src/surf/maxmin.c

   1 /*      $Id$     */
   2
   3 /* Copyright (c) 2004 Arnaud Legrand. All rights reserved.                  */
   4
   5 /* This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the license (GNU LGPL) which comes with this package. */
   7
   8
   9 #include "xbt/sysdep.h"
  10 #include "xbt/log.h"
  11 #include "xbt/mallocator.h"
  12 #include "maxmin_private.h"
  13 #include <stdlib.h>
  14 #include <stdio.h>              /* sprintf */
  15 #include <math.h>
  16 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_maxmin, surf,
  17                                 "Logging specific to SURF (maxmin)");
  18
  19 static void *lmm_variable_mallocator_new_f(void);
  20 static void lmm_variable_mallocator_free_f(void *var);
  21 static void lmm_variable_mallocator_reset_f(void *var);
  22 static void lmm_update_modified_set(lmm_system_t sys, lmm_constraint_t cnst);
  23 static void lmm_remove_all_modified_set(lmm_system_t sys);
  24 int sg_maxmin_selective_update = 1;
  25 static int Global_debug_id = 1;
  26 static int Global_const_debug_id = 1;
  27 lmm_system_t lmm_system_new(void)
  28 {
  29   lmm_system_t l = NULL;
  30   s_lmm_variable_t var;
  31   s_lmm_constraint_t cnst;
  32
  33   l = xbt_new0(s_lmm_system_t, 1);
  34
  35   l->modified = 0;
  36   l->selective_update_active = sg_maxmin_selective_update;
  37
  38   DEBUG1("Setting selective_update_active flag to %d\n",
  39          l->selective_update_active);
  40
  41   xbt_swag_init(&(l->variable_set),
  42                 xbt_swag_offset(var, variable_set_hookup));
  43   xbt_swag_init(&(l->constraint_set),
  44                 xbt_swag_offset(cnst, constraint_set_hookup));
  45
  46   xbt_swag_init(&(l->active_constraint_set),
  47                 xbt_swag_offset(cnst, active_constraint_set_hookup));
  48
  49   xbt_swag_init(&(l->modified_constraint_set),
  50                 xbt_swag_offset(cnst, modified_constraint_set_hookup));
  51   xbt_swag_init(&(l->saturated_variable_set),
  52                 xbt_swag_offset(var, saturated_variable_set_hookup));
  53   xbt_swag_init(&(l->saturated_constraint_set),
  54                 xbt_swag_offset(cnst, saturated_constraint_set_hookup));
  55
  56   l->variable_mallocator = xbt_mallocator_new(64,
  57                                               lmm_variable_mallocator_new_f,
  58                                               lmm_variable_mallocator_free_f,
  59                                               lmm_variable_mallocator_reset_f);
  60
  61   return l;
  62 }
  63
  64 void lmm_system_free(lmm_system_t sys)
  65 {
  66   lmm_variable_t var = NULL;
  67   lmm_constraint_t cnst = NULL;
  68
  69   while ((var = extract_variable(sys))) {
  70     WARN2("Variable %p (%d) still in LMM system when freing it: this may be a bug",
  71         var,var->id_int);
  72     lmm_var_free(sys, var);
  73   }
  74
  75   while ((cnst = extract_constraint(sys)))
  76     lmm_cnst_free(sys, cnst);
  77
  78   xbt_mallocator_free(sys->variable_mallocator);
  79   free(sys);
  80 }
  81
  82 XBT_INLINE void lmm_variable_disable(lmm_system_t sys, lmm_variable_t var)
  83 {
  84   int i;
  85   lmm_element_t elem = NULL;
  86
  87   XBT_IN2("(sys=%p, var=%p)", sys, var);
  88   sys->modified = 1;
  89
  90   for (i = 0; i < var->cnsts_number; i++) {
  91     elem = &var->cnsts[i];
  92     xbt_swag_remove(elem, &(elem->constraint->element_set));
  93     xbt_swag_remove(elem, &(elem->constraint->active_element_set));
  94     if (!xbt_swag_size(&(elem->constraint->element_set)))
  95       make_constraint_inactive(sys, elem->constraint);
  96     else
  97       lmm_update_modified_set(sys, elem->constraint);
