[IOTDB-5284] Fix some iotdb-server code smells (#8754)

* fix some code smells

server/src/main/java/org/apache/iotdb/db/protocol/influxdb/function/InfluxFunction.java

@@ -28,11 +28,11 @@ public abstract class InfluxFunction {
   // contain possible parameters
   private List<Expression> expressionList;
 
-  public InfluxFunction(List<Expression> expressionList) {
+  protected InfluxFunction(List<Expression> expressionList) {
     this.expressionList = expressionList;
   }
 
-  public InfluxFunction() {}
+  protected InfluxFunction() {}
 
   public List<Expression> getExpressions() {
     return this.expressionList;

server/src/main/java/org/apache/iotdb/db/protocol/influxdb/function/aggregator/InfluxAggregator.java

@@ -27,7 +27,7 @@ import java.util.List;
 
 public abstract class InfluxAggregator extends InfluxFunction {
 
-  public InfluxAggregator(List<Expression> expressionList) {
+  protected InfluxAggregator(List<Expression> expressionList) {
     super(expressionList);
   }
 

server/src/main/java/org/apache/iotdb/db/protocol/influxdb/function/aggregator/InfluxMeanFunction.java

@@ -38,7 +38,7 @@ public class InfluxMeanFunction extends InfluxAggregator {
 
   @Override
   public InfluxFunctionValue calculateBruteForce() {
-    return new InfluxFunctionValue(numbers.size() == 0 ? numbers : MathUtils.mean(numbers), 0L);
+    return new InfluxFunctionValue(numbers.isEmpty() ? numbers : MathUtils.mean(numbers), 0L);
   }
 
   @Override

server/src/main/java/org/apache/iotdb/db/protocol/influxdb/function/aggregator/InfluxStddevFunction.java

@@ -36,8 +36,7 @@ public class InfluxStddevFunction extends InfluxAggregator {
 
   @Override
   public InfluxFunctionValue calculateBruteForce() {
-    return new InfluxFunctionValue(
-        numbers.size() == 0 ? numbers : MathUtils.popStdDev(numbers), 0L);
+    return new InfluxFunctionValue(numbers.isEmpty() ? numbers : MathUtils.popStdDev(numbers), 0L);
   }
 
   @Override

server/src/main/java/org/apache/iotdb/db/protocol/influxdb/function/aggregator/InfluxSumFunction.java

@@ -37,7 +37,7 @@ public class InfluxSumFunction extends InfluxAggregator {
 
   @Override
   public InfluxFunctionValue calculateBruteForce() {
-    return new InfluxFunctionValue(numbers.size() == 0 ? numbers : MathUtils.sum(numbers), 0L);
+    return new InfluxFunctionValue(numbers.isEmpty() ? numbers : MathUtils.sum(numbers), 0L);
   }
 
   @Override

server/src/main/java/org/apache/iotdb/db/protocol/influxdb/function/selector/InfluxSelector.java

@@ -32,7 +32,7 @@ public abstract class InfluxSelector extends InfluxFunction {
 
   private List<Object> relatedValues;
 
-  public InfluxSelector(List<Expression> expressionList) {
+  protected InfluxSelector(List<Expression> expressionList) {
     super(expressionList);
   }
 

server/src/main/java/org/apache/iotdb/db/protocol/influxdb/handler/AbstractQueryHandler.java

@@ -223,7 +223,7 @@ public abstract class AbstractQueryHandler {
       } else {
         // If there are no common queries, they are all function queries
         for (InfluxFunction function : functions) {
-          if (value.size() == 0) {
+          if (value.isEmpty()) {
             value.add(function.calculateBruteForce().getTimestamp());
           } else {
             value.set(0, function.calculateBruteForce().getTimestamp());
@@ -298,7 +298,7 @@ public abstract class AbstractQueryHandler {
       InfluxFunctionValue functionValue =
           updateByIoTDBFunc(database, measurement, function, sessionid);
       //      InfluxFunctionValue functionValue = function.calculateByIoTDBFunc();
-      if (value.size() == 0) {
+      if (value.isEmpty()) {
         value.add(functionValue.getTimestamp());
       } else {
         value.set(0, functionValue.getTimestamp());
@@ -445,7 +445,7 @@ public abstract class AbstractQueryHandler {
     String realQuerySql;
 
     realQuerySql = "select * from " + curQueryPath;
-    if (!(realIotDBCondition.length() == 0)) {
+    if (realIotDBCondition.length() != 0) {
       realQuerySql += " where " + realIotDBCondition;
     }
     realQuerySql += " align by device";

server/src/main/java/org/apache/iotdb/db/protocol/influxdb/handler/NewQueryHandler.java

