Use try with resources, move unnecessary members to local vars

Use try with resources
Make some class members final
Remove redundant throws declarations
Use JanusGraphFactory.drop() instead of .clear()
Inline some local variables and return
Remove unused methods
Make some members local

Addresses JanusGraph#783, JanusGraph#781, JanusGraph#740. JanusGraph#819, JanusGraph#820 in part

Signed-off-by: Alexander Patrikalakis <amcp@amazon.co.jp>

Author: Alexander Patrikalakis

janusgraph-berkeleyje/src/main/java/org/janusgraph/diskstorage/berkeleyje/BerkeleyJEKeyValueStore.java

@@ -118,17 +118,15 @@ public void acquireLock(StaticBuffer key, StaticBuffer expectedValue, StoreTrans
     @Override
     public RecordIterator<KeyValueEntry> getSlice(KVQuery query, StoreTransaction txh) throws BackendException {
         log.trace("beginning db={}, op=getSlice, tx={}", name, txh);
-        Transaction tx = getTransaction(txh);
-        Cursor cursor = null;
+        final Transaction tx = getTransaction(txh);
         final StaticBuffer keyStart = query.getStart();
         final StaticBuffer keyEnd = query.getEnd();
         final KeySelector selector = query.getKeySelector();
         final List<KeyValueEntry> result = new ArrayList<>();
-        try {
-            DatabaseEntry foundKey = keyStart.as(ENTRY_FACTORY);
-            DatabaseEntry foundData = new DatabaseEntry();
+        final DatabaseEntry foundKey = keyStart.as(ENTRY_FACTORY);
+        final DatabaseEntry foundData = new DatabaseEntry();
 
-            cursor = db.openCursor(tx, null);
+        try (final Cursor cursor = db.openCursor(tx, null)) {
             OperationStatus status = cursor.getSearchKeyRange(foundKey, foundData, getLockMode(txh));
             //Iterate until given condition is satisfied or end of records
             while (status == OperationStatus.SUCCESS) {
@@ -146,40 +144,34 @@ public RecordIterator<KeyValueEntry> getSlice(KVQuery query, StoreTransaction tx
 
                 status = cursor.getNext(foundKey, foundData, getLockMode(txh));
             }
-            log.trace("db={}, op=getSlice, tx={}, resultcount={}", name, txh, result.size());
-//            log.trace("db={}, op=getSlice, tx={}, resultcount={}", name, txh, result.size(), new Throwable("getSlice trace"));
+        } catch (Exception e) {
+            throw new PermanentBackendException(e);
+        }
 
-            return new RecordIterator<KeyValueEntry>() {
-                private final Iterator<KeyValueEntry> entries = result.iterator();
+        log.trace("db={}, op=getSlice, tx={}, resultcount={}", name, txh, result.size());
 
-                @Override
-                public boolean hasNext() {
-                    return entries.hasNext();
-                }
+        return new RecordIterator<KeyValueEntry>() {
+            private final Iterator<KeyValueEntry> entries = result.iterator();
 
-                @Override
-                public KeyValueEntry next() {
-                    return entries.next();
-                }
+            @Override
+            public boolean hasNext() {
+                return entries.hasNext();
+            }
 
-                @Override
-                public void close() {
-                }
+            @Override
+            public KeyValueEntry next() {
+                return entries.next();
+            }
 
-                @Override
-                public void remove() {
-                    throw new UnsupportedOperationException();
-                }
-            };
-        } catch (Exception e) {
-            throw new PermanentBackendException(e);
-        } finally {
-            try {
-                if (cursor != null) cursor.close();
-            } catch (Exception e) {
-                throw new PermanentBackendException(e);
+            @Override
+            public void close() {
             }
-        }
+
+            @Override
+            public void remove() {
+                throw new UnsupportedOperationException();
+            }
+        };
     }
 
     @Override

janusgraph-berkeleyje/src/main/java/org/janusgraph/diskstorage/berkeleyje/BerkeleyJETx.java

@@ -50,18 +50,8 @@ public Transaction getTransaction() {
         return tx;
     }
 
-    void registerCursor(Cursor cursor) {
-        Preconditions.checkArgument(cursor != null);
-        synchronized (openCursors) {
-            //TODO: attempt to remove closed cursors if there are too many
-            openCursors.add(cursor);
-        }
-    }
-
-    private void closeOpenIterators() throws BackendException {
-        for (Cursor cursor : openCursors) {
-            cursor.close();
-        }
+    private void closeOpenIterators() {
+        openCursors.forEach(Cursor::close);
     }
 
     LockMode getLockMode() {

janusgraph-berkeleyje/src/test/java/org/janusgraph/diskstorage/berkeleyje/BerkeleyFixedLengthKCVSTest.java

@@ -22,9 +22,6 @@
 import org.janusgraph.diskstorage.keycolumnvalue.keyvalue.OrderedKeyValueStoreManagerAdapter;
 import org.junit.Test;
 
-import java.util.concurrent.ExecutionException;
-
-
 public class BerkeleyFixedLengthKCVSTest extends KeyColumnValueStoreTest {
 
     public KeyColumnValueStoreManager openStorageManager() throws BackendException {
@@ -33,12 +30,12 @@ public KeyColumnValueStoreManager openStorageManager() throws BackendException {
     }
 
