fix cassandra&rocksdb&scylladb code checkstyle

hugegraph-cassandra/src/main/java/com/baidu/hugegraph/backend/store/cassandra/CassandraSessionPool.java

@@ -213,7 +213,9 @@ private void tryOpen() {
             assert this.session == null;
             try {
                 this.open();
-            } catch (InvalidQueryException ignored) {}
+            } catch (InvalidQueryException ignored) {
+                // ignore
+            }
         }
 
         @Override

hugegraph-cassandra/src/main/java/com/baidu/hugegraph/backend/store/cassandra/CassandraShard.java

@@ -208,8 +208,8 @@ private Map<TokenRange, Long> getSubSplits(TokenRange tokenRange,
     private Map<TokenRange, Set<Host>> getRangeMap() {
         Metadata metadata = this.session.metadata();
         return metadata.getTokenRanges().stream().collect(Collectors.toMap(
-                p -> p,
-                p -> metadata.getReplicas('"' + this.keyspace + '"', p)));
+            p -> p,
+            p -> metadata.getReplicas('"' + this.keyspace + '"', p)));
     }
 
     private static Map<TokenRange, Long> describeSplits(

hugegraph-cassandra/src/main/java/com/baidu/hugegraph/backend/store/cassandra/CassandraStore.java

@@ -475,12 +475,12 @@ protected boolean existsKeyspace() {
     }
 
     protected boolean existsTable(String table) {
-         KeyspaceMetadata keyspace = this.cluster().getMetadata()
+        KeyspaceMetadata keyspace = this.cluster().getMetadata()
                                          .getKeyspace(this.keyspace);
-         if (keyspace != null && keyspace.getTable(table) != null) {
-             return true;
-         }
-         return false;
+        if (keyspace != null && keyspace.getTable(table) != null) {
+            return true;
+        }
+        return false;
     }
 
     protected void initKeyspace() {

hugegraph-cassandra/src/main/java/com/baidu/hugegraph/backend/store/cassandra/CassandraTable.java

@@ -107,12 +107,12 @@ public Number queryNumber(CassandraSessionPool.Session session,
             statement.setReadTimeoutMillis(timeout * 1000);
             return session.query(statement);
         }, (q, rs) -> {
-            Row row = rs.one();
-            if (row == null) {
-                return IteratorUtils.of(aggregate.defaultValue());
-            }
-            return IteratorUtils.of(row.getLong(0));
-        });
+                Row row = rs.one();
+                if (row == null) {
+                    return IteratorUtils.of(aggregate.defaultValue());
+                }
+                return IteratorUtils.of(row.getLong(0));
+            });
         return aggregate.reduce(results);
     }
 

hugegraph-rocksdb/src/main/java/com/baidu/hugegraph/backend/store/rocksdb/RocksDBMetrics.java

@@ -198,7 +198,7 @@ private double sum(RocksDBSessions.Session session, String property) {
         double total = 0;
         for (RocksDBSessions db : this.dbs) {
             List<String> cfValues = db.property(property);
-            for(String value : cfValues) {
+            for (String value : cfValues) {
                 total += Double.parseDouble(value);
             }
             for (String table : db.openedTables()) {
@@ -212,7 +212,7 @@ private double sum(String property) {
         double total = 0;
         for (RocksDBSessions db : this.dbs) {
             List<String> cfValues = db.property(property);
-            for(String value : cfValues) {
+            for (String value : cfValues) {
                 total += Double.parseDouble(value);
             }
         }

hugegraph-rocksdb/src/main/java/com/baidu/hugegraph/backend/store/rocksdb/RocksDBOptions.java

@@ -168,7 +168,8 @@ public static synchronized RocksDBOptions instance() {
     public static final ConfigOption<Integer> MAX_BG_JOBS =
             new ConfigOption<>(
                     "rocksdb.max_background_jobs",
-                    "Maximum number of concurrent background jobs, including flushes and compactions.",
+                    "Maximum number of concurrent background jobs, " +
+                    "including flushes and compactions.",
                     rangeInt(1, Integer.MAX_VALUE),
                     8
             );

hugegraph-rocksdb/src/main/java/com/baidu/hugegraph/backend/store/rocksdb/RocksDBSessions.java

@@ -39,10 +39,13 @@ public RocksDBSessions(HugeConfig config, String database, String store) {
     public abstract Set<String> openedTables();
 
     public abstract void createTable(String... tables) throws RocksDBException;
+
     public abstract void dropTable(String... tables) throws RocksDBException;
+
     public abstract boolean existsTable(String table);
 
     public abstract List<String> property(String property);
+
     public abstract void compactRange();
 
     public abstract RocksDBSessions copy(HugeConfig config,
@@ -67,7 +70,7 @@ public abstract String hardLinkSnapshot(String snapshotPath)
     /**
      * Session for RocksDB
      */
-    public static abstract class Session extends AbstractBackendSession {
+    public abstract static class Session extends AbstractBackendSession {
 
         public static final int SCAN_ANY = 0x80;
         public static final int SCAN_PREFIX_BEGIN = 0x01;
@@ -78,29 +81,40 @@ public static abstract class Session extends AbstractBackendSession {
         public static final int SCAN_LTE_END = 0x30;
 
