Merge pull request #195 from eed3si9n/wip/cache

throw error on deserialization error

util-cache/src/main/scala/sbt/internal/util/EmptyCacheError.scala

@@ -0,0 +1,5 @@
+package sbt
+package internal
+package util
+
+class EmptyCacheError extends RuntimeException

util-cache/src/main/scala/sbt/util/Input.scala

@@ -4,6 +4,7 @@ import java.io.{ Closeable, InputStream }
 import scala.util.control.NonFatal
 import sjsonnew.{ IsoString, JsonReader, SupportConverter }
 import sbt.io.{ IO, Using }
+import sbt.internal.util.EmptyCacheError
 
 trait Input extends Closeable {
   def read[T: JsonReader](): T
@@ -28,7 +29,11 @@ class PlainInput[J: IsoString](input: InputStream, converter: SupportConverter[J
     }
   }
 
-  def read[T: JsonReader]() = converter.fromJson(isoFormat.from(readFully())).get
+  def read[T: JsonReader](): T = {
+    val str = readFully()
+    if (str == "") throw new EmptyCacheError()
+    else converter.fromJson(isoFormat.from(str)).get
+  }
 
   def close() = input.close()
 }

util-tracking/src/main/scala/sbt/util/Tracked.scala

@@ -8,6 +8,7 @@ import scala.util.{ Failure, Try, Success }
 import java.io.File
 import sbt.io.IO
 import sbt.io.syntax._
+import sbt.internal.util.EmptyCacheError
 
 import sjsonnew.JsonFormat
 import sjsonnew.support.murmurhash.Hasher
@@ -178,7 +179,9 @@ object Tracked {
     def save(store: CacheStore, value: I): Unit = {
       Hasher.hash(value) match {
         case Success(keyHash) => store.write[Long](keyHash.toLong)
-        case Failure(_)       => ()
+        case Failure(e) =>
+          if (isStrictMode) throw e
+          else ()
       }
     }
 
@@ -187,12 +190,19 @@ object Tracked {
         case Success(prev: Long) =>
           Hasher.hash(value) match {
             case Success(keyHash: Int) => keyHash.toLong != prev
-            case Failure(_)            => true
+            case Failure(e) =>
+              if (isStrictMode) throw e
+              else true
           }
-        case Failure(_) => true
+        case Failure(_: EmptyCacheError) => true
+        case Failure(e) =>
+          if (isStrictMode) throw e
+          else true
       }
   }
 
+  private[sbt] def isStrictMode: Boolean =
+    java.lang.Boolean.getBoolean("sbt.strict")
 }
 
 trait Tracked {