  98   }
  99   var->cnsts_number = 0;
 100   XBT_OUT;
 101 }
 102
 103 static void lmm_var_free(lmm_system_t sys, lmm_variable_t var)
 104 {
 105
 106   lmm_variable_disable(sys, var);
 107   free(var->cnsts);
 108   xbt_mallocator_release(sys->variable_mallocator, var);
 109 }
 110
 111 static XBT_INLINE void lmm_cnst_free(lmm_system_t sys, lmm_constraint_t cnst)
 112 {
 113 /*   xbt_assert0(xbt_swag_size(&(cnst->element_set)), */
 114 /*            "This list should be empty!"); */
 115   remove_active_constraint(sys, cnst);
 116   free(cnst);
 117 }
 118
 119 lmm_constraint_t lmm_constraint_new(lmm_system_t sys, void *id,
 120                                     double bound_value)
 121 {
 122   lmm_constraint_t cnst = NULL;
 123   s_lmm_element_t elem;
 124
 125   cnst = xbt_new0(s_lmm_constraint_t, 1);
 126   cnst->id = id;
 127   cnst->id_int = Global_const_debug_id++;
 128   xbt_swag_init(&(cnst->element_set),
 129                 xbt_swag_offset(elem, element_set_hookup));
 130   xbt_swag_init(&(cnst->active_element_set),
 131                 xbt_swag_offset(elem, active_element_set_hookup));
 132
 133   cnst->bound = bound_value;
 134   cnst->usage = 0;
 135   cnst->shared = 1;
 136   insert_constraint(sys, cnst);
 137
 138   return cnst;
 139 }
 140
 141 XBT_INLINE void lmm_constraint_shared(lmm_constraint_t cnst)
 142 {
 143   cnst->shared = 0;
 144 }
 145
 146 XBT_INLINE int lmm_constraint_is_shared(lmm_constraint_t cnst)
 147 {
 148   return (cnst->shared);
 149 }
 150
 151 XBT_INLINE void lmm_constraint_free(lmm_system_t sys, lmm_constraint_t cnst)
 152 {
 153   remove_constraint(sys, cnst);
 154   lmm_cnst_free(sys, cnst);
 155 }
 156
 157 static void *lmm_variable_mallocator_new_f(void)
 158 {
 159   return xbt_new(s_lmm_variable_t, 1);
 160 }
 161
 162 static void lmm_variable_mallocator_free_f(void *var)
 163 {
 164   xbt_free(var);
 165 }
 166
 167 static void lmm_variable_mallocator_reset_f(void *var)
 168 {
 169   /* memset to zero like calloc */
 170   memset(var, 0, sizeof(s_lmm_variable_t));
 171 }
 172
 173 lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
 174                                 double weight,
 175                                 double bound, int number_of_constraints)
 176 {
 177   lmm_variable_t var = NULL;
 178   int i;
 179
 180   XBT_IN5("(sys=%p, id=%p, weight=%f, bound=%f, num_cons =%d)",
 181           sys, id, weight, bound, number_of_constraints);
 182
 183   var = xbt_mallocator_get(sys->variable_mallocator);
 184   var->id = id;
 185   var->id_int = Global_debug_id++;
 186   var->cnsts = xbt_new0(s_lmm_element_t, number_of_constraints);
 187   for (i = 0; i < number_of_constraints; i++) {
 188     /* Should be useless because of the
 189        calloc but it seems to help valgrind... */
 190     var->cnsts[i].element_set_hookup.next = NULL;
 191     var->cnsts[i].element_set_hookup.prev = NULL;
 192     var->cnsts[i].active_element_set_hookup.next = NULL;
 193     var->cnsts[i].active_element_set_hookup.prev = NULL;
 194     var->cnsts[i].constraint = NULL;
 195     var->cnsts[i].variable = NULL;
 196     var->cnsts[i].value = 0.0;
 197   }
 198   var->cnsts_size = number_of_constraints;
 199   var->cnsts_number = 0;        /* Should be useless because of the
 200                                    calloc but it seems to help valgrind... */
 201   var->weight = weight;
 202   var->bound = bound;
 203   var->value = 0.0;
 204
 205
 206   var->func_f = func_f_def;
 207   var->func_fp = func_fp_def;
 208   var->func_fpi = func_fpi_def;
 209
 210   if (weight)
 211     xbt_swag_insert_at_head(var, &(sys->variable_set));
 212   else
