[IOTDB-74]fix that the damaged log will be skipped if it is the only log (#166)

* fix that the damaged log will be skipped if it is the only log

* add error log

* fix test

iotdb/src/main/java/org/apache/iotdb/db/tools/WalChecker.java

@@ -54,6 +54,7 @@ public class WalChecker {
    */
   public List<File> doCheck() throws SysCheckException {
     File walFolderFile = new File(walFolder);
+    LOGGER.info("Checking folder: {}", walFolderFile.getAbsolutePath());
     if(!walFolderFile.exists() || !walFolderFile.isDirectory()) {
       throw new SysCheckException(String.format("%s is not a directory", walFolder));
     }
@@ -67,13 +68,21 @@ public class WalChecker {
     List<File> failedFiles = new ArrayList<>();
     for (int dirIndex = 0; dirIndex < storageWalFolders.length; dirIndex++) {
       File storageWalFolder = storageWalFolders[dirIndex];
-      LOGGER.debug("Checking the No.{} directory {}", dirIndex, storageWalFolder.getName());
+      LOGGER.info("Checking the No.{} directory {}", dirIndex, storageWalFolder.getName());
       File walFile = new File(storageWalFolder, WAL_FILE_NAME);
       if (!walFile.exists()) {
         LOGGER.debug("No wal file in this dir, skipping");
         continue;
       }
 
+      if (walFile.length() > 0 && walFile.length() < RAFLogReader.LEAST_LOG_SIZE) {
+        // contains only one damaged log
+        LOGGER.error("{} fails the check because it is non-empty but does not contain enough bytes "
+            + "even for one log.", walFile.getAbsoluteFile());
+        failedFiles.add(walFile);
+        continue;
+      }
+
       RAFLogReader logReader = null;
       try {
         logReader = new RAFLogReader(walFile);

iotdb/src/main/java/org/apache/iotdb/db/writelog/io/RAFLogReader.java

@@ -32,6 +32,7 @@ import org.slf4j.LoggerFactory;
 public class RAFLogReader implements ILogReader {
 
   private static final Logger logger = LoggerFactory.getLogger(RAFLogReader.class);
+  public static final int LEAST_LOG_SIZE = 12; // size + checksum
   private RandomAccessFile logRaf;
   private String filepath;
   private int bufferSize = 4 * 1024 * 1024;
@@ -53,7 +54,7 @@ public class RAFLogReader implements ILogReader {
       return true;
     }
 
-    if (logRaf.getFilePointer() + 12 > logRaf.length()) {
+    if (logRaf.getFilePointer() + LEAST_LOG_SIZE > logRaf.length()) {
       return false;
     }
 

iotdb/src/test/java/org/apache/iotdb/db/tools/WalCheckerTest.java

@@ -24,6 +24,8 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
 import java.io.File;
+import java.io.FileOutputStream;
+import java.io.FileWriter;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -129,5 +131,29 @@ public class WalCheckerTest {
     } finally {
       FileUtils.deleteDirectory(tempRoot);
     }
+
+  }
+
+  @Test
+  public void testOneDamagedCheck() throws IOException, SysCheckException {
+    File tempRoot = new File("root");
+    tempRoot.mkdir();
+
+    try {
+      for (int i = 0; i < 5; i++) {
+        File subDir = new File(tempRoot, "storage_group" + i);
+        subDir.mkdir();
+
+        FileOutputStream fileOutputStream = new FileOutputStream(new File(subDir, WAL_FILE_NAME));
+        fileOutputStream.write(i);
+        fileOutputStream.close();
+      }
+
+      WalChecker checker = new WalChecker(tempRoot.getAbsolutePath());
+      assertEquals(5, checker.doCheck().size());
+    } finally {
+      FileUtils.deleteDirectory(tempRoot);
+    }
+
   }
 }