Add Store.get():Option[V], fix $3

src/main/scala/io/iohk/iodb/LSMStore.scala

@@ -153,7 +153,8 @@ class LSMStore(
   }
 
   var counter = 0
-  override def get(key: K): V = {
+
+  override def get(key: K): Option[V] = {
     lock.readLock().lock()
     try {
       counter += 1
@@ -164,11 +165,11 @@ class LSMStore(
         .getValue
       val mainLogVersion = lastVersion
       val shardVersion = shard.lastVersion
-      if(mainLogVersion!=shardVersion){
+      if (mainLogVersion != shardVersion) {
         //some entries were not sharded yet, try main log
-        val ret = mainLog.get(key=key, versionId = mainLogVersion, stopAtVersion = shardVersion)
-        if(ret!=null)
-          return ret.getOrElse(null); //null is for tombstones found in main log
+        val ret = mainLog.get(key = key, versionId = mainLogVersion, stopAtVersion = shardVersion)
+        if (ret != null)
+          return ret
       }
 
       return shard.get(key)
@@ -178,7 +179,7 @@ class LSMStore(
   }
 
   /** gets value from sharded log, ignore main log */
-  protected[iodb] def getFromShard(key: K): V = {
+  protected[iodb] def getFromShard(key: K): Option[V] = {
     lock.readLock().lock()
     try {
       val shard = shards.lastEntry().getValue.floorEntry(key).getValue

src/main/scala/io/iohk/iodb/LogStore.scala

@@ -218,16 +218,13 @@ class LogStore(
     iter.toBuffer
   }
 
-  def get(key: K): V = {
-    val v = get(key, lastVersion)
-    if (v == null || v.isEmpty)
-      return null
-    v.get
+  def get(key: K): Option[V] = {
+    return get(key, lastVersion)
   }
 
   protected[iodb] def get(key: K, versionId: Long, stopAtVersion: Long = 0): Option[V] = {
     if (files.isEmpty)
-      return null
+      return None
     val versions =
       if (stopAtVersion > 0)
         files.subMap(versionId, true, stopAtVersion, false).asScala
@@ -240,9 +237,9 @@ class LogStore(
       if (ret != null)
         return Some(ret) // value was found
       if (logFile.isMerged)
-        return null //contains all versions, will not be found in next versions
+        return None //contains all versions, will not be found in next versions
     }
-    null
+    None
   }
 
   protected def versionGet(logFile: LogFile, key: K): V = {

src/main/scala/io/iohk/iodb/Store.scala

@@ -29,7 +29,16 @@ trait Store {
     * @param key to lookup
     * @return value associated with key or null
     */
-  def get(key: K): V
+  def get(key: K): Option[V]
+
+  /** Returns value associated with the key, or defualt value from user
+    */
+  def getOrElse(key: K, default: => V): V = get(key).getOrElse(default)
+
+  /** returns value associated with the key or throws `NoSuchElementException` */
+  def apply(key: K): V = getOrElse(key, {
+    throw new NoSuchElementException()
+  })
 
   /**
     * Batch get.
@@ -43,9 +52,9 @@ trait Store {
     * @param keys keys to loopup
     * @return iterable over key-value pairs found in store
     */
-  def get(keys: Iterable[K]): Iterable[(K, V)] = {
-    val ret = scala.collection.mutable.ArrayBuffer.empty[(K, V)]
-    get(keys, (key: K, value: V) =>
+  def get(keys: Iterable[K]): Iterable[(K, Option[V])] = {
+    val ret = scala.collection.mutable.ArrayBuffer.empty[(K, Option[V])]
+    get(keys, (key: K, value: Option[V]) =>
       ret += ((key, value))
     )
     ret
@@ -56,14 +65,13 @@ trait Store {
     *
     * Finds all keys from given iterable.
     * Results are passed to callable consumer.
-    * If key is not found, null value is passed to callable consumer.
     *
     * It uses lattest (most recent) version available in store
     *
     * @param keys     keys to lookup
     * @param consumer callback method to consume results
     */
-  def get(keys: Iterable[K], consumer: (K, V) => Unit): Unit = {
+  def get(keys: Iterable[K], consumer: (K, Option[V]) => Unit): Unit = {
     for (key <- keys) {
       val value = get(key)
       consumer(key, value)

src/test/scala/io/iohk/iodb/LSMStoreTest.scala

@@ -46,7 +46,7 @@ class LSMStoreTest extends TestWithTempDir {
     assert(!lastFiles.logFile.exists())
 
     assert(store.mainLog.files.size == 2)
-    assert(store.get(key) == fromLong(2))
+    assert(store.get(key) == Some(fromLong(2)))
     store.close()
   }
 
@@ -77,7 +77,7 @@ class LSMStoreTest extends TestWithTempDir {
     assert(!lastFiles.logFile.exists())
 
     assert(store.mainLog.files.size == 2)
-    assert(store.get(key) == fromLong(2))
+    assert(store(key) == fromLong(2))
 
     store.close()
   }
@@ -132,7 +132,7 @@ class LSMStoreTest extends TestWithTempDir {
     assert(!lastFiles.logFile.exists())
 
     assert(store.mainLog.files.size == 2)
-    assert(store.get(key) == fromLong(2))
+    assert(store(key) == fromLong(2))
 
