HADOOP-12634. Change Lazy Rename Pending Operation Completion of WASB to address case of potential data loss due to partial copy. Contributed by Gaurav Kanade.

(cherry picked from commit 978bbdfeb2)

hadoop-common-project/hadoop-common/CHANGES.txt

@@ -926,6 +926,10 @@ Release 2.8.0 - UNRELEASED
     HADOOP-12689. S3 filesystem operations stopped working correctly
     (Matt Paduano via raviprak)
 
+    HADOOP-12634. Change Lazy Rename Pending Operation Completion of WASB to
+    address case of potential data loss due to partial copy
+    (Gaurav Kanade via cnauroth)
+
 Release 2.7.3 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-tools/hadoop-azure/src/main/java/org/apache/hadoop/fs/azure/NativeAzureFileSystem.java

@@ -536,45 +536,13 @@ public class NativeAzureFileSystem extends FileSystem {
       Path dstFile = fullPath(dstKey, fileName);
       boolean srcExists = fs.exists(srcFile);
       boolean dstExists = fs.exists(dstFile);
-      if (srcExists && !dstExists) {
+      if(srcExists) {
-
         // Rename gets exclusive access (via a lease) for HBase write-ahead log
         // (WAL) file processing correctness.  See the rename code for details.
         String srcName = fs.pathToKey(srcFile);
         String dstName = fs.pathToKey(dstFile);
         fs.getStoreInterface().rename(srcName, dstName, true, null);
-      } else if (srcExists && dstExists) {
-
-        // Get a lease on source to block write access.
-        String srcName = fs.pathToKey(srcFile);
-        SelfRenewingLease lease = null;
-        try {
-          lease = fs.acquireLease(srcFile);
-          // Delete the file. This will free the lease too.
-          fs.getStoreInterface().delete(srcName, lease);
-        } catch(AzureException e) {
-            String errorCode = "";
-            try {
-              StorageException e2 = (StorageException) e.getCause();
-              errorCode = e2.getErrorCode();
-            } catch(Exception e3) {
-              // do nothing if cast fails
-            }
-            // If the rename already finished do nothing
-            if(!errorCode.equals("BlobNotFound")){
-              throw e;
-            }
-        } finally {
-          try {
-            if(lease != null){
-              lease.free();
-            }
-          } catch(StorageException e) {
-            LOG.warn("Unable to free lease because: " + e.getMessage());
-          }
-        }
       } else if (!srcExists && dstExists) {
-
         // The rename already finished, so do nothing.
         ;
       } else {

hadoop-tools/hadoop-azure/src/test/java/org/apache/hadoop/fs/azure/TestNativeAzureFileSystemLive.java

@@ -24,6 +24,8 @@ import static org.junit.Assert.assertTrue;
 
 import java.util.concurrent.CountDownLatch;
 
+import org.apache.hadoop.io.IOUtils;
+import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.Path;
 import org.apache.hadoop.fs.permission.FsPermission;
 
@@ -43,6 +45,26 @@ public class TestNativeAzureFileSystemLive extends
     return AzureBlobStorageTestAccount.create();
   }
 
+  @Test
+  public void testLazyRenamePendingCanOverwriteExistingFile()
+    throws Exception {
+    final String SRC_FILE_KEY = "srcFile";
+    final String DST_FILE_KEY = "dstFile";
+    Path srcPath = new Path(SRC_FILE_KEY);
+    FSDataOutputStream srcStream = fs.create(srcPath);
+    assertTrue(fs.exists(srcPath));
+    Path dstPath = new Path(DST_FILE_KEY);
+    FSDataOutputStream dstStream = fs.create(dstPath);
+    assertTrue(fs.exists(dstPath));
+    NativeAzureFileSystem nfs = (NativeAzureFileSystem)fs;
+    final String fullSrcKey = nfs.pathToKey(nfs.makeAbsolute(srcPath));
+    final String fullDstKey = nfs.pathToKey(nfs.makeAbsolute(dstPath));
+    nfs.getStoreInterface().rename(fullSrcKey, fullDstKey, true, null);
+    assertTrue(fs.exists(dstPath));
+    assertFalse(fs.exists(srcPath));
+    IOUtils.cleanup(null, srcStream);
+    IOUtils.cleanup(null, dstStream);
+  }
   /**
    * Tests fs.delete() function to delete a blob when another blob is holding a
    * lease on it. Delete if called without a lease should fail if another process