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      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 {
     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 int eventSize();
    103 
    104     private static native int eventsOffset();
    105 
    106     private static native int dataOffset();
    107 
    108     static native int epollCreate() throws IOException;
    109 
    110     static native int epollCtl(int epfd, int opcode, int fd, int events);
    111 
    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