Fix sonar check in schema module (#10297)

server/src/main/java/org/apache/iotdb/db/exception/metadata/AlignedTimeseriesException.java

@@ -24,10 +24,6 @@ import org.apache.iotdb.rpc.TSStatusCode;
 
 public class AlignedTimeseriesException extends MetadataException {
 
-  /**
-   * @param message excepetion message
-   * @param path related timeseries path
-   */
   public AlignedTimeseriesException(String message, String path) {
     super(String.format("%s (Path: %s)", message, path));
     errorCode = TSStatusCode.ALIGNED_TIMESERIES_ERROR.getStatusCode();

server/src/main/java/org/apache/iotdb/db/exception/metadata/DataTypeMismatchException.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.exception.metadata;
 
 import org.apache.iotdb.commons.exception.MetadataException;
@@ -31,16 +32,17 @@ public class DataTypeMismatchException extends MetadataException {
       Object value) {
     super(
         String.format(
-            "data type of %s.%s is not consistent, registered type %s, inserting type %s, timestamp %s, value %s",
+            "data type of %s.%s is not consistent, "
+                + "registered type %s, inserting type %s, timestamp %s, value %s",
             deviceName,
             measurementName,
             typeInSchema,
             insertType,
             time,
-            value == null
-                ? "null"
-                : value.toString().length() < 100
-                    ? value.toString()
-                    : value.toString().substring(0, 100)));
+            value == null ? "null" : processValue(value.toString())));
+  }
+
+  private static String processValue(String value) {
+    return value.length() < 100 ? value : value.substring(0, 100);
   }
 }

server/src/main/java/org/apache/iotdb/db/exception/metadata/DuplicateInsertException.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.exception.metadata;
 
 import org.apache.iotdb.commons.exception.MetadataException;

server/src/main/java/org/apache/iotdb/db/exception/metadata/IllegalParameterOfPathException.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.exception.metadata;
 
 import org.apache.iotdb.commons.exception.MetadataException;

server/src/main/java/org/apache/iotdb/db/exception/metadata/MNodeTypeMismatchException.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.exception.metadata;
 
 import org.apache.iotdb.commons.exception.MetadataException;

server/src/main/java/org/apache/iotdb/db/exception/metadata/MeasurementAlreadyExistException.java

@@ -26,7 +26,7 @@ import org.apache.iotdb.rpc.TSStatusCode;
 
 public class MeasurementAlreadyExistException extends MetadataException {
 
-  private MeasurementPath measurementPath;
+  private final MeasurementPath measurementPath;
 
   public MeasurementAlreadyExistException(String path, MeasurementPath measurementPath) {
     super(

server/src/main/java/org/apache/iotdb/db/exception/metadata/SchemaDirCreationFailureException.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.exception.metadata;
 
 import org.apache.iotdb.commons.exception.MetadataException;

server/src/main/java/org/apache/iotdb/db/exception/metadata/SchemaQuotaExceededException.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.exception.metadata;
 
 import org.apache.iotdb.commons.exception.MetadataException;
@@ -26,7 +27,10 @@ public class SchemaQuotaExceededException extends MetadataException {
   public SchemaQuotaExceededException(ClusterSchemaQuotaLevel level, long limit) {
     super(
         String.format(
-            "The current metadata capacity has exceeded the cluster quota. The cluster quota is set at the %s level, with a limit number of %d. Please review your configuration or delete some existing time series to comply with the quota.",
+            "The current metadata capacity has exceeded the cluster quota. "
+                + "The cluster quota is set at the %s level, with a limit number of %d. "
+                + "Please review your configuration "
+                + "or delete some existing time series to comply with the quota.",
             level.toString(), limit),
         TSStatusCode.SCHEMA_QUOTA_EXCEEDED.getStatusCode());
   }

server/src/main/java/org/apache/iotdb/db/exception/metadata/SeriesNumberOverflowException.java

-/*
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements.  See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership.  The ASF licenses this file
- * to you under the Apache License, Version 2.0 (the
- * "License"); you may not use this file except in compliance
- * with the License.  You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-package org.apache.iotdb.db.exception.metadata;
-
-import org.apache.iotdb.commons.exception.MetadataException;
-import org.apache.iotdb.rpc.TSStatusCode;
-
-public class SeriesNumberOverflowException extends MetadataException {
-
-  public SeriesNumberOverflowException() {
-    super("exceed max allowed series number.", TSStatusCode.SERIES_OVERFLOW.getStatusCode());
-  }
-}

server/src/main/java/org/apache/iotdb/db/exception/metadata/SeriesOverflowException.java

@@ -28,8 +28,10 @@ public class SeriesOverflowException extends MetadataException {
   public SeriesOverflowException(long memoryUsage, long seriesNum) {
     super(
         String.format(
-            "There are too many timeseries in memory. Current memory usage is %s and series num is %s. "
-                + "Please increase MAX_HEAP_SIZE in datanode-env.sh/bat, restart and create timeseries again.",
+            "There are too many timeseries in memory. "
+                + "Current memory usage is %s and series num is %s. "
+                + "Please increase MAX_HEAP_SIZE in datanode-env.sh/bat, "
+                + "restart and create timeseries again.",
             memoryUsage, seriesNum),
         TSStatusCode.SERIES_OVERFLOW.getStatusCode());
   }

server/src/main/java/org/apache/iotdb/db/exception/metadata/cache/MNodeNotCachedException.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.exception.metadata.cache;
 
 import org.apache.iotdb.commons.exception.MetadataException;

server/src/main/java/org/apache/iotdb/db/exception/metadata/schemafile/ColossalRecordException.java

@@ -17,6 +17,7 @@
  * under the License.
  *
  */
+
 package org.apache.iotdb.db.exception.metadata.schemafile;
 
 import org.apache.iotdb.commons.exception.MetadataException;

server/src/main/java/org/apache/iotdb/db/exception/metadata/template/TemplateImcompatibeException.java

@@ -39,7 +39,8 @@ public class TemplateImcompatibeException extends MetadataException {
   public TemplateImcompatibeException(String templateName, PartialPath templateSetPath) {
     super(
         String.format(
-            "Cannot set schema template [%s] to path [%s] since there's timeseries under path [%s].",
+            "Cannot set schema template [%s] to path [%s] "
+                + "since there's timeseries under path [%s].",
             templateName, templateSetPath, templateSetPath),
         TSStatusCode.TEMPLATE_INCOMPATIBLE.getStatusCode());
     this.isUserException = true;

server/src/main/java/org/apache/iotdb/db/exception/metadata/view/BrokenViewException.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.exception.metadata.view;
 
 import org.apache.iotdb.commons.exception.MetadataException;
@@ -29,13 +30,13 @@ public class BrokenViewException extends MetadataException {
     super(
         String.format(
             "View is broken! The source path [%s] maps to unmatched %s path(s): %s.",
-            sourcePath, matchedPaths.size(), matchedPaths.toString()));
+            sourcePath, matchedPaths.size(), matchedPaths));
   }
 
   public BrokenViewException(String viewPath, String sourcePath, List<PartialPath> matchedPaths) {
     super(
         String.format(
             "View [%s] is broken! The source path [%s] maps to unmatched %s path(s): %s.",
-            viewPath, sourcePath, matchedPaths.size(), matchedPaths.toString()));
+            viewPath, sourcePath, matchedPaths.size(), matchedPaths));
   }
 }

server/src/main/java/org/apache/iotdb/db/exception/metadata/view/InsertNonWritableViewException.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.exception.metadata.view;
 
 import org.apache.iotdb.commons.exception.MetadataException;

server/src/main/java/org/apache/iotdb/db/exception/metadata/view/UnsupportedViewException.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.exception.metadata.view;
 
 import org.apache.iotdb.commons.exception.MetadataException;

server/src/main/java/org/apache/iotdb/db/exception/metadata/view/ViewContainsAggregationException.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.exception.metadata.view;
 
 public class ViewContainsAggregationException extends UnsupportedViewException {

server/src/main/java/org/apache/iotdb/db/exception/metadata/view/ViewNotExistException.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.exception.metadata.view;
 
 import org.apache.iotdb.commons.exception.MetadataException;

server/src/main/java/org/apache/iotdb/db/metadata/idtable/AppendOnlyDiskSchemaManager.java

@@ -43,7 +43,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 
-/** store id table schema in append only file */
+/** Store id table schema in append only file. */
 public class AppendOnlyDiskSchemaManager implements IDiskSchemaManager {
 
   private static final String FILE_NAME = "SeriesKeyMapping.meta";
@@ -200,7 +200,7 @@ public class AppendOnlyDiskSchemaManager implements IDiskSchemaManager {
   }
 