@@ -111,8 +111,9 @@ public class NewQueryHandler extends AbstractQueryHandler {
           TSExecuteStatementResp tsExecuteStatementResp =
               NewInfluxDBServiceImpl.executeStatement(functionSql, sessionid);
           Map<String, Object> map = QueryResultUtils.getColumnNameAndValue(tsExecuteStatementResp);
-          for (String colume : map.keySet()) {
-            Object o = map.get(colume);
+          for (Map.Entry<String, Object> entry : map.entrySet()) {
+            String colume = entry.getKey();
+            Object o = entry.getValue();
             String fullPath = colume.substring(functionName.length() + 1, colume.length() - 1);
             String devicePath = StringUtils.getDeviceByPath(fullPath);
             String specificSql =

server/src/main/java/org/apache/iotdb/db/protocol/influxdb/handler/TagQueryHandler.java

@@ -130,7 +130,7 @@ public class TagQueryHandler extends NewQueryHandler {
     String realQuerySql;
 
     realQuerySql = "select * from " + curQueryPath;
-    if (!(realIotDBCondition.length() == 0)) {
+    if (realIotDBCondition.length() != 0) {
       realQuerySql += " where " + realIotDBCondition;
     }
     realQuerySql += " align by device";

server/src/main/java/org/apache/iotdb/db/protocol/influxdb/statement/InfluxSelectComponent.java

@@ -41,6 +41,7 @@ public final class InfluxSelectComponent extends SelectComponent {
     super(null);
   }
 
+  @Override
   public void addResultColumn(ResultColumn resultColumn) {
     Expression expression = resultColumn.getExpression();
     if (expression instanceof FunctionExpression) {

server/src/main/java/org/apache/iotdb/db/protocol/rest/impl/GrafanaApiServiceImpl.java

@@ -216,7 +216,7 @@ public class GrafanaApiServiceImpl extends GrafanaApiService {
   public Response node(List<String> requestBody, SecurityContext securityContext)
       throws NotFoundException {
     try {
-      if (requestBody != null && requestBody.size() > 0) {
+      if (requestBody != null && !requestBody.isEmpty()) {
         PartialPath path = new PartialPath(Joiner.on(".").join(requestBody));
         String sql = "show child paths " + path;
         Statement statement = StatementGenerator.createStatement(sql, ZoneId.systemDefault());

server/src/main/java/org/apache/iotdb/db/query/control/FileReaderManager.java

@@ -246,7 +246,7 @@ public class FileReaderManager {
   public synchronized void writeFileReferenceInfo() {
     DEBUG_LOGGER.info("[closedReferenceMap]\n");
     for (Map.Entry<String, AtomicInteger> entry : closedReferenceMap.entrySet()) {
-      DEBUG_LOGGER.info(String.format("\t%s: %d\n", entry.getKey(), entry.getValue().get()));
+      DEBUG_LOGGER.info(String.format("\t%s: %d%n", entry.getKey(), entry.getValue().get()));
     }
     DEBUG_LOGGER.info("[unclosedReferenceMap]\n");
     for (Map.Entry<String, AtomicInteger> entry : unclosedReferenceMap.entrySet()) {

server/src/main/java/org/apache/iotdb/db/query/control/QueryFileManager.java

@@ -139,9 +139,9 @@ public class QueryFileManager {
         sealedFilePathsMap.entrySet()) {
       long queryId = entry.getKey();
       Set<TsFileResource> tsFileResources = entry.getValue().keySet();
-      DEBUG_LOGGER.info(String.format("\t[queryId: %d]\n", queryId));
+      DEBUG_LOGGER.info("\t[queryId: {}]\n", queryId);
       for (TsFileResource tsFileResource : tsFileResources) {
-        DEBUG_LOGGER.info(String.format("\t\t%s\n", tsFileResource.getTsFile().getAbsolutePath()));
+        DEBUG_LOGGER.info("\t\t{}\n", tsFileResource.getTsFile().getAbsolutePath());
       }
     }
     DEBUG_LOGGER.info("[Query Unsealed File Info]\n");
@@ -149,9 +149,9 @@ public class QueryFileManager {
         unsealedFilePathsMap.entrySet()) {
       long queryId = entry.getKey();
       Set<TsFileResource> tsFileResources = entry.getValue().keySet();
-      DEBUG_LOGGER.info(String.format("\t[queryId: %d]\n", queryId));
+      DEBUG_LOGGER.info("\t[queryId: {}]\n", queryId);
       for (TsFileResource tsFileResource : tsFileResources) {
-        DEBUG_LOGGER.info(String.format("\t\t%s\n", tsFileResource.getTsFile().getAbsolutePath()));
+        DEBUG_LOGGER.info("\t\t{}\n", tsFileResource.getTsFile().getAbsolutePath());
       }
     }
   }

server/src/main/java/org/apache/iotdb/db/service/DataNodeServerCommandLine.java

@@ -111,7 +111,7 @@ public class DataNodeServerCommandLine extends ServerCommandLine {
     TDataNodeRemoveReq removeReq = new TDataNodeRemoveReq(dataNodeLocations);
     try (ConfigNodeClient configNodeClient = new ConfigNodeClient()) {
       TDataNodeRemoveResp removeResp = configNodeClient.removeDataNode(removeReq);
-      LOGGER.info("Remove result {} ", removeResp.toString());
+      LOGGER.info("Remove result {} ", removeResp);
       if (removeResp.getStatus().getCode() != TSStatusCode.SUCCESS_STATUS.getStatusCode()) {
         throw new IoTDBException(
             removeResp.getStatus().toString(), removeResp.getStatus().getCode());

