1 | /*
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2 | * MGRetrieveWrapperImpl.c
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3 | * Copyright (C) 2002 New Zealand Digital Library, http://www.nzdl.org
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4 | *
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5 | * This program is free software; you can redistribute it and/or modify
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6 | * it under the terms of the GNU General Public License as published by
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7 | * the Free Software Foundation; either version 2 of the License, or
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8 | * (at your option) any later version.
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9 | *
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10 | * This program is distributed in the hope that it will be useful,
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11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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13 | * GNU General Public License for more details.
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14 | *
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15 | * You should have received a copy of the GNU General Public License
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16 | * along with this program; if not, write to the Free Software
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17 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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18 | */
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19 |
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20 |
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21 | #include "MGWrapperImpl.h"
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22 | #include <jni.h>
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23 | #include "org_greenstone_mg_MGRetrieveWrapper.h"
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24 |
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25 | #include "backend.h"
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26 | #include "environment.h"
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27 | #include "text_get.h"
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28 | #include "stemmer.h"
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29 |
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30 | #define MAX_INDEXES_CACHED 3
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31 |
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32 | /* copied from mgquery, needed to convert paragraph numbers to document numbers
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33 | for greenstone */
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34 | #if defined(PARADOCNUM) || defined(NZDL)
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35 | static int GetDocNumFromParaNum(query_data *qd, int paranum) {
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36 | int Documents = qd->td->cth.num_of_docs;
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37 | int *Paragraph = qd->paragraph;
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38 | int low = 1, high = Documents;
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39 | int mid = (low+high)/2;
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40 |
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41 | while ((mid = (low+high)/2) >=1 && mid <= Documents)
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42 | {
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43 | if (paranum > Paragraph[mid])
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44 | low = mid+1;
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45 | else if (paranum <= Paragraph[mid-1])
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46 | high = mid-1;
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47 | else
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48 | return mid;
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49 | }
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50 | FatalError(1, "Bad paragraph number.\n");
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51 | return 0;
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52 | }
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53 | #endif
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54 |
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55 |
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56 | /*********************************************
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57 | initialisation stuff
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58 | *********************************************/
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59 |
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60 | /* cached ids for java stuff */
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61 | jfieldID FID_mg_data = NULL; /* MGWrapperData */
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62 | jfieldID FID_query_result = NULL; /* MGQueryResult */
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63 | jmethodID MID_addDoc = NULL; /* MGQueryResult.addDoc() */
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64 | jmethodID MID_addTerm = NULL; /* MGQueryResult.addTerm() */
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65 | jmethodID MID_addEquivTerm = NULL; /* MGQueryResult.addEquivTerm() */
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66 | jmethodID MID_setTotalDocs = NULL; /* MGQueryResult.setTotalDocs() */
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67 | jmethodID MID_clearResult = NULL; /* MGQueryResult.clear() */
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68 |
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69 |
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70 | /*******************************************
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71 | Index caching
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72 | *******************************************/
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73 |
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74 | query_data* cached_indexes[MAX_INDEXES_CACHED] = { NULL };
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75 |
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76 |
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77 | /* Get the index data necessary to perform a query or document retrieval */
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78 | query_data*
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79 | loadIndexData(char* base_dir, char* index_path, char* text_path)
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80 | {
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81 | char* index_path_name;
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82 | char* text_path_name;
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83 | query_data* qd;
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84 | int i = 0;
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85 |
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86 | /* Form the path name of the desired indexes */
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87 | index_path_name = (char*) malloc(strlen(base_dir) + strlen(index_path) + 1);
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88 | assert(index_path_name != NULL);
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89 | strcpy(index_path_name, base_dir);
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90 | strcat(index_path_name, index_path);
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91 | printf("Index pathname: %s\n", index_path_name);
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92 |
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93 | text_path_name = (char*) malloc(strlen(base_dir) + strlen(text_path) + 1);
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94 | assert(text_path_name != NULL);
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95 | strcpy(text_path_name, base_dir);
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96 | strcat(text_path_name, text_path);
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97 | printf("Text pathname: %s\n", text_path_name);
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98 |
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99 | /* Search through the cached indexes for the desired one */
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100 | while (i < MAX_INDEXES_CACHED && cached_indexes[i] != NULL) {
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101 | printf("(Cached) Pathname: %s\n", cached_indexes[i]->pathname);
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102 | printf("(Cached) Textpathname: %s\n", cached_indexes[i]->textpathname);
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103 |
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104 | /* Check if the index has already been loaded */
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105 | if ((strcmp(index_path_name, cached_indexes[i]->pathname) == 0) &&