   /**
-   * get DiskSchemaEntries from disk file
+   * Get DiskSchemaEntries from disk file.
    *
    * @param offsets the offset of each record on the disk file
    * @return DiskSchemaEntries
@@ -220,10 +220,10 @@ public class AppendOnlyDiskSchemaManager implements IDiskSchemaManager {
   }
 
   /**
-   * delete DiskSchemaEntry on disk
+   * Delete DiskSchemaEntry on disk
    *
    * @param offset the offset of a record on the disk file
-   * @throws MetadataException
+   * @throws MetadataException metadata exception
    */
   @Override
   public void deleteDiskSchemaEntryByOffset(long offset) throws MetadataException {

server/src/main/java/org/apache/iotdb/db/metadata/idtable/IDTable.java

@@ -28,8 +28,6 @@ import org.apache.iotdb.db.conf.IoTDBConfig;
 import org.apache.iotdb.db.conf.IoTDBDescriptor;
 import org.apache.iotdb.db.metadata.idtable.entry.DeviceEntry;
 import org.apache.iotdb.db.metadata.idtable.entry.DeviceIDFactory;
-import org.apache.iotdb.db.metadata.idtable.entry.DiskSchemaEntry;
-import org.apache.iotdb.db.metadata.idtable.entry.IDeviceID;
 import org.apache.iotdb.db.metadata.idtable.entry.SchemaEntry;
 import org.apache.iotdb.db.metadata.idtable.entry.TimeseriesID;
 import org.apache.iotdb.db.metadata.plan.schemaregion.write.ICreateAlignedTimeSeriesPlan;
@@ -42,18 +40,17 @@ import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 import java.util.List;
-import java.util.Map;
 import java.util.Set;
 
 public interface IDTable {
-  /** logger */
+  // logger
   Logger logger = LoggerFactory.getLogger(IDTable.class);
 
-  /** iotdb config */
+  // iotdb confi
   IoTDBConfig config = IoTDBDescriptor.getInstance().getConfig();
 
   /**
-   * create aligned timeseries
+   * Create aligned timeseries.
    *
    * @param plan create aligned timeseries plan
    * @throws MetadataException if the device is not aligned, throw it
@@ -61,7 +58,7 @@ public interface IDTable {
   void createAlignedTimeseries(ICreateAlignedTimeSeriesPlan plan) throws MetadataException;
 
   /**
-   * create timeseries
+   * Create timeseries.
    *
    * @param plan create timeseries plan
    * @throws MetadataException if the device is aligned, throw it
@@ -69,28 +66,23 @@ public interface IDTable {
   void createTimeseries(ICreateTimeSeriesPlan plan) throws MetadataException;
 
   /**
-   * Delete all timeseries matching the given paths
+   * Delete all timeseries matching the given paths.
    *
    * @param fullPaths paths to be deleted
    * @return deletion failed Timeseries
-   * @throws MetadataException
+   * @throws MetadataException metadata exception
    */
   Pair<Integer, Set<String>> deleteTimeseries(List<PartialPath> fullPaths) throws MetadataException;
 
   /**
-   * check inserting timeseries existence and fill their measurement mnode
+   * Clear id table and close file.
    *
-   * @param plan insert plan
-   * @return reusable device id
-   * @throws MetadataException if insert plan's aligned value is inconsistent with device
+   * @throws IOException IOException
    */
-  // IDeviceID getSeriesSchemas(InsertPlan plan) throws MetadataException;
-
-  /** clear id table and close file */
   void clear() throws IOException;
 
   /**
-   * get device entry from device path
+   * Get device entry from device path.
    *
    * @param deviceName device name of the time series
    * @return device entry of the timeseries
@@ -98,7 +90,7 @@ public interface IDTable {
   DeviceEntry getDeviceEntry(String deviceName);
 
   /**
-   * get schema from device and measurements
+   * Get schema from device and measurements.
    *
    * @param deviceName device name of the time series
    * @param measurementName measurement name of the time series
@@ -107,26 +99,27 @@ public interface IDTable {
   IMeasurementSchema getSeriesSchema(String deviceName, String measurementName);
 
   /**
-   * get all device entries
+   * Get all device entries.
    *
    * @return all device entries
    */
   List<DeviceEntry> getAllDeviceEntry();
 
   /**
-   * put schema entry to id table, currently used in recover
+   * Put schema entry to id table, currently used in recover.
    *
    * @param devicePath device path (can be device id formed path)
    * @param measurement measurement name
    * @param schemaEntry schema entry to put
    * @param isAligned is the device aligned
+   * @throws MetadataException metadata exception
    */
   void putSchemaEntry(
       String devicePath, String measurement, SchemaEntry schemaEntry, boolean isAligned)
       throws MetadataException;
 
   /**
-   * translate query path's device path to device id
+   * Translate query path's device path to device id.
    *
    * @param fullPath full query path
    * @return translated query path
@@ -160,18 +153,6 @@ public interface IDTable {
     }
   }
 
-  /**
-   * get DiskSchemaEntries from disk file
-   *
-   * @param schemaEntries get the disk pointers from schemaEntries
-   * @return DiskSchemaEntries
-   */
-  @TestOnly
-  List<DiskSchemaEntry> getDiskSchemaEntries(List<SchemaEntry> schemaEntries);
-
-  @TestOnly
-  Map<IDeviceID, DeviceEntry>[] getIdTables();
-
   @TestOnly
   IDiskSchemaManager getIDiskSchemaManager();
 }

server/src/main/java/org/apache/iotdb/db/metadata/idtable/IDTableHashmapImpl.java

@@ -26,10 +26,8 @@ import org.apache.iotdb.db.conf.IoTDBConfig;
 import org.apache.iotdb.db.conf.IoTDBDescriptor;
 import org.apache.iotdb.db.metadata.idtable.entry.DeviceEntry;
 import org.apache.iotdb.db.metadata.idtable.entry.DeviceIDFactory;
-import org.apache.iotdb.db.metadata.idtable.entry.DiskSchemaEntry;
 import org.apache.iotdb.db.metadata.idtable.entry.IDeviceID;
 import org.apache.iotdb.db.metadata.idtable.entry.SchemaEntry;
-import org.apache.iotdb.db.metadata.idtable.entry.TimeseriesID;
 import org.apache.iotdb.db.metadata.plan.schemaregion.write.ICreateAlignedTimeSeriesPlan;
 import org.apache.iotdb.db.metadata.plan.schemaregion.write.ICreateTimeSeriesPlan;
 import org.apache.iotdb.tsfile.utils.Pair;
@@ -54,18 +52,16 @@ public class IDTableHashmapImpl implements IDTable {
 
   // number of table slot
   private static final int NUM_OF_SLOTS = 256;
-  /** logger */
+  // logger
   private static final Logger logger = LoggerFactory.getLogger(IDTableHashmapImpl.class);
 
-  /**
-   * 256 hashmap for avoiding rehash performance issue and lock competition device ID ->
-   * (measurement name -> schema entry)
-   */
+  // 256 hashmap for avoiding rehash performance issue and lock competition
+  // device ID -> (measurement name -> schema entry)
   private Map<IDeviceID, DeviceEntry>[] idTables;
 
-  /** disk schema manager to manage disk schema entry */
+  // disk schema manager to manage disk schema entry
   private IDiskSchemaManager IDiskSchemaManager;
-  /** iotdb config */
+  // iotdb config
   protected static IoTDBConfig config = IoTDBDescriptor.getInstance().getConfig();
 
   public IDTableHashmapImpl(File storageGroupDir) {
@@ -80,7 +76,7 @@ public class IDTableHashmapImpl implements IDTable {
   }
 
   /**
-   * create aligned timeseries
+   * Create aligned timeseries.
    *
    * @param plan create aligned timeseries plan
    * @throws MetadataException if the device is not aligned, throw it
@@ -107,7 +103,7 @@ public class IDTableHashmapImpl implements IDTable {
   }
 
   /**
-   * create timeseries
+   * Create timeseries.
    *
    * @param plan create timeseries plan
    * @throws MetadataException if the device is aligned, throw it
@@ -128,11 +124,11 @@ public class IDTableHashmapImpl implements IDTable {
   }
 
