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 = 0;
  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     lmm_var_free(sys, var);
  71
  72   while ((cnst = extract_constraint(sys)))
  73     lmm_cnst_free(sys, cnst);
  74
  75   xbt_mallocator_free(sys->variable_mallocator);
  76   free(sys);
  77 }
  78
  79 void lmm_variable_disable(lmm_system_t sys, lmm_variable_t var)
  80 {
  81   int i;
  82   lmm_element_t elem = NULL;
  83
  84   XBT_IN2("(sys=%p, var=%p)", sys, var);
  85   sys->modified = 1;
  86
  87   for (i = 0; i < var->cnsts_number; i++) {
  88     elem = &var->cnsts[i];
  89     xbt_swag_remove(elem, &(elem->constraint->element_set));
  90     xbt_swag_remove(elem, &(elem->constraint->active_element_set));
  91     if (!xbt_swag_size(&(elem->constraint->element_set)))
  92       make_constraint_inactive(sys, elem->constraint);
  93     else
  94       lmm_update_modified_set(sys, elem->constraint);
  95   }
  96   var->cnsts_number = 0;
  97   XBT_OUT;
  98 }
  99
 100 static void lmm_var_free(lmm_system_t sys, lmm_variable_t var)
 101 {
 102
 103   lmm_variable_disable(sys, var);
 104   free(var->cnsts);
 105   xbt_mallocator_release(sys->variable_mallocator, var);
 106 }
 107
 108 static void lmm_cnst_free(lmm_system_t sys, lmm_constraint_t cnst)
 109 {
 110 /*   xbt_assert0(xbt_swag_size(&(cnst->element_set)), */
 111 /*            "This list should be empty!"); */
 112   remove_active_constraint(sys, cnst);
 113   free(cnst);
 114 }
 115
 116 lmm_constraint_t lmm_constraint_new(lmm_system_t sys, void *id,
 117                                     double bound_value)
 118 {
 119   lmm_constraint_t cnst = NULL;
 120   s_lmm_element_t elem;
 121
 122   cnst = xbt_new0(s_lmm_constraint_t, 1);
 123   cnst->id = id;
 124   cnst->id_int = Global_const_debug_id++;
 125   xbt_swag_init(&(cnst->element_set),
 126                 xbt_swag_offset(elem, element_set_hookup));
 127   xbt_swag_init(&(cnst->active_element_set),
 128                 xbt_swag_offset(elem, active_element_set_hookup));
 129
 130   cnst->bound = bound_value;
 131   cnst->usage = 0;
 132   cnst->shared = 1;
 133   insert_constraint(sys, cnst);
 134
 135   return cnst;
 136 }
 137
 138 void lmm_constraint_shared(lmm_constraint_t cnst)
 139 {
 140   cnst->shared = 0;
 141 }
 142
 143 int lmm_constraint_is_shared(lmm_constraint_t cnst)
 144 {
 145   return (cnst->shared);
 146 }
 147
 148 void lmm_constraint_free(lmm_system_t sys, lmm_constraint_t cnst)
 149 {
 150   remove_constraint(sys, cnst);
 151   lmm_cnst_free(sys, cnst);
 152 }
 153
 154 static void *lmm_variable_mallocator_new_f(void)
 155 {
 156   return xbt_new(s_lmm_variable_t, 1);
 157 }
 158
 159 static void lmm_variable_mallocator_free_f(void *var)
 160 {
 161   xbt_free(var);
 162 }
 163
 164 static void lmm_variable_mallocator_reset_f(void *var)
 165 {
 166   /* memset to zero like calloc */
 167   memset(var, 0, sizeof(s_lmm_variable_t));
 168 }
 169
 170 lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
 171                                 double weight,
 172                                 double bound, int number_of_constraints)
 173 {
 174   lmm_variable_t var = NULL;
 175   int i;
 176
 177   XBT_IN5("(sys=%p, id=%p, weight=%f, bound=%f, num_cons =%d)",
 178           sys, id, weight, bound, number_of_constraints);
 179
 180   var = xbt_mallocator_get(sys->variable_mallocator);
 181   var->id = id;
 182   var->id_int = Global_debug_id++;
 183   var->cnsts = xbt_new0(s_lmm_element_t, number_of_constraints);
 184   for (i = 0; i < number_of_constraints; i++) {
 185     /* Should be useless because of the
 186        calloc but it seems to help valgrind... */
 187     var->cnsts[i].element_set_hookup.next = NULL;
 188     var->cnsts[i].element_set_hookup.prev = NULL;
 189     var->cnsts[i].active_element_set_hookup.next = NULL;
 190     var->cnsts[i].active_element_set_hookup.prev = NULL;