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106 | (strcmp(text_path_name, cached_indexes[i]->textpathname) == 0)) {
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107 | /* Index has already been loaded and cached, so return it */
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108 | printf("Found index!\n");
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109 | free(index_path_name);
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110 | free(text_path_name);
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111 | return cached_indexes[i];
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112 | }
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113 |
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114 | i++;
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115 | }
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116 |
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117 | /* Text strings no longer needed */
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118 | free(index_path_name);
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119 | free(text_path_name);
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120 |
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121 | /* The index is not cached, so load it now */
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122 | qd = InitQuerySystem(base_dir, index_path, text_path, NULL);
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123 | if (!qd) {
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124 | printf("Error: Could not InitQuerySystem()...\n");
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125 | return NULL;
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126 | }
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127 |
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128 | /* The index loaded OK, so cache it */
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129 | /* This could be a little more sophisticated, eg. replace least frequently used index */
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130 | if (i >= MAX_INDEXES_CACHED)
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131 | i = MAX_INDEXES_CACHED - 1;
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132 |
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133 | /* Free the index being replaced */
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134 | if (cached_indexes[i] != NULL)
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135 | FinishQuerySystem(cached_indexes[i]);
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136 |
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137 | /* Cache the loaded index, and return it */
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138 | cached_indexes[i] = qd;
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139 | return cached_indexes[i];
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140 | }
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141 |
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142 | /*
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143 | * Class: org_greenstone_mg_MGRetrieveWrapper
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144 | * Method: initIDs
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145 | * Signature: ()V
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146 | */
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147 | JNIEXPORT void JNICALL
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148 | Java_org_greenstone_mg_MGRetrieveWrapper_initIDs(JNIEnv *j_env, jclass j_cls)
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149 | {
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150 | /* a long-"J" */
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151 | FID_mg_data = (*j_env)->GetFieldID(j_env, j_cls, "mg_data_ptr_", "J");
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152 | assert(FID_mg_data != NULL);
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153 |
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154 | }
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155 |
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156 | /*
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157 | * Class: org_greenstone_mg_MGRetrieveWrapper
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158 | * Method: initCSide
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159 | * Signature: ()Z
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160 | */
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161 | JNIEXPORT jboolean JNICALL Java_org_greenstone_mg_MGRetrieveWrapper_initCSide
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162 | (JNIEnv *j_env, jobject j_obj)
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163 | {
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164 | /* Allocate a MGWrapperData object to store query parameters */
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165 | MGWrapperData* data = (MGWrapperData*) malloc(sizeof(MGWrapperData));
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166 | assert(data != NULL);
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167 |
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168 | /* Set default values - no stemming, no case-folding, boolean OR queries */
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169 | data->defaultStemMethod = 0;
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170 | data->defaultBoolCombine = 0;
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171 |
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172 | /* Allocate a QueryInfo object to store more query parameters */
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173 | data->queryInfo = (QueryInfo*) malloc(sizeof(QueryInfo));
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174 | assert(data->queryInfo != NULL);
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175 |
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176 | /* Set default values - 50 documents max, return term freqs, sort by rank */
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177 | data->queryInfo->index = NULL;
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178 | data->queryInfo->maxDocs = 50;
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179 | data->queryInfo->needTermFreqs = 1;
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180 |
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181 | /* Save the object on the Java side */
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182 | (*j_env)->SetIntField(j_env, j_obj, FID_mg_data, (mg_s_long) data);
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183 |
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184 | /* Initialise MG environment variables */
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185 | InitEnv();
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186 | SetEnv("expert", "true", NULL);
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187 | SetEnv("mode", "docnums", NULL);
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188 |
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189 | return 1; /* true - no errors */
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190 | }
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191 |
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192 | /*
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193 | * Class: org_greenstone_mg_MGRetrieveWrapper
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194 | * Method: unloadIndexData
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195 | * Signature: ()Z
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196 | */
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197 | JNIEXPORT jboolean JNICALL Java_org_greenstone_mg_MGRetrieveWrapper_unloadIndexData
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198 | (JNIEnv* j_env, jobject j_obj)
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199 | {
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200 | /* Free all the loaded indexes */
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201 | int i = 0;
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202 | while (i < MAX_INDEXES_CACHED && cached_indexes[i] != NULL) {
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203 | FinishQuerySystem(cached_indexes[i]);
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204 | cached_indexes[i] = NULL;
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205 | i++;
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206 | }
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207 |
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208 | return 1; /* true - no errors */
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209 | }
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210 | /* Choose MG index to search */
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211 | JNIEXPORT void JNICALL
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212 | Java_org_greenstone_mg_MGRetrieveWrapper_setIndex(JNIEnv *j_env, jobject j_obj,
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213 | jstring j_index)
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214 | {
