Move BlockHandlerLocal to LocalFileBlockReader

servers/src/main/java/tachyon/worker/block/io/LocalFileBlockReader.java

@@ -0,0 +1,67 @@
+/*
+ * Licensed to the University of California, Berkeley 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 tachyon.worker.block.io;
+
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.channels.ReadableByteChannel;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.google.common.base.Preconditions;
+import com.google.common.io.Closer;
+
+import tachyon.Constants;
+import tachyon.worker.block.meta.BlockMeta;
+
+/**
+ * This class provides read access to a block data file locally stored in managed storage.
+ * <p>
+ * This class does not provide thread-safety. Corresponding lock must be acquired.
+ */
+public class LocalFileBlockReader implements BlockReader {
+  private static final Logger LOG = LoggerFactory.getLogger(Constants.LOGGER_TYPE);
+  private final BlockMeta mBlockMeta;
+  private final String mFilePath;
+  private final RandomAccessFile mLocalFile;
+  private final FileChannel mLocalFileChannel;
+  private final Closer mCloser = Closer.create();
+  private final long mFileSize;
+
+  public LocalFileBlockReader(BlockMeta blockMeta) throws IOException {
+    mBlockMeta = Preconditions.checkNotNull(blockMeta);
+    mFilePath = mBlockMeta.getPath();
+    mLocalFile = mCloser.register(new RandomAccessFile(mFilePath, "r"));
+    mLocalFileChannel = mCloser.register(mLocalFile.getChannel());
+    mFileSize = mLocalFile.length();
+  }
+
+  @Override
+  public ReadableByteChannel getChannel() {
+    return mLocalFileChannel;
+  }
+
+  @Override
+  public ByteBuffer read(long offset, long length) throws IOException {
+    Preconditions.checkArgument(offset + length <= mFileSize,
+        "offset=%s, length=%s, exceeds file size(%s)", offset, length, mFileSize);
+    ByteBuffer buf = mLocalFileChannel.map(FileChannel.MapMode.READ_ONLY, offset, length);
+    return buf;
+  }
+}