   /**
-   * Delete all timeseries matching the given paths
+   * Delete all timeseries matching the given paths.
    *
    * @param fullPaths paths to be deleted
    * @return deletion failed Timeseries
-   * @throws MetadataException
+   * @throws MetadataException metadata exception
    */
   @Override
   public synchronized Pair<Integer, Set<String>> deleteTimeseries(List<PartialPath> fullPaths)
@@ -158,7 +154,6 @@ public class IDTableHashmapImpl implements IDTable {
     for (Pair<PartialPath, Long> pair : deletedPairs) {
       try {
         getIDiskSchemaManager().deleteDiskSchemaEntryByOffset(pair.right);
-        DeviceEntry deviceEntry = getDeviceEntry(pair.left.getDevice());
         Map<String, SchemaEntry> map = getDeviceEntry(pair.left.getDevice()).getMeasurementMap();
         map.keySet().remove(pair.left.getMeasurement());
         deletedNum++;
@@ -177,7 +172,7 @@ public class IDTableHashmapImpl implements IDTable {
   }
 
   /**
-   * get device entry from device path
+   * Get device entry from device path.
    *
    * @param deviceName device name of the time series
    * @return device entry of the timeseries
@@ -192,7 +187,7 @@ public class IDTableHashmapImpl implements IDTable {
   }
 
   /**
-   * get schema from device and measurements
+   * Get schema from device and measurements.
    *
    * @param deviceName device name of the time series
    * @param measurementName measurement name of the time series
@@ -237,27 +232,12 @@ public class IDTableHashmapImpl implements IDTable {
   }
 
   /**
-   * get DiskSchemaEntries from disk file
-   *
-   * @param schemaEntries get the disk pointers from schemaEntries
-   * @return DiskSchemaEntries
-   */
-  @Override
-  @TestOnly
-  public synchronized List<DiskSchemaEntry> getDiskSchemaEntries(List<SchemaEntry> schemaEntries) {
-    List<Long> offsets = new ArrayList<>(schemaEntries.size());
-    for (SchemaEntry schemaEntry : schemaEntries) {
-      offsets.add(schemaEntry.getDiskPointer());
-    }
-    return getIDiskSchemaManager().getDiskSchemaEntriesByOffset(offsets);
-  }
-
-  /**
-   * get device id from device path and check is aligned,
+   * Get device id from device path and check is aligned.
    *
    * @param deviceName device name of the time series
    * @param isAligned whether the insert plan is aligned
    * @return device entry of the timeseries
+   * @throws MetadataException metadata exception
    */
   private DeviceEntry getDeviceEntryWithAlignedCheck(String deviceName, boolean isAligned)
       throws MetadataException {
@@ -287,7 +267,7 @@ public class IDTableHashmapImpl implements IDTable {
   }
 
   /**
-   * calculate slot that this deviceID should in
+   * Calculate slot that this deviceID should be in.
    *
    * @param deviceID device id
    * @return slot number
@@ -297,38 +277,6 @@ public class IDTableHashmapImpl implements IDTable {
     return Math.abs(hashVal == Integer.MIN_VALUE ? 0 : hashVal) % NUM_OF_SLOTS;
   }
 
-  /**
-   * get schema entry
-   *
-   * @param timeseriesID the timeseries ID
-   * @return schema entry of the timeseries
-   * @throws MetadataException throw if this timeseries is not exist
-   */
-  private SchemaEntry getSchemaEntry(TimeseriesID timeseriesID) throws MetadataException {
-    IDeviceID deviceID = timeseriesID.getDeviceID();
-    int slot = calculateSlot(deviceID);
-
-    DeviceEntry deviceEntry = idTables[slot].get(deviceID);
-    if (deviceEntry == null) {
-      throw new MetadataException(
-          "get non exist timeseries's schema entry, timeseries id is: " + timeseriesID);
-    }
-
-    SchemaEntry schemaEntry = deviceEntry.getSchemaEntry(timeseriesID.getMeasurement());
-    if (schemaEntry == null) {
-      throw new MetadataException(
-          "get non exist timeseries's schema entry, timeseries id is: " + timeseriesID);
-    }
-
-    return schemaEntry;
-  }
-
-  @Override
-  @TestOnly
-  public Map<IDeviceID, DeviceEntry>[] getIdTables() {
-    return idTables;
-  }
-
   @Override
   @TestOnly
   public IDiskSchemaManager getIDiskSchemaManager() {

server/src/main/java/org/apache/iotdb/db/metadata/idtable/IDTableManager.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.metadata.idtable;
 
 import org.apache.iotdb.commons.exception.MetadataException;
@@ -33,16 +34,16 @@ import java.io.File;
 import java.io.IOException;
 import java.util.HashMap;
 
-/** This class manages one id table for each logical database */
+/** This class manages one id table for each logical database. */
 public class IDTableManager {
 
-  /** logger */
+  // logger
   Logger logger = LoggerFactory.getLogger(IDTableManager.class);
 
-  /** database path -> id table */
+  // database path -> id table
   HashMap<String, IDTable> idTableMap;
 
-  /** system dir */
+  // system dir
   private final String systemDir =
       FilePathUtils.regularizePath(IoTDBDescriptor.getInstance().getConfig().getSystemDir())
           + "databases";
@@ -58,7 +59,7 @@ public class IDTableManager {
   }
 
   /**
-   * get instance
+   * Get instance.
    *
    * @return instance of the factory
    */
@@ -72,10 +73,11 @@ public class IDTableManager {
   // endregion
 
   /**
-   * get id table by device path
+   * Get id table by device path.
    *
    * @param devicePath device path
    * @return id table belongs to path's database
+   * @throws UnsupportedOperationException not supported yet
    */
   public synchronized IDTable getIDTable(PartialPath devicePath) {
     //    try {
@@ -95,7 +97,7 @@ public class IDTableManager {
   }
 
   /**
-   * get id table by database path
+   * Get id table by database path.
    *
    * @param sgPath database path
    * @return id table belongs to path's database
@@ -109,11 +111,12 @@ public class IDTableManager {
   }
 
   /**
-   * get schema from device and measurements
+   * Get schema from device and measurements.
    *
    * @param deviceName device name of the time series
    * @param measurementName measurement name of the time series
    * @return schema entry of the time series
+   * @throws MetadataException path may not exist
    */
   public synchronized IMeasurementSchema getSeriesSchema(String deviceName, String measurementName)
       throws MetadataException {
@@ -127,7 +130,11 @@ public class IDTableManager {
     throw new PathNotExistException(new PartialPath(deviceName, measurementName).toString());
   }
 
-  /** clear id table map */
+  /**
+   * Clear id table map.
+   *
+   * @throws IOException IOException
+   */
   public void clear() throws IOException {
     for (IDTable idTable : idTableMap.values()) {
       idTable.clear();

server/src/main/java/org/apache/iotdb/db/metadata/idtable/IDiskSchemaManager.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.metadata.idtable;
 
 import org.apache.iotdb.commons.exception.MetadataException;
@@ -26,11 +27,11 @@ import java.io.IOException;
 import java.util.Collection;
 import java.util.List;
 
-/** This class manages IO of id table's schema entry */
+/** This class manages IO of id table's schema entry. */
 public interface IDiskSchemaManager {
 
   /**
-   * serialize a disk schema entry
+   * Serialize a disk schema entry.
    *
    * @param schemaEntry disk schema entry
    * @return disk position of that entry
@@ -38,22 +39,23 @@ public interface IDiskSchemaManager {
   long serialize(DiskSchemaEntry schemaEntry);
 
   /**
-   * recover id table from log file
+   * Recover id table from log file.
    *
    * @param idTable id table need to be recovered
    */
   void recover(IDTable idTable);
 
   /**
-   * get all disk schema entries from file
+   * Get all disk schema entries from file.
    *
    * @return collection of all disk schema entires
+   * @throws IOException IOException
    */
   @TestOnly
   Collection<DiskSchemaEntry> getAllSchemaEntry() throws IOException;
 
   /**
-   * get DiskSchemaEntries from disk file
+   * Get DiskSchemaEntries from disk file.
    *
    * @param offsets the offset of each record on the disk file
    * @return DiskSchemaEntries
@@ -61,13 +63,17 @@ public interface IDiskSchemaManager {
   List<DiskSchemaEntry> getDiskSchemaEntriesByOffset(List<Long> offsets);
 
   /**
-   * delete DiskSchemaEntries on disk
+   * Delete DiskSchemaEntries on disk.
    *
    * @param offset the offset of a record on the disk file
-   * @throws MetadataException
+   * @throws MetadataException metadata exception
    */
   void deleteDiskSchemaEntryByOffset(long offset) throws MetadataException;
 