server/src/main/java/org/apache/iotdb/db/service/SettleService.java

@@ -123,9 +123,8 @@ public class SettleService implements IService {
       return;
     }
     logger.info(
-        "Totally find "
-            + (seqResourcesToBeSettled.size() + unseqResourcesToBeSettled.size())
-            + " tsFiles to be settled.");
+        "Totally find {} tsFiles to be settled.",
+        seqResourcesToBeSettled.size() + unseqResourcesToBeSettled.size());
     // settle seqTsFile
     for (TsFileResource resource : seqResourcesToBeSettled) {
       resource.readLock();

server/src/main/java/org/apache/iotdb/db/service/thrift/impl/ClientRPCServiceImpl.java

@@ -433,7 +433,7 @@ public class ClientRPCServiceImpl implements IClientRPCServiceWithHandler {
             QueryDataSetUtils.convertQueryResultByFetchSize(queryExecution, req.fetchSize);
         List<ByteBuffer> result = pair.left;
         finished = pair.right;
-        boolean hasResultSet = !(result.size() == 0);
+        boolean hasResultSet = !result.isEmpty();
         resp.setHasResultSet(hasResultSet);
         resp.setIsAlign(true);
         resp.setQueryResult(result);

server/src/main/java/org/apache/iotdb/db/service/thrift/impl/DataNodeInternalRPCServiceImpl.java

@@ -341,7 +341,7 @@ public class DataNodeInternalRPCServiceImpl implements IDataNodeRPCService.Iface
 
   @Override
   public TLoadResp sendTsFilePieceNode(TTsFilePieceReq req) throws TException {
-    LOGGER.info(String.format("Receive load node from uuid %s.", req.uuid));
+    LOGGER.info("Receive load node from uuid {}.", req.uuid);
 
     ConsensusGroupId groupId =
         ConsensusGroupId.Factory.createFromTConsensusGroupId(req.consensusGroupId);

server/src/main/java/org/apache/iotdb/db/sync/SyncService.java

@@ -349,7 +349,7 @@ public class SyncService implements IService {
 
   public void recordMessage(String pipeName, PipeMessage message) {
     if (!pipes.containsKey(pipeName)) {
-      logger.warn(String.format("No running PIPE for message %s.", message));
+      logger.warn("No running PIPE for message {}.", message);
       return;
     }
     TSStatus status = null;
@@ -365,10 +365,10 @@ public class SyncService implements IService {
         status = syncInfoFetcher.recordMsg(pipeName, message);
         break;
       default:
-        logger.error(String.format("Unknown message type: %s", message));
+        logger.error("Unknown message type: {}", message);
     }
     if (status != null && status.getCode() != TSStatusCode.SUCCESS_STATUS.getStatusCode()) {
-      logger.error(String.format("Failed to record message: %s", message));
+      logger.error("Failed to record message: {}", message);
     }
   }
 
@@ -420,13 +420,13 @@ public class SyncService implements IService {
   private void startExternalPipeManager(String pipeName, boolean startExtPipe)
       throws PipeException {
     if (!(pipes.get(pipeName) instanceof TsFilePipe)) {
-      logger.error("startExternalPipeManager(), runningPipe is not TsFilePipe. " + pipeName);
+      logger.error("startExternalPipeManager(), runningPipe is not TsFilePipe. {}", pipeName);
       return;
     }
 
     PipeSink pipeSink = pipes.get(pipeName).getPipeSink();
     if (!(pipeSink instanceof ExternalPipeSink)) {
-      logger.error("startExternalPipeManager(), pipeSink is not ExternalPipeSink." + pipeSink);
+      logger.error("startExternalPipeManager(), pipeSink is not ExternalPipeSink. {}", pipeSink);
       return;
     }
 
@@ -435,9 +435,8 @@ public class SyncService implements IService {
         ExtPipePluginRegister.getInstance().getWriteFactory(extPipeSinkTypeName);
     if (externalPipeSinkWriterFactory == null) {
       logger.error(
-          String.format(
-              "startExternalPipeManager(), can not found ExternalPipe plugin for %s.",
-              extPipeSinkTypeName));
+          "startExternalPipeManager(), can not found ExternalPipe plugin for {}.",
+          extPipeSinkTypeName);
       throw new PipeException("Can not found ExternalPipe plugin for " + extPipeSinkTypeName + ".");
     }
 

server/src/main/java/org/apache/iotdb/db/sync/datasource/AbstractOpBlock.java

@@ -42,7 +42,7 @@ public abstract class AbstractOpBlock implements Comparable<AbstractOpBlock> {
   // data number of this OpBlock
   protected long dataCount = -1;
 