     //ensure shard layout was restored
     assert(store.shards.size() == 1)
@@ -175,7 +175,7 @@ class LSMStoreTest extends TestWithTempDir {
       splitSize = 1024)
 
     for (i <- 1 until keyCount) {
-      val value = store.get(fromLong(i))
+      val value = store(fromLong(i))
       assert(value == fromLong((commitCount - 1) * i))
     }
     store.close()

src/test/scala/io/iohk/iodb/LogShardTest.scala

@@ -27,7 +27,7 @@ class LogShardTest extends TestWithTempDir {
       val key = TestUtils.fromLong(i)
       s.update(TestUtils.fromLong(i), Nil, List((key, key)))
       s.taskShardLogForce()
-      assert(s.getFromShard(key) === key)
+      assert(s.getFromShard(key) === Some(key))
       s.close()
     }
   }

src/test/scala/io/iohk/iodb/LogStoreTest.scala

@@ -20,8 +20,7 @@ class LogStoreTest extends TestWithTempDir {
       Seq.empty, s.map { a => (a, a) })
 
     for (a <- s) {
-      val a2 = store.get(a)
-      assert(a == a2)
+      assert(Some(a) == store.get(a))
     }
     store.close()
   }
@@ -52,7 +51,7 @@ class LogStoreTest extends TestWithTempDir {
     def checkExists(version: Long) = {
       for (i <- 1L until 100) {
         val b = TestUtils.fromLong(i)
-        assert(b == store.get(b))
+        assert(Some(b) == store.get(b))
 
         assert((i == version) == LogStore.logFile(i, dir = dir, filePrefix = filePrefix, isMerged = true).exists())
         assert((i > version) == LogStore.logFile(i, dir = dir, filePrefix = filePrefix).exists())

src/test/scala/io/iohk/iodb/StoreBurnTest.scala

@@ -21,7 +21,7 @@ abstract class StoreBurnTest extends TestWithTempDir {
       keys.foreach { it =>
         if (it != store.get(it))
           store.get(it)
-        assert(it == store.get(it))
+        assert(it == store(it))
       }
 
       val newKeys = (0 until 10000).map(i => TestUtils.randomA())
@@ -50,7 +50,7 @@ abstract class StoreBurnTest extends TestWithTempDir {
 
     while (System.currentTimeMillis() < endTime) {
       keys.foreach { it =>
-        assert(it == store.get(it))
+        assert(it == store(it))
       }
 
       val newKeys = (0 until 10000).map(i => TestUtils.randomA())
@@ -87,8 +87,7 @@ abstract class StoreBurnTest extends TestWithTempDir {
     var version = 1
     while (System.currentTimeMillis() < endTime) {
       keys.foreach { it =>
-
-        assert(it == store.get(it))
+        assert(it == store(it))
       }
 
       val newKeys = (0 until 10000).map(i => TestUtils.randomA())
@@ -121,7 +120,7 @@ abstract class StoreBurnTest extends TestWithTempDir {
 
     while (System.currentTimeMillis() < endTime) {
       keys.foreach { it =>
-        assert(it === store.get(it))
+        assert(it == store(it))
       }
 
       val newKeys = (0 until 10000).map(i => TestUtils.randomA())

src/test/scala/io/iohk/iodb/StoreTest.scala

@@ -34,24 +34,24 @@ abstract class StoreTest extends TestWithTempDir {
     assert(countFiles() === 1 * numberOfFilesPerUpdate)
     assert(file(1).exists())
     assert(store.lastVersionID === v1)
-    assert(a(1) === store.get(a(0)))
-    assert(store.get(a(1)) === null)
+    assert(Some(a(1)) === store.get(a(0)))
+    assert(store.get(a(1)) === None)
 
     store.update(v2, List(a(0)), List.empty)
 
     assert(countFiles() === 2 * numberOfFilesPerUpdate)
     assert(file(2).exists())
     assert(store.lastVersionID === v2)
 
-    assert(store.get(a(0)) === null)
+    assert(store.get(a(0)) === None)
 
     store.rollback(v1)
 
     assert(countFiles() === 1 * numberOfFilesPerUpdate)
     assert(file(1).exists())
     assert(store.lastVersionID === v1)
-    assert(a(1) === store.get(a(0)))
-    assert(store.get(a(1)) === null)
+    assert(a(1) === store(a(0)))
+    assert(store.get(a(1)) === None)
     store.close()
   }
 
@@ -62,7 +62,7 @@ abstract class StoreTest extends TestWithTempDir {
 
     store = makeStore(dir)
     assert(v3 === store.lastVersionID)
-    assert(a(1) === store.get(a(0)))
+    assert(Some(a(1)) === store.get(a(0)))
     store.close()
   }
 
@@ -75,13 +75,13 @@ abstract class StoreTest extends TestWithTempDir {
       store.update(v2, List(a(0)), List((null, a(1))))
     }
     assert(v1 === store.lastVersionID)
-    assert(a(1) === store.get(a(0)))
+    assert(Some(a(1)) === store.get(a(0)))
 
     intercept[NullPointerException] {
       store.update(v3, List(null), List((a(0), a(2))))
     }
     assert(v1 === store.lastVersionID)
-    assert(a(1) === store.get(a(0)))
+    assert(a(1) === store(a(0)))
     store.close()
   }
 
@@ -95,7 +95,7 @@ abstract class StoreTest extends TestWithTempDir {
       store.update(v2, List(a(0)), List((wrongKey, a(1))))
     }
     assert(v1 === store.lastVersionID)
-    assert(a(1) === store.get(a(0)))
+    assert(Some(a(1)) === store.get(a(0)))
     store.close()
   }
 }

src/test/scala/io/iohk/iodb/bench/RocksStore.scala

@@ -32,9 +32,9 @@ class RocksStore(val dir: File) extends Store {
 
 
   /** returns value associated with key */
-  override def get(key: K): V = {
+  override def get(key: K): Option[V] = {
     val ret = db.get(key.data)
-    if (ret == null) null else ByteArrayWrapper(ret)
+    if (ret == null) None else Some(ByteArrayWrapper(ret))
   }
 
   /** returns versionID from last update, used when Scorex starts */