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annotate src/org/tmatesoft/hg/internal/ByteArrayDataAccess.java @ 200:114c9fe7b643

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Performance optimization: reduce memory ParentWalker hogs
author Artem Tikhomirov <tikhomirov.artem@gmail.com>
date Wed, 20 Apr 2011 21:14:51 +0200
parents b413b16d10a5
children 6c22bdc0bdfd
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1 /*
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2 * Copyright (c) 2011 TMate Software Ltd
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3 *
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4 * This program is free software; you can redistribute it and/or modify
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5 * it under the terms of the GNU General Public License as published by
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6 * the Free Software Foundation; version 2 of the License.
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7 *
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8 * This program is distributed in the hope that it will be useful,
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9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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11 * GNU General Public License for more details.
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12 *
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13 * For information on how to redistribute this software under
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14 * the terms of a license other than GNU General Public License
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15 * contact TMate Software at support@hg4j.com
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16 */
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17 package org.tmatesoft.hg.internal;
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18
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19 import java.io.IOException;
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20
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21
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22 /**
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23 *
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24 * @author Artem Tikhomirov
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25 * @author TMate Software Ltd.
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26 */
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27 public class ByteArrayDataAccess extends DataAccess {
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28
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29 private final byte[] data;
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30 private final int offset;
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31 private final int length;
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32 private int pos;
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33
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34 public ByteArrayDataAccess(byte[] data) {
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35 this(data, 0, data.length);
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36 }
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38 public ByteArrayDataAccess(byte[] data, int offset, int length) {
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39 this.data = data;
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40 this.offset = offset;
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41 this.length = length;
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42 pos = 0;
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43 }
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44
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45 @Override
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46 public byte readByte() throws IOException {
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47 if (pos >= length) {
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48 throw new IOException();
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49 }
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50 return data[offset + pos++];
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51 }
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52 @Override
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53 public void readBytes(byte[] buf, int off, int len) throws IOException {
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54 if (len > (this.length - pos)) {
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55 throw new IOException();
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56 }
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57 System.arraycopy(data, pos, buf, off, len);
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58 pos += len;
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59 }
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60
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61 @Override
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62 public ByteArrayDataAccess reset() {
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63 pos = 0;
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64 return this;
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65 }
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66 @Override
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67 public int length() {
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68 return length;
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69 }
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70 @Override
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71 public void seek(int offset) {
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72 pos = (int) offset;
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73 }
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74 @Override
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75 public void skip(int bytes) throws IOException {
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76 seek(pos + bytes);
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77 }
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78 @Override
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79 public boolean isEmpty() {
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80 return pos >= length;
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81 }
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82
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83 //
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84
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85 // when byte[] needed from DA, we may save few cycles and some memory giving this (otherwise unsafe) access to underlying data
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86 @Override
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87 public byte[] byteArray() {
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88 return data;
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89 }
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90 }