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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.io.compress;
import java.io.IOException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
/**
* Specification of a stream-based 'de-compressor' which can be
* plugged into a {@link CompressionInputStream} to compress data.
* This is modelled after {@link java.util.zip.Inflater}
*
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public interface Decompressor {
/**
* Sets input data for decompression.
* This should be called if and only if {@link #needsInput()} returns
* true indicating that more input data is required.
* (Both native and non-native versions of various Decompressors require
* that the data passed in via b[] remain unmodified until
* the caller is explicitly notified--via {@link #needsInput()}--that the
* buffer may be safely modified. With this requirement, an extra
* buffer-copy can be avoided.)
*
* @param b Input data
* @param off Start offset
* @param len Length
*/
public void setInput(byte[] b, int off, int len);
/**
* Returns true if the input data buffer is empty and
* {@link #setInput(byte[], int, int)} should be called to
* provide more input.
*
* @return true if the input data buffer is empty and
* {@link #setInput(byte[], int, int)} should be called in
* order to provide more input.
*/
public boolean needsInput();
/**
* Sets preset dictionary for compression. A preset dictionary
* is used when the history buffer can be predetermined.
*
* @param b Dictionary data bytes
* @param off Start offset
* @param len Length
*/
public void setDictionary(byte[] b, int off, int len);
/**
* Returns true if a preset dictionary is needed for decompression.
* @return true if a preset dictionary is needed for decompression
*/
public boolean needsDictionary();
/**
* Returns true if the end of the decompressed
* data output stream has been reached.
* @return true if the end of the decompressed
* data output stream has been reached.
*/
public boolean finished();
/**
* Fills specified buffer with uncompressed data. Returns actual number
* of bytes of uncompressed data. A return value of 0 indicates that
* {@link #needsInput()} should be called in order to determine if more
* input data is required.
*
* @param b Buffer for the compressed data
* @param off Start offset of the data
* @param len Size of the buffer
* @return The actual number of bytes of compressed data.
* @throws IOException
*/
public int decompress(byte[] b, int off, int len) throws IOException;
/**
* Returns the number of bytes remaining in the compressed-data buffer;
* typically called after the decompressor has finished decompressing
* the current gzip stream (a.k.a. "member").
*/
public int getRemaining();
/**
* Resets decompressor and input and output buffers so that a new set of
* input data can be processed.
*/
public void reset();
/**
* Closes the decompressor and discards any unprocessed input.
*/
public void end();
}