-  /** close file and free resource */
+  /**
+   * Close file and free resource.
+   *
+   * @throws IOException IOException
+   */
   void close() throws IOException;
 }

server/src/main/java/org/apache/iotdb/db/metadata/idtable/entry/DiskSchemaEntry.java

@@ -26,7 +26,7 @@ import java.io.InputStream;
 import java.io.OutputStream;
 
 /**
- * the disk schema entry of schema entry of id table. This is a po class, so every field is public
+ * The disk schema entry of schema entry of id table. This is a po class, so every field is public.
  */
 public class DiskSchemaEntry {
 

server/src/main/java/org/apache/iotdb/db/metadata/idtable/entry/IDeviceID.java

@@ -21,15 +21,15 @@ package org.apache.iotdb.db.metadata.idtable.entry;
 
 import java.nio.ByteBuffer;
 
-/** device id interface */
+/** Device id interface. */
 public interface IDeviceID {
 
   /**
-   * to string format
+   * To string format.
    *
    * @return string format device id
    */
-  public String toStringID();
+  String toStringID();
 
-  public void serialize(ByteBuffer byteBuffer);
+  void serialize(ByteBuffer byteBuffer);
 }

server/src/main/java/org/apache/iotdb/db/metadata/idtable/entry/PlainDeviceID.java

@@ -24,7 +24,7 @@ import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils;
 import java.nio.ByteBuffer;
 import java.util.Objects;
 
-/** Using device id path as id */
+/** Using device id path as id. */
 public class PlainDeviceID implements IDeviceID {
   String deviceID;
 

server/src/main/java/org/apache/iotdb/db/metadata/idtable/entry/SHA256DeviceID.java

@@ -28,7 +28,7 @@ import java.nio.ByteBuffer;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 
-/** Using sha 256 hash value of device path as device ID */
+/** Using sha 256 hash value of device path as device ID. */
 public class SHA256DeviceID implements IDeviceID {
   // four long value form a 32 bytes sha 256 value
   long l1;
@@ -38,13 +38,13 @@ public class SHA256DeviceID implements IDeviceID {
 
   private static final String SEPARATOR = "_";
 
-  /** using lots of message digest for improving parallelism */
+  // using lots of message digest for improving parallelism
   private static MessageDigest[] md;
 
-  /** number of message digest, for improve parallelism */
+  // number of message digest, for improve parallelism
   private static final int MD_NUM = 256;
 
-  /** logger */
+  // logger
   private static Logger logger = LoggerFactory.getLogger(IDTable.class);
 
   static {
@@ -70,7 +70,7 @@ public class SHA256DeviceID implements IDeviceID {
   }
 
   /**
-   * build device id from a sha 256 string, like "1#1#1#1"
+   * Build device id from a sha 256 string, like "1#1#1#1".
    *
    * @param deviceID a sha 256 string
    */
@@ -86,7 +86,7 @@ public class SHA256DeviceID implements IDeviceID {
   }
 
   /**
-   * build device id from a device path
+   * Build device id from a device path.
    *
    * @param deviceID device path
    */
@@ -105,7 +105,7 @@ public class SHA256DeviceID implements IDeviceID {
     l4 = toLong(hashVal, 24);
   }
 
-  /** The probability that each bit of sha 256 is 0 or 1 is equal */
+  /** The probability that each bit of sha 256 is 0 or 1 is equal. */
   public int hashCode() {
     return (int) l1;
   }
@@ -133,7 +133,7 @@ public class SHA256DeviceID implements IDeviceID {
   }
 
   /**
-   * calculate slot that this deviceID should in
+   * Calculate slot that this deviceID should in.
    *
    * @param deviceID device id
    * @return slot number

server/src/main/java/org/apache/iotdb/db/metadata/idtable/entry/SchemaEntry.java

@@ -35,7 +35,7 @@ import static org.apache.iotdb.db.utils.EncodingInferenceUtils.getDefaultEncodin
 
 /**
  * Schema entry of id table <br>
- * Notice that this class is also a last cache container for last cache
+ * Notice that this class is also a last cache container for last cache.
  */
 public class SchemaEntry {
 
@@ -45,7 +45,7 @@ public class SchemaEntry {
   /*    1 byte of type      */
   private long schema;
 
-  /** This static field will not occupy memory */
+  // This static field will not occupy memory
   private static IoTDBConfig config = IoTDBDescriptor.getInstance().getConfig();
 
   @TestOnly
@@ -75,7 +75,7 @@ public class SchemaEntry {
       IDeviceID deviceID,
       PartialPath fullPath,
       boolean isAligned,
-      IDiskSchemaManager IDiskSchemaManager) {
+      IDiskSchemaManager diskSchemaManager) {
     schema |= dataType.serialize();
     schema |= (((long) encoding.serialize()) << 8);
     schema |= (((long) compressionType.serialize()) << 16);
@@ -91,12 +91,12 @@ public class SchemaEntry {
               encoding.serialize(),
               compressionType.serialize(),
               isAligned);
-      schema |= (IDiskSchemaManager.serialize(diskSchemaEntry) << 24);
+      schema |= (diskSchemaManager.serialize(diskSchemaEntry) << 24);
     }
   }
 
   /**
-   * get disk pointer of ts from long value of schema
+   * Get disk pointer of ts from long value of schema.
    *
    * @return disk pointer
    */
@@ -105,7 +105,7 @@ public class SchemaEntry {
   }
 
   /**
-   * get ts data type from long value of schema
+   * Get ts data type from long value of schema.
    *
    * @return ts data type
    */
@@ -114,7 +114,7 @@ public class SchemaEntry {
   }
 
   /**
-   * get ts encoding from long value of schema
+   * Get ts encoding from long value of schema.
    *
    * @return ts encoding
    */
@@ -123,7 +123,7 @@ public class SchemaEntry {
   }
 
   /**
-   * get compression type from long value of schema
+   * Get compression type from long value of schema.
    *
    * @return compression type
    */

server/src/main/java/org/apache/iotdb/db/metadata/idtable/entry/TimeseriesID.java

@@ -16,17 +16,18 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.metadata.idtable.entry;
 
 import org.apache.iotdb.commons.path.PartialPath;
 
-/** A po class contains device id and measurement, represents a timeseries */
+/** A po class contains device id and measurement, represents a timeseries. */
 public class TimeseriesID {
 
   private IDeviceID deviceID;
   private String measurement;
 
-  /** build timeseries id from full path */
+  /** Build timeseries id from full path. */
   public TimeseriesID(PartialPath fullPath) {
     deviceID = DeviceIDFactory.getInstance().getDeviceID(fullPath.getDevicePath());
     measurement = fullPath.getMeasurement();

server/src/main/java/org/apache/iotdb/db/metadata/logfile/BufferedSerializer.java

@@ -28,7 +28,7 @@ import java.io.OutputStream;
 /**
  * This class provides the ability to buffer the data serialized by nested serializer.
  *
- * @param <T>
+ * @param <T> the generic type
  */
 @NotThreadSafe
 public class BufferedSerializer<T> implements ISerializer<T> {

server/src/main/java/org/apache/iotdb/db/metadata/logfile/IDeserializer.java

@@ -27,7 +27,7 @@ import java.nio.ByteBuffer;
  * This interface defines the behaviour of a Deserializer of T. An instance of this interface
  * provides the ability to deserialize an instance of T from InputStream or Bytebuffer.
  *
- * @param <T>
+ * @param <T> the generic type
  */
 public interface IDeserializer<T> {
 

server/src/main/java/org/apache/iotdb/db/metadata/logfile/ISerializer.java

@@ -28,7 +28,7 @@ import java.nio.ByteBuffer;
  * This interface defines the behaviour of a Serializer of T. An instance of this interface provides
  * the ability to serialize an instance of T to InputStream or Bytebuffer.
  *
- * @param <T>
+ * @param <T> the generic type
  */
 public interface ISerializer<T> {
 

server/src/main/java/org/apache/iotdb/db/metadata/logfile/MLogDescription.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.metadata.logfile;
 
 import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils;

server/src/main/java/org/apache/iotdb/db/metadata/logfile/MLogDescriptionReader.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.metadata.logfile;
 
 import java.io.File;
@@ -32,14 +33,14 @@ public class MLogDescriptionReader {
 
   private MLogDescription deserializeMLogDescription() throws IOException {
     try (FileInputStream fileInputStream = new FileInputStream(file)) {
-      MLogDescription mLogDescription = new MLogDescription();
-      mLogDescription.deserialize(fileInputStream);
-      return mLogDescription;
+      MLogDescription mlogdescription = new MLogDescription();
+      mlogdescription.deserialize(fileInputStream);
+      return mlogdescription;
     }
   }
 
