HADOOP-14769. WASB: delete recursive should not fail if a file is deleted.

Contributed by Thomas Marquardt

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

@@ -2459,8 +2459,11 @@ public class AzureNativeFileSystemStore implements NativeFileSystemStore {
     try {
       blob.delete(operationContext, lease);
     } catch (StorageException e) {
-      LOG.error("Encountered Storage Exception for delete on Blob: {}, Exception Details: {} Error Code: {}",
+      if (!NativeAzureFileSystemHelper.isFileNotFoundException(e)) {
+        LOG.error("Encountered Storage Exception for delete on Blob: {}"
+            + ", Exception Details: {} Error Code: {}",
             blob.getUri(), e.getMessage(), e.getErrorCode());
+      }
       // On exception, check that if:
       // 1. It's a BlobNotFound exception AND
       // 2. It got there after one-or-more retries THEN
@@ -2491,17 +2494,17 @@ public class AzureNativeFileSystemStore implements NativeFileSystemStore {
         // Container doesn't exist, no need to do anything
         return true;
       }
-
       // Get the blob reference and delete it.
       CloudBlobWrapper blob = getBlobReference(key);
-      if (blob.exists(getInstrumentedContext())) {
       safeDelete(blob, lease);
       return true;
-      } else {
+    } catch (Exception e) {
+      if (e instanceof StorageException
+          && NativeAzureFileSystemHelper.isFileNotFoundException(
+              (StorageException) e)) {
+        // the file or directory does not exist
         return false;
       }
-    } catch (Exception e) {
-      // Re-throw as an Azure storage exception.
       throw new AzureException(e);
     }
   }

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

@@ -2043,7 +2043,12 @@ public class NativeAzureFileSystem extends FileSystem {
       AzureFileSystemThreadTask task = new AzureFileSystemThreadTask() {
         @Override
         public boolean execute(FileMetadata file) throws IOException{
-          return deleteFile(file.getKey(), file.isDir());
+          if (!deleteFile(file.getKey(), file.isDir())) {
+            LOG.warn("Attempt to delete non-existent {} {}",
+                file.isDir() ? "directory" : "file",
+                file.getKey());
+          }
+          return true;
         }
       };
 
@@ -2080,30 +2085,28 @@ public class NativeAzureFileSystem extends FileSystem {
     return new AzureFileSystemThreadPoolExecutor(threadCount, threadNamePrefix, operation, key, config);
   }
 
-  // Delete single file / directory from key.
+  /**
+   * Delete the specified file or directory and increment metrics.
+   * If the file or directory does not exist, the operation returns false.
+   * @param path the path to a file or directory.
+   * @param isDir true if the path is a directory; otherwise false.
+   * @return true if delete is successful; otherwise false.
+   * @throws IOException if an IO error occurs while attempting to delete the
+   * path.
+   *
+   */
   @VisibleForTesting
-  boolean deleteFile(String key, boolean isDir) throws IOException {
-    try {
-      if (store.delete(key)) {
+  boolean deleteFile(String path, boolean isDir) throws IOException {
+    if (!store.delete(path)) {
+      return false;
+    }
+
     if (isDir) {
       instrumentation.directoryDeleted();
     } else {
       instrumentation.fileDeleted();
     }
     return true;
-      } else {
-        return false;
-      }
-    } catch(IOException e) {
-      Throwable innerException = NativeAzureFileSystemHelper.checkForAzureStorageException(e);
-
-      if (innerException instanceof StorageException
-          && NativeAzureFileSystemHelper.isFileNotFoundException((StorageException) innerException)) {
-        return false;
-      }
-
-      throw e;
-    }
   }
 
   @Override

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

@@ -39,6 +39,8 @@ import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
 import org.mockito.Mockito;
+import org.mockito.invocation.InvocationOnMock;
+import org.mockito.stubbing.Answer;
 
 /**
  * Tests the Native Azure file system (WASB) using parallel threads for rename and delete operations.
@@ -529,30 +531,65 @@ public class TestFileSystemOperationsWithThreads extends AbstractWasbTestBase {
   }
 
   /*
-   * Test case for delete operation with multiple threads and flat listing enabled.
+   * Validate that when a directory is deleted recursively, the operation succeeds
+   * even if a child directory delete fails because the directory does not exist.
+   * This can happen if a child directory is deleted by an external agent while
+   * the parent is in progress of being deleted recursively.
    */
   @Test
-  public void testDeleteSingleDeleteFailure() throws Exception {
+  public void testRecursiveDirectoryDeleteWhenChildDirectoryDeleted()
+      throws Exception {
+    testRecusiveDirectoryDelete(true);
+  }
 
+  /*
+   * Validate that when a directory is deleted recursively, the operation succeeds
+   * even if a file delete fails because it does not exist.
+   * This can happen if a file is deleted by an external agent while
+   * the parent directory is in progress of being deleted.
+   */
+  @Test
+  public void testRecursiveDirectoryDeleteWhenDeletingChildFileReturnsFalse()
+      throws Exception {
+    testRecusiveDirectoryDelete(false);
+  }
+
+  private void testRecusiveDirectoryDelete(boolean useDir) throws Exception {
+    String childPathToBeDeletedByExternalAgent = (useDir)
+        ? "root/0"
+        : "root/0/fileToRename";
     // Spy azure file system object and return false for deleting one file
-    LOG.info("testDeleteSingleDeleteFailure");
     NativeAzureFileSystem mockFs = Mockito.spy((NativeAzureFileSystem) fs);
-    String path = mockFs.pathToKey(mockFs.makeAbsolute(new Path("root/0")));
-    Mockito.when(mockFs.deleteFile(path, true)).thenReturn(false);
+    String path = mockFs.pathToKey(mockFs.makeAbsolute(new Path(
+        childPathToBeDeletedByExternalAgent)));
+
+    Answer<Boolean> answer = new Answer<Boolean>() {
+      public Boolean answer(InvocationOnMock invocation) throws Throwable {
+        String path = (String) invocation.getArguments()[0];
+        boolean isDir = (boolean) invocation.getArguments()[1];
+        boolean realResult = fs.deleteFile(path, isDir);
+        assertTrue(realResult);
+        boolean fakeResult = false;
+        return fakeResult;
+      }
+    };
+
+    Mockito.when(mockFs.deleteFile(path, useDir)).thenAnswer(answer);
 
     createFolder(mockFs, "root");
     Path sourceFolder = new Path("root");
-    assertFalse(mockFs.delete(sourceFolder, true));
-    assertTrue(mockFs.exists(sourceFolder));
 
-    // Validate from logs that threads are enabled and delete operation failed.
+    assertTrue(mockFs.delete(sourceFolder, true));
+    assertFalse(mockFs.exists(sourceFolder));
+
+    // Validate from logs that threads are enabled, that a child directory was
+    // deleted by an external caller, and the parent delete operation still
+    // succeeds.
     String content = logs.getOutput();
     assertInLog(content,
         "Using thread pool for Delete operation with threads");
-    assertInLog(content, "Delete operation failed for file " + path);
-    assertInLog(content,
-        "Terminating execution of Delete operation now as some other thread already got exception or operation failed");
-    assertInLog(content, "Failed to delete files / subfolders in blob");
+    assertInLog(content, String.format("Attempt to delete non-existent %s %s",
+        useDir ? "directory" : "file", path));
   }
 
   /*