 191     var->cnsts[i].constraint = NULL;
 192     var->cnsts[i].variable = NULL;
 193     var->cnsts[i].value = 0.0;
 194   }
 195   var->cnsts_size = number_of_constraints;
 196   var->cnsts_number = 0;        /* Should be useless because of the
 197                                    calloc but it seems to help valgrind... */
 198   var->weight = weight;
 199   var->bound = bound;
 200   var->value = 0.0;
 201
 202
 203   var->func_f = func_f_def;
 204   var->func_fp = func_fp_def;
 205   var->func_fpi = func_fpi_def;
 206
 207   if (weight)
 208     xbt_swag_insert_at_head(var, &(sys->variable_set));
 209   else
 210     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 211   XBT_OUT;
 212   return var;
 213 }
 214
 215 void lmm_variable_free(lmm_system_t sys, lmm_variable_t var)
 216 {
 217   remove_variable(sys, var);
 218   lmm_var_free(sys, var);
 219 }
 220
 221 double lmm_variable_getvalue(lmm_variable_t var)
 222 {
 223   return (var->value);
 224 }
 225
 226 double lmm_variable_getbound(lmm_variable_t var)
 227 {
 228   return (var->bound);
 229 }
 230
 231 void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
 232                 lmm_variable_t var, double value)
 233 {
 234   lmm_element_t elem = NULL;
 235
 236   sys->modified = 1;
 237
 238   xbt_assert0(var->cnsts_number < var->cnsts_size, "Too much constraints");
 239
 240   elem = &(var->cnsts[var->cnsts_number++]);
 241
 242   elem->value = value;
 243   elem->constraint = cnst;
 244   elem->variable = var;
 245
 246   if (var->weight)
 247     xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 248   else
 249     xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 250
 251   make_constraint_active(sys, cnst);
 252   lmm_update_modified_set(sys, cnst);
 253 }
 254
 255 void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
 256                     lmm_variable_t var, double value)
 257 {
 258   int i;
 259   sys->modified = 1;
 260
 261   for (i = 0; i < var->cnsts_number; i++)
 262     if (var->cnsts[i].constraint == cnst)
 263       break;
 264
 265   if (i < var->cnsts_number) {
 266     if (cnst->shared)
 267       var->cnsts[i].value += value;
 268     else
 269       var->cnsts[i].value = MAX(var->cnsts[i].value, value);
 270     lmm_update_modified_set(sys, cnst);
 271   } else
 272     lmm_expand(sys, cnst, var, value);
 273 }
 274
 275 void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
 276                         lmm_variable_t var, double value)
 277 {
 278   int i;
 279
 280   for (i = 0; i < var->cnsts_number; i++)
 281     if (var->cnsts[i].constraint == cnst)
 282       break;
 283
 284   if (i < var->cnsts_number) {
 285     var->cnsts[i].value = value;
 286     sys->modified = 1;
 287     lmm_update_modified_set(sys, cnst);
 288   } else
 289     DIE_IMPOSSIBLE;
 290 }
 291
 292 lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
 293                                        lmm_variable_t var, int num)
 294 {
 295   if (num < var->cnsts_number)
 296     return (var->cnsts[num].constraint);
 297   else
 298     return NULL;
 299 }
 300
 301 int lmm_get_number_of_cnst_from_var(lmm_system_t sys, lmm_variable_t var)
 302 {
 303   return (var->cnsts_number);
 304 }
 305
 306 lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys,
 307                                      lmm_constraint_t cnst,
 308                                      lmm_element_t * elem)
 309 {
 310   if (!(*elem))
 311     *elem = xbt_swag_getFirst(&(cnst->element_set));
 312   else
 313     *elem = xbt_swag_getNext(*elem, cnst->element_set.offset);
 314   if (*elem)
 315     return (*elem)->variable;
 316   else
 317     return NULL;
 318 }
 319
 320 void *lmm_constraint_id(lmm_constraint_t cnst)
 321 {
 322   return cnst->id;
 323 }
 324
 325 void *lmm_variable_id(lmm_variable_t var)
 326 {
 327   return var->id;
 328 }
 329
 330 static void saturated_constraint_set_update(lmm_system_t sys,