-  public AbstractOpBlock(String storageGroupName, long pipeDataSerialNumber, long beginIndex) {
+  protected AbstractOpBlock(String storageGroupName, long pipeDataSerialNumber, long beginIndex) {
     this.storageGroup = storageGroupName;
     this.pipeDataSerialNumber = pipeDataSerialNumber;
     this.beginIndex = beginIndex;

server/src/main/java/org/apache/iotdb/db/sync/datasource/PipeOpManager.java

@@ -228,11 +228,11 @@ public class PipeOpManager {
    *     in list can be discrete
    */
   private void commitFilePipe(List<Long> filePipeSerialNumberList) {
-    if (filePipeSerialNumberList.size() <= 0) {
+    if (filePipeSerialNumberList.isEmpty()) {
       return;
     }
 
-    if (filePipeSerialNumberSet.size() <= 0) {
+    if (filePipeSerialNumberSet.isEmpty()) {
       logger.error("commitFilePipe(), filePipeSerialNumberSet should not be empty.");
       return;
     }
@@ -250,7 +250,7 @@ public class PipeOpManager {
       return;
     }
 
-    if (filePipeSerialNumberSet.size() > 0) {
+    if (!filePipeSerialNumberSet.isEmpty()) {
       if (filePipeSerialNumberSet.first() > minNum) {
         filePipe.commit(filePipeSerialNumberSet.first() - 1);
       }
@@ -276,7 +276,7 @@ public class PipeOpManager {
    * @return True - PipeOpManager has no Pipe data
    */
   public boolean isEmpty() {
-    return (filePipeSerialNumberSet.size() <= 0);
+    return filePipeSerialNumberSet.isEmpty();
   }
 
   /**

server/src/main/java/org/apache/iotdb/db/sync/datasource/PipeOpSgManager.java

@@ -122,11 +122,7 @@ public class PipeOpSgManager {
       return true;
     }
 
-    if (opBlockBeginIndex > currentOpBlockBeginIndex) {
-      return true;
-    }
-
-    return false;
+    return opBlockBeginIndex > currentOpBlockBeginIndex;
   }
 
   /**

server/src/main/java/org/apache/iotdb/db/sync/datasource/TsFileOpBlock.java

@@ -281,7 +281,6 @@ public class TsFileOpBlock extends AbstractOpBlock {
             timeChunkOffset = entry.getKey();
             timeChunkPointCount = chunkInfo.pointCount;
             iter.remove();
-            continue;
           } else {
             chunkInfo.isTimeAligned = true;
             chunkInfo.timeChunkOffsetInFile = timeChunkOffset;
@@ -577,9 +576,9 @@ public class TsFileOpBlock extends AbstractOpBlock {
         new PageReader(pageData, chunkHeader.getDataType(), valueDecoder, timeDecoder, null);
     BatchData batchData = pageReader.getAllSatisfiedPageData();
     if (chunkHeader.getChunkType() == MetaMarker.CHUNK_HEADER) {
-      logger.debug("points in the page(by pageHeader): " + pageHeader.getNumOfValues());
+      logger.debug("points in the page(by pageHeader): {}", pageHeader.getNumOfValues());
     } else {
-      logger.debug("points in the page(by batchData): " + batchData.length());
+      logger.debug("points in the page(by batchData): {}", batchData.length());
     }
 
     if (batchData.isEmpty()) {
@@ -1008,7 +1007,7 @@ public class TsFileOpBlock extends AbstractOpBlock {
       long lengthInChunk = min(chunkPointCount - indexInChunk, remain);
 
       if (!sensorFullPath.equals(lastSensorFullPath)) {
-        if ((tvPairList != null) && (tvPairList.size() > 0)) {
+        if ((tvPairList != null) && (!tvPairList.isEmpty())) {
           insertToDataList(dataList, lastSensorFullPath, tvPairList);
           tvPairList = null;
         }
@@ -1037,7 +1036,7 @@ public class TsFileOpBlock extends AbstractOpBlock {
       }
     }
 
-    if ((tvPairList != null) && (tvPairList.size() > 0)) {
+    if ((tvPairList != null) && (!tvPairList.isEmpty())) {
       insertToDataList(dataList, lastSensorFullPath, tvPairList);
     }
 
@@ -1174,6 +1173,7 @@ public class TsFileOpBlock extends AbstractOpBlock {
      * @return
      * @throws IOException
      */
+    @Override
     public TsFileMetadata readFileMetadata() throws IOException {
       if (tsFileMetaData != null) {
         return tsFileMetaData;

server/src/main/java/org/apache/iotdb/db/sync/externalpipe/ExtPipePlugin.java

@@ -182,7 +182,7 @@ public class ExtPipePlugin {
     }
 
     alive = true;
-    logger.info("External pipe " + extPipeTypeName + " begin to START");
+    logger.info("External pipe {} begin to START", extPipeTypeName);
 
