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[simgrid.git] / src / mc / mc_dpor.c
1 /* Copyright (c) 2008-2014. 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 #include "mc_private.h"
8
9 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_dpor, mc,
10                                 "Logging specific to MC DPOR exploration");
11
12 /********** Global variables **********/
13
14 xbt_dynar_t visited_states;
15 xbt_dict_t first_enabled_state;
16 xbt_dynar_t initial_communications_pattern;
17 xbt_dynar_t communications_pattern;
18 int nb_comm_pattern;
19
20 /********** Static functions ***********/
21
22 static void comm_pattern_free(mc_comm_pattern_t p){
23   xbt_free(p->rdv);
24   xbt_free(p->data);
25   xbt_free(p);
26   p = NULL;
27 }
28
29 static void comm_pattern_free_voidp( void *p){
30   comm_pattern_free((mc_comm_pattern_t) * (void **)p);
31 }
32
33 static mc_comm_pattern_t get_comm_pattern_from_idx(xbt_dynar_t pattern, unsigned int *idx, e_smx_comm_type_t type, unsigned long proc){
34   mc_comm_pattern_t current_comm;
35   while(*idx < xbt_dynar_length(pattern)){
36     current_comm = (mc_comm_pattern_t)xbt_dynar_get_as(pattern, *idx, mc_comm_pattern_t);
37     if(current_comm->type == type && type == SIMIX_COMM_SEND){
38       if(current_comm->src_proc == proc)
39         return current_comm;
40     }else if(current_comm->type == type && type == SIMIX_COMM_RECEIVE){
41       if(current_comm->dst_proc == proc)
42         return current_comm;
43     }
44     (*idx)++;
45   }
46   return NULL;
47 }
48
49 static int compare_comm_pattern(mc_comm_pattern_t comm1, mc_comm_pattern_t comm2){
50   if(strcmp(comm1->rdv, comm2->rdv) != 0)
51     return 1;
52   if(comm1->src_proc != comm2->src_proc)
53     return 1;
54   if(comm1->dst_proc != comm2->dst_proc)
55     return 1;
56   if(comm1->data_size != comm2->data_size)
57     return 1;
58   if(memcmp(comm1->data, comm2->data, comm1->data_size) != 0)
59     return 1;
60   return 0;
61 }
62
63 static void deterministic_pattern(xbt_dynar_t initial_pattern, xbt_dynar_t pattern){
64   unsigned int cursor = 0, send_index = 0, recv_index = 0;
65   mc_comm_pattern_t comm1, comm2;
66   int comm_comparison = 0;
67   int current_process = 0;
68   while(current_process < simix_process_maxpid){
69     while(cursor < xbt_dynar_length(initial_pattern)){
70       comm1 = (mc_comm_pattern_t)xbt_dynar_get_as(initial_pattern, cursor, mc_comm_pattern_t);
71       if(comm1->type == SIMIX_COMM_SEND && comm1->src_proc == current_process){
72         comm2 = get_comm_pattern_from_idx(pattern, &send_index, comm1->type, current_process);
73         comm_comparison = compare_comm_pattern(comm1, comm2);
74         if(comm_comparison == 1){
75           initial_state_safety->send_deterministic = 0;
76           initial_state_safety->comm_deterministic = 0;
77           return;
78         }
79         send_index++;
80       }else if(comm1->type == SIMIX_COMM_RECEIVE && comm1->dst_proc == current_process){
81         comm2 = get_comm_pattern_from_idx(pattern, &recv_index, comm1->type, current_process);
82         comm_comparison = compare_comm_pattern(comm1, comm2);
83         if(comm_comparison == 1){
84           initial_state_safety->comm_deterministic = 0;
85         }
86         recv_index++;
87       }
88       cursor++;
89     }
90     cursor = 0;
91     send_index = 0;
92     recv_index = 0;
93     current_process++;
94   }
95 }
96
97 static int complete_comm_pattern(xbt_dynar_t list, mc_comm_pattern_t pattern){
98   mc_comm_pattern_t current_pattern;
99   unsigned int cursor = 0;
100   xbt_dynar_foreach(list, cursor, current_pattern){
101     if(current_pattern->comm == pattern->comm){
102       if(!current_pattern->completed){
103         current_pattern->src_proc = pattern->comm->comm.src_proc->pid;
104         current_pattern->src_host = simcall_host_get_name(pattern->comm->comm.src_proc->smx_host);
105         current_pattern->dst_proc = pattern->comm->comm.dst_proc->pid;
106         current_pattern->dst_host = simcall_host_get_name(pattern->comm->comm.dst_proc->smx_host);
107         current_pattern->data_size = pattern->comm->comm.src_buff_size;
108         current_pattern->data = xbt_malloc0(current_pattern->data_size);
109         current_pattern->matched_comm = pattern->num;
