src/surf/maxmin.c

   1 /* Copyright (c) 2004, 2005, 2006, 2007, 2008, 2009, 2010. The SimGrid Team.
   2  * All rights reserved.                                                     */
   3
   4 /* This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the license (GNU LGPL) which comes with this package. */
   6
   7
   8 #include "xbt/sysdep.h"
   9 #include "xbt/log.h"
  10 #include "xbt/mallocator.h"
  11 #include "maxmin_private.h"
  12 #include <stdlib.h>
  13 #include <stdio.h>              /* sprintf */
  14 #include <math.h>
  15 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(surf_maxmin, surf,
  16                                 "Logging specific to SURF (maxmin)");
  17
  18 static void *lmm_variable_mallocator_new_f(void);
  19 static void lmm_variable_mallocator_free_f(void *var);
  20 static void lmm_variable_mallocator_reset_f(void *var);
  21 static void lmm_update_modified_set(lmm_system_t sys,
  22                                     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
  71         ("Variable %p (%d) still in LMM system when freing it: this may be a bug",
  72          var, var->id_int);
  73     lmm_var_free(sys, var);
  74   }
  75
  76   while ((cnst = extract_constraint(sys)))
  77     lmm_cnst_free(sys, cnst);
  78
  79   xbt_mallocator_free(sys->variable_mallocator);
  80   free(sys);
  81 }
  82
  83 XBT_INLINE void lmm_variable_disable(lmm_system_t sys, lmm_variable_t var)
  84 {
  85   int i;
  86   lmm_element_t elem = NULL;
  87
  88   XBT_IN2("(sys=%p, var=%p)", sys, var);
  89   sys->modified = 1;
  90
  91   for (i = 0; i < var->cnsts_number; i++) {
  92     elem = &var->cnsts[i];
  93     xbt_swag_remove(elem, &(elem->constraint->element_set));
  94     xbt_swag_remove(elem, &(elem->constraint->active_element_set));
  95     if (!xbt_swag_size(&(elem->constraint->element_set)))
  96       make_constraint_inactive(sys, elem->constraint);
  97     else
  98       lmm_update_modified_set(sys, elem->constraint);
  99   }
 100   var->cnsts_number = 0;
 101   XBT_OUT;
 102 }
 103
 104 static void lmm_var_free(lmm_system_t sys, lmm_variable_t var)
 105 {
 106
 107   lmm_variable_disable(sys, var);
 108   free(var->cnsts);
 109   xbt_mallocator_release(sys->variable_mallocator, var);
 110 }
 111
 112 static XBT_INLINE void lmm_cnst_free(lmm_system_t sys,
 113                                      lmm_constraint_t cnst)
 114 {
 115 /*   xbt_assert0(xbt_swag_size(&(cnst->element_set)), */
 116 /*            "This list should be empty!"); */
 117   remove_active_constraint(sys, cnst);
 118   free(cnst);
 119 }
 120
 121 lmm_constraint_t lmm_constraint_new(lmm_system_t sys, void *id,
 122                                     double bound_value)
 123 {
 124   lmm_constraint_t cnst = NULL;
 125   s_lmm_element_t elem;
 126
 127   cnst = xbt_new0(s_lmm_constraint_t, 1);
 128   cnst->id = id;
 129   cnst->id_int = Global_const_debug_id++;
 130   xbt_swag_init(&(cnst->element_set),
 131                 xbt_swag_offset(elem, element_set_hookup));
 132   xbt_swag_init(&(cnst->active_element_set),
 133                 xbt_swag_offset(elem, active_element_set_hookup));
 134
 135   cnst->bound = bound_value;
 136   cnst->usage = 0;
 137   cnst->shared = 1;
 138   insert_constraint(sys, cnst);
 139
 140   return cnst;
 141 }
 142
 143 XBT_INLINE void lmm_constraint_shared(lmm_constraint_t cnst)
 144 {
 145   cnst->shared = 0;
 146 }
 147
 148 XBT_INLINE int lmm_constraint_is_shared(lmm_constraint_t cnst)
 149 {
 150   return (cnst->shared);
 151 }
 152
 153 XBT_INLINE void lmm_constraint_free(lmm_system_t sys,
 154                                     lmm_constraint_t cnst)
 155 {
 156   remove_constraint(sys, cnst);
