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 #define g_info(format...) g_log (G_LOG_DOMAIN, G_LOG_LEVEL_INFO, format)
   9 #define g_debug(format...) g_log (G_LOG_DOMAIN, G_LOG_LEVEL_DEBUG, format)
  10
  11 struct _LttvModule
  12 {
  13   GModule *module;
  14   guint ref_count;
  15   guint load_count;
  16   GPtrArray *dependents;
  17 };
  18
  19
  20 /* Table of loaded modules and paths where to search for modules */
  21
  22 static GHashTable *modules = NULL;
  23
  24 static GPtrArray *modulesPaths = NULL;
  25
  26 static void lttv_module_unload_all();
  27
  28
  29 void lttv_module_init(int argc, char **argv)
  30 {
  31   g_info("Init module.c");
  32   modules = g_hash_table_new(g_str_hash, g_str_equal);
  33   modulesPaths = g_ptr_array_new();
  34 }
  35
  36
  37 void lttv_module_destroy()
  38 {
  39   int i;
  40
  41   g_info("Destroy module.c");
  42
  43   /* Unload all modules */
  44   lttv_module_unload_all();
  45
  46   /* Free the modules paths pointer array as well as the elements */
  47   for(i = 0; i < modulesPaths->len ; i++) {
  48     g_free(modulesPaths->pdata[i]);
  49   }
  50   g_ptr_array_free(modulesPaths,TRUE) ;
  51   modulesPaths = NULL;
  52
  53   /* destroy the hash table */
  54   g_hash_table_destroy(modules) ;
  55   modules = NULL;
  56 }
  57
  58
  59 /* Add a new pathname to the modules loading search path */
  60
  61 void lttv_module_path_add(const char *name)
  62 {
  63   g_info("Add module path %s", name);
  64   g_ptr_array_add(modulesPaths,(char*)g_strdup(name));
  65 }
  66
  67
  68 static LttvModule *
  69 module_load(const char *name, int argc, char **argv)
  70 {
  71   GModule *gm;
  72
  73   LttvModule *m;
  74
  75   int i;
  76
  77   char *pathname;
  78
  79   const char *module_name;
  80
  81   LttvModuleInit init_function;
  82
  83   g_info("Load module %s", name);
  84
  85   /* Try to find the module along all the user specified paths */
  86
  87   for(i = 0 ; i < modulesPaths->len ; i++) {
  88     pathname = g_module_build_path(modulesPaths->pdata[i],name);
  89     g_info("Try path %s", pathname);
  90     gm = g_module_open(pathname,0);
  91     g_free(pathname);
  92
  93     if(gm != NULL) break;
  94     g_info("Trial failed, %s", g_module_error());
  95   }
  96
  97   /* Try the default system path */
  98
  99   if(gm == NULL) {
 100     pathname = g_module_build_path(NULL,name);
 101     g_info("Try default path");
 102     gm = g_module_open(pathname,0);
 103     g_free(pathname);
 104   }
 105
 106   /* Module cannot be found */
 107   if(gm == NULL) {
 108     g_info("Trial failed, %s", g_module_error());
 109     g_info("Failed to load %s", name);
 110     return NULL;
 111   }
 112
 113   /* Check if the module was already opened using the hopefully canonical name
 114      returned by g_module_name. */
 115
 116   module_name = g_module_name(gm);
 117
 118   m = g_hash_table_lookup(modules, module_name);
 119
 120   if(m == NULL) {
 121     g_info("Module %s (%s) loaded, call its init function", name, module_name);
 122
 123     /* Module loaded for the first time. Insert it in the table and call the
 124        init function if any. */
 125
 126     m = g_new(LttvModule, 1);
 127     m->module = gm;
 128     m->ref_count = 0;
 129     m->load_count = 0;
 130     m->dependents = g_ptr_array_new();
 131     g_hash_table_insert(modules, (gpointer)module_name, m);
 132
 133     if(!g_module_symbol(gm, "init", (gpointer)&init_function)) {
 134       g_warning("module %s (%s) has no init function", name, pathname);
 135     }
 136     else init_function(m, argc, argv);
 137   }
 138   else {
 139
 140     /* Module was already opened, check that it really is the same and
 141        undo the extra g_module_open */
 142
 143     g_info("Module %s (%s) was already loaded, no need to call init function",
 144            name, module_name);
 145     if(m->module != gm) g_error("Two gmodules with the same pathname");
 146     g_module_close(gm);
 147   }
 148
 149   m->ref_count++;
 150   return m;
 151 }
 152
 153
 154 LttvModule *
