| /* |
| * 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; |
| import org.apache.hadoop.conf.Configuration; |
| |
| /** |
| * Specification of a stream-based 'compressor' which can be |
| * plugged into a {@link CompressionOutputStream} to compress data. |
| * This is modelled after {@link java.util.zip.Deflater} |
| * |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Evolving |
| public interface Compressor { |
| /** |
| * Sets input data for compression. |
| * This should be called whenever #needsInput() returns |
| * <code>true</code> indicating that more input data is required. |
| * |
| * @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 |
| * #setInput() should be called to provide more input. |
| * |
| * @return <code>true</code> if the input data buffer is empty and |
| * #setInput() 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); |
| |
| /** |
| * Return number of uncompressed bytes input so far. |
| */ |
| public long getBytesRead(); |
| |
| /** |
| * Return number of compressed bytes output so far. |
| */ |
| public long getBytesWritten(); |
| |
| /** |
| * When called, indicates that compression should end |
| * with the current contents of the input buffer. |
| */ |
| public void finish(); |
| |
| /** |
| * Returns true if the end of the compressed |
| * data output stream has been reached. |
| * @return <code>true</code> if the end of the compressed |
| * data output stream has been reached. |
| */ |
| public boolean finished(); |
| |
| /** |
| * Fills specified buffer with compressed data. Returns actual number |
| * of bytes of compressed data. A return value of 0 indicates that |
| * 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. |
| */ |
| public int compress(byte[] b, int off, int len) throws IOException; |
| |
| /** |
| * Resets compressor so that a new set of input data can be processed. |
| */ |
| public void reset(); |
| |
| /** |
| * Closes the compressor and discards any unprocessed input. |
| */ |
| public void end(); |
| |
| /** |
| * Prepare the compressor to be used in a new stream with settings defined in |
| * the given Configuration |
| * |
| * @param conf Configuration from which new setting are fetched |
| */ |
| public void reinit(Configuration conf); |
| } |