   public long readCheckPoint() throws IOException {
-    MLogDescription mLogDescription = deserializeMLogDescription();
-    return mLogDescription.getCheckPoint();
+    MLogDescription mlogdescription = deserializeMLogDescription();
+    return mlogdescription.getCheckPoint();
   }
 }

server/src/main/java/org/apache/iotdb/db/metadata/logfile/MLogDescriptionWriter.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.metadata.logfile;
 
 import java.io.File;
@@ -26,25 +27,24 @@ import java.nio.file.StandardOpenOption;
 public class MLogDescriptionWriter {
 
   private final FileChannel fileChannel;
-  private final MLogDescription mLogDescription;
+
+  private final MLogDescription mlogdescription;
 
   public MLogDescriptionWriter(String schemaDir, String logFileName) throws IOException {
     File file = new File(schemaDir, logFileName);
-    if (!file.exists()) {
-      if (!file.createNewFile()) {
-        throw new IOException(
-            String.format(
-                "Failed to create file %s because the named file already exists", file.getName()));
-      }
+    if (!file.exists() && !file.createNewFile()) {
+      throw new IOException(
+          String.format(
+              "Failed to create file %s because the named file already exists", file.getName()));
     }
     fileChannel =
         FileChannel.open(new File(schemaDir, logFileName).toPath(), StandardOpenOption.WRITE);
-    mLogDescription = new MLogDescription();
+    mlogdescription = new MLogDescription();
   }
 
   public synchronized void updateCheckPoint(long checkPoint) throws IOException {
-    mLogDescription.setCheckPoint(checkPoint);
-    mLogDescription.serialize(fileChannel);
+    mlogdescription.setCheckPoint(checkPoint);
+    mlogdescription.serialize(fileChannel);
   }
 
   public synchronized void close() throws IOException {

server/src/main/java/org/apache/iotdb/db/metadata/logfile/MetadataOperationType.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.metadata.logfile;
 
 public class MetadataOperationType {

server/src/main/java/org/apache/iotdb/db/metadata/logfile/SchemaLogReader.java

@@ -41,12 +41,15 @@ import java.util.NoSuchElementException;
  * truncate during read process. If some middle part of the log file is corrupted, the read process
  * will end and the file will be marked corrupted.
  *
- * @param <T>
+ * @param <T> the generic type
  */
 public class SchemaLogReader<T> implements AutoCloseable {
 
   private static final Logger LOGGER = LoggerFactory.getLogger(SchemaLogReader.class);
 
+  private static final String FILE_CORRUPTED_MSG_TEMPLATE =
+      "File {} is corrupted. The uncorrupted size is {}.";
+
   private final File logFile;
 
   private final RecordableInputStream inputStream;
@@ -105,8 +108,7 @@ public class SchemaLogReader<T> implements AutoCloseable {
       // failed to read file
       nextSchemaPlan = null;
       isFileCorrupted = true;
-      LOGGER.error(
-          "File {} is corrupted. The uncorrupted size is {}.", logFile.getPath(), currentIndex, e);
+      LOGGER.error(FILE_CORRUPTED_MSG_TEMPLATE, logFile.getPath(), currentIndex, e);
     } catch (Exception e) {
       // error occurred when deserializing the entry
       nextSchemaPlan = null;
@@ -114,11 +116,7 @@ public class SchemaLogReader<T> implements AutoCloseable {
         if (inputStream.available() > 0) {
           // error occurred when deserializing some middle part of the file
           isFileCorrupted = true;
-          LOGGER.error(
-              "File {} is corrupted. The uncorrupted size is {}.",
-              logFile.getPath(),
-              currentIndex,
-              e);
+          LOGGER.error(FILE_CORRUPTED_MSG_TEMPLATE, logFile.getPath(), currentIndex, e);
         } else {
           // the file has already been all read out, but error occurred during deserializing the
           // last entry in file ending.
@@ -128,11 +126,7 @@ public class SchemaLogReader<T> implements AutoCloseable {
       } catch (IOException ex) {
         // failed to read file
         isFileCorrupted = true;
-        LOGGER.error(
-            "File {} is corrupted. The uncorrupted size is {}.",
-            logFile.getPath(),
-            currentIndex,
-            e);
+        LOGGER.error(FILE_CORRUPTED_MSG_TEMPLATE, logFile.getPath(), currentIndex, e);
       }
     }
   }
@@ -152,7 +146,9 @@ public class SchemaLogReader<T> implements AutoCloseable {
         FileChannel channel = outputStream.getChannel()) {
       if (currentIndex != channel.size()) {
         LOGGER.warn(
-            "The end of log file {} is corrupted. Start truncate it. The unbroken size is {}. The file size is {}.",
+            "The end of log file {} is corrupted. "
+                + "Start truncate it. "
+                + "The unbroken size is {}. The file size is {}.",
             logFile.getName(),
             currentIndex,
             channel.size());
@@ -170,7 +166,9 @@ public class SchemaLogReader<T> implements AutoCloseable {
     ReadWriteIOUtils.skip(inputStream, n);
   }
 
-  /** This class provides the ability to record the num of read bytes from the nested InputStream */
+  /**
+   * This class provides the ability to record the num of read bytes from the nested InputStream.
+   */
   private static class RecordableInputStream extends InputStream {
 
     private final InputStream inputStream;

server/src/main/java/org/apache/iotdb/db/metadata/logfile/SchemaLogWriter.java

@@ -32,7 +32,7 @@ import java.nio.file.Files;
 /**
  * This class provides the common ability to write a log storing T.
  *
- * @param <T>
+ * @param <T> the generic type
  */
 public class SchemaLogWriter<T> implements AutoCloseable {
 

server/src/main/java/org/apache/iotdb/db/metadata/path/PatternTreeMapFactory.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.metadata.path;
 
 import org.apache.iotdb.commons.path.PartialPath;
@@ -32,6 +33,11 @@ import java.nio.ByteBuffer;
 import java.util.HashSet;
 
 public class PatternTreeMapFactory {
+
+  private PatternTreeMapFactory() {
+    // not allowed construction
+  }
+
   public static PatternTreeMap<String, StringSerializer> getTriggerPatternTreeMap() {
     return new PatternTreeMap<>(
         HashSet::new,

server/src/main/java/org/apache/iotdb/db/metadata/tag/TagLogFile.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.metadata.tag;
 
 import org.apache.iotdb.commons.conf.CommonDescriptor;
@@ -88,7 +89,12 @@ public class TagLogFile implements AutoCloseable {
     FileUtils.copyFile(tagFile, targetFile);
   }
 
-  /** @return tags map, attributes map */
+  /**
+   * Read tags and attributes from tag file.
+   *
+   * @return tags map, attributes map
+   * @throws IOException error occurred when reading disk
+   */
   public Pair<Map<String, String>, Map<String, String>> read(int size, long position)
       throws IOException {
     if (position < 0) {
@@ -113,7 +119,12 @@ public class TagLogFile implements AutoCloseable {
     return write(byteBuffer, -1);
   }
 
-  /** This method does not modify this file's current position. */
+  /**
+   * This method does not modify this file's current position.
+   *
+   * @throws IOException IOException
+   * @throws MetadataException metadata exception
+   */
   public void write(Map<String, String> tagMap, Map<String, String> attributeMap, long position)
       throws IOException, MetadataException {
     ByteBuffer byteBuffer = convertMapToByteBuffer(tagMap, attributeMap);

server/src/main/java/org/apache/iotdb/db/metadata/tag/TagManager.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.metadata.tag;
 
 import org.apache.iotdb.commons.conf.CommonConfig;
@@ -26,8 +27,6 @@ import org.apache.iotdb.commons.path.PartialPath;
 import org.apache.iotdb.commons.schema.filter.impl.TagFilter;
 import org.apache.iotdb.commons.schema.node.IMNode;
 import org.apache.iotdb.commons.schema.node.role.IMeasurementMNode;
-import org.apache.iotdb.db.conf.IoTDBConfig;
-import org.apache.iotdb.db.conf.IoTDBDescriptor;
 import org.apache.iotdb.db.metadata.MetadataConstant;
 import org.apache.iotdb.db.metadata.plan.schemaregion.read.IShowTimeSeriesPlan;
 import org.apache.iotdb.db.metadata.plan.schemaregion.result.ShowTimeSeriesResult;
@@ -65,16 +64,14 @@ public class TagManager {
       "before deleting it, tag key is %s, tag value is %s, tlog offset is %d, contains key %b";
 
   private static final Logger logger = LoggerFactory.getLogger(TagManager.class);
-  private static IoTDBConfig config = IoTDBDescriptor.getInstance().getConfig();
   private static final CommonConfig COMMON_CONFIG = CommonDescriptor.getInstance().getConfig();
 