 157   lmm_cnst_free(sys, cnst);
 158 }
 159
 160 static void *lmm_variable_mallocator_new_f(void)
 161 {
 162   return xbt_new(s_lmm_variable_t, 1);
 163 }
 164
 165 static void lmm_variable_mallocator_free_f(void *var)
 166 {
 167   xbt_free(var);
 168 }
 169
 170 static void lmm_variable_mallocator_reset_f(void *var)
 171 {
 172   /* memset to zero like calloc */
 173   memset(var, 0, sizeof(s_lmm_variable_t));
 174 }
 175
 176 lmm_variable_t lmm_variable_new(lmm_system_t sys, void *id,
 177                                 double weight,
 178                                 double bound, int number_of_constraints)
 179 {
 180   lmm_variable_t var = NULL;
 181   int i;
 182
 183   XBT_IN5("(sys=%p, id=%p, weight=%f, bound=%f, num_cons =%d)",
 184           sys, id, weight, bound, number_of_constraints);
 185
 186   var = xbt_mallocator_get(sys->variable_mallocator);
 187   var->id = id;
 188   var->id_int = Global_debug_id++;
 189   var->cnsts = xbt_new0(s_lmm_element_t, number_of_constraints);
 190   for (i = 0; i < number_of_constraints; i++) {
 191     /* Should be useless because of the
 192        calloc but it seems to help valgrind... */
 193     var->cnsts[i].element_set_hookup.next = NULL;
 194     var->cnsts[i].element_set_hookup.prev = NULL;
 195     var->cnsts[i].active_element_set_hookup.next = NULL;
 196     var->cnsts[i].active_element_set_hookup.prev = NULL;
 197     var->cnsts[i].constraint = NULL;
 198     var->cnsts[i].variable = NULL;
 199     var->cnsts[i].value = 0.0;
 200   }
 201   var->cnsts_size = number_of_constraints;
 202   var->cnsts_number = 0;        /* Should be useless because of the
 203                                    calloc but it seems to help valgrind... */
 204   var->weight = weight;
 205   var->bound = bound;
 206   var->value = 0.0;
 207
 208
 209   var->func_f = func_f_def;
 210   var->func_fp = func_fp_def;
 211   var->func_fpi = func_fpi_def;
 212
 213   if (weight)
 214     xbt_swag_insert_at_head(var, &(sys->variable_set));
 215   else
 216     xbt_swag_insert_at_tail(var, &(sys->variable_set));
 217   XBT_OUT;
 218   return var;
 219 }
 220
 221 void lmm_variable_free(lmm_system_t sys, lmm_variable_t var)
 222 {
 223   remove_variable(sys, var);
 224   lmm_var_free(sys, var);
 225 }
 226
 227 XBT_INLINE double lmm_variable_getvalue(lmm_variable_t var)
 228 {
 229   return (var->value);
 230 }
 231
 232 XBT_INLINE double lmm_variable_getbound(lmm_variable_t var)
 233 {
 234   return (var->bound);
 235 }
 236
 237 void lmm_expand(lmm_system_t sys, lmm_constraint_t cnst,
 238                 lmm_variable_t var, double value)
 239 {
 240   lmm_element_t elem = NULL;
 241
 242   sys->modified = 1;
 243
 244   xbt_assert0(var->cnsts_number < var->cnsts_size, "Too much constraints");
 245
 246   elem = &(var->cnsts[var->cnsts_number++]);
 247
 248   elem->value = value;
 249   elem->constraint = cnst;
 250   elem->variable = var;
 251
 252   if (var->weight)
 253     xbt_swag_insert_at_head(elem, &(elem->constraint->element_set));
 254   else
 255     xbt_swag_insert_at_tail(elem, &(elem->constraint->element_set));
 256
 257   make_constraint_active(sys, cnst);
 258   lmm_update_modified_set(sys, cnst);
 259 }
 260
 261 void lmm_expand_add(lmm_system_t sys, lmm_constraint_t cnst,
 262                     lmm_variable_t var, double value)
 263 {
 264   int i;
 265   sys->modified = 1;
 266
 267   for (i = 0; i < var->cnsts_number; i++)
 268     if (var->cnsts[i].constraint == cnst)
 269       break;
 270
 271   if (i < var->cnsts_number) {
 272     if (cnst->shared)
 273       var->cnsts[i].value += value;
 274     else
 275       var->cnsts[i].value = MAX(var->cnsts[i].value, value);
 276     lmm_update_modified_set(sys, cnst);