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215 | MGWrapperData* data = (MGWrapperData*) (*j_env)->GetIntField(j_env, j_obj, FID_mg_data);
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216 |
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217 | /* Get the index name as a C string */
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218 | const char* index = (*j_env)->GetStringUTFChars(j_env, j_index, NULL);
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219 | assert(index != NULL);
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220 | printf("Choosing index %s...\n", index);
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221 |
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222 | /* Free the previous index name */
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223 | if (data->queryInfo->index)
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224 | free(data->queryInfo->index);
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225 |
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226 | /* Allocate memory for the index name, and fill it */
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227 | data->queryInfo->index = (char*) malloc(strlen(index) + 1);
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228 | assert(data->queryInfo->index != NULL);
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229 | strcpy(data->queryInfo->index, index);
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230 |
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231 | /* Release the index string */
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232 | (*j_env)->ReleaseStringUTFChars(j_env, j_index, index);
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233 | }
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234 |
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235 | /*
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236 | * Class: org_greenstone_mg_MGRetrieveWrapper
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237 | * Method: getDocument
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238 | * Signature: (Ljava/lang/String;Ljava/lang/String;J)Ljava/lang/String;
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239 | */
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240 | JNIEXPORT jstring JNICALL Java_org_greenstone_mg_MGRetrieveWrapper_getDocument
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241 | (JNIEnv *j_env, jobject j_obj,
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242 | jstring j_base_dir, jstring j_text_path,
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243 | jlong j_docnum)
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244 | {
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245 | MGWrapperData* data = (MGWrapperData*) (*j_env)->GetIntField(j_env, j_obj, FID_mg_data);
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246 |
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247 | char* index_path;
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248 | const char* base_dir;
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249 | const char* text_path;
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250 | query_data* qd;
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251 |
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252 | mg_u_long pos, len;
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253 | u_char* c_buffer = NULL;
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254 | u_char* uc_buffer = NULL;
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255 | int ULen;
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256 |
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257 | jstring result;
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258 |
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259 | /* Make sure an index has been specified */
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260 | index_path = data->queryInfo->index;
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261 | assert(index_path != NULL);
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262 |
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263 | /* Obtain C versions of the two string parameters */
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264 | base_dir = (*j_env)->GetStringUTFChars(j_env, j_base_dir, NULL);
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265 | if (base_dir == NULL) {
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266 | return NULL;
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267 | }
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268 | text_path = (*j_env)->GetStringUTFChars(j_env, j_text_path, NULL);
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269 | if (text_path == NULL) {
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270 | (*j_env)->ReleaseStringUTFChars(j_env, j_base_dir, base_dir);
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271 | return NULL;
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272 | }
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273 |
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274 | /* Load the appropriate index for satisfying this request */
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275 | printf("Document retrieval, index path: %s\n", index_path);
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276 | qd = loadIndexData((char*) base_dir, (char*) index_path, (char*) text_path);
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277 |
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278 | /* The C text strings are no longer needed */
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279 | (*j_env)->ReleaseStringUTFChars(j_env, j_base_dir, base_dir);
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280 | (*j_env)->ReleaseStringUTFChars(j_env, j_text_path, text_path);
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281 |
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282 | /* Check that the index was loaded successfully */
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283 | if (qd==NULL) {
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284 | return NULL;
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285 | }
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286 | /*assert(qd != NULL);*/
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287 |
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288 | /* Get the document position and length in the text file */
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289 | printf("Fetching document number %d...\n", (mg_u_long) j_docnum);
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290 | FetchDocStart(qd, (mg_u_long) j_docnum, &pos, &len);
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291 | printf("Fetched document start. Pos: %d, Len: %d\n", pos, len);
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292 |
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293 | /* Allocate memory for the document text (from mg/src/text/mgquery.c:RawDocOutput()) */
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294 | c_buffer = (u_char*) malloc(len);
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295 | assert(c_buffer != NULL);
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296 | uc_buffer = (u_char*) malloc((int) (qd->td->cth.ratio * 1.01 * len) + 100);
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297 | assert(uc_buffer != NULL);
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298 |
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299 | /* Seek to the correct position in the file and read the document text */
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300 | Fseek (qd->td->TextFile, pos, 0);
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301 | Fread (c_buffer, 1, len, qd->td->TextFile);
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302 |
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303 | /* Decompress the document text into another buffer, and terminate it */
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304 | DecodeText (qd->cd, c_buffer, len, uc_buffer, &ULen);
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305 | uc_buffer[ULen] = '\0';
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306 |
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307 | /* Load the document text into a Java string */
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308 | result = (*j_env)->NewStringUTF(j_env, uc_buffer);
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309 | assert(result != NULL);
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310 |
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311 | /* Free C buffers */
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312 | free(c_buffer);
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313 | free(uc_buffer);
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314 |
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315 | /* Return the document text */
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316 | return result;
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317 | }
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318 |
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