WIP reduce file stats in classpath setup

src/compiler/scala/tools/nsc/classpath/ZipAndJarFileLookupFactory.scala

@@ -36,15 +36,16 @@ sealed trait ZipAndJarFileLookupFactory {
   private val cache = new FileBasedCache[ZipSettings, ClassPath with Closeable]
 
   def create(zipFile: AbstractFile, settings: Settings, closeableRegistry: CloseableRegistry): ClassPath = {
-    val disabled = (settings.YdisableFlatCpCaching.value && !settings.YforceFlatCpCaching.value) || zipFile.file == null
+    val jfile = zipFile.file
+    val disabled = (settings.YdisableFlatCpCaching.value && !settings.YforceFlatCpCaching.value) || jfile == null
     val zipSettings = ZipSettings(settings.releaseValue)
-    cache.checkCacheability(zipFile.toURL :: Nil, checkStamps = true, disableCache = disabled) match {
-      case Left(_) =>
-        val result: ClassPath with Closeable = createForZipFile(zipFile, zipSettings)
-        closeableRegistry.registerCloseable(result)
-        result
-      case Right(paths) =>
-        cache.getOrCreate(zipSettings, paths, () => createForZipFile(zipFile, zipSettings), closeableRegistry, checkStamps = true)
+
+    if (disabled) {
+      val result: ClassPath with Closeable = createForZipFile(zipFile, zipSettings)
+      closeableRegistry.registerCloseable(result)
+      result
+    } else {
+      cache.getOrCreate(zipSettings, Seq(jfile.toPath -> zipFile.basicFileAttributes), () => createForZipFile(zipFile, zipSettings), closeableRegistry, checkStamps = true)
     }
   }
 
@@ -258,14 +259,18 @@ final class FileBasedCache[K, T] {
     }
   }
 
-  def getOrCreate(k: K, paths: Seq[Path], create: () => T, closeableRegistry: CloseableRegistry, checkStamps: Boolean): T = cache.synchronized {
-    val stamps = if (!checkStamps) Nil else paths.map { path =>
+  def getOrCreate(k: K, paths: Seq[Path], create: () => T,
+                  closeableRegistry: CloseableRegistry, checkStamps: Boolean): T = {
+    val pathsAndAttrs = paths.map(x => (x, Files.readAttributes(x, classOf[BasicFileAttributes])))
+    getOrCreate0(k, pathsAndAttrs, create, closeableRegistry, checkStamps)
+  }
+  def getOrCreate0(k: K, paths: Seq[(Path, BasicFileAttributes)], create: () => T, closeableRegistry: CloseableRegistry, checkStamps: Boolean): T = cache.synchronized {
+    val stamps = if (!checkStamps) Nil else paths.map { case (path, attrs) =>
       try {
-      val attrs = Files.readAttributes(path, classOf[BasicFileAttributes])
-      val lastModified = attrs.lastModifiedTime()
-      // only null on some platforms, but that's okay, we just use the last modified timestamp as our stamp
-      val fileKey = attrs.fileKey()
-      Stamp(lastModified, attrs.size(), if (fileKey == null) NoFileKey else fileKey)
+        val lastModified = attrs.lastModifiedTime()
+        // only null on some platforms, but that's okay, we just use the last modified timestamp as our stamp
+        val fileKey = attrs.fileKey()
+        Stamp(lastModified, attrs.size(), if (fileKey == null) NoFileKey else fileKey)
       } catch {
         case _: java.nio.file.NoSuchFileException =>
           // Dummy stamp for (currently) non-existent file.

src/compiler/scala/tools/nsc/settings/PathFactory.scala

@@ -12,6 +12,7 @@
 
 package scala.tools.nsc.settings
 
+import java.io.File
 import scala.reflect.io.{AbstractFile, PlainFile}
 
 /** Converts paths provided in compiler options (e.g elements of `-classpath` or the target directory of `-d`) to
@@ -37,6 +38,6 @@ trait PathFactory {
 }
 
 object DefaultPathFactory extends PathFactory {
-  override def getDirectory(path: String): AbstractFile = AbstractFile.getDirectory(path)
+  override def getDirectory(path: String): AbstractFile = AbstractFile.getDirectory(new File(path))
   override def getFile(path: String): AbstractFile = new PlainFile(path)
 }

src/reflect/scala/reflect/io/AbstractFile.scala

@@ -18,7 +18,8 @@ import java.io.{BufferedOutputStream, ByteArrayOutputStream, IOException, InputS
 import java.io.{File => JFile}
 import java.net.URL
 import java.nio.ByteBuffer
-
+import java.nio.file.attribute.BasicFileAttributes
+import java.nio.file.Files
 import scala.collection.AbstractIterable
 
 /**
@@ -46,10 +47,22 @@ object AbstractFile {
    * readable zip or jar archive, returns an abstract directory
    * backed by it. Otherwise, returns `null`.
    */
-  def getDirectory(file: File): AbstractFile =
-    if (file.isDirectory) new PlainFile(file)
-    else if (file.isFile && Path.isExtensionJarOrZip(file.jfile)) ZipArchive.fromFile(file)
+  def getDirectory(file: File): AbstractFile = {
+    val attrs = try {
+       Files.readAttributes(file.jfile.toPath, classOf[BasicFileAttributes])
+    } catch {
+      case _: IOException =>
+        return null
+    }
+
+    if (attrs.isDirectory) new PlainFile(file)
+    else if (attrs.isRegularFile && Path.isExtensionJarOrZip(file.jfile)) {
+      val za = ZipArchive.fromFile(file)
+      za.setBasicFileAttributesCached(attrs)
+      za
+    }
     else null
+  }
 
   /**
    * If the specified URL exists and is a regular file or a directory, returns an
@@ -115,6 +128,18 @@ abstract class AbstractFile extends AbstractIterable[AbstractFile] {
 
   /** Returns the underlying File if any and null otherwise. */
   def file: JFile
+  def basicFileAttributes: BasicFileAttributes = {
+    if (basicFileAttributesCached != null)
+      basicFileAttributesCached
+    else file match {
+      case null => null
+      case f => Files.readAttributes(f.toPath, classOf[BasicFileAttributes])
+    }
+  }
+  private var basicFileAttributesCached: BasicFileAttributes = null
+  final def setBasicFileAttributesCached(attrs: BasicFileAttributes): Unit = {
+    basicFileAttributesCached = attrs
+  }
 
   /** An underlying source, if known.  Mostly, a zip/jar file. */
   def underlyingSource: Option[AbstractFile] = None