Optimistic locking option

src/main/kotlin/nl/astraeus/persistence/Datastore.kt

@@ -17,16 +17,29 @@ enum class ActionType {
 class TypeData(
   var nextId: AtomicLong = AtomicLong(1L),
   val data: MutableMap<Serializable, Persistable> = ConcurrentHashMap(),
-) : Serializable
+) : Serializable {
+  companion object {
+    private const val serialVersionUID: Long = 1L
+  }
+}
 
 class Action(
   val type: ActionType,
   val obj: Persistable
-) : Serializable
+) : Serializable {
+  override fun toString(): String {
+    return "Action(type=$type, obj=$obj)"
+  }
+
+  companion object {
+    private const val serialVersionUID: Long = 1L
+  }
+}
 
 class Datastore(
   private val directory: File,
   indexes: Array<PersistableIndex> = arrayOf(),
+  val enableOptimisticLocking: Boolean = false,
 ) {
   private val fileManager = FileManager(directory)
   private val transactionFormatter = DecimalFormat("#")
@@ -58,7 +71,8 @@ class Datastore(
 
   fun setMaxId(javaClass: Class<Persistable>, id: Long) {
     val nextId = data.getOrPut(javaClass) { TypeData() }.nextId
-    if (nextId.get() <= id) nextId.set(id + 1)
+    val current = nextId.get()
+    if (current <= id) nextId.addAndGet(id - current)
   }
 
   override fun toString(): String {
@@ -97,15 +111,24 @@ class Datastore(
       }
     }
 
-    Logger.debug("Loaded transactions in ${(System.nanoTime() - start) / 1_000_000}ms")
+    Logger.debug("Loaded transactions in %6.3fms", ((System.nanoTime() - start) / 1_000_000f))
   }
 
-  private fun getTrnx(file: File): Long {
-    return file.name.substringAfterLast('/').substringAfter("transaction-").substringBefore(".").toLong()
-  }
-
-  fun execute(actions: MutableList<Action>) {
+  private fun execute(actions: Set<Action>) {
     synchronized(this) {
+      if (enableOptimisticLocking) {
+        for (action in actions) {
+          val typeData = data.getOrPut(action.obj::class.java) {
+            TypeData()
+          }
+          if (action.type == ActionType.STORE) {
+            if ((typeData.data[action.obj.id]?.version ?: -1L) >= action.obj.version) {
+              throw OptimisticLockingException(action.obj)
+            }
+          }
+        }
+      }
+
       for (action in actions) {
         val typeData = data.getOrPut(action.obj::class.java) {
           TypeData()
@@ -137,7 +160,6 @@ class Datastore(
     }
   }
 
-
   fun <T : Persistable> count(clazz: KClass<T>): Int {
     val typeData = data.getOrPut(clazz.java) {
       TypeData()
@@ -176,25 +198,25 @@ class Datastore(
     return indexes[kClass.java]?.get(indexName)
   }
 
-  fun storeAndExecute(actions: MutableList<Action>) {
+  fun storeAndExecute(actions: Set<Action>) {
     if (actions.isNotEmpty()) {
       synchronized(this) {
-        writeTransaction(actions)
         execute(actions)
+        writeTransaction(actions)
       }
     }
   }
 
   private fun readTransaction(ois: ObjectInputStream) {
     val versionNumber = ois.readInt()
-    check (versionNumber == 1) { "Unsupported version number: $versionNumber" }
+    check(versionNumber == 1) { "Unsupported version number: $versionNumber" }
     val transactionNumber = ois.readLong()
     nextTransactionNumber = transactionNumber + 1
-    val actions = ois.readObject() as MutableList<Action>
+    val actions = ois.readObject() as Set<Action>
     execute(actions)
   }
 
-  private fun writeTransaction(actions: MutableList<Action>) {
+  private fun writeTransaction(actions: Set<Action>) {
     val number = transactionFormatter.format(nextTransactionNumber)
     val file = File(directory, "transaction-$number.trn")
     ObjectOutputStream(file.outputStream()).use { oos ->
@@ -226,12 +248,12 @@ class Datastore(
         }
       }
     }
-    Logger.debug("Snapshot in ${(System.nanoTime() - start) / 1_000_000}ms")
+    Logger.debug("Snapshot in %6.3fms", ((System.nanoTime() - start) / 1_000_000f))
   }
 
   private fun readSnapshot(ois: ObjectInputStream) {
     val versionNumber = ois.readInt()
-    check (versionNumber == 1) { "Unsupported version number: $versionNumber" }
+    check(versionNumber == 1) { "Unsupported version number: $versionNumber" }
     nextTransactionNumber = ois.readLong() + 1
     data.clear()
     data.putAll(ois.readObject() as MutableMap<Class<*>, TypeData>)