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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    *   http://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.epoll;
17  
18  /**
19   * This class is necessary to break the following cyclic dependency:
20   * <ol>
21   * <li>JNI_OnLoad</li>
22   * <li>JNI Calls FindClass because RegisterNatives (used to register JNI methods) requires a class</li>
23   * <li>FindClass loads the class, but static members variables of that class attempt to call a JNI method which has not
24   * yet been registered.</li>
25   * <li>java.lang.UnsatisfiedLinkError is thrown because native method has not yet been registered.</li>
26   * </ol>
27   * Static members which call JNI methods must not be declared in this class!
28   */
29  final class NativeStaticallyReferencedJniMethods {
30  
31      private NativeStaticallyReferencedJniMethods() { }
32  
33      static native int epollin();
34      static native int epollout();
35      static native int epollrdhup();
36      static native int epollet();
37      static native int epollerr();
38      static native long ssizeMax();
39      static native int tcpMd5SigMaxKeyLen();
40      static native int iovMax();
41      static native int uioMaxIov();
42      static native boolean isSupportingSendmmsg();
43      static native boolean isSupportingTcpFastopen();
44      static native String kernelVersion();
45  }