Fixed the bug that schema region in lower version tree model may lose data when upgrades to table model

Author: Caideyipi

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/attribute/DeviceAttributeStore.java

@@ -53,7 +53,7 @@ public class DeviceAttributeStore implements IDeviceAttributeStore {
 
   private final MemSchemaRegionStatistics regionStatistics;
 
-  public DeviceAttributeStore(MemSchemaRegionStatistics regionStatistics) {
+  public DeviceAttributeStore(final MemSchemaRegionStatistics regionStatistics) {
     this.regionStatistics = regionStatistics;
   }
 
@@ -63,15 +63,15 @@ public void clear() {
   }
 
   @Override
-  public synchronized boolean createSnapshot(File targetDir) {
-    File snapshotTmp =
+  public synchronized boolean createSnapshot(final File targetDir) {
+    final File snapshotTmp =
         SystemFileFactory.INSTANCE.getFile(targetDir, SchemaConstant.DEVICE_ATTRIBUTE_SNAPSHOT_TMP);
-    File snapshot =
+    final File snapshot =
         SystemFileFactory.INSTANCE.getFile(targetDir, SchemaConstant.DEVICE_ATTRIBUTE_SNAPSHOT);
 
     try {
-      FileOutputStream fileOutputStream = new FileOutputStream(snapshotTmp);
-      BufferedOutputStream outputStream = new BufferedOutputStream(fileOutputStream);
+      final FileOutputStream fileOutputStream = new FileOutputStream(snapshotTmp);
+      final BufferedOutputStream outputStream = new BufferedOutputStream(fileOutputStream);
       try {
         serialize(outputStream);
       } finally {
@@ -95,7 +95,7 @@ public synchronized boolean createSnapshot(File targetDir) {
       }
 
       return true;
-    } catch (IOException e) {
+    } catch (final IOException e) {
       logger.error("Failed to create mtree snapshot due to {}", e.getMessage(), e);
       FileUtils.deleteFileIfExist(snapshot);
       return false;
@@ -105,25 +105,30 @@ public synchronized boolean createSnapshot(File targetDir) {
   }
 
   @Override
-  public void loadFromSnapshot(File snapshotDir, String sgSchemaDirPath) throws IOException {
-    try (BufferedInputStream inputStream =
-        new BufferedInputStream(
-            Files.newInputStream(
-                SystemFileFactory.INSTANCE
-                    .getFile(snapshotDir, SchemaConstant.DEVICE_ATTRIBUTE_SNAPSHOT)
-                    .toPath()))) {
+  public void loadFromSnapshot(final File snapshotDir, final String sgSchemaDirPath)
+      throws IOException {
+    final File snapshot =
+        SystemFileFactory.INSTANCE.getFile(snapshotDir, SchemaConstant.DEVICE_ATTRIBUTE_SNAPSHOT);
+    if (!snapshot.exists()) {
+      logger.info(
+          "Device attribute snapshot {} not found, consider it as upgraded from the older version, use empty attributes",
+          snapshot);
+      return;
+    }
+    try (final BufferedInputStream inputStream =
+        new BufferedInputStream(Files.newInputStream(snapshot.toPath()))) {
       deserialize(inputStream);
-    } catch (IOException e) {
+    } catch (final IOException e) {
       logger.warn("Load device attribute snapshot from {} failed", snapshotDir);
       throw e;
     }
   }
 
   @Override
-  public synchronized int createAttribute(List<String> nameList, Object[] valueList) {
+  public synchronized int createAttribute(final List<String> nameList, final Object[] valueList) {
     // todo implement storage for device of diverse data types
     long memUsage = 0L;
-    Map<String, String> attributeMap = new HashMap<>();
+    final Map<String, String> attributeMap = new HashMap<>();
     String value;
     for (int i = 0; i < nameList.size(); i++) {
       value =

iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/impl/SchemaRegionMemoryImpl.java

@@ -504,34 +504,34 @@ public synchronized boolean createSnapshot(File snapshotDir) {
 
   // currently, this method is only used for cluster-ratis mode
   @Override
-  public void loadSnapshot(File latestSnapshotRootDir) {
+  public void loadSnapshot(final File latestSnapshotRootDir) {
     clear();
 
     logger.info("Start loading snapshot of schemaRegion {}", schemaRegionId);
-    long startTime = System.currentTimeMillis();
+    final long startTime = System.currentTimeMillis();
 
     try {
       usingMLog = false;
 
       isRecovering = true;
 
-      long deviceAttributeSnapshotStartTime = System.currentTimeMillis();
+      final long deviceAttributeSnapshotStartTime = System.currentTimeMillis();
       deviceAttributeStore = new DeviceAttributeStore(regionStatistics);
       deviceAttributeStore.loadFromSnapshot(latestSnapshotRootDir, schemaRegionDirPath);
       logger.info(
           "Device attribute snapshot loading of schemaRegion {} costs {}ms.",
           schemaRegionId,
           System.currentTimeMillis() - deviceAttributeSnapshotStartTime);
 
-      long tagSnapshotStartTime = System.currentTimeMillis();
+      final long tagSnapshotStartTime = System.currentTimeMillis();
       tagManager =
           TagManager.loadFromSnapshot(latestSnapshotRootDir, schemaRegionDirPath, regionStatistics);
       logger.info(
           "Tag snapshot loading of schemaRegion {} costs {}ms.",
           schemaRegionId,
           System.currentTimeMillis() - tagSnapshotStartTime);
 
-      long mtreeSnapshotStartTime = System.currentTimeMillis();
+      final long mTreeSnapshotStartTime = System.currentTimeMillis();
       mtree =
           MTreeBelowSGMemoryImpl.loadFromSnapshot(
               latestSnapshotRootDir,
@@ -567,7 +567,7 @@ public void loadSnapshot(File latestSnapshotRootDir) {
       logger.info(
           "MTree snapshot loading of schemaRegion {} costs {}ms.",
           schemaRegionId,
-          System.currentTimeMillis() - mtreeSnapshotStartTime);
+          System.currentTimeMillis() - mTreeSnapshotStartTime);
 
       isRecovering = false;
       initialized = true;
@@ -577,7 +577,7 @@ public void loadSnapshot(File latestSnapshotRootDir) {
           schemaRegionId,
           System.currentTimeMillis() - startTime);
       logger.info("Successfully load snapshot of schemaRegion {}", schemaRegionId);
-    } catch (IOException | IllegalPathException e) {
+    } catch (final IOException | IllegalPathException e) {
       logger.error(
           "Failed to load snapshot for schemaRegion {}  due to {}. Use empty schemaRegion",
           schemaRegionId,
@@ -587,7 +587,7 @@ public void loadSnapshot(File latestSnapshotRootDir) {
         initialized = false;
         isRecovering = true;
         init();
-      } catch (MetadataException metadataException) {
+      } catch (final MetadataException metadataException) {
         logger.error(
             "Error occurred during initializing schemaRegion {}",
             schemaRegionId,