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 EventFD eventfd; // wakeup event, used for shutdown
44
45 // close action, and cleaner if this is subpoller
46 private final Runnable closer;
47 private final Cleanable cleaner;
48
49 EPollPoller(boolean subPoller, boolean read) throws IOException {
50 int maxEvents = (subPoller) ? 16 : 64;
51
52 int epfd = -1;
53 long address = 0L;
54 EventFD eventfd = null;
55 try {
56 epfd = EPoll.create();
57 address = EPoll.allocatePollArray(maxEvents);
58
59 // register event with epoll to allow for wakeup
60 eventfd = new EventFD();
61 IOUtil.configureBlocking(eventfd.efd(), false);
62 EPoll.ctl(epfd, EPOLL_CTL_ADD, eventfd.efd(), EPOLLIN);
63 } catch (Throwable e) {
64 if (epfd >= 0) FileDispatcherImpl.closeIntFD(epfd);
65 if (address != 0L) EPoll.freePollArray(address);
66 if (eventfd != null) eventfd.close();
67 throw e;
68 }
69
70 this.epfd = epfd;
71 this.event = (read) ? EPOLLIN : EPOLLOUT;
72 this.maxEvents = maxEvents;
73 this.address = address;
74 this.eventfd = eventfd;
75
76 // create action to close epoll instance, register cleaner if this is a subpoller
77 this.closer = closer(epfd, address, eventfd);
78 if (subPoller) {
79 this.cleaner = CleanerFactory.cleaner().register(this, closer);
80 } else {
81 this.cleaner = null;
82 }
83 }
84
85 /**
86 * Returns an action to close the epoll instance and release other resources.
87 */
88 private static Runnable closer(int epfd, long address, EventFD eventfd) {
89 return () -> {
90 try {
91 FileDispatcherImpl.closeIntFD(epfd);
92 EPoll.freePollArray(address);
93 eventfd.close();
94 } catch (IOException _) { }
95 };
96 }
97
98 @Override
99 void close() {
100 if (cleaner != null) {
101 cleaner.clean();
102 } else {
103 closer.run();
104 }
105 }
106
107 @Override
108 int fdVal() {
109 return epfd;
110 }
111
112 @Override
113 void implRegister(int fdVal) throws IOException {
114 // re-enable if already registered but disabled (previously polled)
115 int err = EPoll.ctl(epfd, EPOLL_CTL_MOD, fdVal, (event | EPOLLONESHOT));
116 if (err == ENOENT)
117 err = EPoll.ctl(epfd, EPOLL_CTL_ADD, fdVal, (event | EPOLLONESHOT));
118 if (err != 0)
119 throw new IOException("epoll_ctl failed: " + err);
120 }
121
122 @Override
123 void implDeregister(int fdVal, boolean polled) {
124 // event is disabled if already polled
125 if (!polled) {
126 EPoll.ctl(epfd, EPOLL_CTL_DEL, fdVal, 0);
127 }
128 }
129
130 @Override
131 void wakeupPoller() throws IOException {
132 eventfd.set();
133 }
134
135 @Override
136 int poll(int timeout) throws IOException {
137 int n = EPoll.wait(epfd, address, maxEvents, timeout);
138 int polled = 0;
139 int i = 0;
140 while (i < n) {
141 long eventAddress = EPoll.getEvent(address, i);
142 int fd = EPoll.getDescriptor(eventAddress);
143 if (fd != eventfd.efd()) {
144 polled(fd);
145 polled++;
146 }
147 i++;
148 }
149 return polled;
150 }
151 }
152