98 lines
3.1 KiB
Java
98 lines
3.1 KiB
Java
/*
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* Copyright 2014 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.channel.epoll;
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import io.netty.channel.unix.FileDescriptor;
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import io.netty.util.internal.SystemPropertyUtil;
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/**
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* Tells if <a href="https://netty.io/wiki/native-transports.html">{@code netty-transport-native-epoll}</a> is
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* supported.
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*/
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public final class Epoll {
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private static final Throwable UNAVAILABILITY_CAUSE;
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static {
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Throwable cause = null;
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if (SystemPropertyUtil.getBoolean("io.netty.transport.noNative", false)) {
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cause = new UnsupportedOperationException(
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"Native transport was explicit disabled with -Dio.netty.transport.noNative=true");
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} else {
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FileDescriptor epollFd = null;
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FileDescriptor eventFd = null;
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try {
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epollFd = Native.newEpollCreate();
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eventFd = Native.newEventFd();
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} catch (Throwable t) {
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cause = t;
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} finally {
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if (epollFd != null) {
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try {
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epollFd.close();
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} catch (Exception ignore) {
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// ignore
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}
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}
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if (eventFd != null) {
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try {
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eventFd.close();
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} catch (Exception ignore) {
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// ignore
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}
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}
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}
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}
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UNAVAILABILITY_CAUSE = cause;
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}
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/**
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* Returns {@code true} if and only if the <a href="https://netty.io/wiki/native-transports.html">{@code
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* netty-transport-native-epoll}</a> is available.
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*/
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public static boolean isAvailable() {
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return UNAVAILABILITY_CAUSE == null;
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}
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/**
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* Ensure that <a href="https://netty.io/wiki/native-transports.html">{@code netty-transport-native-epoll}</a> is
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* available.
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*
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* @throws UnsatisfiedLinkError if unavailable
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*/
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public static void ensureAvailability() {
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if (UNAVAILABILITY_CAUSE != null) {
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throw (Error) new UnsatisfiedLinkError(
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"failed to load the required native library").initCause(UNAVAILABILITY_CAUSE);
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}
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}
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/**
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* Returns the cause of unavailability of <a href="https://netty.io/wiki/native-transports.html">
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* {@code netty-transport-native-epoll}</a>.
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*
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* @return the cause if unavailable. {@code null} if available.
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*/
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public static Throwable unavailabilityCause() {
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return UNAVAILABILITY_CAUSE;
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}
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private Epoll() {
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}
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}
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