1 /*
2  * Copyright (c) 2008, 2013, 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 
26 package sun.nio.ch;
27 
28 import java.io.IOException;
29 import sun.misc.Unsafe;
30 
31 /**
32  * Provides access to the Linux epoll facility.
33  */
34 
35 class EPoll {
EPoll()36     private EPoll() { }
37 
38     private static final Unsafe unsafe = Unsafe.getUnsafe();
39 
40     /**
41      * typedef union epoll_data {
42      *     void *ptr;
43      *     int fd;
44      *     __uint32_t u32;
45      *     __uint64_t u64;
46      *  } epoll_data_t;
47      *
48      * struct epoll_event {
49      *     __uint32_t events;
50      *     epoll_data_t data;
51      * }
52      */
53     private static final int SIZEOF_EPOLLEVENT   = eventSize();
54     private static final int OFFSETOF_EVENTS     = eventsOffset();
55     private static final int OFFSETOF_FD         = dataOffset();
56 
57     // opcodes
58     static final int EPOLL_CTL_ADD  = 1;
59     static final int EPOLL_CTL_DEL  = 2;
60     static final int EPOLL_CTL_MOD  = 3;
61 
62     // flags
63     static final int EPOLLONESHOT   = (1 << 30);
64 
65     /**
66      * Allocates a poll array to handle up to {@code count} events.
67      */
allocatePollArray(int count)68     static long allocatePollArray(int count) {
69         return unsafe.allocateMemory(count * SIZEOF_EPOLLEVENT);
70     }
71 
72     /**
73      * Free a poll array
74      */
freePollArray(long address)75     static void freePollArray(long address) {
76         unsafe.freeMemory(address);
77     }
78 
79     /**
80      * Returns event[i];
81      */
getEvent(long address, int i)82     static long getEvent(long address, int i) {
83         return address + (SIZEOF_EPOLLEVENT*i);
84     }
85 
86     /**
87      * Returns event->data.fd
88      */
getDescriptor(long eventAddress)89     static int getDescriptor(long eventAddress) {
90         return unsafe.getInt(eventAddress + OFFSETOF_FD);
91     }
92 
93     /**
94      * Returns event->events
95      */
getEvents(long eventAddress)96     static int getEvents(long eventAddress) {
97         return unsafe.getInt(eventAddress + OFFSETOF_EVENTS);
98     }
99 
100     // -- Native methods --
101 
eventSize()102     private static native int eventSize();
103 
eventsOffset()104     private static native int eventsOffset();
105 
dataOffset()106     private static native int dataOffset();
107 
epollCreate()108     static native int epollCreate() throws IOException;
109 
epollCtl(int epfd, int opcode, int fd, int events)110     static native int epollCtl(int epfd, int opcode, int fd, int events);
111 
epollWait(int epfd, long pollAddress, int numfds)112     static native int epollWait(int epfd, long pollAddress, int numfds)
113         throws IOException;
114 
115     // Android-removed: Code to load native libraries, doesn't make sense on Android.
116     /*
117     static {
118         IOUtil.load();
119     }
120     */
121 }
122