HADOOP-13675. Bug in return value for delete() calls in WASB. Contributed by Dushyanth

(cherry picked from commit 15dd1f3381)

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

@@ -2045,10 +2045,10 @@ public class AzureNativeFileSystemStore implements NativeFileSystemStore {
    *          The key to search for.
    * @return The wanted directory, or null if not found.
    */
-  private static FileMetadata getDirectoryInList(
+  private static FileMetadata getFileMetadataInList(
       final Iterable<FileMetadata> list, String key) {
     for (FileMetadata current : list) {
-      if (current.isDir() && current.getKey().equals(key)) {
+      if (current.getKey().equals(key)) {
         return current;
       }
     }
@@ -2114,7 +2114,7 @@ public class AzureNativeFileSystemStore implements NativeFileSystemStore {
 
           // Add the metadata to the list, but remove any existing duplicate
           // entries first that we may have added by finding nested files.
-          FileMetadata existing = getDirectoryInList(fileMetadata, blobKey);
+          FileMetadata existing = getFileMetadataInList(fileMetadata, blobKey);
           if (existing != null) {
             fileMetadata.remove(existing);
           }
@@ -2141,7 +2141,7 @@ public class AzureNativeFileSystemStore implements NativeFileSystemStore {
 
           // Add the directory metadata to the list only if it's not already
           // there.
-          if (getDirectoryInList(fileMetadata, dirKey) == null) {
+          if (getFileMetadataInList(fileMetadata, dirKey) == null) {
             fileMetadata.add(directoryMetadata);
           }
 
@@ -2249,7 +2249,7 @@ public class AzureNativeFileSystemStore implements NativeFileSystemStore {
 
           // Add the directory metadata to the list only if it's not already
           // there.
-          FileMetadata existing = getDirectoryInList(aFileMetadataList, blobKey);
+          FileMetadata existing = getFileMetadataInList(aFileMetadataList, blobKey);
           if (existing != null) {
             aFileMetadataList.remove(existing);
           }
@@ -2278,7 +2278,7 @@ public class AzureNativeFileSystemStore implements NativeFileSystemStore {
             // absolute path is being used or not.
             String dirKey = normalizeKey(directory);
 
-            if (getDirectoryInList(aFileMetadataList, dirKey) == null) {
+            if (getFileMetadataInList(aFileMetadataList, dirKey) == null) {
               // Reached the targeted listing depth. Return metadata for the
               // directory using default permissions.
               //
@@ -2376,18 +2376,24 @@ public class AzureNativeFileSystemStore implements NativeFileSystemStore {
     }
   }
 
+  /**
+   * API implementation to delete a blob in the back end azure storage.
+   */
   @Override
-  public void delete(String key, SelfRenewingLease lease) throws IOException {
+  public boolean delete(String key, SelfRenewingLease lease) throws IOException {
     try {
       if (checkContainer(ContainerAccessType.ReadThenWrite) == ContainerState.DoesntExist) {
         // Container doesn't exist, no need to do anything
-        return;
+        return true;
       }
 
       // Get the blob reference and delete it.
       CloudBlobWrapper blob = getBlobReference(key);
       if (blob.exists(getInstrumentedContext())) {
         safeDelete(blob, lease);
+        return true;
+      } else {
+        return false;
       }
     } catch (Exception e) {
       // Re-throw as an Azure storage exception.
@@ -2395,10 +2401,13 @@ public class AzureNativeFileSystemStore implements NativeFileSystemStore {
     }
   }
 
+  /**
+   * API implementation to delete a blob in the back end azure storage.
+   */
   @Override
-  public void delete(String key) throws IOException {
+  public boolean delete(String key) throws IOException {
     try {
-      delete(key, null);
+      return delete(key, null);
     } catch (IOException e) {
       Throwable t = e.getCause();
       if(t != null && t instanceof StorageException) {
@@ -2407,7 +2416,7 @@ public class AzureNativeFileSystemStore implements NativeFileSystemStore {
           SelfRenewingLease lease = null;
           try {
             lease = acquireLease(key);
-            delete(key, lease);
+            return delete(key, lease);
           } catch (AzureException e3) {
             LOG.warn("Got unexpected exception trying to acquire lease on "
                 + key + "." + e3.getMessage());

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

@@ -1765,8 +1765,11 @@ public class NativeAzureFileSystem extends FileSystem {
       }
 
       try {
-        store.delete(key);
+        if (store.delete(key)) {
           instrumentation.fileDeleted();
+        } else {
+          return false;
+        }
       } catch(IOException e) {
 
         Throwable innerException = NativeAzureFileSystemHelper.checkForAzureStorageException(e);
@@ -1885,7 +1888,7 @@ public class NativeAzureFileSystem extends FileSystem {
       }
 
       // Delete the current directory
-      if (!deleteFile(metaFile.getKey(), metaFile.isDir())) {
+      if (store.retrieveMetadata(metaFile.getKey()) != null && !deleteFile(metaFile.getKey(), metaFile.isDir())) {
         LOG.error("Failed delete directory {}", f.toString());
         return false;
       }
@@ -1913,12 +1916,16 @@ public class NativeAzureFileSystem extends FileSystem {
   @VisibleForTesting
   boolean deleteFile(String key, boolean isDir) throws IOException {
     try {
-      store.delete(key);
+      if (store.delete(key)) {
         if (isDir) {
           instrumentation.directoryDeleted();
         } else {
           instrumentation.fileDeleted();
         }
+        return true;
+      } else {
+        return false;
+      }
     } catch(IOException e) {
       Throwable innerException = NativeAzureFileSystemHelper.checkForAzureStorageException(e);
 
