ltt/branches/poly/lttv/main/module.c

   1 /* This file is part of the Linux Trace Toolkit viewer
   2  * Copyright (C) 2003-2004 Michel Dagenais
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License Version 2 as
   6  * published by the Free Software Foundation;
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program; if not, write to the Free Software
  15  * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  16  * MA 02111-1307, USA.
  17  */
  18
  19
  20 /* module.c : Implementation of the module loading/unloading mechanism.
  21  *
  22  */
  23
  24 #include <lttv/module.h>
  25
  26 #define g_info(format...) g_log (G_LOG_DOMAIN, G_LOG_LEVEL_INFO, format)
  27 #define g_debug(format...) g_log (G_LOG_DOMAIN, G_LOG_LEVEL_DEBUG, format)
  28
  29 struct _LttvModule
  30 {
  31   GModule *module;
  32   guint ref_count;
  33   guint load_count;
  34   GPtrArray *dependents;
  35 };
  36
  37
  38 /* Table of loaded modules and paths where to search for modules */
  39
  40 static GHashTable *modules = NULL;
  41
  42 static GPtrArray *modulesPaths = NULL;
  43
  44 static void lttv_module_unload_all();
  45
  46
  47 void lttv_module_init(int argc, char **argv)
  48 {
  49   g_info("Init module.c");
  50   modules = g_hash_table_new(g_str_hash, g_str_equal);
  51   modulesPaths = g_ptr_array_new();
  52 }
  53
  54
  55 void lttv_module_destroy()
  56 {
  57   int i;
  58
  59   g_info("Destroy module.c");
  60
  61   /* Unload all modules */
  62   lttv_module_unload_all();
  63
  64   /* Free the modules paths pointer array as well as the elements */
  65   for(i = 0; i < modulesPaths->len ; i++) {
  66     g_free(modulesPaths->pdata[i]);
  67   }
  68   g_ptr_array_free(modulesPaths,TRUE) ;
  69   modulesPaths = NULL;
  70
  71   /* destroy the hash table */
  72   g_hash_table_destroy(modules) ;
  73   modules = NULL;
  74 }
  75
  76
  77 /* Add a new pathname to the modules loading search path */
  78
  79 void lttv_module_path_add(const char *name)
  80 {
  81   g_info("Add module path %s", name);
  82   g_ptr_array_add(modulesPaths,(char*)g_strdup(name));
  83 }
  84
  85
  86 static LttvModule *
  87 module_load(const char *name, int argc, char **argv)
  88 {
  89   GModule *gm;
  90
  91   LttvModule *m;
  92
  93   int i;
  94
  95   char *pathname;
  96
  97   const char *module_name;
  98
  99   LttvModuleInit init_function;
 100
 101   g_info("Load module %s", name);
 102
 103   /* Try to find the module along all the user specified paths */
 104
 105   for(i = 0 ; i < modulesPaths->len ; i++) {
 106     pathname = g_module_build_path(modulesPaths->pdata[i],name);
 107     g_info("Try path %s", pathname);
 108     gm = g_module_open(pathname,0);
 109     g_free(pathname);
 110
 111     if(gm != NULL) break;
 112     g_info("Trial failed, %s", g_module_error());
 113   }
 114
 115   /* Try the default system path */
 116
 117   if(gm == NULL) {
 118     pathname = g_module_build_path(NULL,name);
 119     g_info("Try default path");
 120     gm = g_module_open(pathname,0);
 121     g_free(pathname);
 122   }
 123
 124   /* Module cannot be found */
 125   if(gm == NULL) {
 126     g_info("Trial failed, %s", g_module_error());
 127     g_info("Failed to load %s", name);
 128     return NULL;
 129   }
 130
 131   /* Check if the module was already opened using the hopefully canonical name
 132      returned by g_module_name. */
 133
 134   module_name = g_module_name(gm);
 135
 136   m = g_hash_table_lookup(modules, module_name);
 137
 138   if(m == NULL) {
 139     g_info("Module %s (%s) loaded, call its init function", name, module_name);
 140
 141     /* Module loaded for the first time. Insert it in the table and call the
 142        init function if any. */
 143
 144     m = g_new(LttvModule, 1);
 145     m->module = gm;
 146     m->ref_count = 0;
 147     m->load_count = 0;
 148     m->dependents = g_ptr_array_new();
 149     g_hash_table_insert(modules, (gpointer)module_name, m);
 150
 151     if(!g_module_symbol(gm, "init", (gpointer)&init_function)) {
 152       g_warning("module %s (%s) has no init function", name, pathname);
 153     }
 154     else init_function(m, argc, argv);
 155   }
 156   else {
 157
 158     /* Module was already opened, check that it really is the same and
 159        undo the extra g_module_open */
 160
 161     g_info("Module %s (%s) was already loaded, no need to call init function",