     // == Launch pipe worker threads
     executorService =
@@ -201,7 +201,7 @@ public class ExtPipePlugin {
 
     writerInvocationFailures = new ConcurrentHashMap<>();
 
-    logger.info("External pipe " + extPipeTypeName + " finish START.");
+    logger.info("External pipe {} finish START.", extPipeTypeName);
   }
 
   /** Stop all working threads */

server/src/main/java/org/apache/iotdb/db/sync/externalpipe/ExtPipePluginManager.java

@@ -123,7 +123,7 @@ public class ExtPipePluginManager {
     // == Start monitor Pipe data thread
     alive = true;
     ThreadPoolExecutor tpe = ((ThreadPoolExecutor) monitorService);
-    if ((tpe.getActiveCount() <= 0) && (tpe.getQueue().size() <= 0)) {
+    if ((tpe.getActiveCount() <= 0) && (tpe.getQueue().isEmpty())) {
       monitorService.submit(this::monitorPipeData);
     }
 
@@ -221,7 +221,7 @@ public class ExtPipePluginManager {
                     sgName, tsFileFullName, modsFileFullName, pipeDataSerialNumber);
                 lastPipeDataSerialNumber = pipeDataSerialNumber;
               } catch (IOException e) {
-                logger.error("monitorPipeData(), Can not append TsFile: {}" + tsFileFullName);
+                logger.error("monitorPipeData(), Can not append TsFile: {}", tsFileFullName);
               }
               continue;
             } else if (pipeData instanceof DeletionPipeData) {

server/src/main/java/org/apache/iotdb/db/sync/externalpipe/operation/Operation.java

@@ -34,7 +34,7 @@ public abstract class Operation {
   private long startIndex;
   private long endIndex;
 
-  public Operation(
+  protected Operation(
       OperationType operationType, String storageGroup, long startIndex, long endIndex) {
     this.operationType = operationType;
     this.storageGroup = storageGroup;

server/src/main/java/org/apache/iotdb/db/sync/pipedata/DeletionPipeData.java

@@ -65,6 +65,7 @@ public class DeletionPipeData extends PipeData {
         + deletion.serializeWithoutFileOffset(stream);
   }
 
+  @Override
   public void deserialize(DataInputStream stream) throws IOException, IllegalPathException {
     super.deserialize(stream);
     database = ReadWriteIOUtils.readString(stream);

server/src/main/java/org/apache/iotdb/db/sync/pipedata/PipeData.java

@@ -36,9 +36,9 @@ public abstract class PipeData {
 
   protected long serialNumber;
 
-  public PipeData() {}
+  protected PipeData() {}
 
-  public PipeData(long serialNumber) {
+  protected PipeData(long serialNumber) {
     this.serialNumber = serialNumber;
   }
 

server/src/main/java/org/apache/iotdb/db/sync/pipedata/load/DeletionLoader.java

@@ -65,8 +65,8 @@ public class DeletionLoader implements ILoader {
                   SCHEMA_FETCHER,
                   IoTDBDescriptor.getInstance().getConfig().getQueryTimeoutThreshold());
       if (result.status.code != TSStatusCode.SUCCESS_STATUS.getStatusCode()) {
-        logger.error(String.format("Delete %s error, statement: %s.", deletion, statement));
-        logger.error(String.format("Delete result status : %s.", result.status));
+        logger.error("Delete {} error, statement: {}.", deletion, statement);
+        logger.error("Delete result status : {}.", result.status);
         throw new LoadFileException(
             String.format("Can not execute delete statement: %s", statement));
       }

server/src/main/java/org/apache/iotdb/db/sync/pipedata/load/TsFileLoader.java

@@ -68,9 +68,8 @@ public class TsFileLoader implements ILoader {
                   SCHEMA_FETCHER,
                   IoTDBDescriptor.getInstance().getConfig().getQueryTimeoutThreshold());
       if (result.status.code != TSStatusCode.SUCCESS_STATUS.getStatusCode()) {
-        logger.error(
-            String.format("Load TsFile %s error, statement: %s.", tsFile.getPath(), statement));
-        logger.error(String.format("Load TsFile result status : %s.", result.status));
+        logger.error("Load TsFile {} error, statement: {}.", tsFile.getPath(), statement);
+        logger.error("Load TsFile result status : {}.", result.status);
         throw new LoadFileException(
             String.format("Can not execute load TsFile statement: %s", statement));
       }

server/src/main/java/org/apache/iotdb/db/sync/pipedata/queue/BufferedPipeDataQueue.java

@@ -101,7 +101,7 @@ public class BufferedPipeDataQueue implements PipeDataQueue {
       if (file.getName().endsWith(SyncConstant.PIPE_LOG_NAME_SUFFIX) && file.length() > 0) {
         startNumbers.add(SyncPathUtil.getSerialNumberFromPipeLogName(file.getName()));
       }
-    if (startNumbers.size() != 0) {
+    if (!startNumbers.isEmpty()) {
       Collections.sort(startNumbers);
       for (Long startTime : startNumbers) {
         pipeLogStartNumber.offer(startTime);

server/src/main/java/org/apache/iotdb/db/sync/sender/pipe/ExternalPipeSink.java

@@ -39,7 +39,7 @@ import java.util.stream.Collectors;
 public class ExternalPipeSink implements PipeSink {
   private static final Logger logger = LoggerFactory.getLogger(ExternalPipeSink.class);
 
