io.netty.channel.epoll.Epoll Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* 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() {
}
}