Revised the backporting strategy

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/ReconUtils.java

@@ -277,9 +277,11 @@ public static String constructFullPath(OmKeyInfo omKeyInfo,
       if (nsSummary == null) {
         break;
       }
-      if (!hasParentIdField(nsSummary)) {
-        // Call reprocess method if parentId is missing
+      if (nsSummary.getParentId() == -1) {
+        // Call reprocess method if parentId is negative, as it has not been set for this yet.
         reconNamespaceSummaryManager.rebuildNSSummaryTree(omMetadataManager);
+        return constructFullPath(omKeyInfo, reconNamespaceSummaryManager,
+            omMetadataManager);
       }
       fullPath.insert(0, nsSummary.getDirName() + OM_KEY_PREFIX);
 
@@ -298,20 +300,6 @@ public static String constructFullPath(OmKeyInfo omKeyInfo,
     return fullPath.toString();
   }
 
-  public static boolean hasParentIdField(NSSummary nsSummary) {
-    Field field;
-    try {
-      // This line attempts to get the Field object representing the parentId
-      // field from the NSSummary class. If the parentId field does not exist,
-      // a NoSuchFieldException will be thrown.
-      field = NSSummary.class.getDeclaredField("parentId");
-      return true;
-    } catch (NoSuchFieldException e) {
-      return false; // Field not present
-    }
-  }
-
-
   /**
    * Make HTTP GET call on the URL and return HttpURLConnection instance.
    *

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/api/types/NSSummary.java

@@ -36,11 +36,11 @@ public class NSSummary {
   private int[] fileSizeBucket;
   private Set<Long> childDir;
   private String dirName;
-  private long parentId = -1;
+  private long parentId = 0;
 
   public NSSummary() {
     this(0, 0L, new int[ReconConstants.NUM_OF_FILE_SIZE_BINS],
-        new HashSet<>(), "", -1); // -1 can be a default value indicating no parent
+        new HashSet<>(), "", 0);
   }
 
   public NSSummary(int numOfFiles,

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/codec/NSSummaryCodec.java

@@ -113,8 +113,6 @@ public NSSummary fromPersistedFormat(byte[] rawData) throws IOException {
 
     int strLen = in.readInt();
     if (strLen == 0) {
-      long parentId = in.readLong(); // Deserialize parentId
-      res.setParentId(parentId);
       return res;
     }
     byte[] buffer = new byte[strLen];
@@ -123,6 +121,12 @@ public NSSummary fromPersistedFormat(byte[] rawData) throws IOException {
     String dirName = stringCodec.fromPersistedFormat(buffer);
     res.setDirName(dirName);
     long parentId = in.readLong();
+    if (parentId == 0) {
+      // Set the parent ID to -1 to indicate that it is old data from
+      // the cluster and the value has not yet been set.
+      res.setParentId(-1);
+      return res;
+    }
     res.setParentId(parentId);
     return res;
   }

hadoop-ozone/recon/src/main/java/org/apache/hadoop/ozone/recon/tasks/NSSummaryTaskDbEventHandler.java

@@ -30,12 +30,10 @@
 import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
-import java.lang.reflect.Field;
 import java.util.Map;
 
 import static org.apache.hadoop.ozone.recon.ReconServerConfigKeys.OZONE_RECON_NSSUMMARY_FLUSH_TO_DB_MAX_THRESHOLD;
 import static org.apache.hadoop.ozone.recon.ReconServerConfigKeys.OZONE_RECON_NSSUMMARY_FLUSH_TO_DB_MAX_THRESHOLD_DEFAULT;
-import static org.apache.hadoop.ozone.recon.ReconUtils.hasParentIdField;
 
 /**
  * Class for holding all NSSummaryTask methods
@@ -128,10 +126,6 @@ protected void handlePutDirEvent(OmDirectoryInfo directoryInfo,
       // If we don't have it in this batch we try to get it from the DB
       curNSSummary = reconNamespaceSummaryManager.getNSSummary(objectId);
     }
-    if (!hasParentIdField(curNSSummary)) {
-      reconNamespaceSummaryManager.rebuildNSSummaryTree(reconOMMetadataManager);
-      return;
-    }
     if (curNSSummary == null) {
       // If we don't have it locally and in the DB we create a new instance
       // as this is a new ID
@@ -151,10 +145,6 @@ protected void handlePutDirEvent(OmDirectoryInfo directoryInfo,
       // If we don't have it in this batch we try to get it from the DB
       nsSummary = reconNamespaceSummaryManager.getNSSummary(parentObjectId);
     }
-    if (!hasParentIdField(nsSummary)) {
-      reconNamespaceSummaryManager.rebuildNSSummaryTree(reconOMMetadataManager);
-      return;
-    }
     if (nsSummary == null) {
       // If we don't have it locally and in the DB we create a new instance
       // as this is a new ID