-  private final PipeSinkType pipeSinkType = PipeSinkType.ExternalPipe;
+  private static final PipeSinkType pipeSinkType = PipeSinkType.ExternalPipe;
 
   private String pipeSinkName;
   private String extPipeSinkTypeName;

server/src/main/java/org/apache/iotdb/db/sync/sender/pipe/TsFilePipe.java

@@ -192,7 +192,7 @@ public class TsFilePipe implements Pipe {
       // put history data into PipeDataQueue
       int historyTsFilesSize = historyTsFiles.size();
       for (int i = 0; i < historyTsFilesSize; i++) {
-        long serialNumber = 1 - historyTsFilesSize + i;
+        long serialNumber = 1L - historyTsFilesSize + i;
         File tsFile = historyTsFiles.get(i);
         historyQueueMap
             .get(entry.getKey())

server/src/main/java/org/apache/iotdb/db/sync/sender/recovery/TsFilePipeLogger.java

@@ -135,7 +135,7 @@ public class TsFilePipeLogger {
   public void finishCollect() {
     try {
       if (SyncPathUtil.createFile(new File(pipeDir, SyncConstant.FINISH_COLLECT_LOCK_NAME))) {
-        logger.info(String.format("Create finish collecting Lock file in %s.", pipeDir));
+        logger.info("Create finish collecting Lock file in {}.", pipeDir);
       }
     } catch (IOException e) {
       logger.warn(String.format("Can not make lock file in %s, because %s", pipeDir, e));

server/src/main/java/org/apache/iotdb/db/sync/transport/client/SenderManager.java

@@ -225,7 +225,7 @@ public class SenderManager {
             while (!Thread.currentThread().isInterrupted()) {
               PipeData pipeData = pipe.take(dataRegionId);
               if (!syncClient.send(pipeData)) {
-                logger.error(String.format("Can not transfer PipeData %s, skip it.", pipeData));
+                logger.error("Can not transfer PipeData {}, skip it.", pipeData);
                 // can do something.
                 SyncService.getInstance()
                     .recordMessage(

server/src/main/java/org/apache/iotdb/db/sync/transport/server/ReceiverManager.java

@@ -437,8 +437,8 @@ public class ReceiverManager {
                   IoTDBDescriptor.getInstance().getConfig().getQueryTimeoutThreshold());
       if (result.status.code != TSStatusCode.SUCCESS_STATUS.getStatusCode()
           && result.status.code != TSStatusCode.DATABASE_ALREADY_EXISTS.getStatusCode()) {
-        logger.error(String.format("Create Database error, statement: %s.", statement));
-        logger.error(String.format("Create database result status : %s.", result.status));
+        logger.error("Create Database error, statement: {}.", statement);
+        logger.error("Create database result status : {}.", result.status);
         return false;
       }
     } catch (IllegalPathException e) {

server/src/main/java/org/apache/iotdb/db/tools/TsFileSelfCheckTool.java

@@ -78,7 +78,7 @@ public class TsFileSelfCheckTool {
    */
   public long check(String filename, boolean fastFinish)
       throws IOException, TsFileStatisticsMistakesException, TsFileTimeseriesMetadataException {
-    logger.info("file path: " + filename);
+    logger.info("file path: {}", filename);
     TsFileSelfCheckToolReader reader = new TsFileSelfCheckToolReader(filename);
     Map<Long, Pair<Path, TimeseriesMetadata>> timeseriesMetadataMap = null;
     long res = -1;

server/src/main/java/org/apache/iotdb/db/tools/settle/TsFileAndModSettleTool.java

@@ -99,7 +99,7 @@ public class TsFileAndModSettleTool {
         if (arg.endsWith(TSFILE_SUFFIX)) { // it's a file
           File f = new File(arg);
           if (!f.exists()) {
-            logger.warn("Cannot find TsFile : " + arg);
+            logger.warn("Cannot find TsFile : {}", arg);
             continue;
           }
           files.add(f);
@@ -115,11 +115,11 @@ public class TsFileAndModSettleTool {
   private static List<File> getAllFilesInOneDirBySuffix(String dirPath, String suffix) {
     File dir = new File(dirPath);
     if (!dir.isDirectory()) {
-      logger.warn("It's not a directory path : " + dirPath);
+      logger.warn("It's not a directory path : {}", dirPath);
       return Collections.emptyList();
     }
     if (!dir.exists()) {
-      logger.warn("Cannot find Directory : " + dirPath);
+      logger.warn("Cannot find Directory : {}", dirPath);
       return Collections.emptyList();
     }
     List<File> tsFiles =

server/src/main/java/org/apache/iotdb/db/tools/validate/TsFileValidationTool.java

