), "${d.jarSha1}");""").mkString("\n")}
 ${assignments.mkString("\n")}
-  
+
     classLoader = scalaXml_${scalaXmlVersion.replace(".","_")}_;
     classpathArray = scalaXml_${scalaXmlVersion.replace(".","_")}_ClasspathArray;
 
diff --git a/stage2/plugins/Dotty.scala b/stage2/plugins/Dotty.scala
index fe949a3..6fe5dd3 100644
--- a/stage2/plugins/Dotty.scala
+++ b/stage2/plugins/Dotty.scala
@@ -8,17 +8,15 @@ trait Dotty extends BaseBuild{
   def dottyVersion: String = "0.1-20160926-ec28ea1-NIGHTLY"
   def dottyOptions: Seq[String] = Seq()
   override def scalaTarget: File = target ++ s"/dotty-$dottyVersion"
-  
+
   private lazy val dottyLib = new DottyLib(
-    logger, context.cbtHasChanged, context.paths.mavenCache,
+    logger, context.cbtLastModified, context.paths.mavenCache,
     context.classLoaderCache, dottyVersion = dottyVersion
   )
 
-  override def compile: Option[File] = taskCache[Dotty]("compile").memoize{
+  override def compile: Option[Long] = taskCache[Dotty]("compile").memoize{
     dottyLib.compile(
-      needsUpdate || context.parentBuild.map(_.needsUpdate).getOrElse(false),
-      sourceFiles, compileTarget, compileStatusFile, compileClasspath,
-      dottyOptions
+      sourceFiles, compileTarget, compileStatusFile, compileDependencies, dottyOptions
     )
   }
 
@@ -36,7 +34,7 @@ trait Dotty extends BaseBuild{
 
 class DottyLib(
   logger: Logger,
-  cbtHasChanged: Boolean,
+  cbtLastModified: Long,
   mavenCache: File,
   classLoaderCache: ClassLoaderCache,
   dottyVersion: String
@@ -44,7 +42,7 @@ class DottyLib(
   val lib = new Lib(logger)
   import lib._
 
-  private def Resolver(urls: URL*) = MavenResolver(cbtHasChanged, mavenCache, urls: _*)
+  private def Resolver(urls: URL*) = MavenResolver(cbtLastModified, mavenCache, urls: _*)
   private lazy val dottyDependency = Resolver(mavenCentral).bindOne(
     MavenDependency("ch.epfl.lamp","dotty_2.11",dottyVersion)
   )
@@ -94,22 +92,24 @@ class DottyLib(
   }
 
   def compile(
-    needsRecompile: Boolean,
-    files: Seq[File],
+    sourceFiles: Seq[File],
     compileTarget: File,
     statusFile: File,
-    classpath: ClassPath,
+    dependencies: Seq[Dependency],
     dottyOptions: Seq[String]
-  ): Option[File] = {
-
+  ): Option[Long] = {
+    val d = Dependencies(dependencies)
+    val classpath = d.classpath
+    val cp = classpath.string
     if(classpath.files.isEmpty)
-      throw new Exception("Trying to compile with empty classpath. Source files: " ++ files.toString)
+      throw new Exception("Trying to compile with empty classpath. Source files: " ++ sourceFiles.toString)
 
-    if( files.isEmpty ){
+    if( sourceFiles.isEmpty ){
       None
     }else{
-      if( needsRecompile ){
-        val start = System.currentTimeMillis
+      val start = System.currentTimeMillis
+      val lastCompiled = statusFile.lastModified
+      if( d.lastModified > lastCompiled || sourceFiles.exists(_.lastModified > lastCompiled) ){
 
         val _class = "dotty.tools.dotc.Main"
         val dualArgs =
@@ -118,7 +118,7 @@ class DottyLib(
           )
         val singleArgs = dottyOptions.map( "-S" ++ _ )
 
-        val code = 
+        val code =
           try{
             System.err.println("Compiling with Dotty to " ++ compileTarget.toString)
             compileTarget.mkdirs
@@ -128,7 +128,7 @@ class DottyLib(
                 dualArgs ++ singleArgs ++ Seq(
                   "-bootclasspath", dottyDependency.classpath.string, // let's put cp last. It so long
                   "-classpath", classpath.string // let's put cp last. It so long
-                ) ++ files.map(_.toString),
+                ) ++ sourceFiles.map(_.toString),
                 dottyDependency.classLoader(classLoaderCache)
               )
             }
@@ -150,7 +150,7 @@ ${dottyDependency.classpath.strings.mkString(":\\\n")} \\
 -classpath \\
 ${classpath.strings.mkString(":\\\n")} \\
 \\
-${files.sorted.mkString(" \\\n")}
+${sourceFiles.sorted.mkString(" \\\n")}
 """
             )
             ExitCode.Failure
@@ -164,8 +164,10 @@ ${files.sorted.mkString(" \\\n")}
         } else {
           System.exit(code.integer) // FIXME: let's find a better solution for error handling. Maybe a monad after all.
         }
+        Some( start )
+      } else {
+        Some( lastCompiled )
       }
-      Some( compileTarget )
     }
   }
 }