 277   } else
 278     lmm_expand(sys, cnst, var, value);
 279 }
 280
 281 void lmm_elem_set_value(lmm_system_t sys, lmm_constraint_t cnst,
 282                         lmm_variable_t var, double value)
 283 {
 284   int i;
 285
 286   for (i = 0; i < var->cnsts_number; i++)
 287     if (var->cnsts[i].constraint == cnst)
 288       break;
 289
 290   if (i < var->cnsts_number) {
 291     var->cnsts[i].value = value;
 292     sys->modified = 1;
 293     lmm_update_modified_set(sys, cnst);
 294   } else
 295     DIE_IMPOSSIBLE;
 296 }
 297
 298 XBT_INLINE lmm_constraint_t lmm_get_cnst_from_var(lmm_system_t sys,
 299                                                   lmm_variable_t var,
 300                                                   int num)
 301 {
 302   if (num < var->cnsts_number)
 303     return (var->cnsts[num].constraint);
 304   else
 305     return NULL;
 306 }
 307
 308 XBT_INLINE int lmm_get_number_of_cnst_from_var(lmm_system_t sys,
 309                                                lmm_variable_t var)
 310 {
 311   return (var->cnsts_number);
 312 }
 313
 314 lmm_variable_t lmm_get_var_from_cnst(lmm_system_t sys,
 315                                      lmm_constraint_t cnst,
 316                                      lmm_element_t * elem)
 317 {
 318   if (!(*elem))
 319     *elem = xbt_swag_getFirst(&(cnst->element_set));
 320   else
 321     *elem = xbt_swag_getNext(*elem, cnst->element_set.offset);
 322   if (*elem)
 323     return (*elem)->variable;
 324   else
 325     return NULL;
 326 }
 327
 328 XBT_INLINE void *lmm_constraint_id(lmm_constraint_t cnst)
 329 {
 330   return cnst->id;
 331 }
 332
 333 XBT_INLINE void *lmm_variable_id(lmm_variable_t var)
 334 {
 335   return var->id;
 336 }
 337
 338 static XBT_INLINE void saturated_constraint_set_update(lmm_system_t sys,
 339                                                        lmm_constraint_t
 340                                                        cnst,
 341                                                        double *min_usage)
 342 {
 343   lmm_constraint_t useless_cnst = NULL;
 344
 345   XBT_IN3("sys=%p, cnst=%p, min_usage=%f", sys, cnst, *min_usage);
 346   if (cnst->usage <= 0) {
 347     XBT_OUT;
 348     return;
 349   }
 350   if (cnst->remaining <= 0) {
 351     XBT_OUT;
 352     return;
 353   }
 354   if ((*min_usage < 0) || (*min_usage > cnst->remaining / cnst->usage)) {
 355     *min_usage = cnst->remaining / cnst->usage;
 356     LOG3(xbt_log_priority_trace,
 357          "min_usage=%f (cnst->remaining=%f, cnst->usage=%f)", *min_usage,
 358          cnst->remaining, cnst->usage);
 359     while ((useless_cnst =
 360             xbt_swag_getFirst(&(sys->saturated_constraint_set))))
 361       xbt_swag_remove(useless_cnst, &(sys->saturated_constraint_set));
 362
 363     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 364   } else if (*min_usage == cnst->remaining / cnst->usage) {
 365     xbt_swag_insert(cnst, &(sys->saturated_constraint_set));
 366   }
 367   XBT_OUT;
 368 }
 369
 370 static XBT_INLINE void saturated_variable_set_update(lmm_system_t sys)
 371 {
 372   lmm_constraint_t cnst = NULL;
 373   xbt_swag_t cnst_list = NULL;
 374   lmm_element_t elem = NULL;
 375   xbt_swag_t elem_list = NULL;
 376
 377   cnst_list = &(sys->saturated_constraint_set);
 378   while ((cnst = xbt_swag_getFirst(cnst_list))) {
 379     elem_list = &(cnst->active_element_set);
 380     xbt_swag_foreach(elem, elem_list) {
 381       if (elem->variable->weight <= 0)
 382         break;
 383       if ((elem->value > 0))
 384         xbt_swag_insert(elem->variable, &(sys->saturated_variable_set));
 385     }
 386     xbt_swag_remove(cnst, cnst_list);
 387   }
 388 }
 389
