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