1 /*

     2  * Copyright 2008-2009 Sun Microsystems, Inc.  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.  Sun designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any 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 {

    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      */

    68     static long allocatePollArray(int count) {

    69         return unsafe.allocateMemory(count * SIZEOF_EPOLLEVENT);

    70     }

    71 

    72     /**

    73      * Free a poll array

    74      */

    75     static void freePollArray(long address) {

    76         unsafe.freeMemory(address);

    77     }

    78 

    79     /**

    80      * Returns event[i];

    81      */

    82     static long getEvent(long address, int i) {

    83         return address + (SIZEOF_EPOLLEVENT*i);

    84     }

    85 

    86     /**

    87      * Returns event->data.fd

    88      */

    89     static int getDescriptor(long eventAddress) {

    90         return unsafe.getInt(eventAddress + OFFSETOF_FD);

    91     }

    92 

    93     /**

    94      * Returns event->events

    95      */

    96     static int getEvents(long eventAddress) {

    97         return unsafe.getInt(eventAddress + OFFSETOF_EVENTS);

    98     }

    99 

   100     // -- Native methods --

   101 

   102     private static native void init();

   103 

   104     private static native int eventSize();

   105 

   106     private static native int eventsOffset();

   107 

   108     private static native int dataOffset();

   109 

   110     static native int epollCreate() throws IOException;

   111 

   112     static native int epollCtl(int epfd, int opcode, int fd, int events);

   113 

   114     static native int epollWait(int epfd, long pollAddress, int numfds)

   115         throws IOException;

   116 

   117     static {

   118         Util.load();

   119         init();

   120     }

   121 }