 390 void lmm_print(lmm_system_t sys)
 391 {
 392   lmm_constraint_t cnst = NULL;
 393   lmm_element_t elem = NULL;
 394   lmm_variable_t var = NULL;
 395   xbt_swag_t cnst_list = NULL;
 396   xbt_swag_t var_list = NULL;
 397   xbt_swag_t elem_list = NULL;
 398   char print_buf[1024];
 399   char *trace_buf = xbt_malloc0(sizeof(char));
 400   double sum = 0.0;
 401
 402   /* Printing Objective */
 403   var_list = &(sys->variable_set);
 404   sprintf(print_buf, "MAX-MIN ( ");
 405   trace_buf =
 406       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 407   strcat(trace_buf, print_buf);
 408   xbt_swag_foreach(var, var_list) {
 409     sprintf(print_buf, "'%d'(%f) ", var->id_int, var->weight);
 410     trace_buf =
 411         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 412     strcat(trace_buf, print_buf);
 413   }
 414   sprintf(print_buf, ")");
 415   trace_buf =
 416       xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 417   strcat(trace_buf, print_buf);
 418   fprintf(stderr, "%s", trace_buf);
 419   //DEBUG1("%20s", trace_buf); FIXME
 420   trace_buf[0] = '\000';
 421
 422   DEBUG0("Constraints");
 423   /* Printing Constraints */
 424   cnst_list = &(sys->active_constraint_set);
 425   xbt_swag_foreach(cnst, cnst_list) {
 426     sum = 0.0;
 427     elem_list = &(cnst->element_set);
 428     sprintf(print_buf, "\t");
 429     trace_buf =
 430         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 431     strcat(trace_buf, print_buf);
 432     xbt_swag_foreach(elem, elem_list) {
 433       sprintf(print_buf, "%f.'%d'(%f) + ", elem->value,
 434               elem->variable->id_int, elem->variable->value);
 435       trace_buf =
 436           xbt_realloc(trace_buf,
 437                       strlen(trace_buf) + strlen(print_buf) + 1);
 438       strcat(trace_buf, print_buf);
 439       sum += elem->value * elem->variable->value;
 440     }
 441     sprintf(print_buf, "0 <= %f ('%d')", cnst->bound, cnst->id_int);
 442     trace_buf =
 443         xbt_realloc(trace_buf, strlen(trace_buf) + strlen(print_buf) + 1);
 444     strcat(trace_buf, print_buf);
 445
 446     if (!cnst->shared) {
 447       sprintf(print_buf, " [MAX-Constraint]");
 448       trace_buf =
 449           xbt_realloc(trace_buf,
 450                       strlen(trace_buf) + strlen(print_buf) + 1);
 451       strcat(trace_buf, print_buf);
 452     }
 453     //   DEBUG1("%s", trace_buf);
 454     fprintf(stderr, "%s", trace_buf);
 455     trace_buf[0] = '\000';
 456     xbt_assert3(!double_positive(sum - cnst->bound),
 457                 "Incorrect value (%f is not smaller than %f): %g",
 458                 sum, cnst->bound, sum - cnst->bound);
 459   }
 460
 461   DEBUG0("Variables");
 462   /* Printing Result */
 463   xbt_swag_foreach(var, var_list) {
 464     if (var->bound > 0) {
 465       DEBUG4("'%d'(%f) : %f (<=%f)", var->id_int, var->weight, var->value,
 466              var->bound);
 467       xbt_assert2(!double_positive(var->value - var->bound),
 468                   "Incorrect value (%f is not smaller than %f",
 469                   var->value, var->bound);
 470     } else {
 471       DEBUG3("'%d'(%f) : %f", var->id_int, var->weight, var->value);
 472     }
 473   }
 474
 475   free(trace_buf);
 476 }
 477
 478 void lmm_solve(lmm_system_t sys)
 479 {
 480   lmm_variable_t var = NULL;
 481   lmm_constraint_t cnst = NULL;
 482   lmm_element_t elem = NULL;
 483   xbt_swag_t cnst_list = NULL;
 484   xbt_swag_t var_list = NULL;
 485   xbt_swag_t elem_list = NULL;
 486   double min_usage = -1;
 487   double min_bound = -1;
 488
 489   if (!(sys->modified))
 490     return;
 491
 492   /*
 493    * Compute Usage and store the variables that reach the maximum.