110         memcpy(current_pattern->data, current_pattern->comm->comm.src_buff, current_pattern->data_size);
111         current_pattern->completed = 1;
112         return current_pattern->num;
113       }
114     }
115   }
116   return -1;
117 }
118
119 void get_comm_pattern(xbt_dynar_t list, smx_simcall_t request, int call){
120   mc_comm_pattern_t pattern = NULL;
121   pattern = xbt_new0(s_mc_comm_pattern_t, 1);
122   pattern->num = ++nb_comm_pattern;
123   pattern->completed = 0;
124   if(call == 1){ // ISEND
125     pattern->comm = simcall_comm_isend__get__result(request);
126     pattern->type = SIMIX_COMM_SEND;
127     if(pattern->comm->comm.dst_proc != NULL){ 
128       pattern->matched_comm = complete_comm_pattern(list, pattern);
129       pattern->dst_proc = pattern->comm->comm.dst_proc->pid;
130       pattern->completed = 1;
131       pattern->dst_host = simcall_host_get_name(pattern->comm->comm.dst_proc->smx_host);
132     }
133     pattern->src_proc = pattern->comm->comm.src_proc->pid;
134     pattern->src_host = simcall_host_get_name(request->issuer->smx_host);
135     pattern->data_size = pattern->comm->comm.src_buff_size;
136     pattern->data=xbt_malloc0(pattern->data_size);
137     memcpy(pattern->data, pattern->comm->comm.src_buff, pattern->data_size);
138   }else{ // IRECV
139     pattern->comm = simcall_comm_irecv__get__result(request);
140     pattern->type = SIMIX_COMM_RECEIVE;
141     if(pattern->comm->comm.src_proc != NULL){
142       pattern->matched_comm = complete_comm_pattern(list, pattern);
143       pattern->src_proc = pattern->comm->comm.src_proc->pid;
144       pattern->src_host = simcall_host_get_name(pattern->comm->comm.src_proc->smx_host);
145       pattern->completed = 1;
146       pattern->data_size = pattern->comm->comm.src_buff_size;
147       pattern->data=xbt_malloc0(pattern->data_size);
148       memcpy(pattern->data, pattern->comm->comm.src_buff, pattern->data_size);
149     }
150     pattern->dst_proc = pattern->comm->comm.dst_proc->pid;
151     pattern->dst_host = simcall_host_get_name(request->issuer->smx_host);
152   }
153   if(pattern->comm->comm.rdv != NULL)
154     pattern->rdv = strdup(pattern->comm->comm.rdv->name);
155   else
156     pattern->rdv = strdup(pattern->comm->comm.rdv_cpy->name);
157   xbt_dynar_push(list, &pattern);
158 }
159
160 static void print_communications_pattern(xbt_dynar_t comms_pattern){
161   unsigned int cursor = 0;
162   mc_comm_pattern_t current_comm;
163   xbt_dynar_foreach(comms_pattern, cursor, current_comm){
164     if(current_comm->type == SIMIX_COMM_SEND)
165       XBT_INFO("[(%lu) %s -> %s] %s ", current_comm->src_proc, current_comm->src_host, current_comm->dst_host, "iSend");
166     else
167       XBT_INFO("[(%lu) %s <- %s] %s ", current_comm->dst_proc, current_comm->dst_host, current_comm->src_host, "iRecv");
168   }
169 }
170
171 static void visited_state_free(mc_visited_state_t state){
172   if(state){
173     MC_free_snapshot(state->system_state);
174     xbt_free(state);
175   }
176 }
177
178 static void visited_state_free_voidp(void *s){
179   visited_state_free((mc_visited_state_t) * (void **) s);
180 }
181
182 /** \brief Save the current state
183  *
184  *  \return Snapshot of the current state.
185  */
186 static mc_visited_state_t visited_state_new(){
187
188   mc_visited_state_t new_state = NULL;
189   new_state = xbt_new0(s_mc_visited_state_t, 1);
190   new_state->heap_bytes_used = mmalloc_get_bytes_used(std_heap);
191   new_state->nb_processes = xbt_swag_size(simix_global->process_list);
192   new_state->system_state = MC_take_snapshot(mc_stats->expanded_states);
193   new_state->num = mc_stats->expanded_states;
194   new_state->other_num = -1;
195
196   return new_state;
197   
198 }
199
200 /** \brief Find a suitable subrange of candidate duplicates for a given state
201  *
202  *  \param all_ pairs dynamic array of states with candidate duplicates of the current state;
203  *  \param pair current state;
204  *  \param min (output) index of the beginning of the the subrange
205  *  \param max (output) index of the enf of the subrange
206  *
207  *  Given a suitably ordered array of state, this function extracts a subrange
208  *  (with index *min <= i <= *max) with candidate duplicates of the given state.
