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    1   /*
    2    *  Licensed to the Apache Software Foundation (ASF) under one
    3    *  or more contributor license agreements.  See the NOTICE file
    4    *  distributed with this work for additional information
    5    *  regarding copyright ownership.  The ASF licenses this file
    6    *  to you under the Apache License, Version 2.0 (the
    7    *  "License"); you may not use this file except in compliance
    8    *  with the License.  You may obtain a copy of the License at
    9    *
    10   *    http://www.apache.org/licenses/LICENSE-2.0
    11   *
    12   *  Unless required by applicable law or agreed to in writing,
    13   *  software distributed under the License is distributed on an
    14   *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    15   *  KIND, either express or implied.  See the License for the
    16   *  specific language governing permissions and limitations
    17   *  under the License.
    18   *
    19   */
    20  package org.apache.mina.util.byteaccess;
    21
    22  import java.util.ArrayList;
    23  import java.util.Stack;
    24
    25  import org.apache.mina.core.buffer.IoBuffer;
    26
    27  /**
    28   * Creates <code>ByteArray</code>s, using a pool to reduce allocation where possible.
    29   *
    30   * WARNING: This code has never been run!
    31   *
    32   *
    33   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
    34   */
    35  public class ByteArrayPool implements ByteArrayFactory {
    36
    37      private final int MAX_BITS = 32;
    38
    39      private boolean freed;
    40
    41      private final boolean direct;
    42
    43      private ArrayList<Stack<DirectBufferByteArray>> freeBuffers;
    44
    45      private int freeBufferCount = 0;
    46
    47      private long freeMemory = 0;
    48
    49      private final int maxFreeBuffers;
    50
    51      private final int maxFreeMemory;
    52
    53      /**
    54       * Creates a new instance of ByteArrayPool.
    55       *
    56       * @param direct
    57       *  If we should use direct buffers
    58       * @param maxFreeBuffers
    59       *  The maximum number of free buffers
    60       * @param maxFreeMemory
    61       *  The maximum amount of free memory allowed
    62       */
    63      public ByteArrayPool(boolean direct, int maxFreeBuffers, int maxFreeMemory) {
    64          this.direct = direct;
    65          freeBuffers = new ArrayList<Stack<DirectBufferByteArray>>();
    66          for (int i = 0; i < MAX_BITS; i++) {
    67              freeBuffers.add(new Stack<DirectBufferByteArray>());
    68          }
    69          this.maxFreeBuffers = maxFreeBuffers;
    70          this.maxFreeMemory = maxFreeMemory;
    71          this.freed = false;
    72      }
    73
    74      /**
    75       * Creates a new instance of a {@link ByteArray}
    76       *
    77       * @param size
    78       *  The size of the array to build
    79       */
    80      public ByteArray create(int size) {
    81          if (size < 1) {
    82              throw new IllegalArgumentException("Buffer size must be at least 1: " + size);
    83          }
    84          int bits = bits(size);
    85          synchronized (this) {
    86              if (!freeBuffers.get(bits).isEmpty()) {
    87                  DirectBufferByteArray ba = freeBuffers.get(bits).pop();
    88                  ba.setFreed(false);
    89                  ba.getSingleIoBuffer().limit(size);
    90                  return ba;
    91              }
    92          }
    93          IoBuffer bb;
    94          int bbSize = 1 << bits;
    95          bb = IoBuffer.allocate(bbSize, direct);
    96          bb.limit(size);
    97          DirectBufferByteArray ba = new DirectBufferByteArray(bb);
    98          ba.setFreed(false);
    99          return ba;
    100     }
    101
    102     private int bits(int index) {
    103         int bits = 0;
    104         while (1 << bits < index) {
    105             bits++;
    106         }
    107         return bits;
    108     }
    109
    110     /**
    111      * Frees the buffers
    112      *
    113      */
    114     public void free() {
    115         synchronized (this) {
    116             if (freed) {
    117                 throw new IllegalStateException("Already freed.");
    118             }
    119             freed = true;
    120             freeBuffers.clear();
    121             freeBuffers = null;
    122         }
    123     }
    124
    125     private class DirectBufferByteArray extends BufferByteArray {
    126
    127         public boolean freed;
    128
    129         public DirectBufferByteArray(IoBuffer bb) {
    130             super(bb);
    131         }
    132
    133         public void setFreed(boolean freed) {
    134             this.freed = freed;
    135         }
    136
    137         @Override
    138         public void free() {
    139             synchronized (this) {
    140                 if (freed) {
    141                     throw new IllegalStateException("Already freed.");
    142                 }
    143                 freed = true;
    144             }
    145             int bits = bits(last());
    146             synchronized (ByteArrayPool.this) {
    147                 if (freeBuffers != null && freeBufferCount < maxFreeBuffers && freeMemory + last() <= maxFreeMemory) {
    148                     freeBuffers.get(bits).push(this);
    149                     freeBufferCount++;
    150                     freeMemory += last();
    151                     return;
    152                 }
    153             }
    154         }
    155
    156     }
    157
    158 }