-  private String sgSchemaDirPath;
   private TagLogFile tagLogFile;
   // tag key -> tag value -> LeafMNode
-  private Map<String, Map<String, Set<IMeasurementMNode<?>>>> tagIndex = new ConcurrentHashMap<>();
+  private final Map<String, Map<String, Set<IMeasurementMNode<?>>>> tagIndex =
+      new ConcurrentHashMap<>();
 
   public TagManager(String sgSchemaDirPath) throws IOException {
-    this.sgSchemaDirPath = sgSchemaDirPath;
     tagLogFile = new TagLogFile(sgSchemaDirPath, MetadataConstant.TAG_LOG);
   }
 
@@ -86,27 +83,35 @@ public class TagManager {
     try {
       tagLogFile.copyTo(tagLogSnapshotTmp);
       if (tagLogSnapshot.exists() && !tagLogSnapshot.delete()) {
-        logger.error(
+        logger.warn(
             "Failed to delete old snapshot {} while creating tagManager snapshot.",
             tagLogSnapshot.getName());
         return false;
       }
       if (!tagLogSnapshotTmp.renameTo(tagLogSnapshot)) {
-        logger.error(
+        logger.warn(
             "Failed to rename {} to {} while creating tagManager snapshot.",
             tagLogSnapshotTmp.getName(),
             tagLogSnapshot.getName());
-        tagLogSnapshot.delete();
+        if (!tagLogSnapshot.delete()) {
+          logger.warn("Failed to delete {} after renaming failure.", tagLogSnapshot.getName());
+        }
         return false;
       }
 
       return true;
     } catch (IOException e) {
       logger.error("Failed to create tagManager snapshot due to {}", e.getMessage(), e);
-      tagLogSnapshot.delete();
+      if (!tagLogSnapshot.delete()) {
+        logger.warn(
+            "Failed to delete {} after creating tagManager snapshot failure.",
+            tagLogSnapshot.getName());
+      }
       return false;
     } finally {
-      tagLogSnapshotTmp.delete();
+      if (!tagLogSnapshotTmp.delete()) {
+        logger.warn("Failed to delete {}.", tagLogSnapshotTmp.getName());
+      }
     }
   }
 
@@ -115,15 +120,18 @@ public class TagManager {
     File tagSnapshot =
         SystemFileFactory.INSTANCE.getFile(snapshotDir, MetadataConstant.TAG_LOG_SNAPSHOT);
     File tagFile = SystemFileFactory.INSTANCE.getFile(sgSchemaDirPath, MetadataConstant.TAG_LOG);
-    if (tagFile.exists()) {
-      tagFile.delete();
+    if (tagFile.exists() && !tagFile.delete()) {
+      logger.warn("Failed to delete existing {} when loading snapshot.", tagFile.getName());
     }
 
     try {
       FileUtils.copyFile(tagSnapshot, tagFile);
       return new TagManager(sgSchemaDirPath);
     } catch (IOException e) {
-      tagFile.delete();
+      if (!tagFile.delete()) {
+        logger.warn(
+            "Failed to delete existing {} when copying snapshot failure.", tagFile.getName());
+      }
       throw e;
     }
   }
@@ -237,7 +245,9 @@ public class TagManager {
       }
 
       @Override
-      public void close() {}
+      public void close() {
+        // do nothing
+      }
 
       @Override
       public boolean hasNext() {
@@ -289,7 +299,11 @@ public class TagManager {
     };
   }
 
-  /** remove the node from the tag inverted index */
+  /**
+   * Remove the node from the tag inverted index.
+   *
+   * @throws IOException error occurred when reading disk
+   */
   public void removeFromTagInvertedIndex(IMeasurementMNode<?> node) throws IOException {
     if (node.getOffset() < 0) {
       return;
@@ -331,8 +345,11 @@ public class TagManager {
   }
 
   /**
-   * upsert tags and attributes key-value for the timeseries if the key has existed, just use the
+   * Upsert tags and attributes key-value for the timeseries if the key has existed, just use the
    * new value to update it.
+   *
+   * @throws MetadataException metadata exception
+   * @throws IOException error occurred when reading disk
    */
   public void updateTagsAndAttributes(
       Map<String, String> tagsMap,
@@ -395,10 +412,11 @@ public class TagManager {
   }
 
   /**
-   * add new attributes key-value for the timeseries
+   * Add new attributes key-value for the timeseries.
    *
    * @param attributesMap newly added attributes map
    * @throws MetadataException tagLogFile write error or attributes already exist
+   * @throws IOException error occurred when reading disk
    */
   public void addAttributes(
       Map<String, String> attributesMap, PartialPath fullPath, IMeasurementMNode<?> leafMNode)
@@ -422,11 +440,12 @@ public class TagManager {
   }
 
   /**
-   * add new tags key-value for the timeseries
+   * Add new tags key-value for the timeseries.
    *
    * @param tagsMap newly added tags map
    * @param fullPath timeseries
    * @throws MetadataException tagLogFile write error or tag already exists
+   * @throws IOException error occurred when reading disk
    */
   public void addTags(
       Map<String, String> tagsMap, PartialPath fullPath, IMeasurementMNode<?> leafMNode)
@@ -457,6 +476,8 @@ public class TagManager {
    * exist.
    *
    * @param keySet tags key or attributes key
+   * @throws MetadataException metadata exception
+   * @throws IOException error occurred when reading disk
    */
   public void dropTagsOrAttributes(
       Set<String> keySet, PartialPath fullPath, IMeasurementMNode<?> leafMNode)
@@ -483,15 +504,15 @@ public class TagManager {
     tagLogFile.write(pair.left, pair.right, leafMNode.getOffset());
 
     Map<String, Set<IMeasurementMNode<?>>> tagVal2LeafMNodeSet;
-    Set<IMeasurementMNode<?>> MMNodes;
+    Set<IMeasurementMNode<?>> nodeSet;
     for (Map.Entry<String, String> entry : deleteTag.entrySet()) {
       String key = entry.getKey();
       String value = entry.getValue();
       // change the tag inverted index map
       tagVal2LeafMNodeSet = tagIndex.get(key);
       if (tagVal2LeafMNodeSet != null) {
-        MMNodes = tagVal2LeafMNodeSet.get(value);
-        if (MMNodes != null) {
+        nodeSet = tagVal2LeafMNodeSet.get(value);
+        if (nodeSet != null) {
           if (logger.isDebugEnabled()) {
             logger.debug(
                 String.format(
@@ -501,8 +522,8 @@ public class TagManager {
                     leafMNode.getOffset()));
           }
 
-          MMNodes.remove(leafMNode);
-          if (MMNodes.isEmpty()) {
+          nodeSet.remove(leafMNode);
+          if (nodeSet.isEmpty()) {
             tagVal2LeafMNodeSet.remove(value);
             if (tagVal2LeafMNodeSet.isEmpty()) {
               tagIndex.remove(key);
@@ -524,10 +545,11 @@ public class TagManager {
   }
 
   /**
-   * set/change the values of tags or attributes
+   * Set/change the values of tags or attributes.
    *
    * @param alterMap the new tags or attributes key-value
    * @throws MetadataException tagLogFile write error or tags/attributes do not exist
+   * @throws IOException error occurred when reading disk
    */
   public void setTagsOrAttributesValue(
       Map<String, String> alterMap, PartialPath fullPath, IMeasurementMNode<?> leafMNode)
@@ -592,12 +614,13 @@ public class TagManager {
   }
 
   /**
-   * Rename the tag or attribute's key of the timeseries
+   * Rename the tag or attribute's key of the timeseries.
    *
    * @param oldKey old key of tag or attribute
    * @param newKey new key of tag or attribute
    * @throws MetadataException tagLogFile write error or does not have tag/attribute or already has
    *     a tag/attribute named newKey
+   * @throws IOException error occurred when reading disk
    */
   public void renameTagOrAttributeKey(
       String oldKey, String newKey, PartialPath fullPath, IMeasurementMNode<?> leafMNode)

server/src/main/java/org/apache/iotdb/db/metadata/template/ClusterTemplateManager.java

