[GitHub] [ozone] szetszwo commented on a diff in pull request #4205: HDDS-7826. Add support for application to probe output stream capability

["szetszwo (via GitHub)" <gi...@apache.org>]

szetszwo commented on code in PR #4205:
URL: https://github.com/apache/ozone/pull/4205#discussion_r1092730505


##########
hadoop-ozone/ozonefs-common/src/main/java/org/apache/hadoop/fs/ozone/CapableOzoneFSOutputStream.java:
##########
@@ -0,0 +1,63 @@
+/*
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.ozone;
+
+import org.apache.hadoop.fs.StreamCapabilities;
+import org.apache.hadoop.fs.impl.StoreImplementationUtils;
+import org.apache.hadoop.ozone.client.io.ECKeyOutputStream;
+import org.apache.hadoop.ozone.client.io.KeyOutputStream;
+import org.apache.hadoop.util.StringUtils;
+
+import java.io.OutputStream;
+
+/**
+ * This class is used to workaround Hadoop2 compatibility issues.
+ *
+ * Hadoop 2 does not support StreamCapabilities, so we create different modules
+ * for Hadoop2 and Hadoop3 profiles.
+ *
+ * The OzoneFileSystem and RootedOzoneFileSystem in Hadoop3 profile uses
+ * CapableOzoneFSOutputStream which implements StreamCapabilities interface,
+ * whereas the ones in Hadoop2 profile does not.
+ */
+public class CapableOzoneFSOutputStream  extends OzoneFSOutputStream
+    implements StreamCapabilities {
+  public CapableOzoneFSOutputStream(OzoneFSOutputStream outputStream) {
+    super(outputStream.getWrappedOutputStream());
+  }
+
+  @Override
+  public boolean hasCapability(String capability) {
+    OutputStream os = getWrappedOutputStream().getOutputStream();
+    if (os instanceof ECKeyOutputStream) {
+      return false;
+    } else if (os instanceof KeyOutputStream) {
+      switch (StringUtils.toLowerCase(capability)) {
+      case OzoneStreamCapabilities.HFLUSH:
+      case OzoneStreamCapabilities.HSYNC:
+        // TODO: switch to true after HDDS-7688
+        return false;
+      default:
+        return false;
+      }
+    }
+    // deal with CryptoOutputStream
+    return StoreImplementationUtils.hasCapability(
+      getWrappedOutputStream().getOutputStream(), capability);

Review Comment:
   We may use `os` here.



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