refact(cassandra): update pom & ApiVersion & fix style

TODO: and we need also check the 0.69 in pom

hugegraph-api/pom.xml

@@ -185,6 +185,7 @@
                             </addDefaultSpecificationEntries>
                         </manifest>
                         <manifestEntries>
+                            <!-- TODO: update it -->
                             <Implementation-Version>0.69.0.0</Implementation-Version>
                         </manifestEntries>
                     </archive>

hugegraph-api/src/main/java/org/apache/hugegraph/version/ApiVersion.java

@@ -24,38 +24,35 @@
 
 public final class ApiVersion {
 
-    /**
+    /*
      * API Version change log
-     *
+     * <p>
      * version 0.2:
      * [0.2] HugeGraph-527: First add the version to the hugegraph module
      * [0.3] HugeGraph-525: Add versions check of components and api
-     * [0.4] HugeGraph-162: Add schema builder to separate client and
-     *       inner interface.
+     * [0.4] HugeGraph-162: Add schema builder to separate client and inner interface.
      * [0.5] HugeGraph-498: Support three kind of id strategy
-     *
+     * <p>
      * version 0.3:
-     *
-     * [0.6] HugeGraph-614: Add update api of VL/EL to support append and
-     *       eliminate action
+     * <p>
+     * [0.6] HugeGraph-614: Add update api of VL/EL to support append and eliminate action
      * [0.7] HugeGraph-245: Add nullable-props for vertex label and edge label
      * [0.8] HugeGraph-396: Continue to improve variables implementation
-     * [0.9] HugeGraph-894: Add vertex/edge update api to add property and
-     *       remove property
+     * [0.9] HugeGraph-894: Add vertex/edge update api to add property and remove property
      * [0.10] HugeGraph-919: Add condition query for vertex/edge list API
-     *
+     * <p>
      * version 0.4:
-     * [0.11] HugeGraph-938: Remove useless indexnames field in VL/EL API
+     * [0.11] HugeGraph-938: Remove useless index-names field in VL/EL API
      * [0.12] HugeGraph-589: Add schema id for all schema element
      * [0.13] HugeGraph-956: Support customize string/number id strategy
-     *
+     * <p>
      * version 0.5:
      * [0.14] HugeGraph-1085: Add enable_label_index to VL/EL
      * [0.15] HugeGraph-1105: Support paging for large amounts of records
      * [0.16] HugeGraph-944: Support rest shortest path, k-out, k-neighbor
      * [0.17] HugeGraph-944: Support rest shortest path, k-out, k-neighbor
      * [0.18] HugeGraph-81: Change argument "checkVertex" to "check_vertex"
-     *
+     * <p>
      * version 0.6:
      * [0.19] HugeGraph-1195: Support eliminate userdata on schema
      * [0.20] HugeGraph-1210: Add paths api to find paths between two nodes
@@ -67,35 +64,35 @@ public final class ApiVersion {
      * [0.26] HugeGraph-1273: Add some monitoring counters to integrate with
      *        gremlin's monitoring framework
      * [0.27] HugeGraph-889: Use asynchronous mechanism to do schema deletion
-     *
+     * <p>
      * version 0.8:
      * [0.28] Issue-153: Add task-cancel API
      * [0.29] Issue-39: Add rays and rings RESTful API
      * [0.30] Issue-32: Change index create API to return indexLabel and task id
      * [0.31] Issue-182: Support restore graph in restoring and merging mode
-     *
+     * <p>
      * version 0.9:
      * [0.32] Issue-250: Keep depth and degree consistent for traverser api
      * [0.33] Issue-305: Implement customized paths and crosspoints RESTful API
      * [0.34] Issue-307: Let VertexAPI use simplified property serializer
      * [0.35] Issue-287: Support pagination when do index query
      * [0.36] Issue-360: Support paging for scan api
      * [0.37] Issue-391: Add skip_super_node for shortest path
-     * [0.38] Issue-274: Add personalrank and neighborrank RESTful API
-     *
+     * [0.38] Issue-274: Add personal-rank and neighbor-rank RESTful API
+     * <p>
      * version 0.10:
      * [0.39] Issue-522: Add profile RESTful API
      * [0.40] Issue-523: Add source_in_ring args for rings RESTful API
      * [0.41] Issue-493: Support batch updating properties by multiple strategy
      * [0.42] Issue-176: Let gremlin error response consistent with RESTful's
-     * [0.43] Issue-270 & 398: support shard-index and vertex + sortkey prefix,
+     * [0.43] Issue-270 & 398: support shard-index and vertex + sort-key prefix,
      *        and split range to rangeInt, rangeFloat, rangeLong and rangeDouble
      * [0.44] Issue-633: Support unique index
      * [0.45] Issue-673: Add 'OVERRIDE' update strategy
      * [0.46] Issue-618 & 694: Support UUID id type
      * [0.47] Issue-691: Support aggregate property
      * [0.48] Issue-686: Support get schema by names
-     *
+     * <p>
      * version 0.11:
      * [0.49] Issue-670: Support fusiform similarity API
      * [0.50] Issue-746: Support userdata for index label
@@ -121,11 +118,15 @@ public final class ApiVersion {
      * [0.69] Issue-1748: Support Cypher query RESTful API
      */
 
