1 /*
2 * Copyright 2012 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the License. You may obtain a copy of the License at:
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package org.jboss.netty.channel;
17
18 import org.jboss.netty.buffer.ChannelBuffer;
19
20 /**
21 * Predicts the number of readable bytes in the receive buffer of a
22 * {@link Channel}.
23 * <p>
24 * It calculates the close-to-optimal capacity of the {@link ChannelBuffer}
25 * for the next read operation depending on the actual number of read bytes
26 * in the previous read operation. More accurate the prediction is, more
27 * effective the memory utilization will be.
28 * <p>
29 * Once a read operation is performed and the actual number of read bytes is
30 * known, an I/O thread will call {@link #previousReceiveBufferSize(int)} to
31 * update the predictor so it can predict more accurately next time.
32 */
33 public interface ReceiveBufferSizePredictor {
34
35 /**
36 * Predicts the capacity of the {@link ChannelBuffer} for the next
37 * read operation depending on the actual number of read bytes in the
38 * previous read operation.
39 *
40 * @return the expected number of readable bytes this time
41 */
42 int nextReceiveBufferSize();
43
44 /**
45 * Updates this predictor by specifying the actual number of read bytes
46 * in the previous read operation.
47 *
48 * @param previousReceiveBufferSize
49 * the actual number of read bytes in the previous read operation
50 */
51 void previousReceiveBufferSize(int previousReceiveBufferSize);
52 }
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