209  *  This function uses only fast discriminating criterions and does not use the
210  *  full state comparison algorithms.
211  *
212  *  The states in all_pairs MUST be ordered using a (given) weak order
213  *  (based on nb_processes and heap_bytes_used).
214  *  The subrange is the subrange of "equivalence" of the given state.
215  */
216 static int get_search_interval(xbt_dynar_t all_states, mc_visited_state_t state, int *min, int *max){
217   XBT_VERB("Searching interval for state %i: nd_processes=%zu heap_bytes_used=%zu",
218     state->num, (size_t)state->nb_processes, (size_t)state->heap_bytes_used);
219
220   int raw_mem_set = (mmalloc_get_current_heap() == raw_heap);
221
222   MC_SET_RAW_MEM;
223
224   int cursor = 0, previous_cursor, next_cursor;
225   mc_visited_state_t state_test;
226   int start = 0;
227   int end = xbt_dynar_length(all_states) - 1;
228   
229   while(start <= end){
230     cursor = (start + end) / 2;
231     state_test = (mc_visited_state_t)xbt_dynar_get_as(all_states, cursor, mc_visited_state_t);
232     if(state_test->nb_processes < state->nb_processes){
233       start = cursor + 1;
234     }else if(state_test->nb_processes > state->nb_processes){
235       end = cursor - 1;
236     }else{
237       if(state_test->heap_bytes_used < state->heap_bytes_used){
238         start = cursor +1;
239       }else if(state_test->heap_bytes_used > state->heap_bytes_used){
240         end = cursor - 1;
241       }else{
242         *min = *max = cursor;
243         previous_cursor = cursor - 1;
244         while(previous_cursor >= 0){
245           state_test = (mc_visited_state_t)xbt_dynar_get_as(all_states, previous_cursor, mc_visited_state_t);
246           if(state_test->nb_processes != state->nb_processes || state_test->heap_bytes_used != state->heap_bytes_used)
247             break;
248           *min = previous_cursor;
249           previous_cursor--;
250         }
251         next_cursor = cursor + 1;
252         while(next_cursor < xbt_dynar_length(all_states)){
253           state_test = (mc_visited_state_t)xbt_dynar_get_as(all_states, next_cursor, mc_visited_state_t);
254           if(state_test->nb_processes != state->nb_processes || state_test->heap_bytes_used != state->heap_bytes_used)
255             break;
256           *max = next_cursor;
257           next_cursor++;
258         }
259         if(!raw_mem_set)
260           MC_UNSET_RAW_MEM;
261         return -1;
262       }
263      }
264   }
265
266   if(!raw_mem_set)
267     MC_UNSET_RAW_MEM;
268
269   return cursor;
270 }
271
272 /** \brief Take a snapshot the current state and process it.
273  *
274  *  \return number of the duplicate state or -1 (not visited)
275  */
276 static int is_visited_state(){
277
278   if(_sg_mc_visited == 0)
279     return -1;
280
281   int raw_mem_set = (mmalloc_get_current_heap() == raw_heap);
282
283   MC_SET_RAW_MEM;
284
285   mc_visited_state_t new_state = visited_state_new();
286   
287   if(xbt_dynar_is_empty(visited_states)){
288
289     xbt_dynar_push(visited_states, &new_state); 
290
291     if(!raw_mem_set)
292       MC_UNSET_RAW_MEM;
293
294     return -1;
295
296   }else{
297
298     int min = -1, max = -1, index;
299     //int res;
300     mc_visited_state_t state_test;
301     int cursor;
302
303     index = get_search_interval(visited_states, new_state, &min, &max);
304
305     if(min != -1 && max != -1){
306
307       // Parallell implementation
308       /*res = xbt_parmap_mc_apply(parmap, snapshot_compare, xbt_dynar_get_ptr(visited_states, min), (max-min)+1, new_state);
309       if(res != -1){
310         state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, (min+res)-1, mc_visited_state_t);
311         if(state_test->other_num == -1)
312           new_state->other_num = state_test->num;
313         else
314           new_state->other_num = state_test->other_num;
315         if(dot_output == NULL)
316           XBT_DEBUG("State %d already visited ! (equal to state %d)", new_state->num, state_test->num);
317         else
318           XBT_DEBUG("State %d already visited ! (equal to state %d (state %d in dot_output))", new_state->num, state_test->num, new_state->other_num);
319         xbt_dynar_remove_at(visited_states, (min + res) - 1, NULL);
