1 /*
 2  * Copyright (c) 2017, 2021, 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 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 MAX_EVENTS_TO_POLL = 512;
36     private static final int ENOENT = 2;
37 
38     private final int epfd;
39     private final int event;
40     private final long address;
41 
42     EPollPoller(boolean read) throws IOException {
43         this.epfd = EPoll.create();
44         this.event = (read) ? EPOLLIN : EPOLLOUT;
45         this.address = EPoll.allocatePollArray(MAX_EVENTS_TO_POLL);
46     }
47 
48     @Override
49     int fdVal() {
50         return epfd;
51     }
52 
53     @Override
54     void implRegister(int fdVal) throws IOException {
55         // re-arm
56         int err = EPoll.ctl(epfd, EPOLL_CTL_MOD, fdVal, (event | EPOLLONESHOT));
57         if (err == ENOENT)
58             err = EPoll.ctl(epfd, EPOLL_CTL_ADD, fdVal, (event | EPOLLONESHOT));
59         if (err != 0)
60             throw new IOException("epoll_ctl failed: " + err);
61     }
62 
63     @Override
64     void implDeregister(int fdVal) {
65         EPoll.ctl(epfd, EPOLL_CTL_DEL, fdVal, 0);
66     }
67 
68     @Override
69     int poll(int timeout) throws IOException {
70         int n = EPoll.wait(epfd, address, MAX_EVENTS_TO_POLL, timeout);
71         int i = 0;
72         while (i < n) {
73             long eventAddress = EPoll.getEvent(address, i);
74             int fdVal = EPoll.getDescriptor(eventAddress);
75             polled(fdVal);
76             i++;
77         }
78         return n;
79     }
80 }
81