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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.hc.core5.http.impl.nio;
29  
30  import java.io.IOException;
31  import java.nio.ByteBuffer;
32  import java.nio.channels.ReadableByteChannel;
33  import java.util.List;
34  
35  import org.apache.hc.core5.http.Header;
36  import org.apache.hc.core5.http.impl.BasicHttpTransportMetrics;
37  import org.apache.hc.core5.http.nio.ContentDecoder;
38  import org.apache.hc.core5.http.nio.SessionInputBuffer;
39  import org.apache.hc.core5.util.Args;
40  
41  /**
42   * Abstract {@link ContentDecoder} that serves as a base for all content
43   * decoder implementations.
44   *
45   * @since 4.0
46   */
47  public abstract class AbstractContentDecoder implements ContentDecoder {
48  
49      final ReadableByteChannel channel;
50      final SessionInputBuffer buffer;
51      final BasicHttpTransportMetrics metrics;
52  
53      boolean completed;
54  
55      /**
56       * Creates an instance of this class.
57       *
58       * @param channel the source channel.
59       * @param buffer the session input buffer that can be used to store
60       *    session data for intermediate processing.
61       * @param metrics Transport metrics of the underlying HTTP transport.
62       */
63      public AbstractContentDecoder(
64              final ReadableByteChannel channel,
65              final SessionInputBuffer buffer,
66              final BasicHttpTransportMetrics metrics) {
67          super();
68          Args.notNull(channel, "Channel");
69          Args.notNull(buffer, "Session input buffer");
70          Args.notNull(metrics, "Transport metrics");
71          this.buffer = buffer;
72          this.channel = channel;
73          this.metrics = metrics;
74      }
75  
76      protected ReadableByteChannel channel() {
77          return this.channel;
78      }
79  
80      protected SessionInputBuffer buffer() {
81          return this.buffer;
82      }
83  
84      protected BasicHttpTransportMetrics metrics() {
85          return this.metrics;
86      }
87  
88      @Override
89      public boolean isCompleted() {
90          return this.completed;
91      }
92  
93      /**
94       * Reads from the channel to the destination.
95       *
96       * @param dst destination.
97       * @return number of bytes transferred.
98       *
99       * @since 4.3
100      */
101     protected int readFromChannel(final ByteBuffer dst) throws IOException {
102         final int bytesRead = this.channel.read(dst);
103         if (bytesRead > 0) {
104             this.metrics.incrementBytesTransferred(bytesRead);
105         }
106         return bytesRead;
107     }
108 
109     /**
110      * Reads from the channel to the session buffer.
111      * @return number of bytes transferred.
112      *
113      * @since 4.3
114      */
115     protected int fillBufferFromChannel() throws IOException {
116         final int bytesRead = this.buffer.fill(this.channel);
117         if (bytesRead > 0) {
118             this.metrics.incrementBytesTransferred(bytesRead);
119         }
120         return bytesRead;
121     }
122 
123     /**
124      * Reads from the channel to the destination.
125      *
126      * @param dst destination.
127      * @param limit max number of bytes to transfer.
128      * @return number of bytes transferred.
129      *
130      * @since 4.3
131      */
132     protected int readFromChannel(final ByteBuffer dst, final int limit) throws IOException {
133         final int bytesRead;
134         if (dst.remaining() > limit) {
135             final int oldLimit = dst.limit();
136             final int newLimit = oldLimit - (dst.remaining() - limit);
137             dst.limit(newLimit);
138             bytesRead = this.channel.read(dst);
139             dst.limit(oldLimit);
140         } else {
141             bytesRead = this.channel.read(dst);
142         }
143         if (bytesRead > 0) {
144             this.metrics.incrementBytesTransferred(bytesRead);
145         }
146         return bytesRead;
147     }
148 
149     @Override
150     public List<? extends Header> getTrailers() {
151         return null;
152     }
153 
154 }