@@ -1929,8 +1936,6 @@ public class NativeAzureFileSystem extends FileSystem {
 
       throw e;
     }
-
-    return true;
   }
 
   @Override
@@ -2790,6 +2795,8 @@ public class NativeAzureFileSystem extends FileSystem {
         throws IOException {
 
       LOG.debug("Deleting dangling file {}", file.getKey());
+      // Not handling delete return type as false return essentially
+      // means its a no-op for the caller
       store.delete(file.getKey());
       store.delete(tempFile.getKey());
     }

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

@@ -74,7 +74,16 @@ interface NativeFileSystemStore {
   void changePermissionStatus(String key, PermissionStatus newPermission)
       throws AzureException;
 
-  void delete(String key) throws IOException;
+  /**
+   * API to delete a blob in the back end azure storage.
+   * @param key - key to the blob being deleted.
+   * @return return true when delete is successful, false if
+   * blob cannot be found or delete is not possible without
+   * exception.
+   * @throws IOException Exception encountered while deleting in
+   * azure storage.
+   */
+  boolean delete(String key) throws IOException;
 
   void rename(String srcKey, String dstKey) throws IOException;
 
@@ -104,7 +113,17 @@ interface NativeFileSystemStore {
   void updateFolderLastModifiedTime(String key, Date lastModified,
       SelfRenewingLease folderLease) throws AzureException;
 
-  void delete(String key, SelfRenewingLease lease) throws IOException;
+  /**
+   * API to delete a blob in the back end azure storage.
+   * @param key - key to the blob being deleted.
+   * @param lease - Active lease on the blob.
+   * @return return true when delete is successful, false if
+   * blob cannot be found or delete is not possible without
+   * exception.
+   * @throws IOException Exception encountered while deleting in
+   * azure storage.
+   */
+  boolean delete(String key, SelfRenewingLease lease) throws IOException;
       
   SelfRenewingLease acquireLease(String key) throws AzureException;
 

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

@@ -0,0 +1,119 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.hadoop.fs.azure;
+
+
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.junit.Assert;
+import org.junit.Test;
+
+/***
+ * Test class to hold all Live Azure storage concurrency tests.
+ */
+public class TestNativeAzureFileSystemConcurrencyLive
+    extends AbstractWasbTestBase {
+
+  private static final int TEST_COUNT = 102;
+  @Override
+  protected AzureBlobStorageTestAccount createTestAccount() throws Exception {
+    return AzureBlobStorageTestAccount.create();
+  }
+
+  /**
+   * Test multi-threaded deletes in WASB. Expected behavior is one of the thread
+   * should be to successfully delete the file and return true and all other
+   * threads need to return false.
+   */
+  @Test
+  public void testMultiThreadedDeletes() throws Exception {
+    Path testFile = new Path("test.dat");
+    fs.create(testFile).close();
+
+    int threadCount = TEST_COUNT;
+    DeleteHelperThread[] helperThreads = new DeleteHelperThread[threadCount];
+
+    for (int i = 0; i < threadCount; i++) {
+      helperThreads[i] = new DeleteHelperThread(fs, testFile);
+    }
+
+    Thread[] threads = new Thread[threadCount];
+
+    for (int i = 0; i < threadCount; i++) {
+      threads[i] = new Thread(helperThreads[i]);
+      threads[i].start();
+    }
+
+    for (int i = 0; i < threadCount; i++) {
+      threads[i].join();
+    }
+
+    boolean deleteSuccess = false;
+
+    for (int i = 0; i < threadCount; i++) {
+
+      Assert.assertFalse("child thread has exception : " + helperThreads[i].getException(),
+          helperThreads[i].getExceptionEncounteredFlag());
+
+      if (deleteSuccess) {
+        Assert.assertFalse("More than one thread delete() retuhelperThreads[i].getDeleteSuccess()",
+            helperThreads[i].getExceptionEncounteredFlag());
+      } else {
+        deleteSuccess = helperThreads[i].getDeleteSuccess();
+      }
+    }
+
+    Assert.assertTrue("No successfull delete found", deleteSuccess);
+  }
+}
+
+class DeleteHelperThread implements Runnable {
+
+  private FileSystem fs;
+  private Path p;
+  private boolean deleteSuccess;
+  private boolean exceptionEncountered;
+  private Exception ex;
+
+  public DeleteHelperThread(FileSystem fs, Path p) {
+    this.fs = fs;
+    this.p = p;
+  }
+
+  public void run() {
+    try {
+      deleteSuccess = fs.delete(p, false);
+    } catch (Exception ioEx) {
+      exceptionEncountered = true;
+      this.ex = ioEx;
+    }
+  }
+
+  public boolean getDeleteSuccess() {
+    return deleteSuccess;
+  }
+
+  public boolean getExceptionEncounteredFlag() {
+    return exceptionEncountered;
+  }
+
+  public Exception getException() {
+    return ex;
+  }
+}