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
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24  */
25 package sun.nio.ch;
26 
27 import java.io.IOException;
28 import static sun.nio.ch.EPoll.*;
29 
30 /**
31  * Poller implementation based on the epoll facility.
32  */
33 
34 class EPollPoller extends Poller {
35     private static final int ENOENT = 2;
36 
37     private final int epfd;
38     private final int event;
39     private final int maxEvents;
40     private final long address;
41 
42     EPollPoller(boolean subPoller, boolean read) throws IOException {
43         this.epfd = EPoll.create();
44         this.event = (read) ? EPOLLIN : EPOLLOUT;
45         this.maxEvents = (subPoller) ? 64 : 512;
46         this.address = EPoll.allocatePollArray(maxEvents);
47     }
48 
49     @Override
50     int fdVal() {
51         return epfd;
52     }
53 
54     @Override
55     void implRegister(int fdVal) throws IOException {
56         // re-arm
57         int err = EPoll.ctl(epfd, EPOLL_CTL_MOD, fdVal, (event | EPOLLONESHOT));
58         if (err == ENOENT)
59             err = EPoll.ctl(epfd, EPOLL_CTL_ADD, fdVal, (event | EPOLLONESHOT));
60         if (err != 0)
61             throw new IOException("epoll_ctl failed: " + err);
62     }
63 
64     @Override
65     void implDeregister(int fdVal, boolean polled) {
66         // event is disabled if already polled
67         if (!polled) {
68             EPoll.ctl(epfd, EPOLL_CTL_DEL, fdVal, 0);
69         }
70     }
71 
72     @Override
73     int poll(int timeout) throws IOException {
74         int n = EPoll.wait(epfd, address, maxEvents, timeout);
75         int i = 0;
76         while (i < n) {
77             long eventAddress = EPoll.getEvent(address, i);
78             int fdVal = EPoll.getDescriptor(eventAddress);
79             polled(fdVal);
80             i++;
81         }
82         return n;
83     }
84 }
85