 155 lttv_module_load(const char *name, int argc, char **argv)
 156 {
 157   g_info("Load module %s explicitly", name);
 158   LttvModule *m = module_load(name, argc, argv);
 159   if(m != NULL) m->load_count++;
 160   return m;
 161 }
 162
 163
 164 LttvModule *
 165 lttv_module_require(LttvModule *m, const char *name, int argc, char **argv)
 166 {
 167   LttvModule *module;
 168
 169   g_info("Load module %s, as %s is a dependent requiring it", name,
 170       g_module_name(m->module));
 171   module = module_load(name, argc, argv);
 172   if(module != NULL) g_ptr_array_add(m->dependents, module);
 173   return module;
 174 }
 175
 176
 177 static void module_unload(LttvModule *m)
 178 {
 179   LttvModuleDestroy destroy_function;
 180
 181   char *pathname;
 182
 183   guint i, len;
 184
 185   /* Decrement the reference count */
 186
 187   g_info("Unload module %s", g_module_name(m->module));
 188   m->ref_count--;
 189   if(m->ref_count > 0) {
 190     g_info("Module usage count decremented to %d", m->ref_count);
 191     return;
 192   }
 193   /* We really have to unload the module, first unload its dependents */
 194
 195   len = m->dependents->len;
 196   g_info("Unload dependent modules");
 197
 198   for(i = 0 ; i < len ; i++) {
 199     module_unload(m->dependents->pdata[i]);
 200   }
 201
 202   if(len != m->dependents->len) g_error("dependents list modified");
 203
 204   /* Unload the module itself */
 205
 206   g_info("Call the destroy function and unload the module");
 207   if(!g_module_symbol(m->module, "destroy", (gpointer)&destroy_function)) {
 208     g_warning("module (%s) has no destroy function", pathname);
 209   }
 210   else destroy_function();
 211
 212   g_hash_table_remove(modules, g_module_name(m->module));
 213   g_ptr_array_free(m->dependents, TRUE);
 214   g_module_close(m->module);
 215   g_free(m);
 216 }
 217
 218
 219 void lttv_module_unload(LttvModule *m)
 220 {
 221   g_info("Explicitly unload module %s", g_module_name(m->module));
 222   if(m->load_count <= 0) {
 223     g_error("more unload than load (%s)", g_module_name(m->module));
 224     return;
 225   }
 226   m->load_count--;
 227   module_unload(m);
 228 }
 229
 230
 231 static void
 232 list_modules(gpointer key, gpointer value, gpointer user_data)
 233 {
 234   g_ptr_array_add((GPtrArray *)user_data, value);
 235 }
 236
 237
 238 LttvModule **
 239 lttv_module_list(guint *nb)
 240 {
 241   GPtrArray *list = g_ptr_array_new();
 242
 243   LttvModule **array;
 244
 245   g_hash_table_foreach(modules, list_modules, list);
 246   *nb = list->len;
 247   array = (LttvModule **)list->pdata;
 248   g_ptr_array_free(list, FALSE);
 249   return array;
 250 }
 251
 252
 253 LttvModule **
 254 lttv_module_info(LttvModule *m, const char **name,
 255     guint *ref_count, guint *load_count, guint *nb_dependents)
 256 {
 257   guint i, len = m->dependents->len;
 258
 259   LttvModule **array = g_new(LttvModule *, len);
 260
 261   *name = g_module_name(m->module);
 262   *ref_count = m->ref_count;
 263   *load_count = m->load_count;
 264   *nb_dependents = len;
 265   for(i = 0 ; i < len ; i++) array[i] = m->dependents->pdata[i];
 266   return array;
 267 }
 268
 269 char *
 270 lttv_module_name(LttvModule *m)
 271 {
 272   return g_module_name(m->module);
 273 }
 274
 275 static void
 276 list_independent(gpointer key, gpointer value, gpointer user_data)
 277 {
 278   LttvModule *m = (LttvModule *)value;
 279
 280   if(m->load_count > 0) g_ptr_array_add((GPtrArray *)user_data, m);
 281 }
 282
 283
 284 void
 285 lttv_module_unload_all()
 286 {
 287   guint i;
 288
 289   LttvModule *m;
 290
 291   GPtrArray *independent_modules = g_ptr_array_new();
 292
 293   g_hash_table_foreach(modules, list_independent, independent_modules);
 294
 295   for(i = 0 ; i < independent_modules->len ; i++) {
 296     m = (LttvModule *)independent_modules->pdata[i];
 297     while(m->load_count > 0) lttv_module_unload(m);
 298   }
 299
 300   g_ptr_array_free(independent_modules, TRUE);
 301   if(g_hash_table_size(modules) != 0) g_warning("cannot unload all modules");
 302 }