         public abstract String dataPath();
+
         public abstract String walPath();
 
         public abstract String property(String table, String property);
+
         public abstract Pair<byte[], byte[]> keyRange(String table);
+
         public abstract void compactRange(String table);
 
         public abstract void put(String table, byte[] key, byte[] value);
+
         public abstract void merge(String table, byte[] key, byte[] value);
+
         public abstract void increase(String table, byte[] key, byte[] value);
 
         public abstract void delete(String table, byte[] key);
+
         public abstract void deleteSingle(String table, byte[] key);
+
         public abstract void deletePrefix(String table, byte[] key);
+
         public abstract void deleteRange(String table,
                                          byte[] keyFrom, byte[] keyTo);
 
         public abstract byte[] get(String table, byte[] key);
+
         public abstract BackendColumnIterator get(String table,
                                                   List<byte[]> keys);
 
         public abstract BackendColumnIterator scan(String table);
+
         public abstract BackendColumnIterator scan(String table,
                                                    byte[] prefix);
+
         public abstract BackendColumnIterator scan(String table,
                                                    byte[] keyFrom,
                                                    byte[] keyTo,

hugegraph-rocksdb/src/main/java/com/baidu/hugegraph/backend/store/rocksdb/RocksDBStdSessions.java

@@ -236,7 +236,7 @@ public List<String> property(String property) {
                 }
             }
             return values;
-        } catch(RocksDBException | UnsupportedOperationException e) {
+        } catch (RocksDBException | UnsupportedOperationException e) {
             throw new BackendException(e);
         }
     }
@@ -728,7 +728,8 @@ public String property(String table, String property) {
 
         @Override
         public Pair<byte[], byte[]> keyRange(String table) {
-            byte[] startKey, endKey;
+            byte[] startKey;
+            byte[] endKey;
             try (CFHandle cf = cf(table);
                  RocksIterator iter = rocksdb().newIterator(cf.get())) {
                 iter.seekToFirst();
@@ -1058,14 +1059,14 @@ private boolean match(int expected) {
         @SuppressWarnings("unused")
         private void dump() {
             this.seek();
-            System.out.println(">>>> scan from " + this.table + ": "  +
-                               (this.keyBegin == null ? "*" :
-                                StringEncoding.format(this.keyBegin)) +
-                               (this.iter.isValid() ? "" : " - No data"));
+            LOG.info(">>>> scan from {}: {}{}", 
+                      this.table,
+                      this.keyBegin == null ? "*" : StringEncoding.format(this.keyBegin),
+                      this.iter.isValid() ? "" : " - No data");
             for (; this.iter.isValid(); this.iter.next()) {
-                System.out.println(String.format("%s=%s",
-                                   StringEncoding.format(this.iter.key()),
-                                   StringEncoding.format(this.iter.value())));
+                LOG.info("{}={}",
+                          StringEncoding.format(this.iter.key()),
+                          StringEncoding.format(this.iter.value()));
             }
         }
 

hugegraph-rocksdb/src/main/java/com/baidu/hugegraph/backend/store/rocksdb/RocksDBTables.java

@@ -50,7 +50,7 @@ public long getCounter(Session session, HugeType type) {
             byte[] key = new byte[]{type.code()};
             byte[] value = session.get(this.table(), key);
             if (value != null) {
-                return l(value);
+                return toLong(value);
             } else {
                 return 0L;
             }
@@ -59,16 +59,16 @@ public long getCounter(Session session, HugeType type) {
         public void increaseCounter(Session session, HugeType type,
                                     long increment) {
             byte[] key = new byte[]{type.code()};
-            session.increase(this.table(), key, b(increment));
+            session.increase(this.table(), key, toBytes(increment));
         }
 
-        private static byte[] b(long value) {
+        private static byte[] toBytes(long value) {
             return ByteBuffer.allocate(Long.BYTES)
                              .order(ByteOrder.nativeOrder())
                              .putLong(value).array();
         }
 
-        private static long l(byte[] bytes) {
+        private static long toLong(byte[] bytes) {
             assert bytes.length == Long.BYTES;
             return ByteBuffer.wrap(bytes)
                              .order(ByteOrder.nativeOrder())
@@ -282,11 +282,15 @@ protected BackendColumnIterator queryByCond(Session session,
                         break;
                     case GTE:
                         minEq = true;
+                        min = (Id) r.value();
+                        break;
                     case GT:
                         min = (Id) r.value();
                         break;
                     case LTE:
                         maxEq = true;
+                        max = (Id) r.value();
+                        break;
                     case LT:
                         max = (Id) r.value();
                         break;
@@ -323,7 +327,7 @@ public RangeIntIndex(String store) {
         }
     }
 
-    public static class RangeFloatIndex extends RangeIndex{
+    public static class RangeFloatIndex extends RangeIndex {
 
         public static final String TABLE = HugeType.RANGE_FLOAT_INDEX.string();
 
@@ -341,7 +345,7 @@ public RangeLongIndex(String store) {
         }
     }
 
-    public static class RangeDoubleIndex extends RangeIndex{
+    public static class RangeDoubleIndex extends RangeIndex {
 
         public static final String TABLE = HugeType.RANGE_DOUBLE_INDEX.string();