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1   /*
2    * ====================================================================
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *   http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing,
14   * software distributed under the License is distributed on an
15   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16   * KIND, either express or implied.  See the License for the
17   * specific language governing permissions and limitations
18   * under the License.
19   * ====================================================================
20   *
21   * This software consists of voluntary contributions made by many
22   * individuals on behalf of the Apache Software Foundation.  For more
23   * information on the Apache Software Foundation, please see
24   * <http://www.apache.org/>.
25   *
26   */
27  
28  package org.apache.http.nio.reactor;
29  
30  import java.io.IOException;
31  import java.nio.ByteBuffer;
32  import java.nio.channels.ReadableByteChannel;
33  import java.nio.channels.WritableByteChannel;
34  import java.nio.charset.CharacterCodingException;
35  
36  import org.apache.http.util.CharArrayBuffer;
37  
38  /**
39   * Session input buffer for non-blocking connections. This interface facilitates
40   * intermediate buffering of input data streamed from a source channel and
41   * reading buffered data to a destination, usually {@link ByteBuffer} or
42   * {@link WritableByteChannel}. This interface also provides methods for reading
43   * lines of text.
44   *
45   * @since 4.0
46   */
47  public interface SessionInputBuffer {
48  
49      /**
50       * Determines if the buffer contains data.
51       *
52       * @return <code>true</code> if there is data in the buffer,
53       *   <code>false</code> otherwise.
54       */
55      boolean hasData();
56  
57      /**
58       * Returns the length of this buffer.
59       *
60       * @return buffer length.
61       */
62      int length();
63  
64      /**
65       * Makes an attempt to fill the buffer with data from the given
66       * {@link ReadableByteChannel}.
67       *
68       * @param src the source channel
69       * @return The number of bytes read, possibly zero, or <tt>-1</tt> if the
70       *   channel has reached end-of-stream.
71       * @throws IOException in case of an I/O error.
72       */
73      int fill(ReadableByteChannel src) throws IOException;
74  
75      /**
76       * Reads one byte from the buffer. If the buffer is empty this method can
77       * throw a runtime exception. The exact type of runtime exception thrown
78       * by this method depends on implementation.
79       *
80       * @return one byte
81       */
82      int read();
83  
84      /**
85       * Reads a sequence of bytes from this buffer into the destination buffer,
86       * up to the given maximum limit. The exact number of bytes transferred
87       * depends on availability of data in this buffer and capacity of the
88       * destination buffer, but cannot be more than <code>maxLen</code> value.
89       *
90       * @param dst the destination buffer.
91       * @param maxLen the maximum number of bytes to be read.
92       * @return The number of bytes read, possibly zero.
93       */
94      int read(ByteBuffer dst, int maxLen);
95  
96      /**
97       * Reads a sequence of bytes from this buffer into the destination buffer.
98       * The exact number of bytes transferred depends on availability of data
99       * in this buffer and capacity of the destination buffer.
100      *
101      * @param dst the destination buffer.
102      * @return The number of bytes read, possibly zero.
103      */
104     int read(ByteBuffer dst);
105 
106     /**
107      * Reads a sequence of bytes from this buffer into the destination channel,
108      * up to the given maximum limit. The exact number of bytes transferred
109      * depends on availability of data in this buffer, but cannot be more than
110      * <code>maxLen</code> value.
111      *
112      * @param dst the destination channel.
113      * @param maxLen the maximum number of bytes to be read.
114      * @return The number of bytes read, possibly zero.
115      * @throws IOException in case of an I/O error.
116      */
117     int read(WritableByteChannel dst, int maxLen) throws IOException;
118 
119     /**
120      * Reads a sequence of bytes from this buffer into the destination channel.
121      * The exact number of bytes transferred depends on availability of data in
122      * this buffer.
123      *
124      * @param dst the destination channel.
125      * @return The number of bytes read, possibly zero.
126      * @throws IOException in case of an I/O error.
127      */
128     int read(WritableByteChannel dst) throws IOException;
129 
130     /**
131      * Attempts to transfer a complete line of characters up to a line delimiter
132      * from this buffer to the destination buffer. If a complete line is
133      * available in the buffer, the sequence of chars is transferred to the
134      * destination buffer the method returns <code>true</code>. The line
135      * delimiter itself is discarded. If a complete line is not available in
136      * the buffer, this method returns <code>false</code> without transferring
137      * anything to the destination buffer. If <code>endOfStream</code> parameter
138      * is set to <code>true</code> this method assumes the end of stream has
139      * been reached and the content currently stored in the buffer should be
140      * treated as a complete line.
141      * <p>
142      * The choice of a char encoding and line delimiter sequence is up to the
143      * specific implementations of this interface.
144      *
145      * @param dst the destination buffer.
146      * @param endOfStream end of stream flag
147      * @return <code>true</code> if a sequence of chars representing a complete
148      *  line has been transferred to the destination buffer, <code>false</code>
149      *  otherwise.
150      *
151      * @throws CharacterCodingException in case a character encoding or decoding
152      *   error occurs.
153      */
154     boolean readLine(CharArrayBuffer dst, boolean endOfStream)
155         throws CharacterCodingException;
156 
157     /**
158      * Attempts to transfer a complete line of characters up to a line delimiter
159      * from this buffer to a newly created string. If a complete line is
160      * available in the buffer, the sequence of chars is transferred to a newly
161      * created string. The line delimiter itself is discarded. If a complete
162      * line is not available in the buffer, this method returns
163      * <code>null</code>. If <code>endOfStream</code> parameter
164      * is set to <code>true</code> this method assumes the end of stream has
165      * been reached and the content currently stored in the buffer should be
166      * treated as a complete line.
167      * <p>
168      * The choice of a char encoding and line delimiter sequence is up to the
169      * specific implementations of this interface.
170      *
171      * @param endOfStream end of stream flag
172      * @return a string representing a complete line, if available.
173      * <code>null</code> otherwise.
174      *
175      * @throws CharacterCodingException in case a character encoding or decoding
176      *   error occurs.
177      */
178     String readLine(boolean endOfStream)
179         throws CharacterCodingException;
180 
181 }