fix the wal comment (#8673)

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

@@ -112,8 +112,8 @@ public class WALFileUtils {
    * _2-5-1.wal: 6, 7, 8, 9, -1, -1, -1, 10, 11, -1, 12, 12 <br>
    * _3-12-1.wal: 12, 12, 12, 12, 12 <br>
    * _4-12-1.wal: 12, 13, 14, 15, 16, -1 <br>
-   * searching [1, 5] will return 0, searching [6, 12] will return 1, search [13, infinity) will
-   * return 3， others will return -1
+   * searching [1, 5] will return 0, searching [6, 12] will return 2, search [13, infinity) will
+   * return 4， others will return -1
    *
    * @param files files to be searched
    * @param targetSearchIndex search index of target insert plan

server/src/test/java/org/apache/iotdb/db/wal/utils/WALFileUtilsTest.java

@@ -212,4 +212,30 @@ public class WALFileUtilsTest {
     int i = WALFileUtils.binarySearchFileBySearchIndex(files, 12);
     Assert.assertEquals(7, i);
   }
+
+  @Test
+  public void binarySearchFileBySearchIndex13() {
+    File[] files =
+        new File[] {
+          new File(WALFileUtils.getLogFileName(0, 0, WALFileStatus.CONTAINS_SEARCH_INDEX)),
+          new File(WALFileUtils.getLogFileName(1, 5, WALFileStatus.CONTAINS_NONE_SEARCH_INDEX)),
+          new File(WALFileUtils.getLogFileName(2, 5, WALFileStatus.CONTAINS_SEARCH_INDEX)),
+          new File(WALFileUtils.getLogFileName(3, 12, WALFileStatus.CONTAINS_SEARCH_INDEX)),
+          new File(WALFileUtils.getLogFileName(4, 12, WALFileStatus.CONTAINS_SEARCH_INDEX)),
+        };
+    int i = WALFileUtils.binarySearchFileBySearchIndex(files, 5);
+    Assert.assertEquals(0, i);
+
+    i = WALFileUtils.binarySearchFileBySearchIndex(files, 6);
+    Assert.assertEquals(2, i);
+
+    i = WALFileUtils.binarySearchFileBySearchIndex(files, 13);
+    Assert.assertEquals(4, i);
+
+    i = WALFileUtils.binarySearchFileBySearchIndex(files, 100);
+    Assert.assertEquals(4, i);
+
+    i = WALFileUtils.binarySearchFileBySearchIndex(files, 0);
+    Assert.assertEquals(-1, i);
+  }
 }