/**
*
* Copyright (C) 2010 Cloud Conscious, LLC. <info@cloudconscious.com>
*
* ====================================================================
* Licensed 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 org.jclouds.examples.blobstore.hdfs.io;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import java.io.IOException;
import java.io.InputStream;
import javax.inject.Singleton;
import org.apache.hadoop.fs.FSDataInputStream;
import org.jclouds.examples.blobstore.hdfs.io.payloads.HdfsPayload;
import org.jclouds.io.Payload;
import org.jclouds.io.internal.BasePayloadSlicer;
import org.jclouds.io.payloads.InputStreamSupplierPayload;
import com.google.common.io.Closeables;
import com.google.common.io.InputSupplier;
import com.google.common.io.LimitInputStream;
@Singleton
public class HdfsPayloadSlicer extends BasePayloadSlicer {
@Override
public Payload slice(Payload input, long offset, long length) {
checkNotNull(input);
checkArgument(offset >= 0, "offset is negative");
checkArgument(length >= 0, "length is negative");
Payload returnVal;
if (input instanceof HdfsPayload) {
returnVal = doSlice(
(FSDataInputStream) ((HdfsPayload) input).getInput(), offset,
length);
return copyMetadataAndSetLength(input, returnVal, length);
} else {
return super.slice(input, offset, length);
}
}
protected Payload doSlice(final FSDataInputStream inputStream,
final long offset, final long length) {
return new InputStreamSupplierPayload(new InputSupplier<InputStream>() {
public InputStream getInput() throws IOException {
if (offset > 0) {
try {
inputStream.seek(offset);
} catch (IOException e) {
Closeables.closeQuietly(inputStream);
throw e;
}
}
return new LimitInputStream(inputStream, length);
}
});
}
}