-    // The second parameter of Version.of() is for IDE running without JAR
+    /**
+     * The second parameter of Version.of() is for IDE running without JAR
+     * TODO: what shall we set for this version? (consider the basic compatibility)
+     */
     public static final Version VERSION = Version.of(ApiVersion.class, "0.69");
 
     public static void check() {
         // Check version of hugegraph-core. Firstly do check from version 0.3
+        // TODO: what shall we set for this version? (consider the basic compatibility)
         VersionUtil.check(CoreVersion.VERSION, "0.13", "0.14", CoreVersion.NAME);
     }
 }

hugegraph-cassandra/src/main/java/com/datastax/driver/core/querybuilder/Clauses.java

@@ -28,8 +28,7 @@
 public class Clauses {
 
     public static boolean needAllowFiltering(Clause clause) {
-        return ContainsKeyClause.class.isInstance(clause) ||
-               ContainsClause.class.isInstance(clause);
+        return clause instanceof ContainsKeyClause || clause instanceof ContainsClause;
     }
 
     public static Clause and(Clause left, Clause right) {
@@ -42,9 +41,9 @@ public static Clause in(String name, List<?> values) {
 
     static class BinClause extends Clause {
 
-        private Clause left;
-        private String op;
-        private Clause right;
+        private final Clause left;
+        private final String op;
+        private final Clause right;
 
         public BinClause(Clause left, String op, Clause right) {
             this.left = left;
@@ -64,11 +63,7 @@ Object firstValue() {
 
         @Override
         boolean containsBindMarker() {
-            if (Utils.containsBindMarker(this.left) ||
-                Utils.containsBindMarker(this.right)) {
-                return true;
-            }
-            return false;
+            return Utils.containsBindMarker(this.left) || Utils.containsBindMarker(this.right);
         }
 
         @Override
@@ -89,7 +84,7 @@ void appendTo(StringBuilder sb, List<Object> variables,
     static class AndClause extends BinClause {
 
         public AndClause(Clause left, Clause right) {
-            super(left, "AND",  right);
+            super(left, "AND", right);
         }
     }
 }

hugegraph-cassandra/src/main/java/org/apache/hugegraph/backend/store/cassandra/CassandraEntryIterator.java

@@ -28,6 +28,7 @@
 import org.apache.hugegraph.backend.store.BackendEntry;
 import org.apache.hugegraph.backend.store.BackendEntryIterator;
 import org.apache.hugegraph.util.E;
+
 import com.datastax.driver.core.ExecutionInfo;
 import com.datastax.driver.core.PagingState;
 import com.datastax.driver.core.ResultSet;
@@ -39,7 +40,7 @@ public class CassandraEntryIterator extends BackendEntryIterator {
     private final Iterator<Row> rows;
     private final BiFunction<BackendEntry, Row, BackendEntry> merger;
 
-    private int fetchdPageSize;
+    private int fetchedPageSize;
     private long expected;
     private BackendEntry next;
 
@@ -50,7 +51,7 @@ public CassandraEntryIterator(ResultSet results, Query query,
         this.rows = results.iterator();
         this.merger = merger;
 
-        this.fetchdPageSize = results.getAvailableWithoutFetching();
+        this.fetchedPageSize = results.getAvailableWithoutFetching();
         this.next = null;
 
         if (query.paging()) {
@@ -60,20 +61,20 @@ public CassandraEntryIterator(ResultSet results, Query query,
             this.expected = PageState.fromString(query.page()).offset();
             this.skipPageOffset(query.page());
             // Check the number of available rows
-            E.checkState(this.fetchdPageSize <= query.limit(),
+            E.checkState(this.fetchedPageSize <= query.limit(),
                          "Unexpected fetched page size: %s",
-                         this.fetchdPageSize);
+                         this.fetchedPageSize);
             if (results.isFullyFetched()) {
                 /*
                  * All results fetched
                  * NOTE: it may be enough or not enough for the entire page
                  */
-                this.expected = this.fetchdPageSize;
+                this.expected = this.fetchedPageSize;
             } else {
                 /*
-                 * Not fully fetched, that's fetchdPageSize == query.limit(),
+                 * Not fully fetched, that's fetchedPageSize == query.limit(),
                  *
-                 * NOTE: but there may be fetchdPageSize < query.limit(), means
+                 * NOTE: but there may be fetchedPageSize < query.limit(), means
                  * not fetched the entire page (ScyllaDB may go here #1340),
                  * try to fetch next page later until got the expected count.
                  * Can simulate by: `select.setFetchSize(total - 1)`
@@ -104,10 +105,10 @@ protected final boolean fetch() {
             this.expected--;
             Row row = this.rows.next();
             if (this.query.paging()) {
-                // Update fetchdPageSize if auto fetch the next page
+                // Update fetchedPageSize if auto fetch the next page
                 if (this.expected > 0L && this.availableLocal() == 0) {
                     if (this.rows.hasNext()) {
-                        this.fetchdPageSize = this.availableLocal();
+                        this.fetchedPageSize = this.availableLocal();
                     }
                 }
             }
@@ -167,7 +168,7 @@ protected PageState pageState() {
             ExecutionInfo previous = infos.get(infos.size() - 2);
             PagingState page = previous.getPagingState();
             position = page.toBytes();
-            offset = this.fetchdPageSize - extra;
+            offset = this.fetchedPageSize - extra;
         } else {
             PagingState page = this.results.getExecutionInfo().getPagingState();
             if (page == null || this.expected > 0L) {