 213     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 214   XBT_OUT;
 215   return var;
 216 }
 217
 218 void lmm_variable_free(lmm_system_t sys, lmm_variable_t var)
 219 {
 220   remove_variable(sys, var);
 221   lmm_var_free(sys, var);
 222 }
 223
 224 XBT_INLINE double lmm_variable_getvalue(lmm_variable_t var)
 225 {
 226   return (var->value);
 227 }
 228
 229 XBT_INLINE double lmm_variable_getbound(lmm_variable_t var)
 230 {
 231   return (var->bound);
 232 }
 233
 234 void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
 235                 lmm_variable_t var, double value)
 236 {
 237   lmm_element_t elem = NULL;
 238
 239   sys->modified = 1;
 240
 241   xbt_assert0(var->cnsts_number < var->cnsts_size, "Too much constraints");
 242
 243   elem = &(var->cnsts[var->cnsts_number++]);
 244
 245   elem->value = value;
 246   elem->constraint = cnst;
 247   elem->variable = var;
 248
 249   if (var->weight)
 250     xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 251   else
 252     xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 253
 254   make_constraint_active(sys, cnst);
 255   lmm_update_modified_set(sys, cnst);
 256 }
 257
 258 void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
 259                     lmm_variable_t var, double value)
 260 {
 261   int i;
 262   sys->modified = 1;
 263
 264   for (i = 0; i < var->cnsts_number; i++)
 265     if (var->cnsts[i].constraint == cnst)
 266       break;
 267
 268   if (i < var->cnsts_number) {
 269     if (cnst->shared)
 270       var->cnsts[i].value += value;
 271     else
 272       var->cnsts[i].value = MAX(var->cnsts[i].value, value);
 273     lmm_update_modified_set(sys, cnst);
 274   } else
 275     lmm_expand(sys, cnst, var, value);
 276 }
 277
 278 void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
 279                         lmm_variable_t var, double value)
 280 {
 281   int i;
 282
 283   for (i = 0; i < var->cnsts_number; i++)
 284     if (var->cnsts[i].constraint == cnst)
 285       break;
 286
 287   if (i < var->cnsts_number) {
 288     var->cnsts[i].value = value;
 289     sys->modified = 1;
 290     lmm_update_modified_set(sys, cnst);
 291   } else
 292     DIE_IMPOSSIBLE;
 293 }
 294
 295 XBT_INLINE lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
 296                                        lmm_variable_t var, int num)
 297 {
 298   if (num < var->cnsts_number)
 299     return (var->cnsts[num].constraint);
 300   else
 301     return NULL;
 302 }
 303
 304 XBT_INLINE int lmm_get_number_of_cnst_from_var(lmm_system_t sys, lmm_variable_t var)
 305 {
 306   return (var->cnsts_number);
 307 }
 308
 309 lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys,
 310                                      lmm_constraint_t cnst,
 311                                      lmm_element_t * elem)
 312 {
 313   if (!(*elem))
 314     *elem = xbt_swag_getFirst(&(cnst->element_set));
 315   else
 316     *elem = xbt_swag_getNext(*elem, cnst->element_set.offset);
 317   if (*elem)
 318     return (*elem)->variable;
 319   else
 320     return NULL;
 321 }
 322
 323 XBT_INLINE void *lmm_constraint_id(lmm_constraint_t cnst)
 324 {
 325   return cnst->id;
 326 }
 327
 328 XBT_INLINE void *lmm_variable_id(lmm_variable_t var)
 329 {
 330   return var->id;
 331 }
 332
 333 static XBT_INLINE void saturated_constraint_set_update(lmm_system_t sys,
 334                                             lmm_constraint_t cnst,
 335                                             double *min_usage)
 336 {
 337   lmm_constraint_t useless_cnst = NULL;
 338
 339   XBT_IN3("sys=%p, cnst=%p, min_usage=%f", sys, cnst, *min_usage);
 340   if (cnst->usage <= 0) {
