org.apache.hadoop.mapred.BufferSorter Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) 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 org.apache.hadoop.mapred;
import org.apache.hadoop.io.OutputBuffer;
import org.apache.hadoop.io.SequenceFile.Sorter.RawKeyValueIterator;
import org.apache.hadoop.util.Progressable;
/** This class provides a generic sort interface that should be implemented
* by specific sort algorithms. The use case is the following:
* A user class writes key/value records to a buffer, and finally wants to
* sort the buffer. This interface defines methods by which the user class
* can update the interface implementation with the offsets of the records
* and the lengths of the keys/values. The user class gives a reference to
* the buffer when the latter wishes to sort the records written to the buffer
* so far. Typically, the user class decides the point at which sort should
* happen based on the memory consumed so far by the buffer and the data
* structures maintained by an implementation of this interface. That is why
* a method is provided to get the memory consumed so far by the datastructures
* in the interface implementation.
*/
interface BufferSorter extends JobConfigurable {
/** Pass the Progressable object so that sort can call progress while it is sorting
* @param reporter the Progressable object reference
*/
public void setProgressable(Progressable reporter);
/** When a key/value is added at a particular offset in the key/value buffer,
* this method is invoked by the user class so that the impl of this sort
* interface can update its datastructures.
* @param recordOffset the offset of the key in the buffer
* @param keyLength the length of the key
* @param valLength the length of the val in the buffer
*/
public void addKeyValue(int recordoffset, int keyLength, int valLength);
/** The user class invokes this method to set the buffer that the specific
* sort algorithm should "indirectly" sort (generally, sort algorithm impl
* should access this buffer via comparators and sort offset-indices to the
* buffer).
* @param buffer the map output buffer
*/
public void setInputBuffer(OutputBuffer buffer);
/** The framework invokes this method to get the memory consumed so far
* by an implementation of this interface.
* @return memoryUsed in bytes
*/
public long getMemoryUtilized();
/** Framework decides when to actually sort
*/
public RawKeyValueIterator sort();
/** Framework invokes this to signal the sorter to cleanup
*/
public void close();
}