 494    */
 495   cnst_list =
 496       sys->
 497       selective_update_active ? &(sys->modified_constraint_set) :
 498       &(sys->active_constraint_set);
 499
 500   DEBUG1("Active constraints : %d", xbt_swag_size(cnst_list));
 501   /* Init: Only modified code portions */
 502   xbt_swag_foreach(cnst, cnst_list) {
 503     elem_list = &(cnst->element_set);
 504     //DEBUG1("Variable set : %d", xbt_swag_size(elem_list));
 505     xbt_swag_foreach(elem, elem_list) {
 506       var = elem->variable;
 507       if (var->weight <= 0.0)
 508         break;
 509       var->value = 0.0;
 510     }
 511   }
 512
 513   DEBUG1("Active constraints : %d", xbt_swag_size(cnst_list));
 514   xbt_swag_foreach(cnst, cnst_list) {
 515     /* INIT */
 516     cnst->remaining = cnst->bound;
 517     if (cnst->remaining == 0)
 518       continue;
 519     cnst->usage = 0;
 520     elem_list = &(cnst->element_set);
 521     xbt_swag_foreach(elem, elem_list) {
 522       /* 0-weighted elements (ie, sleep actions) are at the end of the swag and we don't want to consider them */
 523       if (elem->variable->weight <= 0)
 524         break;
 525       if ((elem->value > 0)) {
 526         if (cnst->shared)
 527           cnst->usage += elem->value / elem->variable->weight;
 528         else if (cnst->usage < elem->value / elem->variable->weight)
 529           cnst->usage = elem->value / elem->variable->weight;
 530
 531         make_elem_active(elem);
 532       }
 533     }
 534     DEBUG2("Constraint Usage %d : %f", cnst->id_int, cnst->usage);
 535     /* Saturated constraints update */
 536     saturated_constraint_set_update(sys, cnst, &min_usage);
 537   }
 538   saturated_variable_set_update(sys);
 539
 540   /* Saturated variables update */
 541
 542   do {
 543     /* Fix the variables that have to be */
 544     var_list = &(sys->saturated_variable_set);
 545
 546     xbt_swag_foreach(var, var_list) {
 547       if (var->weight <= 0.0)
 548         DIE_IMPOSSIBLE;
 549       /* First check if some of these variables have reach their upper
 550          bound and update min_usage accordingly. */
 551       DEBUG5
 552           ("var=%d, var->bound=%f, var->weight=%f, min_usage=%f, var->bound*var->weight=%f",
 553            var->id_int, var->bound, var->weight, min_usage,
 554            var->bound * var->weight);
 555       if ((var->bound > 0) && (var->bound * var->weight < min_usage)) {
 556         if (min_bound < 0)
 557           min_bound = var->bound;
 558         else
 559           min_bound = MIN(min_bound, var->bound);
 560         DEBUG1("Updated min_bound=%f", min_bound);
 561       }
 562     }
 563
 564
 565     while ((var = xbt_swag_getFirst(var_list))) {
 566       int i;
 567
 568       if (min_bound < 0) {
 569         var->value = min_usage / var->weight;
 570       } else {
 571         if (min_bound == var->bound)
 572           var->value = var->bound;
 573         else {
 574           xbt_swag_remove(var, var_list);
 575           continue;
 576         }
 577       }
 578       DEBUG5("Min usage: %f, Var(%d)->weight: %f, Var(%d)->value: %f ",
 579              min_usage, var->id_int, var->weight, var->id_int, var->value);
 580
 581
 582       /* Update usage */
 583
 584       for (i = 0; i < var->cnsts_number; i++) {
 585         elem = &var->cnsts[i];
 586         cnst = elem->constraint;
 587         if (cnst->shared) {
 588           double_update(&(cnst->remaining), elem->value * var->value);
 589           double_update(&(cnst->usage), elem->value / var->weight);
 590           make_elem_inactive(elem);
 591         } else {                /* FIXME one day: We recompute usage.... :( */
 592           cnst->usage = 0.0;
 593           make_elem_inactive(elem);
 594           elem_list = &(cnst->element_set);
 595           xbt_swag_foreach(elem, elem_list) {
 596             if (elem->variable->weight <= 0)
 597               break;
