add ChecksummedSequentialWriter

src/java/org/apache/cassandra/io/util/ChecksummedSequentialWriter.java

@@ -0,0 +1,36 @@
+package org.apache.cassandra.io.util;
+
+import java.io.File;
+
+import org.apache.cassandra.io.sstable.Descriptor;
+
+public class ChecksummedSequentialWriter extends SequentialWriter
+{
+    private final SequentialWriter crcWriter;
+    private final DataIntegrityMetadata.ChecksumWriter crcMetadata;
+
+    public ChecksummedSequentialWriter(File file, int bufferSize, boolean skipIOCache, File crcPath)
+    {
+        super(file, bufferSize, skipIOCache);
+        crcWriter = new SequentialWriter(crcPath, 8 * 1024, true);
+        crcMetadata = new DataIntegrityMetadata.ChecksumWriter(crcWriter.stream);
+        crcMetadata.writeChunkSize(buffer.length);
+    }
+
+    protected void flushData()
+    {
+        super.flushData();
+        crcMetadata.append(buffer, 0, validBufferBytes);
+    }
+
+    public void writeFullChecksum(Descriptor descriptor)
+    {
+        crcMetadata.writeFullChecksum(descriptor);
+    }
+
+    public void close()
+    {
+        super.close();
+        crcWriter.close();
+    }
+}