@@ -556,7 +556,7 @@ public class TsFileValidationTool {
           }
         }
       }
-      if (seqDataDirList.size() == 0 && fileList.size() == 0) {
+      if (seqDataDirList.isEmpty() && fileList.isEmpty()) {
         System.out.println(
             "Please input correct param, which is [path of data dir] [-pd = print details or not] [-f = path of outFile]. Eg: xxx/iotdb/data/data -pd=true -f=xxx/TsFile_validation_view.txt");
         return false;

server/src/main/java/org/apache/iotdb/db/trigger/executor/TriggerExecutor.java

@@ -87,7 +87,7 @@ public class TriggerExecutor {
       LOGGER.warn(
           "Trigger {} was fired with wrong event {}",
           triggerInformation.getTriggerName(),
-          triggerInformation.getEvent().toString());
+          triggerInformation.getEvent());
     }
     return true;
   }

server/src/main/java/org/apache/iotdb/db/trigger/executor/TriggerFireVisitor.java

@@ -295,7 +295,7 @@ public class TriggerFireVisitor extends PlanVisitor<TriggerFireResult, TriggerEv
         TriggerManagementService.getInstance().getMatchedTriggerListForPath(device, measurements);
     boolean isAllEmpty = true;
     for (List<String> triggerNameList : triggerNameLists) {
-      if (triggerNameList.size() != 0) {
+      if (!triggerNameList.isEmpty()) {
         isAllEmpty = false;
         break;
       }
@@ -350,7 +350,7 @@ public class TriggerFireVisitor extends PlanVisitor<TriggerFireResult, TriggerEv
           LOGGER.warn(
               "Error occurred when trying to fire trigger({}) on TEndPoint: {}, the cause is: {}",
               triggerName,
-              tDataNodeLocation.getInternalEndPoint().toString(),
+              tDataNodeLocation.getInternalEndPoint(),
               e);
           // update TDataNodeLocation of stateful trigger through config node
           updateLocationOfStatefulTrigger(triggerName, tDataNodeLocation.getDataNodeId());
@@ -361,7 +361,7 @@ public class TriggerFireVisitor extends PlanVisitor<TriggerFireResult, TriggerEv
           LOGGER.warn(
               "Error occurred when trying to fire trigger({}) on TEndPoint: {}, the cause is: {}",
               triggerName,
-              tDataNodeLocation.getInternalEndPoint().toString(),
+              tDataNodeLocation.getInternalEndPoint(),
               e);
           // do not retry if it is not due to bad network or no executor found
           return TriggerManagementService.getInstance()
@@ -407,14 +407,13 @@ public class TriggerFireVisitor extends PlanVisitor<TriggerFireResult, TriggerEv
         CONFIG_NODE_CLIENT_MANAGER.borrowClient(ConfigNodeInfo.configNodeRegionId)) {
       TDataNodeLocation newTDataNodeLocation =
           configNodeClient.getLocationOfStatefulTrigger(triggerName).getDataNodeLocation();
-      if (newTDataNodeLocation != null) {
-        if (currentDataNodeId != newTDataNodeLocation.getDataNodeId()) {
+      if (newTDataNodeLocation != null
+          && currentDataNodeId != newTDataNodeLocation.getDataNodeId()) {
         // indicates that the location of this stateful trigger has changed
         TriggerManagementService.getInstance()
             .updateLocationOfStatefulTrigger(triggerName, newTDataNodeLocation);
         return true;
       }
-      }
       return false;
     } catch (ClientManagerException | TException | IOException e) {
       LOGGER.error(

server/src/main/java/org/apache/iotdb/db/trigger/service/TriggerInformationUpdater.java

@@ -55,7 +55,7 @@ public class TriggerInformationUpdater {
 
   private Future<?> updateFuture;
 
-  private static final long UPDATE_INTERVAL = 1000 * 60;
+  private static final long UPDATE_INTERVAL = 1000L * 60;
 
   public void startTriggerInformationUpdater() {
     if (updateFuture == null) {

server/src/main/java/org/apache/iotdb/db/utils/datastructure/AlignedTVList.java

@@ -854,9 +854,9 @@ public abstract class AlignedTVList extends TVList {
       return size;
     }
     // time array mem size
-    size += (long) PrimitiveArrayManager.ARRAY_SIZE * 8L;
+    size += PrimitiveArrayManager.ARRAY_SIZE * 8L;
     // index array mem size
-    size += (long) PrimitiveArrayManager.ARRAY_SIZE * 4L;
+    size += PrimitiveArrayManager.ARRAY_SIZE * 4L;
     // array headers mem size
     size += (long) NUM_BYTES_ARRAY_HEADER * (2 + types.length);
     // Object references size in ArrayList

server/src/main/java/org/apache/iotdb/db/utils/datastructure/FixedPriorityBlockingQueue.java

