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(Poller.Mode mode, boolean subPoller, boolean read) throws IOException {
50 int maxEvents = (subPoller) ? 16 : 64;
51
52 int epfd = EPoll.create();
53 long address = 0L;
54 EventFD eventfd = null;
55 try {
56 address = EPoll.allocatePollArray(maxEvents);
57
58 // register event with epoll to allow for wakeup
59 if (subPoller && (mode == Poller.Mode.POLLER_PER_CARRIER)) {
60 eventfd = new EventFD();
61 IOUtil.configureBlocking(eventfd.efd(), false);
62 EPoll.ctl(epfd, EPOLL_CTL_ADD, eventfd.efd(), EPOLLIN);
63 }
64 } catch (Throwable e) {
65 FileDispatcherImpl.closeIntFD(epfd);
66 if (address != 0L) EPoll.freePollArray(address);
67 if (eventfd != null) eventfd.close();
68 throw e;
69 }
70
71 this.epfd = epfd;
72 this.event = (read) ? EPOLLIN : EPOLLOUT;
73 this.maxEvents = maxEvents;
74 this.address = address;
75 this.eventfd = eventfd;
76
77 // create action to close epoll instance, register cleaner if this is a subpoller
78 this.closer = closer(epfd, address, eventfd);
79 if (subPoller) {
80 this.cleaner = CleanerFactory.cleaner().register(this, closer);
81 } else {
82 this.cleaner = null;
83 }
84 }
85
86 /**
87 * Returns an action to close the epoll instance and release other resources.
88 */
89 private static Runnable closer(int epfd, long address, EventFD eventfd) {
90 return () -> {
91 try {
92 FileDispatcherImpl.closeIntFD(epfd);
93 EPoll.freePollArray(address);
94 if (eventfd != null) eventfd.close();
95 } catch (IOException _) { }
96 };
97 }
98
99 @Override
100 void close() {
101 if (cleaner != null) {
102 cleaner.clean();
103 } else {
104 closer.run();
105 }
106 }
107
108 @Override
109 int fdVal() {
110 return epfd;
111 }
112
113 @Override
114 void implRegister(int fdVal) throws IOException {
115 // re-enable if already registered but disabled (previously polled)
116 int err = EPoll.ctl(epfd, EPOLL_CTL_MOD, fdVal, (event | EPOLLONESHOT));
117 if (err == ENOENT)
118 err = EPoll.ctl(epfd, EPOLL_CTL_ADD, fdVal, (event | EPOLLONESHOT));
119 if (err != 0)
120 throw new IOException("epoll_ctl failed: " + err);
121 }
122
123 @Override
124 void implDeregister(int fdVal, boolean polled) {
125 // event is disabled if already polled
126 if (!polled) {
127 EPoll.ctl(epfd, EPOLL_CTL_DEL, fdVal, 0);
128 }
129 }
130
131 @Override
132 void wakeupPoller() throws IOException {
133 if (eventfd == null) {
134 throw new UnsupportedOperationException();
135 }
136 eventfd.set();
137 }
138
139 @Override
140 int poll(int timeout) throws IOException {
141 int n = EPoll.wait(epfd, address, maxEvents, timeout);
142 int polled = 0;
143 int i = 0;
144 while (i < n) {
145 long eventAddress = EPoll.getEvent(address, i);
146 int fd = EPoll.getDescriptor(eventAddress);
147 if (eventfd == null || fd != eventfd.efd()) {
148 polled(fd);
149 polled++;
150 }
151 i++;
152 }
153 return polled;
154 }
155 }
156