@@ -135,20 +135,16 @@ public class ClusterTemplateManager implements ITemplateManager {
   private TCreateSchemaTemplateReq constructTCreateSchemaTemplateReq(
       CreateSchemaTemplateStatement statement) {
     TCreateSchemaTemplateReq req = new TCreateSchemaTemplateReq();
-    try {
-      Template template =
-          new Template(
-              statement.getName(),
-              statement.getMeasurements(),
-              statement.getDataTypes(),
-              statement.getEncodings(),
-              statement.getCompressors(),
-              statement.isAligned());
-      req.setName(template.getName());
-      req.setSerializedTemplate(template.serialize());
-    } catch (IllegalPathException e) {
-      throw new RuntimeException(e);
-    }
+    Template template =
+        new Template(
+            statement.getName(),
+            statement.getMeasurements(),
+            statement.getDataTypes(),
+            statement.getEncodings(),
+            statement.getCompressors(),
+            statement.isAligned());
+    req.setName(template.getName());
+    req.setSerializedTemplate(template.serialize());
     return req;
   }
 
@@ -157,11 +153,10 @@ public class ClusterTemplateManager implements ITemplateManager {
     List<Template> templatesList = new ArrayList<>();
     try (ConfigNodeClient configNodeClient =
         CONFIG_NODE_CLIENT_MANAGER.borrowClient(ConfigNodeInfo.CONFIG_REGION_ID)) {
-      TGetAllTemplatesResp tGetAllTemplatesResp = configNodeClient.getAllTemplates();
+      TGetAllTemplatesResp resp = configNodeClient.getAllTemplates();
       // Get response or throw exception
-      if (tGetAllTemplatesResp.getStatus().getCode()
-          == TSStatusCode.SUCCESS_STATUS.getStatusCode()) {
-        List<ByteBuffer> list = tGetAllTemplatesResp.getTemplateList();
+      if (resp.getStatus().getCode() == TSStatusCode.SUCCESS_STATUS.getStatusCode()) {
+        List<ByteBuffer> list = resp.getTemplateList();
         list.forEach(
             templateData -> {
               Template template = new Template();
@@ -170,9 +165,7 @@ public class ClusterTemplateManager implements ITemplateManager {
             });
       } else {
         throw new RuntimeException(
-            new IoTDBException(
-                tGetAllTemplatesResp.getStatus().getMessage(),
-                tGetAllTemplatesResp.getStatus().getCode()));
+            new IoTDBException(resp.getStatus().getMessage(), resp.getStatus().getCode()));
       }
     } catch (ClientManagerException | TException e) {
       throw new RuntimeException(
@@ -431,7 +424,7 @@ public class ClusterTemplateManager implements ITemplateManager {
             }
 
           } catch (IllegalPathException ignored) {
-
+            // won't reach here
           }
         }
       }

server/src/main/java/org/apache/iotdb/db/metadata/template/ITemplateManager.java

@@ -31,22 +31,20 @@ import java.util.Map;
 public interface ITemplateManager {
 
   /**
+   * Create schema template by sending request to ConfigNode.
+   *
    * @param statement CreateSchemaTemplateStatement
    * @return TSStatus
    */
   TSStatus createSchemaTemplate(CreateSchemaTemplateStatement statement);
 
-  /**
-   * show schema templates
-   *
-   * @return List<Template>
-   */
+  /** Show schema templates. */
   List<Template> getAllTemplates();
 
   /**
    * show nodes in schema template xx
    *
-   * @param name
+   * @param name template name
    * @return Template
    */
   Template getTemplate(String name) throws IoTDBException;
@@ -54,18 +52,17 @@ public interface ITemplateManager {
   Template getTemplate(int id);
 
   /**
-   * mount template
+   * Set template to given path.
    *
    * @param name templateName
-   * @param path mount path
+   * @param path set path
    */
   void setSchemaTemplate(String queryId, String name, PartialPath path);
 
   /**
-   * get info of mounted template
+   * Get info of mounted template.
    *
-   * @param name
-   * @return
+   * @param name template name
    */
   List<PartialPath> getPathsSetTemplate(String name);
 

server/src/main/java/org/apache/iotdb/db/metadata/template/Template.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.metadata.template;
 
 import org.apache.iotdb.commons.exception.IllegalPathException;
@@ -45,8 +46,6 @@ public class Template implements Serializable {
   private boolean isDirectAligned;
   private Map<String, IMeasurementSchema> schemaMap;
 
-  private transient int rehashCode;
-
   public Template() {
     schemaMap = new ConcurrentHashMap<>();
   }
@@ -56,8 +55,7 @@ public class Template implements Serializable {
       List<String> measurements,
       List<TSDataType> dataTypes,
       List<TSEncoding> encodings,
-      List<CompressionType> compressors)
-      throws IllegalPathException {
+      List<CompressionType> compressors) {
     this(name, measurements, dataTypes, encodings, compressors, false);
   }
 
@@ -67,8 +65,7 @@ public class Template implements Serializable {
       List<TSDataType> dataTypes,
       List<TSEncoding> encodings,
       List<CompressionType> compressors,
-      boolean isAligned)
-      throws IllegalPathException {
+      boolean isAligned) {
     this.isDirectAligned = isAligned;
     this.schemaMap = new ConcurrentHashMap<>();
     this.name = name;
@@ -184,7 +181,7 @@ public class Template implements Serializable {
     try {
       serialize(outputStream);
     } catch (IOException ignored) {
-
+      // won't reach here
     }
     return ByteBuffer.wrap(outputStream.toByteArray());
   }
@@ -222,8 +219,6 @@ public class Template implements Serializable {
 
   @Override
   public int hashCode() {
-    return rehashCode != 0
-        ? rehashCode
-        : new HashCodeBuilder(17, 37).append(name).append(schemaMap).toHashCode();
+    return new HashCodeBuilder(17, 37).append(name).append(schemaMap).toHashCode();
   }
 }

server/src/main/java/org/apache/iotdb/db/metadata/template/TemplateInternalRPCUtil.java

@@ -42,6 +42,7 @@ public class TemplateInternalRPCUtil {
       ReadWriteIOUtils.write(1, outputStream);
       ReadWriteIOUtils.write(templateSetPath, outputStream);
     } catch (IOException ignored) {
+      // won't reach here
     }
     return outputStream.toByteArray();
   }
@@ -79,6 +80,7 @@ public class TemplateInternalRPCUtil {
         }
       }
     } catch (IOException ignored) {
+      // won't reach here
     }
     return outputStream.toByteArray();
   }
@@ -110,7 +112,7 @@ public class TemplateInternalRPCUtil {
       ReadWriteIOUtils.write(templateId, outputStream);
       ReadWriteIOUtils.write(path, outputStream);
     } catch (IOException ignored) {
-
+      // won't reach here
     }
     return outputStream.toByteArray();
   }

server/src/main/java/org/apache/iotdb/db/metadata/template/alter/TemplateAlterOperationUtil.java

@@ -27,6 +27,10 @@ import java.nio.ByteBuffer;
 
 public class TemplateAlterOperationUtil {
 
+  private TemplateAlterOperationUtil() {
+    // not allowed construction
+  }
+
   public static byte[] generateExtendTemplateReqInfo(
       TemplateAlterOperationType operationType, TemplateAlterInfo templateAlterInfo) {
     ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
@@ -34,7 +38,7 @@ public class TemplateAlterOperationUtil {
       operationType.serialize(outputStream);
       templateAlterInfo.serialize(outputStream);
     } catch (IOException ignored) {
-
+      // won't reach here
     }
     return outputStream.toByteArray();
   }

server/src/main/java/org/apache/iotdb/db/metadata/template/alter/TemplateExtendInfo.java

@@ -58,6 +58,7 @@ public class TemplateExtendInfo extends TemplateAlterInfo {
     this.compressors = compressors;
   }
 
+  @Override
   public String getTemplateName() {
     return templateName;
   }
@@ -148,30 +149,30 @@ public class TemplateExtendInfo extends TemplateAlterInfo {
   public List<String> updateAsDifferenceAndGetIntersection(Set<String> targetMeasurementSet) {
     List<String> removedMeasurements = new ArrayList<>();
 
