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

   1
   2 /* This file is part of the Linux Trace Toolkit viewer
   3  * Copyright (C) 2003-2004 Michel Dagenais
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License Version 2 as
   7  * published by the Free Software Foundation;
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  17  * MA 02111-1307, USA.
  18  */
  19
  20
  21 /* module.c : Implementation of the module loading/unloading mechanism. */
  22
  23 #ifdef HAVE_CONFIG_H
  24 #include <config.h>
  25 #endif
  26
  27 #include <lttv/module.h>
  28 #include <gmodule.h>
  29
  30
  31 struct _LttvLibrary
  32 {
  33   LttvLibraryInfo info;
  34   GPtrArray *modules;
  35   GModule *gm;
  36   guint locked_loaded;
  37 };
  38
  39
  40 struct _LttvModule
  41 {
  42   LttvModuleInfo info;
  43   char **prerequisites_names;
  44   GPtrArray *prerequisites;
  45 };
  46
  47
  48 /* Modules are searched by name. However, a library may be loaded which
  49    provides a module with the same name as an existing one. A stack of
  50    modules is thus maintained for each name.
  51
  52    Libraries correspond to glib modules. The g_module function is
  53    responsible for loading each library only once. */
  54
  55 static GHashTable *modules_by_name = NULL;
  56
  57 static GPtrArray *libraries = NULL;
  58
  59 static GHashTable *libraries_by_g_module = NULL;
  60
  61 static GPtrArray *library_paths = NULL;
  62
  63 static gboolean initialized = FALSE;
  64
  65 static gboolean destroyed = TRUE;
  66
  67 static struct _LttvModuleDescription *builtin_chain = NULL;
  68
  69 static struct _LttvModuleDescription *module_chain = NULL;
  70
  71 static struct _LttvModuleDescription **module_next = &module_chain;
  72
  73 static GQuark lttv_module_error;
  74
  75 static void init();
  76
  77 static void finish_destroy();
  78
  79 static void module_release(LttvModule *m);
  80
  81
  82 static LttvLibrary *library_add(char *name, char *path, GModule *gm)
  83 {
  84   LttvLibrary *l;
  85
  86   LttvModule *m;
  87
  88   struct _LttvModuleDescription *link;
  89
  90   GPtrArray *modules;
  91
  92   l = g_new(LttvLibrary, 1);
  93   l->modules = g_ptr_array_new();
  94   l->gm = gm;
  95   l->locked_loaded = 0;
  96   l->info.name = g_strdup(name);
  97   l->info.path = g_strdup(path);
  98   l->info.load_count = 0;
  99
 100   g_ptr_array_add(libraries, l);
 101   g_hash_table_insert(libraries_by_g_module, gm, l);
 102
 103   *module_next = NULL;
 104   for(link = module_chain; link != NULL; link = link->next) {
 105     m = g_new(LttvModule, 1);
 106     g_ptr_array_add(l->modules, m);
 107
 108     modules = g_hash_table_lookup(modules_by_name, link->name);
 109     if(modules == NULL) {
 110       modules = g_ptr_array_new();
 111       g_hash_table_insert(modules_by_name, g_strdup(link->name), modules);
 112     }
 113     g_ptr_array_add(modules, m);
 114
 115     m->prerequisites_names = link->prerequisites;
 116     m->prerequisites = g_ptr_array_new();
 117     m->info.name = link->name;
 118     m->info.short_description = link->short_description;
 119     m->info.description = link->description;
 120     m->info.init = link->init;
 121     m->info.destroy = link->destroy;
 122     m->info.library = l;
 123     m->info.require_count = 0;
 124     m->info.use_count = 0;
 125     m->info.prerequisites_number = link->prerequisites_number;
 126   }
 127   return l;
 128 }
 129
 130
 131 static void library_remove(LttvLibrary *l)
 132 {
 133   LttvModule *m;
 134
 135   GPtrArray *modules;
 136   GPtrArray **modules_ptr = &modules; /* for strict aliasing */
 137   guint i;
 138
 139   char *key;
 140   char **key_ptr = &key; /* for strict aliasing */
 141
 142   for(i = 0 ; i < l->modules->len ; i++) {
 143     m = (LttvModule *)(l->modules->pdata[i]);
 144
 145     g_hash_table_lookup_extended(modules_by_name, m->info.name,
 146                                  (gpointer *)key_ptr, (gpointer *)modules_ptr);
 147     g_assert(modules != NULL);
 148     g_ptr_array_remove(modules, m);
 149     if(modules->len == 0) {
 150       g_hash_table_remove(modules_by_name, m->info.name);
 151       g_ptr_array_free(modules, TRUE);
