From ad3692b2dfc8a7e2164f4a9b7d578a4723daac8c Mon Sep 17 00:00:00 2001
From: Eugene Yokota <eed3si9n@gmail.com>
Date: Thu, 5 Apr 2018 04:22:16 -0400
Subject: [PATCH] Use NIO Files.getLastModifiedTime for hashing

---
 main-actions/src/main/scala/sbt/compiler/Eval.scala | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/main-actions/src/main/scala/sbt/compiler/Eval.scala b/main-actions/src/main/scala/sbt/compiler/Eval.scala
index d2afb03b9..f9b0ffeee 100644
--- a/main-actions/src/main/scala/sbt/compiler/Eval.scala
+++ b/main-actions/src/main/scala/sbt/compiler/Eval.scala
@@ -509,11 +509,22 @@ private[sbt] object Eval {
     if (f.isDirectory)
       (f listFiles classDirFilter) foreach { x =>
         fileModifiedHash(x, digester)
-      } else digester.update(bytes(IO.getModifiedTimeOrZero(f)))
+      } else digester.update(bytes(JavaMilli.getModifiedTimeOrZero(f)))
 
     digester.update(bytes(f.getAbsolutePath))
   }
 
+  // This uses NIO instead of the JNA-based IO.getModifiedTimeOrZero for speed
+  object JavaMilli {
+    import java.nio.file.{ Files, NoSuchFileException }
+    def getModifiedTimeOrZero(f: File): Long =
+      try {
+        Files.getLastModifiedTime(f.toPath).toMillis
+      } catch {
+        case e: NoSuchFileException => 0L
+      }
+  }
+
   def fileExistsBytes(f: File): Array[Byte] =
     bytes(f.exists) ++
       bytes(f.getAbsolutePath)