ltt/branches/poly/lttv/module.c

   1
   2 /* module.c : Implementation of the module loading/unloading mechanism.
   3  *
   4  */
   5
   6 #include <lttv/module.h>
   7
   8
   9 struct _LttvModule
  10 {
  11   GModule *module;
  12   guint ref_count;
  13   guint load_count;
  14   GPtrArray *dependents;
  15 };
  16
  17
  18 /* Table of loaded modules and paths where to search for modules */
  19
  20 static GHashTable *modules = NULL;
  21
  22 static GPtrArray *modulesPaths = NULL;
  23
  24 static void lttv_module_unload_all();
  25
  26
  27 void lttv_module_init(int argc, char **argv)
  28 {
  29   modules = g_hash_table_new(g_str_hash, g_str_equal);
  30   modulesPaths = g_ptr_array_new();
  31 }
  32
  33
  34 void lttv_module_destroy()
  35 {
  36   int i;
  37
  38   /* Unload all modules */
  39   lttv_module_unload_all();
  40
  41   /* Free the modules paths pointer array as well as the elements */
  42   for(i = 0; i < modulesPaths->len ; i++) {
  43     g_free(modulesPaths->pdata[i]);
  44   }
  45   g_ptr_array_free(modulesPaths,TRUE) ;
  46   modulesPaths = NULL;
  47
  48   /* destroy the hash table */
  49   g_hash_table_destroy(modules) ;
  50   modules = NULL;
  51 }
  52
  53
  54 /* Add a new pathname to the modules loading search path */
  55
  56 void lttv_module_path_add(const char *name)
  57 {
  58   g_ptr_array_add(modulesPaths,(char*)g_strdup(name));
  59 }
  60
  61
  62 static LttvModule *
  63 module_load(const char *name, int argc, char **argv)
  64 {
  65   GModule *gm;
  66
  67   LttvModule *m;
  68
  69   int i;
  70
  71   char *pathname;
  72
  73   const char *module_name;
  74
  75   LttvModuleInit init_function;
  76
  77   /* Try to find the module along all the user specified paths */
  78
  79   for(i = 0 ; i < modulesPaths->len ; i++) {
  80     pathname = g_module_build_path(modulesPaths->pdata[i],name);
  81     gm = g_module_open(pathname,0);
  82     g_free(pathname);
  83
  84     if(gm != NULL) break;
  85   }
  86
  87   /* Try the default system path */
  88
  89   if(gm == NULL) {
  90     pathname = g_module_build_path(NULL,name);
  91     gm = g_module_open(pathname,0);
  92     g_free(pathname);
  93   }
  94
  95   /* Module cannot be found */
  96
  97   if(gm == NULL) return NULL;
  98
  99   /* Check if the module was already opened using the hopefully canonical name
 100      returned by g_module_name. */
 101
 102   module_name = g_module_name(gm);
 103
 104   m = g_hash_table_lookup(modules, module_name);
 105
 106   if(m == NULL) {
 107
 108     /* Module loaded for the first time. Insert it in the table and call the
 109        init function if any. */
 110
 111     m = g_new(LttvModule, 1);
 112     m->module = gm;
 113     m->ref_count = 0;
 114     m->load_count = 0;
 115     m->dependents = g_ptr_array_new();
 116     g_hash_table_insert(modules, (gpointer)module_name, m);
 117
 118     if(!g_module_symbol(gm, "init", (gpointer)&init_function)) {
 119       g_warning("module %s (%s) has no init function", name, pathname);
 120     }
 121     else init_Function(m, argc, argv);
 122   }
 123   else {
 124
 125     /* Module was already opened, check that it really is the same and
 126        undo the extra g_module_open */
 127
 128     if(m->module != gm) g_error("Two gmodules with the same pathname");
 129     g_module_close(gm);
 130   }
 131
 132   m->ref_count++;
 133   return m;
 134 }
 135
 136
 137 LttvModule *
 138 lttv_module_load(const char *name, int argc, char **argv)