 152       g_free(key);
 153     }
 154
 155     g_ptr_array_free(m->prerequisites, TRUE);
 156     g_free(m);
 157   }
 158
 159   g_ptr_array_remove(libraries, l);
 160   g_hash_table_remove(libraries_by_g_module, l->gm);
 161   g_ptr_array_free(l->modules, TRUE);
 162   g_free(l->info.name);
 163   g_free(l->info.path);
 164   g_free(l);
 165 }
 166
 167
 168 static LttvLibrary *library_load(char *name, GError **error)
 169 {
 170   GModule *gm = NULL;
 171
 172   int i, nb;
 173
 174   /* path is always initialized, checked */
 175   char *path = NULL, *pathname;
 176
 177   LttvLibrary *l;
 178
 179   GString *messages = g_string_new("");
 180
 181   /* insure that module.c is initialized */
 182
 183   init();
 184
 185   /* Try to find the library along all the user specified paths */
 186
 187   g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Load library %s", name);
 188   nb = lttv_library_path_number();
 189   for(i = 0 ; i <= nb ; i++) {
 190     if(i < nb) path = lttv_library_path_get(i);
 191     else path = NULL;
 192
 193     pathname = g_module_build_path(path ,name);
 194     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Try path %s", pathname);
 195     module_chain = NULL;
 196     module_next = &module_chain;
 197     gm = g_module_open(pathname,0);
 198     g_free(pathname);
 199
 200     if(gm != NULL) break;
 201
 202     g_string_append(messages, g_module_error());
 203     g_string_append(messages, "\n");
 204     g_log(G_LOG_DOMAIN,G_LOG_LEVEL_INFO,"Trial failed, %s", g_module_error());
 205   }
 206
 207   /* Module cannot be found */
 208
 209   if(gm == NULL) {
 210     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Failed to load %s", name);
 211     g_set_error(error, lttv_module_error, LTTV_MODULE_NOT_FOUND,
 212           "Cannot load library %s: %s", name, messages->str);
 213     g_string_free(messages, TRUE);
 214     return NULL;
 215   }
 216   g_string_free(messages, TRUE);
 217
 218   /* Check if the library was already loaded */
 219
 220   l = g_hash_table_lookup(libraries_by_g_module, gm);
 221
 222   /* This library was not already loaded */
 223
 224   if(l == NULL) {
 225     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Library %s (%s) loaded", name,
 226         g_module_name(gm));
 227     l = library_add(name, path, gm);
 228   }
 229   return l;
 230 }
 231
 232
 233 LttvLibrary *lttv_library_load(char *name, GError **error)
 234 {
 235   LttvLibrary *l = library_load(name, error);
 236   if(l != NULL) l->info.load_count++;
 237   return l;
 238 }
 239
 240
 241 static void library_unload(LttvLibrary *l)
 242 {
 243   guint i;
 244
 245   GModule *gm;
 246
 247   LttvModule *m;
 248
 249   if(l->locked_loaded > 0) {
 250     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Unload library %s: locked loaded",
 251         l->info.name);
 252     return;
 253   }
 254
 255   if(l->info.load_count > 0) {
 256     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Unload library %s: load count %d",
 257         l->info.name, l->info.load_count);
 258     return;
 259   }
 260
 261   /* Check if all its modules have been released */
 262
 263   for(i = 0 ; i < l->modules->len ; i++) {
 264     m = (LttvModule *)(l->modules->pdata[i]);
 265     if(m->info.use_count > 0) {
 266       g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO,"Unload library %s: module %s used",
 267            l->info.name, m->info.name);
 268       return;
 269     }
 270   }
 271
 272   g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Unload library %s: close the GModule",
 273        l->info.name);
 274   gm = l->gm;
 275   library_remove(l);
 276   if(gm != NULL) g_module_close(gm);
 277
 278   /* insure that module.c will be finalized */
 279
 280   finish_destroy();
 281 }
 282
 283
 284 void lttv_library_unload(LttvLibrary *l)
 285 {
 286   /* In the case where we wait for a module to release, the load count is 0
 287    * and should not be decremented. */
 288   if(l->info.load_count != 0) l->info.load_count--;
 289   library_unload(l);
 290 }
 291
 292
 293 static void library_lock_loaded(LttvLibrary *l)
 294 {
 295   l->locked_loaded++;
 296 }
 297
 298