@@ -72,7 +72,7 @@ public class FixedPriorityBlockingQueue<T> {
     final ReentrantLock lock = this.lock;
     lock.lockInterruptibly();
     try {
-      while (queue.size() == 0) {
+      while (queue.isEmpty()) {
         notEmpty.await();
       }
       return queue.pollFirst();
@@ -92,7 +92,7 @@ public class FixedPriorityBlockingQueue<T> {
     final ReentrantLock lock = this.lock;
     lock.lockInterruptibly();
     try {
-      while (queue.size() == 0) {
+      while (queue.isEmpty()) {
         notEmpty.await();
       }
       return queue.pollLast();

server/src/main/java/org/apache/iotdb/db/utils/datastructure/TVList.java

@@ -63,7 +63,7 @@ public abstract class TVList implements WALEntryValue {
   protected AtomicInteger referenceCount;
   private long version;
 
-  public TVList() {
+  protected TVList() {
     timestamps = new ArrayList<>();
     rowCount = 0;
     maxTime = Long.MIN_VALUE;

server/src/main/java/org/apache/iotdb/db/wal/allocation/AbstractNodeAllocationStrategy.java

@@ -42,7 +42,7 @@ public abstract class AbstractNodeAllocationStrategy implements NodeAllocationSt
   /** manage wal folders */
   protected FolderManager folderManager;
 
-  public AbstractNodeAllocationStrategy() {
+  protected AbstractNodeAllocationStrategy() {
     try {
       folderManager =
           new FolderManager(

server/src/main/java/org/apache/iotdb/db/wal/buffer/AbstractWALBuffer.java

@@ -46,7 +46,7 @@ public abstract class AbstractWALBuffer implements IWALBuffer {
   /** current wal file log writer */
   protected volatile WALWriter currentWALFileWriter;
 
-  public AbstractWALBuffer(
+  protected AbstractWALBuffer(
       String identifier, String logDirectory, long startFileVersion, long startSearchIndex)
       throws FileNotFoundException {
     this.identifier = identifier;

server/src/main/java/org/apache/iotdb/db/wal/buffer/WALEntry.java

@@ -56,7 +56,7 @@ public abstract class WALEntry implements SerializedSize {
    */
   protected final WALFlushListener walFlushListener;
 
-  public WALEntry(long memTableId, WALEntryValue value, boolean wait) {
+  protected WALEntry(long memTableId, WALEntryValue value, boolean wait) {
     this.memTableId = memTableId;
     this.value = value;
     if (value instanceof IMemTable) {
@@ -93,6 +93,8 @@ public abstract class WALEntry implements SerializedSize {
       case ROLL_WAL_LOG_WRITER_SIGNAL:
       case WAL_FILE_INFO_END_MARKER:
         return new WALSignalEntry(type);
+      default:
+        break;
     }
 
     // handle info

server/src/main/java/org/apache/iotdb/db/wal/io/LogWriter.java

@@ -44,7 +44,7 @@ public abstract class LogWriter implements ILogWriter {
   protected final FileChannel logChannel;
   protected long size;
 
-  public LogWriter(File logFile) throws FileNotFoundException {
+  protected LogWriter(File logFile) throws FileNotFoundException {
     this.logFile = logFile;
     this.logStream = new FileOutputStream(logFile, true);
     this.logChannel = this.logStream.getChannel();

server/src/main/java/org/apache/iotdb/db/wal/node/WALFakeNode.java

@@ -64,6 +64,8 @@ public class WALFakeNode implements IWALNode {
       case FAILURE:
         walFlushListener.fail(cause);
         break;
+      default:
+        break;
     }
     return walFlushListener;
   }

server/src/main/java/org/apache/iotdb/db/wal/node/WALNode.java

@@ -633,7 +633,7 @@ public class WALNode implements IWALNode {
       }
 
       // update iterator
-      if (insertNodes.size() != 0) {
+      if (!insertNodes.isEmpty()) {
         itr = insertNodes.iterator();
         return true;
       }

server/src/main/java/org/apache/iotdb/db/wal/recover/file/AbstractTsFileRecoverPerformer.java

@@ -46,7 +46,7 @@ public abstract class AbstractTsFileRecoverPerformer implements Closeable {
   /** this writer will be open when .resource file doesn't exist */
   protected RestorableTsFileIOWriter writer;
 
-  public AbstractTsFileRecoverPerformer(TsFileResource tsFileResource) {
+  protected AbstractTsFileRecoverPerformer(TsFileResource tsFileResource) {
     this.tsFileResource = tsFileResource;
   }
 

server/src/main/java/org/apache/iotdb/db/wal/utils/listener/AbstractResultListener.java

@@ -31,7 +31,7 @@ public abstract class AbstractResultListener {
   protected volatile Status status;
   protected volatile Exception cause;
 
-  public AbstractResultListener(boolean wait) {
+  protected AbstractResultListener(boolean wait) {
     this.wait = wait;
     this.status = Status.RUNNING;
     this.cause = null;