[example] Add LogRecords example

Author: LiebingYu

fluss-common/src/test/java/com/alibaba/fluss/record/MemoryLogRecordsTest.java

@@ -17,16 +17,20 @@
 
 package com.alibaba.fluss.record;
 
+import com.alibaba.fluss.row.InternalRow;
 import com.alibaba.fluss.testutils.DataTestUtils;
 import com.alibaba.fluss.testutils.LogRecordsAssert;
+import com.alibaba.fluss.utils.CloseableIterator;
 
 import org.junit.jupiter.api.Test;
 
 import java.nio.ByteBuffer;
+import java.util.Arrays;
 import java.util.function.Function;
 
 import static com.alibaba.fluss.record.TestData.DATA1;
 import static com.alibaba.fluss.record.TestData.DATA1_ROW_TYPE;
+import static com.alibaba.fluss.record.TestData.DEFAULT_SCHEMA_ID;
 
 /** Tests for {@link MemoryLogRecords}. */
 class MemoryLogRecordsTest {
@@ -81,4 +85,29 @@ void verifyPointToByteBuffer(Function<Integer, ByteBuffer> bufferSupplier) throw
                 .withSchema(DATA1_ROW_TYPE)
                 .isEqualTo(records);
     }
+
+    @Test
+    void testReadMemoryLogRecords() throws Exception {
+        MemoryLogRecords records =
+                DataTestUtils.genMemoryLogRecordsByObject(
+                        Arrays.asList(
+                                new Object[] {1, "A"},
+                                new Object[] {2, "B"},
+                                new Object[] {3, "C"}));
+
+        Iterable<LogRecordBatch> batches = records.batches();
+        for (LogRecordBatch batch : batches) {
+            System.out.println(batch.getRecordCount());
+            System.out.println(batch.lastLogOffset());
+            CloseableIterator<LogRecord> it =
+                    batch.records(
+                            LogRecordReadContext.createArrowReadContext(
+                                    DATA1_ROW_TYPE, DEFAULT_SCHEMA_ID));
+            while (it.hasNext()) {
+                LogRecord record = it.next();
+                InternalRow row = record.getRow();
+                System.out.printf("%d, %s\n", row.getInt(0), row.getString(1));
+            }
+        }
+    }
 }