hugegraph-cassandra/src/main/java/org/apache/hugegraph/backend/store/cassandra/CassandraMetrics.java

@@ -24,7 +24,6 @@
 import java.net.Inet4Address;
 import java.net.Inet6Address;
 import java.net.InetAddress;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
@@ -34,9 +33,6 @@
 import org.apache.cassandra.metrics.CassandraMetricsRegistry.JmxTimerMBean;
 import org.apache.cassandra.tools.NodeProbe;
 import org.apache.cassandra.tools.nodetool.Compact;
-import org.apache.tinkerpop.gremlin.util.NumberHelper;
-import org.slf4j.Logger;
-
 import org.apache.hugegraph.backend.store.BackendMetrics;
 import org.apache.hugegraph.backend.store.BackendStoreProvider;
 import org.apache.hugegraph.backend.store.BackendTable;
@@ -48,6 +44,9 @@
 import org.apache.hugegraph.util.InsertionOrderUtil;
 import org.apache.hugegraph.util.Log;
 import org.apache.hugegraph.util.UnitUtil;
+import org.apache.tinkerpop.gremlin.util.NumberHelper;
+import org.slf4j.Logger;
+
 import com.datastax.driver.core.Cluster;
 import com.datastax.driver.core.Host;
 import com.google.common.collect.ImmutableList;
@@ -94,7 +93,7 @@ protected String keyspace() {
     }
 
     protected List<String> tables() {
-        return Collections.unmodifiableList(this.tables);
+        return this.tables;
     }
 
     protected Map<String, Object> getMetricsByHost(String host) {

hugegraph-cassandra/src/main/java/org/apache/hugegraph/backend/store/cassandra/CassandraSessionPool.java

@@ -139,7 +139,7 @@ public final boolean clusterConnected() {
 
     /**
      * The Session class is a wrapper of driver Session
-     * Expect every thread hold a its own session(wrapper)
+     * Expect every thread hold its own session(wrapper)
      */
     public final class Session extends AbstractBackendSession {
 

hugegraph-cassandra/src/main/java/org/apache/hugegraph/backend/store/cassandra/CassandraShard.java

@@ -58,7 +58,8 @@
  * CassandraShard is used for cassandra scanning operations.
  * Each shard represents a range of tokens for a node.
  * Reading data from a given shard does not cross multiple nodes.
- * Refer to AbstractColumnFamilyInputFormat from https://github.com/2013Commons/hive-cassandra/
+ * Refer to AbstractColumnFamilyInputFormat from:
+ * <a href="https://github.com/2013Commons/hive-cassandra/">...</a>
  */
 public class CassandraShard {
 
@@ -89,10 +90,8 @@ public CassandraShard(CassandraSessionPool.Session session,
      */
     public List<Shard> getSplits(long splitPartitions, long splitSize) {
         // Canonical ranges, split into pieces, fetch the splits in parallel
-        ExecutorService executor = new ThreadPoolExecutor(
-                0, 128, 60L,
-                TimeUnit.SECONDS,
-                new LinkedBlockingQueue<Runnable>());
+        ExecutorService executor = new ThreadPoolExecutor(0, 128, 60L, TimeUnit.SECONDS,
+                                                          new LinkedBlockingQueue<>());
 
         List<Shard> splits = new ArrayList<>();
         try {
@@ -140,10 +139,8 @@ public List<Shard> getSplits(long splitPartitions, long splitSize) {
     public List<Shard> getSplits(String start, String end,
                                  int splitPartitions, int splitSize) {
 
-        ExecutorService executor = new ThreadPoolExecutor(
-                0, 128, 60L,
-                TimeUnit.SECONDS,
-                new LinkedBlockingQueue<Runnable>());
+        ExecutorService executor = new ThreadPoolExecutor(0, 128, 60L, TimeUnit.SECONDS,
+                                                          new LinkedBlockingQueue<>());
 
         List<Shard> splits = new ArrayList<>();
         try {
@@ -249,8 +246,7 @@ private static Map<TokenRange, Long> describeSplits(
         /*
          * If we have no data on this split or the size estimate is 0,
          * return the full split i.e., do not sub-split
-         * Assume smallest granularity of partition count available from
-         * CASSANDRA-7688.
+         * Assume the smallest granularity of partition count available from CASSANDRA-7688.
          */
         if (splitCount == 0) {
             return ImmutableMap.of(tokenRange, (long) 128);