 299 static void library_unlock_loaded(LttvLibrary *l)
 300 {
 301   l->locked_loaded--;
 302   library_unload(l);
 303 }
 304
 305
 306 static LttvModule *module_require(char *name, GError **error)
 307 {
 308   GError *tmp_error = NULL;
 309
 310   guint i, j;
 311
 312   LttvModule *m, *required;
 313
 314   LttvLibrary *l = NULL;
 315
 316   GPtrArray *modules;
 317
 318   /* Insure that module.c is initialized */
 319
 320   init();
 321
 322   /* Check if the module is already loaded */
 323
 324   modules = g_hash_table_lookup(modules_by_name, name);
 325
 326   /* Try to load a library having the module name */
 327
 328   if(modules == NULL) {
 329     l = library_load(name, error);
 330     if(l == NULL) return NULL;
 331     else library_lock_loaded(l);
 332
 333     /* A library was found, does it contain the named module */
 334
 335     modules = g_hash_table_lookup(modules_by_name, name);
 336     if(modules == NULL) {
 337       g_set_error(error, lttv_module_error, LTTV_MODULE_NOT_FOUND,
 338           "Module %s not found in library %s", name, l->info.name);
 339       library_unlock_loaded(l);
 340       return NULL;
 341     }
 342   }
 343   m = (LttvModule *)(modules->pdata[modules->len - 1]);
 344
 345   /* We have the module */
 346
 347   m->info.use_count++;
 348
 349   /* First use of the module. Initialize after getting the prerequisites */
 350
 351   if(m->info.use_count == 1) {
 352     for(i = 0 ; i < m->info.prerequisites_number ; i++) {
 353       required = module_require(m->prerequisites_names[i], &tmp_error);
 354
 355       /* A prerequisite could not be found, undo everything and fail */
 356
 357       if(required == NULL) {
 358         for(j = 0 ; j < m->prerequisites->len ; j++) {
 359           module_release((LttvModule *)(m->prerequisites->pdata[j]));
 360         }
 361         g_ptr_array_set_size(m->prerequisites, 0);
 362         if(l != NULL) library_unlock_loaded(l);
 363         g_set_error(error, lttv_module_error, LTTV_MODULE_NOT_FOUND,
 364             "Cannot find prerequisite for module %s: %s", name,
 365             tmp_error->message);
 366         g_clear_error(&tmp_error);
 367         return NULL;
 368       }
 369       g_ptr_array_add(m->prerequisites, required);
 370     }
 371     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Module %s: init()", m->info.name);
 372     m->info.init();
 373   }
 374
 375   /* Decrement the load count of the library. It will not really be
 376      unloaded since it contains a currently used module. */
 377
 378   if(l != NULL) library_unlock_loaded(l);
 379
 380   return(m);
 381 }
 382
 383
 384 /* The require_count for a module is the number of explicit calls to
 385    lttv_module_require, while the use_count also counts the number of times
 386    a module is needed as a prerequisite. */
 387
 388 LttvModule *lttv_module_require(char *name, GError **error)
 389 {
 390   LttvModule *m = module_require(name, error);
 391   if(m != NULL) m->info.require_count++;
 392   return(m);
 393 }
 394
 395
 396 static void module_release(LttvModule *m)
 397 {
 398   guint i;
 399
 400   library_lock_loaded(m->info.library);
 401
 402   m->info.use_count--;
 403   if(m->info.use_count == 0) {
 404     g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Module %s: destroy()",m->info.name);
 405     m->info.destroy();
 406     for(i = 0 ; i < m->prerequisites->len ; i++) {
 407       module_release((LttvModule *)(m->prerequisites->pdata[i]));
 408     }
 409     g_ptr_array_set_size(m->prerequisites, 0);
 410   }
 411   library_unlock_loaded(m->info.library);
 412 }
 413
 414
 415 void lttv_module_release(LttvModule *m)
 416 {
 417   m->info.require_count--;
 418   module_release(m);
 419 }
 420
 421
 422 void lttv_module_info(LttvModule *m, LttvModuleInfo *info)
 423 {
 424   *info = m->info;
 425 }
 426
 427
 428 unsigned lttv_module_prerequisite_number(LttvModule *m)
 429 {
 430   return m->prerequisites->len;
 431 }
 432
 433
 434 LttvModule *lttv_module_prerequisite_get(LttvModule *m, unsigned i)
 435 {
 436   return (LttvModule *)(m->prerequisites->pdata[i]);
 437 }
 438
 439
 440 void lttv_library_info(LttvLibrary *l, LttvLibraryInfo *info)
 441 {
