Fix rocksDB storage so that clear removes all values (#1894)

Signed-off-by: Adrian Sutton <adrian.sutton@consensys.net>

services/kvstore/src/main/java/tech/pegasys/pantheon/services/kvstore/ColumnarRocksDbKeyValueStorage.java

@@ -184,7 +184,9 @@ public class ColumnarRocksDbKeyValueStorage
         final byte[] firstKey = rocksIterator.key();
         rocksIterator.seekToLast();
         if (rocksIterator.isValid()) {
-          db.deleteRange(segmentHandle, firstKey, rocksIterator.key());
+          final byte[] lastKey = rocksIterator.key();
+          db.deleteRange(segmentHandle, firstKey, lastKey);
+          db.delete(segmentHandle, lastKey);
         }
       }
     } catch (final RocksDBException e) {

services/kvstore/src/main/java/tech/pegasys/pantheon/services/kvstore/RocksDbKeyValueStorage.java

@@ -14,6 +14,7 @@ package tech.pegasys.pantheon.services.kvstore;
 
 import tech.pegasys.pantheon.metrics.MetricsSystem;
 import tech.pegasys.pantheon.metrics.OperationTimer;
+import tech.pegasys.pantheon.services.kvstore.SegmentedKeyValueStorage.StorageException;
 import tech.pegasys.pantheon.services.util.RocksDbUtil;
 import tech.pegasys.pantheon.util.bytes.BytesValue;
 
@@ -76,16 +77,16 @@ public class RocksDbKeyValueStorage implements KeyValueStorage, Closeable {
   @Override
   public void clear() {
     try (final RocksIterator rocksIterator = db.newIterator()) {
-      if (!rocksIterator.isValid()) {
-        return;
-      }
       rocksIterator.seekToFirst();
-      final byte[] firstKey = rocksIterator.key();
-      rocksIterator.seekToLast();
-      if (!rocksIterator.isValid()) {
-        return;
+      if (rocksIterator.isValid()) {
+        final byte[] firstKey = rocksIterator.key();
+        rocksIterator.seekToLast();
+        if (rocksIterator.isValid()) {
+          final byte[] lastKey = rocksIterator.key();
+          db.deleteRange(firstKey, lastKey);
+          db.delete(lastKey);
+        }
       }
-      db.deleteRange(firstKey, rocksIterator.key());
     } catch (final RocksDBException e) {
       throw new StorageException(e);
     }

services/kvstore/src/test/java/tech/pegasys/pantheon/services/kvstore/AbstractKeyValueStorageTest.java

@@ -76,6 +76,22 @@ public abstract class AbstractKeyValueStorageTest {
     assertThat(store.containsKey(BytesValue.fromHexString("12"))).isTrue();
   }
 
+  @Test
+  public void clearRemovesAll() throws Exception {
+    final KeyValueStorage store = createStore();
+    Transaction tx = store.startTransaction();
+    tx.put(BytesValue.fromHexString("0F"), BytesValue.fromHexString("0ABC"));
+    tx.put(BytesValue.fromHexString("10"), BytesValue.fromHexString("0ABC"));
+    tx.put(BytesValue.fromHexString("11"), BytesValue.fromHexString("0ABC"));
+    tx.put(BytesValue.fromHexString("12"), BytesValue.fromHexString("0ABC"));
+    tx.commit();
+    store.clear();
+    assertThat(store.containsKey(BytesValue.fromHexString("0F"))).isFalse();
+    assertThat(store.containsKey(BytesValue.fromHexString("10"))).isFalse();
+    assertThat(store.containsKey(BytesValue.fromHexString("11"))).isFalse();
+    assertThat(store.containsKey(BytesValue.fromHexString("12"))).isFalse();
+  }
+
   @Test
   public void containsKey() throws Exception {
     final KeyValueStorage store = createStore();