 341     XBT_OUT;
 342     return;
 343   }
 344   if (cnst->remaining <= 0) {
 345     XBT_OUT;
 346     return;
 347   }
 348   if ((*min_usage < 0) || (*min_usage > cnst->remaining / cnst->usage)) {
 349     *min_usage = cnst->remaining / cnst->usage;
 350     LOG3(xbt_log_priority_trace,
 351          "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)", *min_usage,
 352          cnst->remaining, cnst->usage);
 353     while ((useless_cnst =
 354             xbt_swag_getFirst(&(sys->saturated_constraint_set))))
 355       xbt_swag_remove(useless_cnst, &(sys->saturated_constraint_set));
 356
 357     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 358   } else if (*min_usage == cnst->remaining / cnst->usage) {
 359     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 360   }
 361   XBT_OUT;
 362 }
 363
 364 static XBT_INLINE void saturated_variable_set_update(lmm_system_t sys)
 365 {
 366   lmm_constraint_t cnst = NULL;
 367   xbt_swag_t cnst_list = NULL;
 368   lmm_element_t elem = NULL;
 369   xbt_swag_t elem_list = NULL;
 370
 371   cnst_list = &(sys->saturated_constraint_set);
 372   while ((cnst = xbt_swag_getFirst(cnst_list))) {
 373     elem_list = &(cnst->active_element_set);
 374     xbt_swag_foreach(elem, elem_list) {
 375       if (elem->variable->weight <= 0)
 376         break;
 377       if ((elem->value > 0))
 378         xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
 379     }
 380     xbt_swag_remove(cnst, cnst_list);
 381   }
 382 }
 383
 384 void lmm_print(lmm_system_t sys)
 385 {
 386   lmm_constraint_t cnst = NULL;
 387   lmm_element_t elem = NULL;
 388   lmm_variable_t var = NULL;
 389   xbt_swag_t cnst_list = NULL;
 390   xbt_swag_t var_list = NULL;
 391   xbt_swag_t elem_list = NULL;
 392   char print_buf[1024];
 393   char *trace_buf = xbt_malloc0(sizeof(char));
 394   double sum = 0.0;
 395
 396   /* Printing Objective */
 397   var_list = &(sys->variable_set);
 398   sprintf(print_buf, "MAX-MIN ( ");
 399   trace_buf =
 400     xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 401   strcat(trace_buf, print_buf);
 402   xbt_swag_foreach(var, var_list) {
 403     sprintf(print_buf, "'%d'(%f) ", var->id_int, var->weight);
 404     trace_buf =
 405       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 406     strcat(trace_buf, print_buf);
 407   }
 408   sprintf(print_buf, ")");
 409   trace_buf =
 410     xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 411   strcat(trace_buf, print_buf);
 412   fprintf(stderr, "%s", trace_buf);
 413   //DEBUG1("%20s", trace_buf); FIXME
 414   trace_buf[0] = '\000';
 415
 416   DEBUG0("Constraints");
 417   /* Printing Constraints */
 418   cnst_list = &(sys->active_constraint_set);
 419   xbt_swag_foreach(cnst, cnst_list) {
 420     sum = 0.0;
 421     elem_list = &(cnst->element_set);
 422     sprintf(print_buf, "\t");
 423     trace_buf =
 424       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 425     strcat(trace_buf, print_buf);
 426     xbt_swag_foreach(elem, elem_list) {
 427       sprintf(print_buf, "%f.'%d'(%f) + ", elem->value,
 428               elem->variable->id_int, elem->variable->value);
 429       trace_buf =
 430         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 431       strcat(trace_buf, print_buf);
 432       sum += elem->value * elem->variable->value;
 433     }
 434     sprintf(print_buf, "0 <= %f ('%d')", cnst->bound, cnst->id_int);
 435     trace_buf =
 436       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 437     strcat(trace_buf, print_buf);
 438
 439     if (!cnst->shared) {
 440       sprintf(print_buf, " [MAX-Constraint]");
 441       trace_buf =