 442   *info = l->info;
 443 }
 444
 445
 446 unsigned lttv_library_module_number(LttvLibrary *l)
 447 {
 448   return l->modules->len;
 449 }
 450
 451
 452 LttvModule *lttv_library_module_get(LttvLibrary *l, unsigned i)
 453 {
 454   return (LttvModule *)(l->modules->pdata[i]);
 455 }
 456
 457
 458 unsigned lttv_library_number()
 459 {
 460   return libraries->len;
 461 }
 462
 463
 464 LttvLibrary *lttv_library_get(unsigned i)
 465 {
 466   return (LttvLibrary *)(libraries->pdata[i]);
 467 }
 468
 469
 470 void lttv_library_path_add(const char *name)
 471 {
 472   g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Add library path %s", name);
 473   g_ptr_array_add(library_paths,(char*)g_strdup(name));
 474 }
 475
 476
 477 void lttv_library_path_remove(const char *name)
 478 {
 479   guint i;
 480
 481   for(i = 0 ; i < library_paths->len ; i++) {
 482     if(g_str_equal(name, library_paths->pdata[i])) {
 483       g_free(library_paths->pdata[i]);
 484       g_ptr_array_remove_index(library_paths,i);
 485       return;
 486     }
 487   }
 488 }
 489
 490
 491 unsigned lttv_library_path_number()
 492 {
 493   return library_paths->len;
 494 }
 495
 496
 497 char *lttv_library_path_get(unsigned i)
 498 {
 499   return (char *)(library_paths->pdata[library_paths->len - i - 1]);
 500 }
 501
 502
 503 void lttv_module_register(struct _LttvModuleDescription *d)
 504 {
 505   *module_next = d;
 506   module_next = &(d->next);
 507 }
 508
 509
 510 static void init()
 511 {
 512   if(initialized) return;
 513   g_assert(destroyed);
 514
 515   g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Init module.c");
 516
 517   initialized = TRUE;
 518   destroyed = FALSE;
 519   lttv_module_error = g_quark_from_string("LTTV_MODULE_ERROR");
 520   modules_by_name = g_hash_table_new(g_str_hash, g_str_equal);
 521   libraries = g_ptr_array_new();
 522   libraries_by_g_module = g_hash_table_new(g_direct_hash, g_direct_equal);
 523   library_paths = g_ptr_array_new();
 524
 525   if(builtin_chain == NULL) builtin_chain = module_chain;
 526   module_chain = builtin_chain;
 527   library_add("builtin", NULL, NULL);
 528 }
 529
 530
 531 static void finish_destroy()
 532 {
 533   guint i;
 534
 535   if(initialized) return;
 536   g_assert(!destroyed);
 537
 538   g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Finish destroy module.c");
 539   g_hash_table_destroy(modules_by_name);
 540   g_ptr_array_free(libraries, TRUE);
 541   g_hash_table_destroy(libraries_by_g_module);
 542   for(i = 0 ; i < library_paths->len ; i++) {
 543     g_free(library_paths->pdata[i]);
 544   }
 545   g_ptr_array_free(library_paths, TRUE);
 546   destroyed = TRUE;
 547 }
 548
 549
 550 static void destroy()
 551 {
 552   guint i, j, nb;
 553
 554   LttvLibrary *l, **locked_libraries;
 555
 556   LttvModule *m;
 557
 558   g_log(G_LOG_DOMAIN, G_LOG_LEVEL_INFO, "Destroy module.c");
 559
 560   /* Unload all libraries */
 561
 562   nb = libraries->len;
 563   locked_libraries = g_new(LttvLibrary *, nb);
 564
 565   for(i = 0 ; i < nb ; i++) {
 566     //g_assert(nb == libraries->len);
 567     l = (LttvLibrary *)(libraries->pdata[i]);
 568     locked_libraries[i] = l;
 569     library_lock_loaded(l);
 570     for(j = 0 ; j < l->modules->len ; j++) {
 571       m = (LttvModule *)(l->modules->pdata[j]);
 572       while(m->info.require_count > 0) lttv_module_release(m);
 573     }
 574     library_unlock_loaded(l);
 575     while(l->info.load_count > 0) lttv_library_unload(l);
 576
 577     /* If the number of librairies loaded have changed, restart from the
 578      * beginning */
 579     if(nb != libraries->len) {
 580       i = 0;
 581       nb = libraries->len;
 582     }
 583
 584   }
 585
 586   for(i = 0 ; i < nb ; i++) {
 587     l = locked_libraries[i];
 588     library_unlock_loaded(l);
 589   }
 590   g_free(locked_libraries);
 591
 592   /* The library containing module.c may be locked by our caller */
 593
 594   g_assert(libraries->len <= 1);
 595
 596   initialized = FALSE;
 597 }
 598
 599 LTTV_MODULE("module", "Modules in libraries",                         \
 600     "Load libraries, list, require and initialize contained modules", \
 601     init, destroy)
 602