HDFS-10313. Distcp need to enforce the order of snapshot names passed to -diff. (Lin Yiqun via Yongjun Zhang)

hadoop-tools/hadoop-distcp/src/main/java/org/apache/hadoop/tools/CopyListing.java

@@ -268,6 +268,10 @@ static class InvalidInputException extends RuntimeException {
     public InvalidInputException(String message) {
       super(message);
     }
+
+    public InvalidInputException(String message, Throwable cause) {
+      super(message, cause);
+    }
   }
 
   public static class AclsNotSupportedException extends RuntimeException {

hadoop-tools/hadoop-distcp/src/main/java/org/apache/hadoop/tools/DistCp.java

@@ -179,7 +179,8 @@ public Job createAndSubmitJob() throws Exception {
         if (distCpSync.sync()) {
           createInputFileListingWithDiff(job, distCpSync);
         } else {
-          inputOptions.disableUsingDiff();
+          throw new Exception("DistCp sync failed, input options: "
+              + inputOptions);
         }
       }
 

hadoop-tools/hadoop-distcp/src/main/java/org/apache/hadoop/tools/DistCpSync.java

@@ -17,14 +17,18 @@
  */
 package org.apache.hadoop.tools;
 
+import org.apache.hadoop.HadoopIllegalArgumentException;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.hdfs.DFSUtilClient;
 import org.apache.hadoop.hdfs.DistributedFileSystem;
 import org.apache.hadoop.hdfs.protocol.HdfsConstants;
 import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
+import org.apache.hadoop.tools.CopyListing.InvalidInputException;
 
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.List;
@@ -91,6 +95,28 @@ private boolean preSyncCheck() throws IOException {
           inputOptions.getToSnapshot())));
       return false;
     }
+
+    final String from = getSnapshotName(inputOptions.getFromSnapshot());
+    final String to = getSnapshotName(inputOptions.getToSnapshot());
+
+    try {
+      final FileStatus fromSnapshotStat =
+          sfs.getFileStatus(getSourceSnapshotPath(sourceDir, from));
+
+      final FileStatus toSnapshotStat =
+          sfs.getFileStatus(getSourceSnapshotPath(sourceDir, to));
+
+      // If toSnapshot isn't current dir then do a time check
+      if (!to.equals("")
+          && fromSnapshotStat.getModificationTime() > toSnapshotStat
+              .getModificationTime()) {
+        throw new HadoopIllegalArgumentException("Snapshot " + to
+            + " should be newer than " + from);
+      }
+    } catch (FileNotFoundException nfe) {
+      throw new InvalidInputException("Input snapshot is not found", nfe);
+    }
+
     return true;
   }
 

hadoop-tools/hadoop-distcp/src/test/java/org/apache/hadoop/tools/TestDistCpSync.java

@@ -17,6 +17,7 @@
  */
 package org.apache.hadoop.tools;
 
+import org.apache.hadoop.HadoopIllegalArgumentException;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.Path;
@@ -31,6 +32,7 @@
 import org.apache.hadoop.io.Text;
 import org.apache.hadoop.mapreduce.Mapper;
 import org.apache.hadoop.security.Credentials;
+import org.apache.hadoop.test.GenericTestUtils;
 import org.apache.hadoop.tools.mapred.CopyMapper;
 import org.junit.After;
 import org.junit.Assert;
@@ -712,4 +714,29 @@ public void testSync9() throws Exception {
     verifyCopy(dfs.getFileStatus(sourcePath),
                  dfs.getFileStatus(target), false);
   }
+
+  @Test
+  public void testSyncSnapshotTimeStampChecking() throws Exception {
+    initData(source);
+    initData(target);
+    dfs.allowSnapshot(source);
+    dfs.allowSnapshot(target);
+    dfs.createSnapshot(source, "s2");
+    dfs.createSnapshot(target, "s1");
+    // Sleep one second to make snapshot s1 created later than s2
+    Thread.sleep(1000);
+    dfs.createSnapshot(source, "s1");
+
+    boolean threwException = false;
+    try {
+      DistCpSync distCpSync = new DistCpSync(options, conf);
+      // do the sync
+      distCpSync.sync();
+    } catch (HadoopIllegalArgumentException e) {
+      threwException = true;
+      GenericTestUtils.assertExceptionContains(
+          "Snapshot s2 should be newer than s1", e);
+    }
+    Assert.assertTrue(threwException);
+  }
 }