 331                                             lmm_constraint_t cnst,
 332                                             double *min_usage)
 333 {
 334   lmm_constraint_t useless_cnst = NULL;
 335
 336   XBT_IN3("sys=%p, cnst=%p, min_usage=%f", sys, cnst, *min_usage);
 337   if (cnst->usage <= 0) {
 338     XBT_OUT;
 339     return;
 340   }
 341   if (cnst->remaining <= 0) {
 342     XBT_OUT;
 343     return;
 344   }
 345   if ((*min_usage < 0) || (*min_usage > cnst->remaining / cnst->usage)) {
 346     *min_usage = cnst->remaining / cnst->usage;
 347     LOG3(xbt_log_priority_trace,
 348          "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)", *min_usage,
 349          cnst->remaining, cnst->usage);
 350     while ((useless_cnst =
 351             xbt_swag_getFirst(&(sys->saturated_constraint_set))))
 352       xbt_swag_remove(useless_cnst, &(sys->saturated_constraint_set));
 353
 354     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 355   } else if (*min_usage == cnst->remaining / cnst->usage) {
 356     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 357   }
 358   XBT_OUT;
 359 }
 360
 361 static void saturated_variable_set_update(lmm_system_t sys)
 362 {
 363   lmm_constraint_t cnst = NULL;
 364   xbt_swag_t cnst_list = NULL;
 365   lmm_element_t elem = NULL;
 366   xbt_swag_t elem_list = NULL;
 367
 368   cnst_list = &(sys->saturated_constraint_set);
 369   while ((cnst = xbt_swag_getFirst(cnst_list))) {
 370     elem_list = &(cnst->active_element_set);
 371     xbt_swag_foreach(elem, elem_list) {
 372       if (elem->variable->weight <= 0)
 373         break;
 374       if ((elem->value > 0))
 375         xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
 376     }
 377     xbt_swag_remove(cnst, cnst_list);
 378   }
 379 }
 380
 381 void lmm_print(lmm_system_t sys)
 382 {
 383   lmm_constraint_t cnst = NULL;
 384   lmm_element_t elem = NULL;
 385   lmm_variable_t var = NULL;
 386   xbt_swag_t cnst_list = NULL;
 387   xbt_swag_t var_list = NULL;
 388   xbt_swag_t elem_list = NULL;
 389   char print_buf[1024];
 390   char *trace_buf = xbt_malloc0(sizeof(char));
 391   double sum = 0.0;
 392
 393   /* Printing Objective */
 394   var_list = &(sys->variable_set);
 395   sprintf(print_buf, "MAX-MIN ( ");
 396   trace_buf =
 397     xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 398   strcat(trace_buf, print_buf);
 399   xbt_swag_foreach(var, var_list) {
 400     sprintf(print_buf, "'%d'(%f) ", var->id_int, var->weight);
 401     trace_buf =
 402       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 403     strcat(trace_buf, print_buf);
 404   }
 405   sprintf(print_buf, ")");
 406   trace_buf =
 407     xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 408   strcat(trace_buf, print_buf);
 409   fprintf(stderr, "%s", trace_buf);
 410   //DEBUG1("%20s", trace_buf); FIXME
 411   trace_buf[0] = '\000';
 412
 413   DEBUG0("Constraints");
 414   /* Printing Constraints */
 415   cnst_list = &(sys->active_constraint_set);
 416   xbt_swag_foreach(cnst, cnst_list) {
 417     sum = 0.0;
 418     elem_list = &(cnst->element_set);
 419     sprintf(print_buf, "\t");
 420     trace_buf =
 421       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 422     strcat(trace_buf, print_buf);
 423     xbt_swag_foreach(elem, elem_list) {
 424       sprintf(print_buf, "%f.'%d'(%f) + ", elem->value,
 425               elem->variable->id_int, elem->variable->value);
 426       trace_buf =
 427         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 428       strcat(trace_buf, print_buf);
 429       sum += elem->value * elem->variable->value;
 430     }
 431     sprintf(print_buf, "0 <= %f ('%d')", cnst->bound, cnst->id_int);
 432     trace_buf =
 433       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 434     strcat(trace_buf, print_buf);
 435
 436     if (!cnst->shared) {
 437       sprintf(print_buf, " [MAX-Constraint]");
 438       trace_buf =