 442         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 443       strcat(trace_buf, print_buf);
 444     }
 445     //   DEBUG1("%s", trace_buf);
 446     fprintf(stderr, "%s", trace_buf);
 447     trace_buf[0] = '\000';
 448     xbt_assert3(!double_positive(sum - cnst->bound),
 449                 "Incorrect value (%f is not smaller than %f): %g",
 450                 sum, cnst->bound, sum - cnst->bound);
 451   }
 452
 453   DEBUG0("Variables");
 454   /* Printing Result */
 455   xbt_swag_foreach(var, var_list) {
 456     if (var->bound > 0) {
 457       DEBUG4("'%d'(%f) : %f (<=%f)", var->id_int, var->weight, var->value,
 458              var->bound);
 459       xbt_assert2(!double_positive(var->value - var->bound),
 460                   "Incorrect value (%f is not smaller than %f",
 461                   var->value, var->bound);
 462     } else {
 463       DEBUG3("'%d'(%f) : %f", var->id_int, var->weight, var->value);
 464     }
 465   }
 466
 467   free(trace_buf);
 468 }
 469
 470 void lmm_solve(lmm_system_t sys)
 471 {
 472   lmm_variable_t var = NULL;
 473   lmm_constraint_t cnst = NULL;
 474   lmm_element_t elem = NULL;
 475   xbt_swag_t cnst_list = NULL;
 476   xbt_swag_t var_list = NULL;
 477   xbt_swag_t elem_list = NULL;
 478   double min_usage = -1;
 479   double min_bound = -1;
 480
 481   if (!(sys->modified))
 482     return;
 483
 484   /*
 485    * Compute Usage and store the variables that reach the maximum.
 486    */
 487   cnst_list = sys->selective_update_active ? &(sys->modified_constraint_set) :
 488     &(sys->active_constraint_set);
 489
 490   DEBUG1("Active constraints : %d", xbt_swag_size(cnst_list));
 491   /* Init: Only modified code portions */
 492   xbt_swag_foreach(cnst, cnst_list) {
 493     elem_list = &(cnst->element_set);
 494     //DEBUG1("Variable set : %d", xbt_swag_size(elem_list));
 495     xbt_swag_foreach(elem, elem_list) {
 496       var = elem->variable;
 497       if (var->weight <= 0.0)
 498         break;
 499       var->value = 0.0;
 500     }
 501   }
 502
 503   DEBUG1("Active constraints : %d", xbt_swag_size(cnst_list));
 504   xbt_swag_foreach(cnst, cnst_list) {
 505     /* INIT */
 506     cnst->remaining = cnst->bound;
 507     if (cnst->remaining == 0)
 508       continue;
 509     cnst->usage = 0;
 510     elem_list = &(cnst->element_set);
 511     xbt_swag_foreach(elem, elem_list) {
 512       /* 0-weighted elements (ie, sleep actions) are at the end of the swag and we don't want to consider them */
 513       if (elem->variable->weight <= 0)
 514         break;
 515       if ((elem->value > 0)) {
 516         if (cnst->shared)
 517           cnst->usage += elem->value / elem->variable->weight;
 518         else if (cnst->usage < elem->value / elem->variable->weight)
 519           cnst->usage = elem->value / elem->variable->weight;
 520
 521         make_elem_active(elem);
 522       }
 523     }
 524     DEBUG2("Constraint Usage %d : %f", cnst->id_int, cnst->usage);
 525     /* Saturated constraints update */
 526     saturated_constraint_set_update(sys, cnst, &min_usage);
 527   }
 528   saturated_variable_set_update(sys);
 529
 530   /* Saturated variables update */
 531
 532   do {
 533     /* Fix the variables that have to be */
 534     var_list = &(sys->saturated_variable_set);
 535
 536     xbt_swag_foreach(var, var_list) {
 537       if (var->weight <= 0.0)
 538         DIE_IMPOSSIBLE;
 539       /* First check if some of these variables have reach their upper
 540          bound and update min_usage accordingly. */
 541       DEBUG5
 542         ("var=%d, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
 543          var->id_int, var->bound, var->weight, min_usage,
