1 /*
2 * Copyright 2016 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 * https://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 io.netty5.channel;
17
18 import static io.netty5.util.internal.ObjectUtil.checkPositiveOrZero;
19
20 /**
21 * {@link WriteBufferWaterMark} is used to set low water mark and high water mark for the write buffer.
22 * <p>
23 * If the number of bytes queued in the write buffer exceeds the
24 * {@linkplain #high high water mark}, {@link Channel#writableBytes()}
25 * will start to return {@code 0}.
26 * <p>
27 * If the number of bytes queued in the write buffer exceeds the
28 * {@linkplain #high high water mark} and then
29 * dropped down below the {@linkplain #low low water mark},
30 * {@link Channel#writableBytes()} will start to return
31 * a positive value again.
32 */
33 public final class WriteBufferWaterMark {
34
35 private static final int DEFAULT_LOW_WATER_MARK = 32 * 1024;
36 private static final int DEFAULT_HIGH_WATER_MARK = 64 * 1024;
37
38 public static final WriteBufferWaterMark DEFAULT =
39 new WriteBufferWaterMark(DEFAULT_LOW_WATER_MARK, DEFAULT_HIGH_WATER_MARK, false);
40
41 private final int low;
42 private final int high;
43
44 /**
45 * Create a new instance.
46 *
47 * @param low low water mark for write buffer.
48 * @param high high water mark for write buffer
49 */
50 public WriteBufferWaterMark(int low, int high) {
51 this(low, high, true);
52 }
53
54 /**
55 * This constructor is needed to keep backward-compatibility.
56 */
57 WriteBufferWaterMark(int low, int high, boolean validate) {
58 if (validate) {
59 checkPositiveOrZero(low, "low");
60 if (high < low) {
61 throw new IllegalArgumentException(
62 "write buffer's high water mark cannot be less than " +
63 " low water mark (" + low + "): " +
64 high);
65 }
66 }
67 this.low = low;
68 this.high = high;
69 }
70
71 /**
72 * Returns the low water mark for the write buffer.
73 */
74 public int low() {
75 return low;
76 }
77
78 /**
79 * Returns the high water mark for the write buffer.
80 */
81 public int high() {
82 return high;
83 }
84
85 @Override
86 public String toString() {
87 StringBuilder builder = new StringBuilder(55)
88 .append("WriteBufferWaterMark(low: ")
89 .append(low)
90 .append(", high: ")
91 .append(high)
92 .append(")");
93 return builder.toString();
94 }
95
96 }