 162            name, module_name);
 163     if(m->module != gm) g_error("Two gmodules with the same pathname");
 164     g_module_close(gm);
 165   }
 166
 167   m->ref_count++;
 168   return m;
 169 }
 170
 171
 172 LttvModule *
 173 lttv_module_load(const char *name, int argc, char **argv)
 174 {
 175   g_info("Load module %s explicitly", name);
 176   LttvModule *m = module_load(name, argc, argv);
 177   if(m != NULL) m->load_count++;
 178   return m;
 179 }
 180
 181
 182 LttvModule *
 183 lttv_module_require(LttvModule *m, const char *name, int argc, char **argv)
 184 {
 185   LttvModule *module;
 186
 187   g_info("Load module %s, as %s is a dependent requiring it", name,
 188       g_module_name(m->module));
 189   module = module_load(name, argc, argv);
 190   if(module != NULL) g_ptr_array_add(module->dependents, m);
 191   return module;
 192 }
 193
 194
 195 static void module_unload(LttvModule *m)
 196 {
 197   LttvModuleDestroy destroy_function;
 198
 199   char *pathname;
 200
 201   guint i, len;
 202
 203   /* Decrement the reference count */
 204
 205   g_info("Unload module %s", g_module_name(m->module));
 206   m->ref_count--;
 207   if(m->ref_count > 0) {
 208     g_info("Module usage count decremented to %d", m->ref_count);
 209     return;
 210   }
 211   /* We really have to unload the module, first unload its dependents */
 212
 213   len = m->dependents->len;
 214   g_info("Unload dependent modules");
 215
 216   for(i = 0 ; i < len ; i++) {
 217     module_unload(m->dependents->pdata[i]);
 218   }
 219
 220   if(len != m->dependents->len) g_error("dependents list modified");
 221
 222   /* Unload the module itself */
 223
 224   g_info("Call the destroy function and unload the module");
 225   if(!g_module_symbol(m->module, "destroy", (gpointer)&destroy_function)) {
 226     g_warning("module (%s) has no destroy function", pathname);
 227   }
 228   else destroy_function();
 229
 230   g_hash_table_remove(modules, g_module_name(m->module));
 231   g_ptr_array_free(m->dependents, TRUE);
 232   g_module_close(m->module);
 233   g_free(m);
 234 }
 235
 236
 237 void lttv_module_unload(LttvModule *m)
 238 {
 239   g_info("Explicitly unload module %s", g_module_name(m->module));
 240   if(m->load_count <= 0) {
 241     g_error("more unload than load (%s)", g_module_name(m->module));
 242     return;
 243   }
 244   m->load_count--;
 245   module_unload(m);
 246 }
 247
 248
 249 static void
 250 list_modules(gpointer key, gpointer value, gpointer user_data)
 251 {
 252   g_ptr_array_add((GPtrArray *)user_data, value);
 253 }
 254
 255
 256 LttvModule **
 257 lttv_module_list(guint *nb)
 258 {
 259   GPtrArray *list = g_ptr_array_new();
 260
 261   LttvModule **array;
 262
 263   g_hash_table_foreach(modules, list_modules, list);
 264   *nb = list->len;
 265   array = (LttvModule **)list->pdata;
 266   g_ptr_array_free(list, FALSE);
 267   return array;
 268 }
 269
 270
 271 LttvModule **
 272 lttv_module_info(LttvModule *m, const char **name,
 273     guint *ref_count, guint *load_count, guint *nb_dependents)
 274 {
 275   guint i, len = m->dependents->len;
 276
 277   LttvModule **array = g_new(LttvModule *, len);
 278
 279   *name = g_module_name(m->module);
 280   *ref_count = m->ref_count;
 281   *load_count = m->load_count;
 282   *nb_dependents = len;
 283   for(i = 0 ; i < len ; i++) array[i] = m->dependents->pdata[i];
 284   return array;
 285 }
 286
 287 char *
 288 lttv_module_name(LttvModule *m)
 289 {
 290   return g_module_name(m->module);
 291 }
 292
 293 static void
 294 list_independent(gpointer key, gpointer value, gpointer user_data)
 295 {
 296   LttvModule *m = (LttvModule *)value;
 297
 298   if(m->load_count > 0) g_ptr_array_add((GPtrArray *)user_data, m);
 299 }
 300
 301
 302 void
 303 lttv_module_unload_all()
 304 {
 305   guint i;
 306
 307   LttvModule *m;
 308
 309   GPtrArray *independent_modules = g_ptr_array_new();
 310
 311   g_hash_table_foreach(modules, list_independent, independent_modules);
 312
 313   for(i = 0 ; i < independent_modules->len ; i++) {
 314     m = (LttvModule *)independent_modules->pdata[i];
 315     while(m->load_count > 0) lttv_module_unload(m);
 316   }
 317
 318   g_ptr_array_free(independent_modules, TRUE);
 319   if(g_hash_table_size(modules) != 0) g_warning("cannot unload all modules");
 320 }