 544          var->bound * var->weight);
 545       if ((var->bound > 0) && (var->bound * var->weight < min_usage)) {
 546         if (min_bound < 0)
 547           min_bound = var->bound;
 548         else
 549           min_bound = MIN(min_bound, var->bound);
 550         DEBUG1("Updated min_bound=%f", min_bound);
 551       }
 552     }
 553
 554
 555     while ((var = xbt_swag_getFirst(var_list))) {
 556       int i;
 557
 558       if (min_bound < 0) {
 559         var->value = min_usage / var->weight;
 560       } else {
 561         if (min_bound == var->bound)
 562           var->value = var->bound;
 563         else {
 564           xbt_swag_remove(var, var_list);
 565           continue;
 566         }
 567       }
 568       DEBUG5("Min usage: %f, Var(%d)->weight: %f, Var(%d)->value: %f ",
 569              min_usage, var->id_int, var->weight, var->id_int, var->value);
 570
 571
 572       /* Update usage */
 573
 574       for (i = 0; i < var->cnsts_number; i++) {
 575         elem = &var->cnsts[i];
 576         cnst = elem->constraint;
 577         if (cnst->shared) {
 578           double_update(&(cnst->remaining), elem->value * var->value);
 579           double_update(&(cnst->usage), elem->value / var->weight);
 580           make_elem_inactive(elem);
 581         } else {                /* FIXME one day: We recompute usage.... :( */
 582           cnst->usage = 0.0;
 583           make_elem_inactive(elem);
 584           elem_list = &(cnst->element_set);
 585           xbt_swag_foreach(elem, elem_list) {
 586             if (elem->variable->weight <= 0)
 587               break;
 588             if (elem->variable->value > 0)
 589               break;
 590             if ((elem->value > 0)) {
 591               cnst->usage=MAX(cnst->usage,elem->value / elem->variable->weight);
 592               DEBUG2("Constraint Usage %d : %f", cnst->id_int, cnst->usage);
 593               make_elem_active(elem);
 594             }
 595           }
 596         }
 597       }
 598       xbt_swag_remove(var, var_list);
 599     }
 600
 601     /* Find out which variables reach the maximum */
 602     cnst_list =
 603       sys->selective_update_active ? &(sys->modified_constraint_set) :
 604       &(sys->active_constraint_set);
 605     min_usage = -1;
 606     min_bound = -1;
 607     xbt_swag_foreach(cnst, cnst_list) {
 608       saturated_constraint_set_update(sys, cnst, &min_usage);
 609     }
 610     saturated_variable_set_update(sys);
 611
 612   } while (xbt_swag_size(&(sys->saturated_variable_set)));
 613
 614   sys->modified = 0;
 615   if (sys->selective_update_active)
 616     lmm_remove_all_modified_set(sys);
 617
 618   if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
 619     lmm_print(sys);
 620   }
 621 }
 622
 623 /* Not a O(1) function */
 624
 625 void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
 626                 lmm_variable_t var, double value)
 627 {
 628   int i;
 629
 630   for (i = 0; i < var->cnsts_number; i++)
 631     if (var->cnsts[i].constraint == cnst) {
 632       var->cnsts[i].value = value;
 633       sys->modified = 1;
 634       lmm_update_modified_set(sys, cnst);
 635       return;
 636     }
 637 }
 638
 639 /** \brief Attribute the value bound to var->bound.
 640  *
 641  *  \param sys the lmm_system_t
 642  *  \param var the lmm_variable_t
 643  *  \param bound the new bound to associate with var
 644  *
 645  *  Makes var->bound equal to bound. Whenever this function is called
 646  *  a change is  signed in the system. To
 647  *  avoid false system changing detection it is a good idea to test
 648  *  (bound != 0) before calling it.