 139 {
 140   LttvModule *m = module_load(name, argc, argv);
 141
 142   if(m != NULL) m->load_count++;
 143   return m;
 144 }
 145
 146
 147 LttvModule *
 148 lttv_module_require(LttvModule *m, const char *name, int argc, char **argv)
 149 {
 150   LttvModule *module;
 151
 152   module = module_load(name, argc, argv);
 153   if(module != NULL) g_ptr_array_add(m->dependents, module);
 154   return module;
 155 }
 156
 157
 158 static void module_unload(LttvModule *m)
 159 {
 160   LttvModuleDestroy destroy_function;
 161
 162   char *pathname;
 163
 164   guint i, len;
 165
 166   /* Decrement the reference count */
 167
 168   m->ref_count--;
 169   if(m->ref_count > 0) return;
 170
 171   /* We really have to unload the module, first unload its dependents */
 172
 173   len = m->dependents->len;
 174
 175   for(i = 0 ; i < len ; i++) {
 176     module_unload(m->dependents->pdata[i]);
 177   }
 178
 179   if(len != m->dependents->len) g_error("dependents list modified");
 180
 181   /* Unload the module itself */
 182
 183   if(!g_module_symbol(m->module, "destroy", (gpointer)&destroy_function)) {
 184     g_warning("module (%s) has no destroy function", pathname);
 185   }
 186   else destroy_function();
 187
 188   g_hash_table_remove(modules, g_module_name(m->module));
 189   g_ptr_array_free(m->dependents, TRUE);
 190   g_module_close(m->module);
 191   g_free(m);
 192 }
 193
 194
 195 void lttv_module_unload(LttvModule *m)
 196 {
 197   if(m->load_count <= 0) {
 198     g_error("more unload than load (%s)", g_module_name(m->module));
 199     return;
 200   }
 201   m->load_count--;
 202   module_unload(m);
 203 }
 204
 205
 206 static void
 207 list_modules(gpointer key, gpointer value, gpointer user_data)
 208 {
 209   g_ptr_array_add((GPtrArray *)user_data, value);
 210 }
 211
 212
 213 LttvModule **
 214 lttv_module_list(guint *nb)
 215 {
 216   GPtrArray *list = g_ptr_array_new();
 217
 218   LttvModule **array;
 219
 220   g_hash_table_foreach(modules, list_modules, list);
 221   *nb = list->len;
 222   array = (LttvModule **)list->pdata;
 223   g_ptr_array_free(list, FALSE);
 224   return array;
 225 }
 226
 227
 228 LttvModule **
 229 lttv_module_info(LttvModule *m, const char **name,
 230     guint *ref_count, guint *load_count, guint *nb_dependents)
 231 {
 232   guint i, len = m->dependents->len;
 233
 234   LttvModule **array = g_new(LttvModule *, len);
 235
 236   *name = g_module_name(m->module);
 237   *ref_count = m->ref_count;
 238   *load_count = m->load_count;
 239   *nb_dependents = len;
 240   for(i = 0 ; i < len ; i++) array[i] = m->dependents->pdata[i];
 241   return array;
 242 }
 243
 244
 245 static void
 246 list_independent(gpointer key, gpointer value, gpointer user_data)
 247 {
 248   LttvModule *m = (LttvModule *)value;
 249
 250   if(m->load_count > 0) g_ptr_array_add((GPtrArray *)user_data, m);
 251 }
 252
 253
 254 void
 255 lttv_module_unload_all()
 256 {
 257   guint i;
 258
 259   LttvModule *m;
 260
 261   GPtrArray *independent_modules = g_ptr_array_new();
 262
 263   g_hash_table_foreach(modules, list_independent, independent_modules);
 264
 265   for(i = 0 ; i < independent_modules->len ; i++) {
 266     m = (LttvModule *)independent_modules->pdata[i];
 267     while(m->load_count > 0) lttv_module_unload(m);
 268   }
 269
 270   g_ptr_array_free(independent_modules, TRUE);
 271   if(g_hash_table_size(modules) != 0) g_warning("cannot unload all modules");
 272 }