1 /*
  2  * Copyright (c) 2017, 2023, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.  Oracle designates this
  8  * particular file as subject to the "Classpath" exception as provided
  9  * by Oracle in the LICENSE file that accompanied this code.
 10  *
 11  * This code is distributed in the hope that it will be useful, but WITHOUT
 12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 14  * version 2 for more details (a copy is included in the LICENSE file that
 15  * accompanied this code).
 16  *
 17  * You should have received a copy of the GNU General Public License version
 18  * 2 along with this work; if not, write to the Free Software Foundation,
 19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 20  *
 21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 22  * or visit www.oracle.com if you need additional information or have any
 23  * questions.
 24  */
 25 package sun.nio.ch;
 26 
 27 import java.io.IOException;
 28 import java.lang.ref.Cleaner.Cleanable;
 29 import jdk.internal.ref.CleanerFactory;
 30 import static sun.nio.ch.EPoll.*;
 31 
 32 /**
 33  * Poller implementation based on the epoll facility.
 34  */
 35 
 36 class EPollPoller extends Poller {
 37     private static final int ENOENT = 2;
 38 
 39     private final int epfd;
 40     private final int event;
 41     private final int maxEvents;
 42     private final long address;
 43     private final Cleanable cleaner;
 44 
 45     // file descriptors used for wakeup
 46     private final int fd0;
 47     private final int fd1;
 48 
 49     EPollPoller(boolean subPoller, boolean read) throws IOException {
 50         this.epfd = EPoll.create();
 51         this.event = (read) ? EPOLLIN : EPOLLOUT;
 52         this.maxEvents = (subPoller) ? 64 : 512;
 53         this.address = EPoll.allocatePollArray(maxEvents);
 54 
 55         long fds =  IOUtil.makePipe(false);
 56         this.fd0 = (int) (fds >>> 32);
 57         this.fd1 = (int) fds;
 58         EPoll.ctl(epfd, EPOLL_CTL_ADD, fd0, EPOLLIN);
 59 
 60         this.cleaner = CleanerFactory.cleaner()
 61                 .register(this, releaser(epfd, address, fd0, fd1));
 62     }
 63 
 64     @Override
 65     void close() {
 66         cleaner.clean();
 67     }
 68 
 69     /**
 70      * Releases the epoll instance and other resources.
 71      */
 72     private static Runnable releaser(int epfd, long address, int fd0, int fd1) {
 73         return () -> {
 74             try {
 75                 FileDispatcherImpl.closeIntFD(epfd);
 76                 EPoll.freePollArray(address);
 77 
 78                 FileDispatcherImpl.closeIntFD(fd0);
 79                 FileDispatcherImpl.closeIntFD(fd1);
 80             } catch (IOException _) { }
 81         };
 82     }
 83 
 84     @Override
 85     int fdVal() {
 86         return epfd;
 87     }
 88 
 89     @Override
 90     void implRegister(int fdVal) throws IOException {
 91         // re-arm
 92         int err = EPoll.ctl(epfd, EPOLL_CTL_MOD, fdVal, (event | EPOLLONESHOT));
 93         if (err == ENOENT)
 94             err = EPoll.ctl(epfd, EPOLL_CTL_ADD, fdVal, (event | EPOLLONESHOT));
 95         if (err != 0)
 96             throw new IOException("epoll_ctl failed: " + err);
 97     }
 98 
 99     @Override
100     void implDeregister(int fdVal, boolean polled) {
101         // event is disabled if already polled
102         if (!polled) {
103             EPoll.ctl(epfd, EPOLL_CTL_DEL, fdVal, 0);
104         }
105     }
106 
107     @Override
108     void wakeupPoller() throws IOException {
109         IOUtil.write1(fd1, (byte)0);
110     }
111 
112     @Override
113     int poll(int timeout) throws IOException {
114         int n = EPoll.wait(epfd, address, maxEvents, timeout);
115         int i = 0;
116         while (i < n) {
117             long eventAddress = EPoll.getEvent(address, i);
118             int fdVal = EPoll.getDescriptor(eventAddress);
119             polled(fdVal);
120             i++;
121         }
122         return n;
123     }
124 }
125