 598             if (elem->variable->value > 0)
 599               break;
 600             if ((elem->value > 0)) {
 601               cnst->usage =
 602                   MAX(cnst->usage, elem->value / elem->variable->weight);
 603               DEBUG2("Constraint Usage %d : %f", cnst->id_int,
 604                      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 XBT_INLINE double lmm_get_variable_weight(lmm_variable_t var)
 711 {
 712   return var->weight;
 713 }
 714
 715 XBT_INLINE void lmm_update_constraint_bound(lmm_system_t sys,
 716                                             lmm_constraint_t cnst,
 717                                             double bound)
 718 {
 719   sys->modified = 1;
 720   lmm_update_modified_set(sys, cnst);
 721   cnst->bound = bound;
 722 }
 723
 724 XBT_INLINE int lmm_constraint_used(lmm_system_t sys, lmm_constraint_t cnst)
 725 {
 726   return xbt_swag_belongs(cnst, &(sys->active_constraint_set));
 727 }
 728
 729 XBT_INLINE lmm_constraint_t lmm_get_first_active_constraint(lmm_system_t
 730                                                             sys)
 731 {
 732   return xbt_swag_getFirst(&(sys->active_constraint_set));
 733 }
 734
 735 XBT_INLINE lmm_constraint_t lmm_get_next_active_constraint(lmm_system_t
 736                                                            sys,
 737                                                            lmm_constraint_t
 738                                                            cnst)
 739 {
 740   return xbt_swag_getNext(cnst, (sys->active_constraint_set).offset);
 741 }
 742
 743 #ifdef HAVE_LATENCY_BOUND_TRACKING
 744 XBT_INLINE int lmm_is_variable_limited_by_latency(lmm_variable_t var)
 745 {
 746   return (double_equals(var->bound, var->value));
 747 }
 748 #endif
 749
 750
 751 /** \brief Update the constraint set propagating recursively to
 752  *  other constraints so the system should not be entirely computed.
 753  *
 754  *  \param sys the lmm_system_t
 755  *  \param cnst the lmm_constraint_t affected by the change
 756  *
 757  *  A recursive algorithm to optimize the system recalculation selecting only
 758  *  constraints that have changed. Each constraint change is propagated
 759  *  to the list of constraints for each variable.
 760  */
 761 static void lmm_update_modified_set(lmm_system_t sys,
 762                                     lmm_constraint_t cnst)
 763 {
 764   lmm_element_t elem = NULL;
 765   lmm_variable_t var = NULL;
 766   xbt_swag_t elem_list = NULL;
 767   int i;
 768
 769   /* return if selective update isn't active */
 770   if (!sys->selective_update_active)
 771     return;
 772
 773   //DEBUG1("Updating modified constraint set with constraint %d", cnst->id_int);
 774
 775   if (xbt_swag_belongs(cnst, &(sys->modified_constraint_set)))
 776     return;
 777
 778   //DEBUG1("Inserting into modified constraint set %d", cnst->id_int);
 779
 780   /* add to modified set */
 781   xbt_swag_insert(cnst, &(sys->modified_constraint_set));
 782
 783   elem_list = &(cnst->element_set);
 784   xbt_swag_foreach(elem, elem_list) {
 785     var = elem->variable;
 786     for (i = 0; i < var->cnsts_number; i++)
 787       if (cnst != var->cnsts[i].constraint) {
 788         //DEBUG2("Updating modified %d calling for %d", cnst->id_int, var->cnsts[i].constraint->id_int);
 789         lmm_update_modified_set(sys, var->cnsts[i].constraint);
 790       }
 791   }
 792 }
 793
 794 /** \brief Remove all constraints of the modified_constraint_set.
 795  *
 796  *  \param sys the lmm_system_t
 797  */
 798 static void lmm_remove_all_modified_set(lmm_system_t sys)
 799 {
 800   lmm_element_t elem = NULL;
 801   lmm_element_t elem_next = NULL;
 802   xbt_swag_t elem_list = NULL;
 803
 804   elem_list = &(sys->modified_constraint_set);
 805   xbt_swag_foreach_safe(elem, elem_next, elem_list) {
 806     xbt_swag_remove(elem, elem_list);
 807   }
 808 }