| /* |
| * 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 |
| * <code>true</code> indicating that more input data is required. |
| * (Both native and non-native versions of various Decompressors require |
| * that the data passed in via <code>b[]</code> 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 <code>true</code> if the input data buffer is empty and |
| * {@link #setInput(byte[], int, int)} should be called to |
| * provide more input. |
| * |
| * @return <code>true</code> 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 <code>true</code> if a preset dictionary is needed for decompression. |
| * @return <code>true</code> if a preset dictionary is needed for decompression |
| */ |
| public boolean needsDictionary(); |
| |
| /** |
| * Returns <code>true</code> if the end of the decompressed |
| * data output stream has been reached. Indicates a concatenated data stream |
| * when finished() returns <code>true</code> and {@link #getRemaining()} |
| * returns a positive value. finished() will be reset with the |
| * {@link #reset()} method. |
| * @return <code>true</code> 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. |
| * Indicates a concatenated data stream if {@link #finished()} returns |
| * <code>true</code> and getRemaining() returns a positive value. If |
| * {@link #finished()} returns <code>true</code> and getRemaining() returns |
| * a zero value, indicates that the end of data stream has been reached and |
| * is not a concatenated data stream. |
| * @return The number of bytes remaining in the compressed data buffer. |
| */ |
| public int getRemaining(); |
| |
| /** |
| * Resets decompressor and input and output buffers so that a new set of |
| * input data can be processed. If {@link #finished()}} returns |
| * <code>true</code> and {@link #getRemaining()} returns a positive value, |
| * reset() is called before processing of the next data stream in the |
| * concatenated data stream. {@link #finished()} will be reset and will |
| * return <code>false</code> when reset() is called. |
| */ |
| public void reset(); |
| |
| /** |
| * Closes the decompressor and discards any unprocessed input. |
| */ |
| public void end(); |
| } |