[HUDI-2074] Use while loop instead of recursive call in MergeOnReadInputFormat#MergeIterator to avoid StackOverflow (#3159)

hudi-flink/src/main/java/org/apache/hudi/table/format/mor/MergeOnReadInputFormat.java

@@ -572,13 +572,13 @@ public class MergeOnReadInputFormat
 
     @Override
     public boolean reachedEnd() throws IOException {
-      if (!readLogs && !this.reader.reachedEnd()) {
+      while (!readLogs && !this.reader.reachedEnd()) {
         currentRecord = this.reader.nextRecord();
         if (instantRange != null) {
           boolean isInRange = instantRange.isInRange(currentRecord.getString(HOODIE_COMMIT_TIME_COL_POS).toString());
           if (!isInRange) {
             // filter base file by instant range
-            return reachedEnd();
+            continue;
           }
         }
         final String curKey = currentRecord.getString(HOODIE_RECORD_KEY_COL_POS).toString();
@@ -587,7 +587,7 @@ public class MergeOnReadInputFormat
           Option<IndexedRecord> mergedAvroRecord = mergeRowWithLog(currentRecord, curKey);
           if (!mergedAvroRecord.isPresent()) {
             // deleted
-            return reachedEnd();
+            continue;
           } else {
             GenericRecord record = buildAvroRecordBySchema(
                 mergedAvroRecord.get(),
@@ -601,7 +601,8 @@ public class MergeOnReadInputFormat
         // project the full record in base with required positions
         currentRecord = projection.project(currentRecord);
         return false;
-      } else {
+      }
+      // read the logs
       readLogs = true;
       while (logKeysIterator.hasNext()) {
         final String curKey = logKeysIterator.next();
@@ -622,7 +623,6 @@ public class MergeOnReadInputFormat
       }
       return true;
     }
-    }
 
     @Override
     public RowData nextRecord() {