     @Test @Override
-    public void testConcurrentGetSlice() throws ExecutionException, InterruptedException, BackendException {
+    public void testConcurrentGetSlice() {
 
     }
 
     @Test @Override
-    public void testConcurrentGetSliceAndMutate() throws BackendException, ExecutionException, InterruptedException {
+    public void testConcurrentGetSliceAndMutate() {
 
     }
 }

janusgraph-berkeleyje/src/test/java/org/janusgraph/diskstorage/berkeleyje/BerkeleyVariableLengthKCVSTest.java

@@ -21,9 +21,6 @@
 import org.janusgraph.diskstorage.keycolumnvalue.keyvalue.OrderedKeyValueStoreManagerAdapter;
 import org.junit.Test;
 
-import java.util.concurrent.ExecutionException;
-
-
 public class BerkeleyVariableLengthKCVSTest extends KeyColumnValueStoreTest {
 
     public KeyColumnValueStoreManager openStorageManager() throws BackendException {
@@ -32,12 +29,12 @@ public KeyColumnValueStoreManager openStorageManager() throws BackendException {
     }
 
     @Test @Override
-    public void testConcurrentGetSlice() throws ExecutionException, InterruptedException, BackendException {
+    public void testConcurrentGetSlice() {
 
     }
 
     @Test @Override
-    public void testConcurrentGetSliceAndMutate() throws BackendException, ExecutionException, InterruptedException {
+    public void testConcurrentGetSliceAndMutate() {
 
     }
 }

janusgraph-berkeleyje/src/test/java/org/janusgraph/graphdb/berkeleyje/BerkeleyGraphTest.java

@@ -15,8 +15,9 @@
 package org.janusgraph.graphdb.berkeleyje;
 
 import org.janusgraph.core.JanusGraphException;
-import org.janusgraph.core.util.JanusGraphCleanup;
+import org.janusgraph.core.JanusGraphFactory;
 import org.janusgraph.diskstorage.Backend;
+import org.janusgraph.diskstorage.BackendException;
 import org.janusgraph.diskstorage.configuration.ConfigOption;
 import org.janusgraph.graphdb.configuration.GraphDatabaseConfiguration;
 import org.junit.Rule;
@@ -99,12 +100,11 @@ public void testConcurrentConsistencyEnforcement() {
     }
 
     @Test
-    public void testIDBlockAllocationTimeout()
-    {
+    public void testIDBlockAllocationTimeout() throws BackendException {
         config.set("ids.authority.wait-time", Duration.of(0L, ChronoUnit.NANOS));
         config.set("ids.renew-timeout", Duration.of(1L, ChronoUnit.MILLIS));
         close();
-        JanusGraphCleanup.clear(graph);
+        JanusGraphFactory.drop(graph);
         open(config);
         try {
             graph.addVertex();

janusgraph-cassandra/src/main/java/org/janusgraph/diskstorage/cassandra/embedded/CassandraEmbeddedStoreManager.java

@@ -73,7 +73,7 @@ public class CassandraEmbeddedStoreManager extends AbstractCassandraStoreManager
 
     private final IRequestScheduler requestScheduler;
 
-    public CassandraEmbeddedStoreManager(Configuration config) throws BackendException {
+    public CassandraEmbeddedStoreManager(Configuration config) {
         super(config);
 
         String cassandraConfig = CASSANDRA_YAML_DEFAULT;
@@ -120,7 +120,6 @@ public String toString() {
     @Override
     public void close() {
         openStores.clear();
-        CassandraDaemonWrapper.stop();
     }
 
     @Override

janusgraph-cassandra/src/main/java/org/janusgraph/diskstorage/cassandra/thrift/CassandraThriftStoreManager.java

@@ -470,7 +470,7 @@ public boolean exists() throws BackendException {
         }
     }
 
-    private KsDef ensureKeyspaceExists(String keyspaceName) throws TException, BackendException {
+    private KsDef ensureKeyspaceExists(String keyspaceName) throws BackendException {
         CTConnection connection = null;
 
         try {

janusgraph-cassandra/src/test/java/org/janusgraph/diskstorage/cassandra/AbstractCassandraStoreTest.java

@@ -140,7 +140,7 @@ public void testDisableCFCompressor() throws BackendException {
     }
 
     @Test
-    public void testTTLSupported() throws Exception {
+    public void testTTLSupported() {
         StoreFeatures features = manager.getFeatures();
         assertTrue(features.hasCellTTL());
     }

janusgraph-cassandra/src/test/java/org/janusgraph/graphdb/CassandraGraphTest.java

@@ -45,7 +45,7 @@ public static void startCassandra() {
     }
 
     @Test
-    public void testHasTTL() throws Exception {
+    public void testHasTTL() {
         assertTrue(features.hasCellTTL());
     }
 

janusgraph-cassandra/src/test/java/org/janusgraph/graphdb/thrift/ThriftConnectionTest.java

@@ -46,7 +46,7 @@ public class ThriftConnectionTest {
     private CTConnectionFactory.Config factoryConfig;
 
     @Before
-    public void setUp() throws Exception {
+    public void setUp() {
         try {
             Config.setClientMode(true);
             Schema.instance.load(KSMetaData.newKeyspace("janusgraph", "SimpleStrategy", ImmutableMap.of("replication_factor", "1"), true));