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.netty.channel.kqueue;
17
18 import io.netty.channel.ChannelOption;
19 import io.netty.channel.unix.FileDescriptor;
20 import io.netty.util.internal.SystemPropertyUtil;
21 import io.netty.util.internal.UnstableApi;
22
23 /**
24 * If KQueue is available the JNI resources will be loaded when this class loads.
25 */
26 @UnstableApi
27 public final class KQueue {
28 private static final Throwable UNAVAILABILITY_CAUSE;
29
30 static {
31 Throwable cause = null;
32 if (SystemPropertyUtil.getBoolean("io.netty.transport.noNative", false)) {
33 cause = new UnsupportedOperationException(
34 "Native transport was explicit disabled with -Dio.netty.transport.noNative=true");
35 } else {
36 FileDescriptor kqueueFd = null;
37 try {
38 kqueueFd = Native.newKQueue();
39 } catch (Throwable t) {
40 cause = t;
41 } finally {
42 if (kqueueFd != null) {
43 try {
44 kqueueFd.close();
45 } catch (Exception ignore) {
46 // ignore
47 }
48 }
49 }
50 }
51
52 UNAVAILABILITY_CAUSE = cause;
53 }
54
55 /**
56 * Returns {@code true} if and only if the <a href="https://netty.io/wiki/native-transports.html">{@code
57 * netty-transport-native-kqueue}</a> is available.
58 */
59 public static boolean isAvailable() {
60 return UNAVAILABILITY_CAUSE == null;
61 }
62
63 /**
64 * Ensure that <a href="https://netty.io/wiki/native-transports.html">{@code netty-transport-native-kqueue}</a> is
65 * available.
66 *
67 * @throws UnsatisfiedLinkError if unavailable
68 */
69 public static void ensureAvailability() {
70 if (UNAVAILABILITY_CAUSE != null) {
71 throw (Error) new UnsatisfiedLinkError(
72 "failed to load the required native library").initCause(UNAVAILABILITY_CAUSE);
73 }
74 }
75
76 /**
77 * Returns the cause of unavailability of <a href="https://netty.io/wiki/native-transports.html">{@code
78 * netty-transport-native-kqueue}</a>.
79 *
80 * @return the cause if unavailable. {@code null} if available.
81 */
82 public static Throwable unavailabilityCause() {
83 return UNAVAILABILITY_CAUSE;
84 }
85
86 /**
87 * Returns {@code true} if the kqueue native transport is both {@linkplain #isAvailable() available} and supports
88 * {@linkplain ChannelOption#TCP_FASTOPEN_CONNECT client-side TCP FastOpen}.
89 *
90 * @return {@code true} if it's possible to use client-side TCP FastOpen via kqueue, otherwise {@code false}.
91 */
92 public static boolean isTcpFastOpenClientSideAvailable() {
93 return isAvailable() && Native.IS_SUPPORTING_TCP_FASTOPEN_CLIENT;
94 }
95
96 /**
97 * Returns {@code true} if the kqueue native transport is both {@linkplain #isAvailable() available} and supports
98 * {@linkplain ChannelOption#TCP_FASTOPEN server-side TCP FastOpen}.
99 *
100 * @return {@code true} if it's possible to use server-side TCP FastOpen via kqueue, otherwise {@code false}.
101 */
102 public static boolean isTcpFastOpenServerSideAvailable() {
103 return isAvailable() && Native.IS_SUPPORTING_TCP_FASTOPEN_SERVER;
104 }
105
106 private KQueue() {
107 }
108 }
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