-    List<String> measurements = new ArrayList<>();
-    List<TSDataType> dataTypes = new ArrayList<>();
-    List<TSEncoding> encodings = this.encodings == null ? null : new ArrayList<>();
-    List<CompressionType> compressors = this.compressors == null ? null : new ArrayList<>();
+    List<String> updatedMeasurements = new ArrayList<>();
+    List<TSDataType> updatedDataTypes = new ArrayList<>();
+    List<TSEncoding> updatedEncodings = this.encodings == null ? null : new ArrayList<>();
+    List<CompressionType> updatedCompressors = this.compressors == null ? null : new ArrayList<>();
 
     for (int i = 0; i < this.measurements.size(); i++) {
       if (targetMeasurementSet.contains(this.measurements.get(i))) {
         removedMeasurements.add(this.measurements.get(i));
         continue;
       }
-      measurements.add(this.measurements.get(i));
-      dataTypes.add(this.dataTypes.get(i));
+      updatedMeasurements.add(this.measurements.get(i));
+      updatedDataTypes.add(this.dataTypes.get(i));
       if (this.encodings != null) {
-        encodings.add(this.encodings.get(i));
+        updatedEncodings.add(this.encodings.get(i));
       }
       if (this.compressors != null) {
-        compressors.add(this.compressors.get(i));
+        updatedCompressors.add(this.compressors.get(i));
       }
     }
 
-    this.measurements = measurements;
-    this.dataTypes = dataTypes;
-    this.encodings = encodings;
-    this.compressors = compressors;
+    this.measurements = updatedMeasurements;
+    this.dataTypes = updatedDataTypes;
+    this.encodings = updatedEncodings;
+    this.compressors = updatedCompressors;
 
     return removedMeasurements;
   }
@@ -180,6 +181,7 @@ public class TemplateExtendInfo extends TemplateAlterInfo {
     return measurements == null || measurements.isEmpty();
   }
 
+  @Override
   public void serialize(OutputStream outputStream) throws IOException {
     super.serialize(outputStream);
     ReadWriteIOUtils.write(measurements.size(), outputStream);
@@ -209,6 +211,7 @@ public class TemplateExtendInfo extends TemplateAlterInfo {
     }
   }
 
+  @Override
   public void deserialize(ByteBuffer buffer) {
     super.deserialize(buffer);
     int size = ReadWriteIOUtils.readInt(buffer);

server/src/main/java/org/apache/iotdb/db/mpp/common/schematree/ClusterSchemaTree.java

@@ -200,9 +200,11 @@ public class ClusterSchemaTree implements ISchemaTree {
    *
    * @param schemaComputation the statement
    * @param indexOfTargetLogicalView the index list of logicalViewSchemaList that you want to check
+   * @throws SemanticException path not exist or different source path of view
    */
   public void computeSourceOfLogicalView(
-      ISchemaComputation schemaComputation, List<Integer> indexOfTargetLogicalView) {
+      ISchemaComputation schemaComputation, List<Integer> indexOfTargetLogicalView)
+      throws SemanticException {
     if (!schemaComputation.hasLogicalViewNeedProcess()) {
       return;
     }
@@ -297,11 +299,6 @@ public class ClusterSchemaTree implements ISchemaTree {
     }
   }
 
-  @Override
-  public boolean hasLogicalViewMeasurement() {
-    return this.hasLogicalMeasurementPath;
-  }
-
   public void mergeSchemaTree(ClusterSchemaTree schemaTree) {
     this.hasLogicalMeasurementPath =
         this.hasLogicalMeasurementPath || schemaTree.hasLogicalViewMeasurement();
@@ -338,6 +335,11 @@ public class ClusterSchemaTree implements ISchemaTree {
     }
   }
 
+  @Override
+  public boolean hasLogicalViewMeasurement() {
+    return this.hasLogicalMeasurementPath;
+  }
+
   public void serialize(OutputStream outputStream) throws IOException {
     root.serialize(outputStream);
   }
@@ -395,6 +397,7 @@ public class ClusterSchemaTree implements ISchemaTree {
    *
    * @param pathName only full path, cannot be path pattern
    * @return database in the given path
+   * @throws SemanticException no matched database
    */
   @Override
   public String getBelongedDatabase(String pathName) {

server/src/main/java/org/apache/iotdb/db/mpp/common/schematree/DeviceSchemaInfo.java

@@ -85,17 +85,17 @@ public class DeviceSchemaInfo {
           .collect(Collectors.toList());
     }
     List<MeasurementPath> measurementPaths = new ArrayList<>();
-    for (IMeasurementSchemaInfo iMeasurementSchemaInfo : measurementSchemaInfoList) {
+    for (IMeasurementSchemaInfo measurementSchemaInfo : measurementSchemaInfoList) {
       MeasurementPath measurementPath =
           new MeasurementPath(
-              devicePath.concatNode(iMeasurementSchemaInfo.getName()),
-              iMeasurementSchemaInfo.getSchema());
+              devicePath.concatNode(measurementSchemaInfo.getName()),
+              measurementSchemaInfo.getSchema());
       measurementPath.setUnderAlignedEntity(isAligned);
-      if (measurements.contains(iMeasurementSchemaInfo.getName())) {
+      if (measurements.contains(measurementSchemaInfo.getName())) {
         measurementPaths.add(measurementPath);
-      } else if (iMeasurementSchemaInfo.getAlias() != null
-          && measurements.contains(iMeasurementSchemaInfo.getAlias())) {
-        measurementPath.setMeasurementAlias(iMeasurementSchemaInfo.getAlias());
+      } else if (measurementSchemaInfo.getAlias() != null
+          && measurements.contains(measurementSchemaInfo.getAlias())) {
+        measurementPath.setMeasurementAlias(measurementSchemaInfo.getAlias());
         measurementPaths.add(measurementPath);
       }
     }

server/src/main/java/org/apache/iotdb/db/mpp/common/schematree/IMeasurementSchemaInfo.java

@@ -29,7 +29,11 @@ public interface IMeasurementSchemaInfo {
 
   IMeasurementSchema getSchema();
 
-  /** @return if the IMeasurementSchema is MeasurementSchema, return itself; else return null. */
+  /**
+   * If the IMeasurementSchema is MeasurementSchema, return itself; else return null.
+   *
+   * @return measurementSchema or null if IMeasurementSchema is not MeasurementSchema
+   */
   MeasurementSchema getSchemaAsMeasurementSchema();
 
   LogicalViewSchema getSchemaAsLogicalViewSchema();

server/src/main/java/org/apache/iotdb/db/mpp/common/schematree/ISchemaTree.java

@@ -71,6 +71,10 @@ public interface ISchemaTree {
 
   void mergeSchemaTree(ISchemaTree schemaTree);
 
-  /** @return if there is measurementPath in this schema tree, return true; else return false */
+  /**
+   * If there is view in this schema tree, return true, else return false.
+   *
+   * @return whether there's view in this schema tree
+   */
   boolean hasLogicalViewMeasurement();
 }

server/src/main/java/org/apache/iotdb/db/mpp/common/schematree/node/SchemaMeasurementNode.java

@@ -80,6 +80,11 @@ public class SchemaMeasurementNode extends SchemaNode implements IMeasurementSch
     return tagMap;
   }
 
+  @Override
+  public SchemaNode getChild(String name) {
+    return null;
+  }
+
   @Override
   public void replaceChild(String name, SchemaNode newChild) {
     throw new UnsupportedOperationException(
@@ -138,7 +143,7 @@ public class SchemaMeasurementNode extends SchemaNode implements IMeasurementSch
     String alias = ReadWriteIOUtils.readString(inputStream);
 
     IMeasurementSchema schema = null;
-    Byte measurementSchemaType = ReadWriteIOUtils.readByte(inputStream);
+    byte measurementSchemaType = ReadWriteIOUtils.readByte(inputStream);
     if (measurementSchemaType
         == MeasurementSchemaType.MEASUREMENT_SCHEMA.getMeasurementSchemaTypeInByteEnum()) {
       schema = MeasurementSchema.deserializeFrom(inputStream);

server/src/main/java/org/apache/iotdb/db/mpp/common/schematree/node/SchemaNode.java

@@ -43,9 +43,7 @@ public abstract class SchemaNode implements ITreeNode {
     return name;
   }
 
-  public SchemaNode getChild(String name) {
-    return null;
-  }
+  public abstract SchemaNode getChild(String name);
 
   public void addChild(String name, SchemaNode child) {}
 

server/src/main/java/org/apache/iotdb/db/mpp/common/schematree/visitor/SchemaTreeVisitorFactory.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.mpp.common.schematree.visitor;
 
 import org.apache.iotdb.commons.path.MeasurementPath;

server/src/main/java/org/apache/iotdb/db/mpp/common/schematree/visitor/SchemaTreeVisitorWithLimitOffsetWrapper.java

@@ -16,6 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
+
 package org.apache.iotdb.db.mpp.common.schematree.visitor;
 
 import org.apache.iotdb.db.mpp.common.schematree.node.SchemaNode;