1 /*
   2  * Copyright (c) 2000, 2010, 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.nio.ByteBuffer;
  29 import jdk.internal.ref.Cleaner;
  30 
  31 
  32 /**
  33  * Manipulates a native array of iovec structs on Solaris:
  34  *
  35  * typedef struct iovec {
  36  *    caddr_t  iov_base;
  37       int      iov_len;
  38  * } iovec_t;
  39  *
  40  * @author Mike McCloskey
  41  * @since 1.4
  42  */
  43 
  44 class IOVecWrapper {
  45 
  46     // Miscellaneous constants
  47     private static final int BASE_OFFSET = 0;
  48     private static final int LEN_OFFSET;
  49     private static final int SIZE_IOVEC;
  50 
  51     // The iovec array
  52     private final AllocatedNativeObject vecArray;
  53 
  54     // Number of elements in iovec array
  55     private final int size;
  56 
  57     // Buffers and position/remaining corresponding to elements in iovec array
  58     private final ByteBuffer[] buf;
  59     private final int[] position;
  60     private final int[] remaining;
  61 
  62     // Shadow buffers for cases when original buffer is substituted
  63     private final ByteBuffer[] shadow;
  64 
  65     // Base address of this array
  66     final long address;
  67 
  68     // Address size in bytes
  69     static int addressSize;
  70 
  71     private static class Deallocator implements Runnable {
  72         private final AllocatedNativeObject obj;
  73         Deallocator(AllocatedNativeObject obj) {
  74             this.obj = obj;
  75         }
  76         public void run() {
  77             obj.free();
  78         }
  79     }
  80 
  81     // per thread IOVecWrapper
  82     private static final ThreadLocal<IOVecWrapper> cached =
  83         new ThreadLocal<IOVecWrapper>();
  84 
  85     private IOVecWrapper(int size) {
  86         this.size      = size;
  87         this.buf       = new ByteBuffer[size];
  88         this.position  = new int[size];
  89         this.remaining = new int[size];
  90         this.shadow    = new ByteBuffer[size];
  91         this.vecArray  = new AllocatedNativeObject(size * SIZE_IOVEC, false);
  92         this.address   = vecArray.address();
  93     }
  94 
  95     static IOVecWrapper get(int size) {
  96         IOVecWrapper wrapper = cached.get();
  97         if (wrapper != null && wrapper.size < size) {
  98             // not big enough; eagerly release memory
  99             wrapper.vecArray.free();
 100             wrapper = null;
 101         }
 102         if (wrapper == null) {
 103             wrapper = new IOVecWrapper(size);
 104             Cleaner.create(wrapper, new Deallocator(wrapper.vecArray));
 105             cached.set(wrapper);
 106         }
 107         return wrapper;
 108     }
 109 
 110     void setBuffer(int i, ByteBuffer buf, int pos, int rem) {
 111         this.buf[i] = buf;
 112         this.position[i] = pos;
 113         this.remaining[i] = rem;
 114     }
 115 
 116     void setShadow(int i, ByteBuffer buf) {
 117         shadow[i] = buf;
 118     }
 119 
 120     ByteBuffer getBuffer(int i) {
 121         return buf[i];
 122     }
 123 
 124     int getPosition(int i) {
 125         return position[i];
 126     }
 127 
 128     int getRemaining(int i) {
 129         return remaining[i];
 130     }
 131 
 132     ByteBuffer getShadow(int i) {
 133         return shadow[i];
 134     }
 135 
 136     void clearRefs(int i) {
 137         buf[i] = null;
 138         shadow[i] = null;
 139     }
 140 
 141     void putBase(int i, long base) {
 142         int offset = SIZE_IOVEC * i + BASE_OFFSET;
 143         if (addressSize == 4)
 144             vecArray.putInt(offset, (int)base);
 145         else
 146             vecArray.putLong(offset, base);
 147     }
 148 
 149     void putLen(int i, long len) {
 150         int offset = SIZE_IOVEC * i + LEN_OFFSET;
 151         if (addressSize == 4)
 152             vecArray.putInt(offset, (int)len);
 153         else
 154             vecArray.putLong(offset, len);
 155     }
 156 
 157     static {
 158         addressSize = Util.unsafe().addressSize();
 159         LEN_OFFSET = addressSize;
 160         SIZE_IOVEC = (short) (addressSize * 2);
 161     }
 162 }