 439         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 440       strcat(trace_buf, print_buf);
 441     }
 442     //   DEBUG1("%s", trace_buf);
 443     fprintf(stderr, "%s", trace_buf);
 444     trace_buf[0] = '\000';
 445     xbt_assert3(!double_positive(sum - cnst->bound),
 446                 "Incorrect value (%f is not smaller than %f): %g",
 447                 sum, cnst->bound, sum - cnst->bound);
 448   }
 449
 450   DEBUG0("Variables");
 451   /* Printing Result */
 452   xbt_swag_foreach(var, var_list) {
 453     if (var->bound > 0) {
 454       DEBUG4("'%d'(%f) : %f (<=%f)", var->id_int, var->weight, var->value,
 455              var->bound);
 456       xbt_assert2(!double_positive(var->value - var->bound),
 457                   "Incorrect value (%f is not smaller than %f",
 458                   var->value, var->bound);
 459     } else {
 460       DEBUG3("'%d'(%f) : %f", var->id_int, var->weight, var->value);
 461     }
 462   }
 463
 464   free(trace_buf);
 465 }
 466
 467 void lmm_solve(lmm_system_t sys)
 468 {
 469   lmm_variable_t var = NULL;
 470   lmm_constraint_t cnst = NULL;
 471   lmm_element_t elem = NULL;
 472   xbt_swag_t cnst_list = NULL;
 473   xbt_swag_t var_list = NULL;
 474   xbt_swag_t elem_list = NULL;
 475   double min_usage = -1;
 476   double min_bound = -1;
 477
 478   if (!(sys->modified))
 479     return;
 480
 481   /*
 482    * Compute Usage and store the variables that reach the maximum.
 483    */
 484   cnst_list = sys->selective_update_active ? &(sys->modified_constraint_set) :
 485     &(sys->active_constraint_set);
 486
 487   DEBUG1("Active constraints : %d", xbt_swag_size(cnst_list));
 488   /* Init: Only modified code portions */
 489   xbt_swag_foreach(cnst, cnst_list) {
 490     elem_list = &(cnst->element_set);
 491     //DEBUG1("Variable set : %d", xbt_swag_size(elem_list));
 492     xbt_swag_foreach(elem, elem_list) {
 493       var = elem->variable;
 494       if (var->weight <= 0.0)
 495         break;
 496       var->value = 0.0;
 497     }
 498   }
 499
 500   /* Init: special case where all constraints are 0 */
 501   var_list = &(sys->variable_set);
 502   DEBUG1("Variable set : %d", xbt_swag_size(var_list));
 503   xbt_swag_foreach(var, var_list) {
 504     int nb = 0;
 505     int i;
 506     if (var->weight <= 0.0)
 507       break;
 508     for (i = 0; i < var->cnsts_number; i++) {
 509       if (var->cnsts[i].value == 0.0)
 510         nb++;
 511     }
 512     if ((nb == var->cnsts_number) && (var->weight > 0.0))
 513       var->value = 1.0;
 514   }
 515
 516   DEBUG1("Active constraints : %d", xbt_swag_size(cnst_list));
 517   xbt_swag_foreach(cnst, cnst_list) {
 518     /* INIT */
 519     cnst->remaining = cnst->bound;
 520     cnst->usage = 0;
 521     elem_list = &(cnst->element_set);
 522     cnst->usage = 0.0;
 523     xbt_swag_foreach(elem, elem_list) {
 524       /* 0-weighted elements (ie, sleep actions) are at the end of the swag and we don't want to consider them */
 525       if (elem->variable->weight <= 0)
 526         break;
 527       if ((elem->value > 0)) {
 528         if (cnst->shared)
 529           cnst->usage += elem->value / elem->variable->weight;
 530         else if (cnst->usage < elem->value / elem->variable->weight)
 531           cnst->usage = elem->value / elem->variable->weight;
 532
 533         make_elem_active(elem);
 534       }
 535     }
 536     DEBUG2("Constraint Usage %d : %f", cnst->id_int, cnst->usage);
 537     /* Saturated constraints update */
 538     saturated_constraint_set_update(sys, cnst, &min_usage);
 539   }
 540   saturated_variable_set_update(sys);
 541
 542   /* Saturated variables update */
 543
 544   do {
 545     /* Fix the variables that have to be */
 546     var_list = &(sys->saturated_variable_set);
 547
 548     xbt_swag_foreach(var, var_list) {
 549       if (var->weight <= 0.0)
 550         DIE_IMPOSSIBLE;
