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