/**
* Copyright 2011-2014 Asakusa Framework Team.
*
* 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 com.asakusafw.runtime.stage.temporary;
import java.io.IOException;
import java.io.InputStream;
import java.io.InterruptedIOException;
import org.apache.hadoop.io.Writable;
import com.asakusafw.runtime.io.ModelInput;
import com.asakusafw.runtime.io.util.DataBuffer;
import com.asakusafw.runtime.stage.temporary.TemporaryFileInputHelper.Result;
/**
* Input raw data.
* @param <T> the data model type
* @since 0.7.0
*/
public class TemporaryFileInput<T extends Writable> implements ModelInput<T> {
private final TemporaryFileInputHelper helper;
private DataBuffer buffer;
private int positionInBlock = 0;
private int currentBlock = 0;
private String dataTypeName;
private boolean sawEof = false;
/**
* Creates a new instance.
* @param input the input stream (must be on the head of a block)
* @param blocks the number of blocks to read, or {@code 0} to read all pages in the stream
*/
public TemporaryFileInput(InputStream input, int blocks) {
this.helper = new TemporaryFileInputHelper(input, blocks);
helper.initialize();
}
/**
* Returns the target data type name.
* @return the data type name
* @throws IOException if failed to extract the data type name
*/
public String getDataTypeName() throws IOException {
prepareBuffer();
return dataTypeName;
}
/**
* Returns the current block number ({@code 0..}).
* @return the current block number
*/
public int getCurrentBlock() {
return currentBlock;
}
/**
* Returns the byte position in current block.
* @return the position in block
*/
public int getPositionInBlock() {
return positionInBlock;
}
@Override
public boolean readTo(T model) throws IOException {
if (prepareBuffer() == false) {
return false;
}
assert buffer != null;
int before = buffer.getReadPosition();
model.readFields(buffer);
int position = buffer.getReadPosition();
if (position - before == 0) {
// read 0-bytes entry
int c = buffer.read();
if (c != TemporaryFile.EMPTY_ENTRY_PADDING) {
throw new IOException("Invalid empty entry padding");
}
}
if (buffer.getReadRemaining() == 0) {
helper.releaseBuffer(buffer);
buffer = null;
}
return true;
}
private boolean prepareBuffer() throws IOException {
if (buffer != null && buffer.getReadRemaining() == 0) {
helper.releaseBuffer(buffer);
buffer = null;
}
if (buffer == null) {
try {
Result result = helper.getNextPage();
this.buffer = result.buffer;
this.sawEof = result.sawEof;
this.positionInBlock = result.positionInBlock;
this.currentBlock = result.currentBlock;
if (result.dataTypeName != null) {
this.dataTypeName = result.dataTypeName;
}
} catch (InterruptedException e) {
throw (IOException) new InterruptedIOException().initCause(e);
}
}
return sawEof == false;
}
@Override
public void close() throws IOException {
helper.close();
}
}