 649  *
 650  */
 651 void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
 652                                double bound)
 653 {
 654   int i;
 655
 656   sys->modified = 1;
 657   var->bound = bound;
 658
 659   for (i = 0; i < var->cnsts_number; i++)
 660     lmm_update_modified_set(sys, var->cnsts[i].constraint);
 661
 662 }
 663
 664
 665 void lmm_update_variable_weight(lmm_system_t sys, lmm_variable_t var,
 666                                 double weight)
 667 {
 668   int i;
 669   lmm_element_t elem;
 670
 671   if (weight == var->weight)
 672     return;
 673   XBT_IN3("(sys=%p, var=%p, weight=%f)", sys, var, weight);
 674   sys->modified = 1;
 675   var->weight = weight;
 676   xbt_swag_remove(var, &(sys->variable_set));
 677   if (weight)
 678     xbt_swag_insert_at_head(var, &(sys->variable_set));
 679   else
 680     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 681
 682   for (i = 0; i < var->cnsts_number; i++) {
 683     elem = &var->cnsts[i];
 684     xbt_swag_remove(elem, &(elem->constraint->element_set));
 685     if (weight)
 686       xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 687     else
 688       xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 689
 690     lmm_update_modified_set(sys, elem->constraint);
 691   }
 692   if (!weight)
 693     var->value = 0.0;
 694
 695   XBT_OUT;
 696 }
 697
 698 XBT_INLINE double lmm_get_variable_weight(lmm_variable_t var)
 699 {
 700   return var->weight;
 701 }
 702
 703 XBT_INLINE void lmm_update_constraint_bound(lmm_system_t sys, lmm_constraint_t cnst,
 704                                  double bound)
 705 {
 706   sys->modified = 1;
 707   lmm_update_modified_set(sys, cnst);
 708   cnst->bound = bound;
 709 }
 710
 711 XBT_INLINE int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst)
 712 {
 713   return xbt_swag_belongs(cnst, &(sys->active_constraint_set));
 714 }
 715
 716 XBT_INLINE lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t sys)
 717 {
 718   return xbt_swag_getFirst(&(sys->active_constraint_set));
 719 }
 720
 721 XBT_INLINE lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t sys,
 722                                                 lmm_constraint_t cnst)
 723 {
 724   return xbt_swag_getNext(cnst, (sys->active_constraint_set).offset);
 725 }
 726
 727 /** \brief Update the constraint set propagating recursively to
 728  *  other constraints so the system should not be entirely computed.
 729  *
 730  *  \param sys the lmm_system_t
 731  *  \param cnst the lmm_constraint_t affected by the change
 732  *
 733  *  A recursive algorithm to optimize the system recalculation selecting only
 734  *  constraints that have changed. Each constraint change is propagated
 735  *  to the list of constraints for each variable.
 736  */
 737 static void lmm_update_modified_set(lmm_system_t sys, lmm_constraint_t cnst)
 738 {
 739   lmm_element_t elem = NULL;
 740   lmm_variable_t var = NULL;
 741   xbt_swag_t elem_list = NULL;
 742   int i;
 743
 744   /* return if selective update isn't active */
 745   if (!sys->selective_update_active)
 746     return;
 747
 748   //DEBUG1("Updating modified constraint set with constraint %d", cnst->id_int);
 749
 750   if (xbt_swag_belongs(cnst, &(sys->modified_constraint_set)))
 751     return;
 752
 753   //DEBUG1("Inserting into modified constraint set %d", cnst->id_int);
 754
 755   /* add to modified set */
 756   xbt_swag_insert(cnst, &(sys->modified_constraint_set));
 757
 758   elem_list = &(cnst->element_set);
 759   xbt_swag_foreach(elem, elem_list) {
 760     var = elem->variable;
 761     for (i = 0; i < var->cnsts_number; i++)
 762       if (cnst != var->cnsts[i].constraint) {
 763         //DEBUG2("Updating modified %d calling for %d", cnst->id_int, var->cnsts[i].constraint->id_int);
 764         lmm_update_modified_set(sys, var->cnsts[i].constraint);
 765       }
 766   }
 767 }
 768
 769 /** \brief Remove all constraints of the modified_constraint_set.
 770  *
 771  *  \param sys the lmm_system_t
 772  */
 773 static void lmm_remove_all_modified_set(lmm_system_t sys)
 774 {
 775   lmm_element_t elem = NULL;
 776   lmm_element_t elem_next = NULL;
 777   xbt_swag_t elem_list = NULL;
 778
 779   elem_list = &(sys->modified_constraint_set);
 780   xbt_swag_foreach_safe(elem, elem_next, elem_list) {
 781     xbt_swag_remove(elem, elem_list);
 782   }
 783 }