1/*
2 * Copyright (c) 2012, 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
26package sun.nio.ch;
27
28import java.io.IOException;
29import jdk.internal.misc.Unsafe;
30
31/**
32 * Provides access to the BSD kqueue facility.
33 */
34
35class KQueue {
36    private KQueue() { }
37
38    private static final Unsafe unsafe = Unsafe.getUnsafe();
39
40    /**
41     * struct kevent {
42     *        uintptr_t       ident;          // identifier for this event, usually the fd
43     *        int16_t         filter;         // filter for event
44     *        uint16_t        flags;          // general flags
45     *        uint32_t        fflags;         // filter-specific flags
46     *        intptr_t        data;           // filter-specific data
47     *        void            *udata;         // opaque user data identifier
48     * };
49     */
50    private static final int SIZEOF_KQUEUEEVENT    = keventSize();
51    private static final int OFFSET_IDENT          = identOffset();
52    private static final int OFFSET_FILTER         = filterOffset();
53    private static final int OFFSET_FLAGS          = flagsOffset();
54
55    // filters
56    static final int EVFILT_READ  = -1;
57    static final int EVFILT_WRITE = -2;
58
59    // flags
60    static final int EV_ADD     = 0x0001;
61    static final int EV_ONESHOT = 0x0010;
62    static final int EV_CLEAR   = 0x0020;
63
64    /**
65     * Allocates a poll array to handle up to {@code count} events.
66     */
67    static long allocatePollArray(int count) {
68        return unsafe.allocateMemory(count * SIZEOF_KQUEUEEVENT);
69    }
70
71    /**
72     * Free a poll array
73     */
74    static void freePollArray(long address) {
75        unsafe.freeMemory(address);
76    }
77
78    /**
79     * Returns kevent[i].
80     */
81    static long getEvent(long address, int i) {
82        return address + (SIZEOF_KQUEUEEVENT*i);
83    }
84
85    /**
86     * Returns the file descriptor from a kevent (assuming to be in ident field)
87     */
88    static int getDescriptor(long address) {
89        return unsafe.getInt(address + OFFSET_IDENT);
90    }
91
92    static int getFilter(long address) {
93        return unsafe.getShort(address + OFFSET_FILTER);
94    }
95
96    static int getFlags(long address) {
97        return unsafe.getShort(address + OFFSET_FLAGS);
98    }
99
100    // -- Native methods --
101
102    private static native int keventSize();
103
104    private static native int identOffset();
105
106    private static native int filterOffset();
107
108    private static native int flagsOffset();
109
110    static native int kqueue() throws IOException;
111
112    static native int keventRegister(int kqpfd, int fd, int filter, int flags);
113
114    static native int keventPoll(int kqpfd, long pollAddress, int nevents)
115        throws IOException;
116
117    static {
118        IOUtil.load();
119    }
120}
121