DataBases changes tracker introduced

+ TrackDatabase object wraps the Database and support commit/rollback

ethereumj-core/src/main/java/org/ethereum/db/ByteArrayWrapper.java

@@ -0,0 +1,45 @@
+package org.ethereum.db;
+
+import java.util.Arrays;
+
+/**
+ * www.ethereumJ.com
+ *
+ * @author: Roman Mandeleil
+ * Created on: 11/06/2014 15:02
+ */
+
+public class ByteArrayWrapper {
+
+    private final byte[] data;
+
+    public ByteArrayWrapper(byte[] data)
+    {
+        if (data == null)
+        {
+            throw new NullPointerException();
+        }
+        this.data = data;
+    }
+
+    @Override
+    public boolean equals(Object other)
+    {
+        if (!(other instanceof ByteArrayWrapper))
+        {
+            return false;
+        }
+        return Arrays.equals(data, ((ByteArrayWrapper)other).data);
+    }
+
+    @Override
+    public int hashCode()
+    {
+        return Arrays.hashCode(data);
+    }
+
+
+    public byte[] getData() {
+        return data;
+    }
+}

ethereumj-core/src/main/java/org/ethereum/db/TrackDatabase.java

@@ -0,0 +1,76 @@
+package org.ethereum.db;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * www.ethereumJ.com
+ *
+ * @author: Roman Mandeleil
+ * Created on: 11/06/2014 14:09
+ */
+
+public class TrackDatabase {
+
+    private Database db;
+
+    private boolean trackingChanges;
+    private Map<ByteArrayWrapper, byte[]> changes;
+    private Map<ByteArrayWrapper, byte[]> deletes;
+
+    public TrackDatabase(Database db) {
+        this.db = db;
+    }
+
+
+    public void startTrack(){
+        changes = new HashMap<>();
+        deletes = new HashMap<>();
+        trackingChanges = true;
+    }
+
+    public void commitTrack(){
+        for(ByteArrayWrapper key : changes.keySet()){
+            db.put(key.getData(), changes.get(key));
+        }
+        changes = null;
+        trackingChanges = false;
+    }
+
+    public void rollbackTrack(){
+        changes = new HashMap<>();
+        deletes = new HashMap<>();
+        changes = null;
+        trackingChanges = false;
+    }
+
+    public void put(byte[] key, byte[] value) {
+        if (trackingChanges){
+            changes.put(  new ByteArrayWrapper(key)  , value);
+        } else {
+            db.put(key, value);
+        }
+    }
+
+    public byte[] get(byte[] key) {
+        if(trackingChanges){
+            ByteArrayWrapper wKey = new ByteArrayWrapper(key);
+            if (deletes.get(wKey) != null) return null;
+            if (changes.get(wKey) != null) return changes.get(wKey);
+            return db.get(key);
+        }
+        return db.get(key);
+    }
+
+    /** Delete object (key) from db **/
+    public void delete(byte[] key) {
+        if (trackingChanges){
+            ByteArrayWrapper wKey = new ByteArrayWrapper(key);
+            deletes.put(wKey, null);
+        } else {
+            db.delete(key);
+        }
+    }
+
+
+}