HIVE-24424: Use PreparedStatements in DbNotificationListener getNextN…

…LId (David Mollitor reviewed by Bodor Laszlo, Miklos Gergely)

hcatalog/server-extensions/src/main/java/org/apache/hive/hcatalog/listener/DbNotificationListener.java

@@ -29,6 +29,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.concurrent.TimeUnit;
 
 import com.google.common.annotations.VisibleForTesting;
@@ -151,6 +152,10 @@
 public class DbNotificationListener extends TransactionalMetaStoreEventListener {
 
   private static final Logger LOG = LoggerFactory.getLogger(DbNotificationListener.class.getName());
+
+  private static final String NL_SEL_SQL = "select \"NEXT_VAL\" from \"SEQUENCE_TABLE\" where \"SEQUENCE_NAME\" = ?";
+  private static final String NL_UPD_SQL = "update \"SEQUENCE_TABLE\" set \"NEXT_VAL\" = ? where \"SEQUENCE_NAME\" = ?";
+
   private static CleanerThread cleaner = null;
 
   private Configuration conf;
@@ -972,28 +977,41 @@ private static void close(ResultSet rs) {
     }
   }
 
-  private long getNextNLId(Statement stmt, SQLGenerator sqlGenerator, String sequence)
+  /**
+   * Get the next notification log ID.
+   *
+   * @return The next ID to use for a notification log message
+   * @throws SQLException if a database access error occurs or this method is
+   *           called on a closed connection
+   * @throws MetaException if the sequence table is not properly initialized
+   */
+  private long getNextNLId(Connection con, SQLGenerator sqlGenerator, String sequence)
           throws SQLException, MetaException {
-    String s = sqlGenerator.addForUpdateClause("select \"NEXT_VAL\" from " +
-            "\"SEQUENCE_TABLE\" where \"SEQUENCE_NAME\" = " + quoteString(sequence));
-    LOG.debug("Going to execute query <" + s + ">");
-    ResultSet rs = null;
-    try {
-      rs = stmt.executeQuery(s);
-      if (!rs.next()) {
-        throw new MetaException("Transaction database not properly configured, can't find next NL id.");
+
+    final String sfuSql = sqlGenerator.addForUpdateClause(NL_SEL_SQL);
+    Optional<Long> nextSequenceValue = Optional.empty();
+
+    LOG.debug("Going to execute query [{}][1={}]", sfuSql, sequence);
+    try (PreparedStatement stmt = con.prepareStatement(sfuSql)) {
+      stmt.setString(1, sequence);
+      ResultSet rs = stmt.executeQuery();
+      if (rs.next()) {
+        nextSequenceValue = Optional.of(rs.getLong(1));
       }
+    }
 
-      long nextNLId = rs.getLong(1);
-      long updatedNLId = nextNLId + 1;
-      s = "update \"SEQUENCE_TABLE\" set \"NEXT_VAL\" = " + updatedNLId + " where \"SEQUENCE_NAME\" = " +
-              quoteString(sequence);
-      LOG.debug("Going to execute update <" + s + ">");
-      stmt.executeUpdate(s);
-      return nextNLId;
-    }finally {
-      close(rs);
+    final long updatedNLId = 1L + nextSequenceValue.orElseThrow(
+        () -> new MetaException("Transaction database not properly configured, failed to determine next NL ID"));
+
+    LOG.debug("Going to execute query [{}][1={}][2={}]", NL_UPD_SQL, updatedNLId, sequence);
+    try (PreparedStatement stmt = con.prepareStatement(NL_UPD_SQL)) {
+      stmt.setLong(1, updatedNLId);
+      stmt.setString(2, sequence);
+      final int rowCount = stmt.executeUpdate();
+      LOG.debug("Updated {} rows for sequnce {}", rowCount, sequence);
     }
+
+    return nextSequenceValue.get();
   }
 
   private void addWriteNotificationLog(NotificationEvent event, AcidWriteEvent acidWriteEvent, Connection dbConn,
@@ -1030,7 +1048,7 @@ private void addWriteNotificationLog(NotificationEvent event, AcidWriteEvent aci
       rs = pst.executeQuery();
       if (!rs.next()) {
         // if rs is empty then no lock is taken and thus it can not cause deadlock.
-        long nextNLId = getNextNLId(stmt, sqlGenerator,
+        long nextNLId = getNextNLId(dbConn, sqlGenerator,
                 "org.apache.hadoop.hive.metastore.model.MTxnWriteNotificationLog");
         s = "insert into \"TXN_WRITE_NOTIFICATION_LOG\" " +
                 "(\"WNL_ID\", \"WNL_TXNID\", \"WNL_WRITEID\", \"WNL_DATABASE\", \"WNL_TABLE\", " +
@@ -1135,7 +1153,7 @@ private void addNotificationLog(NotificationEvent event, ListenerEvent listenerE
       LOG.debug("Going to execute update <" + s + ">");
       stmt.executeUpdate(s);
 
-      long nextNLId = getNextNLId(stmt, sqlGenerator,
+      long nextNLId = getNextNLId(dbConn, sqlGenerator,
               "org.apache.hadoop.hive.metastore.model.MNotificationLog");
 
       String insertVal;