Fix deserialization backwards-compatibility (#52)

* Renamed CanGenerateHashFromStringCharArray back to CanGenerateHashFromString to preserve deserialization backwards-compatibility

* Restored private valueOffset field to CanGenerateHashFromString to revert the serialVersionUID back to the same value it had in the 0.12 release

* Added tests for deserializing bloom filters that were serialized with the 0.12 release

* Reverted deserialization tests because they only work when running tests with the same jdk and scala version that were used to create the .ser files

Co-authored-by: Sean Rohead <[email protected]>

Author: seanrohead

bloom-filter/src/main/scala/bloomfilter/CanGenerate128HashFrom.scala

@@ -23,24 +23,26 @@ object CanGenerate128HashFrom {
 
   import bloomfilter.util.Unsafe.unsafe
 
-  case object CanGenerate128HashFromStringCharArray extends CanGenerate128HashFrom[String] {
+  case object CanGenerate128HashFromString extends CanGenerate128HashFrom[String] {
+    private val valueOffset = unsafe.objectFieldOffset(stringValueField)
+
     override def generateHash(from: String): (Long, Long) = {
       val value = unsafe.getObject(from, valueOffset).asInstanceOf[Array[Char]]
       MurmurHash3Generic.murmurhash3_x64_128(value, 0, from.length * 2, 0)
     }
   }
 
   case object CanGenerate128HashFromStringByteArray extends CanGenerate128HashFrom[String] {
+    private val valueOffset = unsafe.objectFieldOffset(stringValueField)
+
     override def generateHash(from: String): (Long, Long) = {
       val value = unsafe.getObject(from, valueOffset).asInstanceOf[Array[Byte]]
       MurmurHash3Generic.murmurhash3_x64_128(value, 0, from.length, 0)
     }
   }
 
   private val stringValueField: Field = classOf[String].getDeclaredField("value")
-  private val valueOffset = unsafe.objectFieldOffset(stringValueField)
-
   implicit val canGenerate128HashFromString: CanGenerate128HashFrom[String] = {
-    if (stringValueField.getType.getComponentType == java.lang.Byte.TYPE) CanGenerate128HashFromStringByteArray else CanGenerate128HashFromStringCharArray
+    if (stringValueField.getType.getComponentType == java.lang.Byte.TYPE) CanGenerate128HashFromStringByteArray else CanGenerate128HashFromString
   }
 }

bloom-filter/src/main/scala/bloomfilter/CanGenerateHashFrom.scala

@@ -20,24 +20,26 @@ object CanGenerateHashFrom {
 
   import bloomfilter.util.Unsafe.unsafe
 
-  case object CanGenerateHashFromStringCharArray extends CanGenerateHashFrom[String] {
+  case object CanGenerateHashFromString extends CanGenerateHashFrom[String] {
+    private val valueOffset = unsafe.objectFieldOffset(stringValueField)
+
     override def generateHash(from: String): Long = {
       val value = unsafe.getObject(from, valueOffset).asInstanceOf[Array[Char]]
       MurmurHash3Generic.murmurhash3_x64_64(value, 0, from.length * 2, 0)
     }
   }
 
   case object CanGenerateHashFromStringByteArray extends CanGenerateHashFrom[String] {
+    private val valueOffset = unsafe.objectFieldOffset(stringValueField)
+
     override def generateHash(from: String): Long = {
       val value = unsafe.getObject(from, valueOffset).asInstanceOf[Array[Byte]]
       MurmurHash3Generic.murmurhash3_x64_64(value, 0, from.length, 0)
     }
   }
 
   private val stringValueField: Field = classOf[String].getDeclaredField("value")
-  private val valueOffset = unsafe.objectFieldOffset(stringValueField)
-
   implicit val canGenerateHashFromString: CanGenerateHashFrom[String] = {
-    if (stringValueField.getType.getComponentType == java.lang.Byte.TYPE) CanGenerateHashFromStringByteArray else CanGenerateHashFromStringCharArray
+    if (stringValueField.getType.getComponentType == java.lang.Byte.TYPE) CanGenerateHashFromStringByteArray else CanGenerateHashFromString
   }
 }