COMPRESSION-11 Add compatability class for files compressed with Hadoop's

compression class.

Author: omalley

CHANGES.txt

@@ -8,3 +8,5 @@ Trunk:
   COMPRESS-2. Add a new native loader, since Hadoop's doesn't know about the
   new library (johan via omalley)
 
+  COMPRESS-11. Add a compatability class for reading data that was compressed
+  by Hadoop's class. (hong via omalley)

src/java/org/apache/hadoop/io/compress/LzoCodec.java

@@ -0,0 +1,59 @@
+/*
+ * This file is part of Hadoop-Gpl-Compression.
+ * 
+ * Hadoop-Gpl-Compression is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ * 
+ * Hadoop-Gpl-Compression is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ * 
+ * You should have received a copy of the GNU General Public License along with
+ * Hadoop-Gpl-Compression. If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.apache.hadoop.io.compress;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+/**
+ * This is a bridging class whose sole purpose is to provide backward
+ * compatibility of applications that historically depend on 
+ * {@link org.apache.hadoop.io.compress.LzoCodec} (such as SequenceFile).
+ * 
+ * The class is marked as @deprecated and should not be used explicitly in the
+ * future.
+ * 
+ * A warning message will be generated when a user wants to use this class to
+ * generate LZO compressed data. Not the case for decompression because this is
+ * the legitimate backward compatibility usage.
+ */
+@Deprecated
+public class LzoCodec extends com.hadoop.compression.lzo.LzoCodec {
+  private static final Log LOG = LogFactory.getLog(LzoCodec.class);
+
+  static final String oahLzoCodec = LzoCodec.class.getName();
+  static final String chclLzoCodec =
+      com.hadoop.compression.lzo.LzoCodec.class.getName();
+  static boolean warned = false;
+  
+  static {
+    LOG.info("Bridging " + oahLzoCodec + " to " + chclLzoCodec + ".");
+  }
+  
+  public CompressionOutputStream createOutputStream(OutputStream out,
+      Compressor compressor) throws IOException {
+    if (!warned) {
+      LOG.warn(oahLzoCodec + " is deprecated. You should use " + chclLzoCodec
+          + " instead to generate LZO compressed data.");
+      warned = true;
+    }
+    return super.createOutputStream(out, compressor);
+  }
+}