 551       /* First check if some of these variables have reach their upper
 552          bound and update min_usage accordingly. */
 553       DEBUG5
 554         ("var=%d, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
 555          var->id_int, var->bound, var->weight, min_usage,
 556          var->bound * var->weight);
 557       if ((var->bound > 0) && (var->bound * var->weight < min_usage)) {
 558         if (min_bound < 0)
 559           min_bound = var->bound;
 560         else
 561           min_bound = MIN(min_bound, var->bound);
 562         DEBUG1("Updated min_bound=%f", min_bound);
 563       }
 564     }
 565
 566
 567     while ((var = xbt_swag_getFirst(var_list))) {
 568       int i;
 569
 570       if (min_bound < 0) {
 571         var->value = min_usage / var->weight;
 572       } else {
 573         if (min_bound == var->bound)
 574           var->value = var->bound;
 575         else {
 576           xbt_swag_remove(var, var_list);
 577           continue;
 578         }
 579       }
 580       DEBUG5("Min usage: %f, Var(%d)->weight: %f, Var(%d)->value: %f ",
 581              min_usage, var->id_int, var->weight, var->id_int, var->value);
 582
 583
 584       /* Update usage */
 585
 586       for (i = 0; i < var->cnsts_number; i++) {
 587         elem = &var->cnsts[i];
 588         cnst = elem->constraint;
 589         if (cnst->shared) {
 590           double_update(&(cnst->remaining), elem->value * var->value);
 591           double_update(&(cnst->usage), elem->value / var->weight);
 592           make_elem_inactive(elem);
 593         } else {                /* FIXME one day: We recompute usage.... :( */
 594           cnst->usage = 0.0;
 595           make_elem_inactive(elem);
 596           xbt_swag_foreach(elem, elem_list) {
 597             if (elem->variable->weight <= 0)
 598               break;
 599             if (elem->variable->value > 0)
 600               break;
 601             if ((elem->value > 0)) {
 602               if (cnst->usage < elem->value / elem->variable->weight)
 603                 cnst->usage = elem->value / elem->variable->weight;
 604               DEBUG2("Constraint Usage %d : %f", cnst->id_int, cnst->usage);
 605               make_elem_active(elem);
 606             }
 607           }
 608         }
 609       }
 610       xbt_swag_remove(var, var_list);
 611     }
 612
 613     /* Find out which variables reach the maximum */
 614     cnst_list =
 615       sys->selective_update_active ? &(sys->modified_constraint_set) :
 616       &(sys->active_constraint_set);
 617     min_usage = -1;
 618     min_bound = -1;
 619     xbt_swag_foreach(cnst, cnst_list) {
 620       saturated_constraint_set_update(sys, cnst, &min_usage);
 621     }
 622     saturated_variable_set_update(sys);
 623
 624   } while (xbt_swag_size(&(sys->saturated_variable_set)));
 625
 626   sys->modified = 0;
 627   if (sys->selective_update_active)
 628     lmm_remove_all_modified_set(sys);
 629
 630   if (XBT_LOG_ISENABLED(surf_maxmin, xbt_log_priority_debug)) {
 631     lmm_print(sys);
 632   }
 633 }
 634
 635 /* Not a O(1) function */
 636
 637 void lmm_update(lmm_system_t sys, lmm_constraint_t cnst,
 638                 lmm_variable_t var, double value)
 639 {
 640   int i;
 641
 642   for (i = 0; i < var->cnsts_number; i++)
 643     if (var->cnsts[i].constraint == cnst) {
 644       var->cnsts[i].value = value;
 645       sys->modified = 1;
 646       lmm_update_modified_set(sys, cnst);
 647       return;
 648     }
 649 }
 650
 651 /** \brief Attribute the value bound to var->bound.
 652  *
 653  *  \param sys the lmm_system_t
 654  *  \param var the lmm_variable_t
 655  *  \param bound the new bound to associate with var
 656  *
 657  *  Makes var->bound equal to bound. Whenever this function is called
 658  *  a change is  signed in the system. To
 659  *  avoid false system changing detection it is a good idea to test
 660  *  (bound != 0) before calling it.
 661  *
 662  */
 663 void lmm_update_variable_bound(lmm_system_t sys, lmm_variable_t var,
 664                                double bound)
 665 {
 666   int i;
 667
 668   sys->modified = 1;
 669   var->bound = bound;
 670
 671   for (i = 0; i < var->cnsts_number; i++)
 672     lmm_update_modified_set(sys, var->cnsts[i].constraint);
 673
 674 }
 675
 676
 677 void lmm_update_variable_weight(lmm_system_t sys, lmm_variable_t var,
 678                                 double weight)
 679 {
 680   int i;
 681   lmm_element_t elem;
 682
 683   if (weight == var->weight)
 684     return;
 685   XBT_IN3("(sys=%p, var=%p, weight=%f)", sys, var, weight);
 686   sys->modified = 1;
 687   var->weight = weight;
 688   xbt_swag_remove(var, &(sys->variable_set));
 689   if (weight)
 690     xbt_swag_insert_at_head(var, &(sys->variable_set));
 691   else
 692     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 693
 694   for (i = 0; i < var->cnsts_number; i++) {
 695     elem = &var->cnsts[i];
 696     xbt_swag_remove(elem, &(elem->constraint->element_set));
 697     if (weight)
 698       xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 699     else
 700       xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 701
 702     lmm_update_modified_set(sys, elem->constraint);
 703   }
 704   if (!weight)
 705     var->value = 0.0;
 706
 707   XBT_OUT;
 708 }
 709
 710 double lmm_get_variable_weight(lmm_variable_t var)
 711 {
 712   return var->weight;
 713 }
 714
 715 void lmm_update_constraint_bound(lmm_system_t sys, lmm_constraint_t cnst,
 716                                  double bound)
 717 {
 718   sys->modified = 1;
 719   lmm_update_modified_set(sys, cnst);
 720   cnst->bound = bound;
 721 }
 722
 723 int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst)
 724 {
 725   return xbt_swag_belongs(cnst, &(sys->active_constraint_set));
 726 }
 727
 728 lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t sys)
 729 {
 730   return xbt_swag_getFirst(&(sys->active_constraint_set));
 731 }
 732
 733 lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t sys,
 734                                                 lmm_constraint_t cnst)
 735 {
 736   return xbt_swag_getNext(cnst, (sys->active_constraint_set).offset);
 737 }
 738
 739 /** \brief Update the constraint set propagating recursively to
 740  *  other constraints so the system should not be entirely computed.
 741  *
 742  *  \param sys the lmm_system_t
 743  *  \param cnst the lmm_constraint_t affected by the change
 744  *
 745  *  A recursive algorithm to optimize the system recalculation selecting only
 746  *  constraints that have changed. Each constraint change is propagated
 747  *  to the list of constraints for each variable.
 748  */
 749 static void lmm_update_modified_set(lmm_system_t sys, lmm_constraint_t cnst)
 750 {
 751   lmm_element_t elem = NULL;
 752   lmm_variable_t var = NULL;
 753   xbt_swag_t elem_list = NULL;
 754   int i;
 755
 756   /* return if selective update isn't active */
 757   if (!sys->selective_update_active)
 758     return;
 759
 760   //DEBUG1("Updating modified constraint set with constraint %d", cnst->id_int);
 761
 762   if (xbt_swag_belongs(cnst, &(sys->modified_constraint_set)))
 763     return;
 764
 765   //DEBUG1("Inserting into modified constraint set %d", cnst->id_int);
 766
 767   /* add to modified set */
 768   xbt_swag_insert(cnst, &(sys->modified_constraint_set));
 769
 770   elem_list = &(cnst->element_set);
 771   xbt_swag_foreach(elem, elem_list) {
 772     var = elem->variable;
 773     for (i = 0; i < var->cnsts_number; i++)
 774       if (cnst != var->cnsts[i].constraint) {
 775         //DEBUG2("Updating modified %d calling for %d", cnst->id_int, var->cnsts[i].constraint->id_int);
 776         lmm_update_modified_set(sys, var->cnsts[i].constraint);
 777       }
 778   }
 779 }
 780
 781 /** \brief Remove all constraints of the modified_constraint_set.
 782  *
 783  *  \param sys the lmm_system_t
 784  */
 785 static void lmm_remove_all_modified_set(lmm_system_t sys)
 786 {
 787   lmm_element_t elem = NULL;
 788   lmm_element_t elem_next = NULL;
 789   xbt_swag_t elem_list = NULL;
 790
 791   elem_list = &(sys->modified_constraint_set);
 792   xbt_swag_foreach_safe(elem, elem_next, elem_list) {
 793     xbt_swag_remove(elem, elem_list);
 794   }
 795 }