320         xbt_dynar_insert_at(visited_states, (min+res) - 1, &new_state);
321         if(!raw_mem_set)
322           MC_UNSET_RAW_MEM;
323         return new_state->other_num;
324         }*/
325
326       cursor = min;
327       while(cursor <= max){
328         state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, cursor, mc_visited_state_t);
329         if(snapshot_compare(state_test, new_state) == 0){
330           // The state has been visited:
331
332           if(state_test->other_num == -1)
333             new_state->other_num = state_test->num;
334           else
335             new_state->other_num = state_test->other_num;
336           if(dot_output == NULL)
337             XBT_DEBUG("State %d already visited ! (equal to state %d)", new_state->num, state_test->num);
338           else
339             XBT_DEBUG("State %d already visited ! (equal to state %d (state %d in dot_output))", new_state->num, state_test->num, new_state->other_num);
340
341           // Replace the old state with the new one (why?):
342           xbt_dynar_remove_at(visited_states, cursor, NULL);
343           xbt_dynar_insert_at(visited_states, cursor, &new_state);
344
345           if(!raw_mem_set)
346             MC_UNSET_RAW_MEM;
347           return new_state->other_num;
348         }
349         cursor++;
350       }
351
352       // The state has not been visited, add it to the list:
353       xbt_dynar_insert_at(visited_states, min, &new_state);
354
355     }else{
356
357       // The state has not been visited: insert the state in the dynamic array.
358       state_test = (mc_visited_state_t)xbt_dynar_get_as(visited_states, index, mc_visited_state_t);
359       if(state_test->nb_processes < new_state->nb_processes){
360         xbt_dynar_insert_at(visited_states, index+1, &new_state);
361       }else{
362         if(state_test->heap_bytes_used < new_state->heap_bytes_used)
363           xbt_dynar_insert_at(visited_states, index + 1, &new_state);
364         else
365           xbt_dynar_insert_at(visited_states, index, &new_state);
366       }
367
368     }
369
370     // We have reached the maximum number of stored states;
371     if(xbt_dynar_length(visited_states) > _sg_mc_visited){
372
373       // Find the (index of the) older state:
374       int min2 = mc_stats->expanded_states;
375       unsigned int cursor2 = 0;
376       unsigned int index2 = 0;
377       xbt_dynar_foreach(visited_states, cursor2, state_test){
378         if(state_test->num < min2){
379           index2 = cursor2;
380           min2 = state_test->num;
381         }
382       }
383
384       // and drop it:
385       xbt_dynar_remove_at(visited_states, index2, NULL);
386     }
387
388     if(!raw_mem_set)
389       MC_UNSET_RAW_MEM;
390     
391     return -1;
392     
393   }
394 }
395
396 /**
397  *  \brief Initialize the DPOR exploration algorithm
398  */
399 void MC_dpor_init()
400 {
401   
402   int raw_mem_set = (mmalloc_get_current_heap() == raw_heap);
403
404   mc_state_t initial_state = NULL;
405   smx_process_t process;
406   
407   /* Create the initial state and push it into the exploration stack */
408   MC_SET_RAW_MEM;
409
410   if(_sg_mc_visited > 0)
411     visited_states = xbt_dynar_new(sizeof(mc_visited_state_t), visited_state_free_voidp);
412
413   first_enabled_state = xbt_dict_new_homogeneous(&xbt_free_f);
414
415   initial_communications_pattern = xbt_dynar_new(sizeof(mc_comm_pattern_t), comm_pattern_free_voidp);
416   communications_pattern = xbt_dynar_new(sizeof(mc_comm_pattern_t), comm_pattern_free_voidp);
417   nb_comm_pattern = 0;
418
419   initial_state = MC_state_new();
420
421   MC_UNSET_RAW_MEM;
422
423   XBT_DEBUG("**************************************************");
424   XBT_DEBUG("Initial state");
425
426   /* Wait for requests (schedules processes) */
427   MC_wait_for_requests();
428
429   MC_ignore_heap(simix_global->process_to_run->data, 0);
430   MC_ignore_heap(simix_global->process_that_ran->data, 0);
431
432   MC_SET_RAW_MEM;
433  
434   /* Get an enabled process and insert it in the interleave set of the initial state */
435   xbt_swag_foreach(process, simix_global->process_list){
436     if(MC_process_is_enabled(process)){
437       MC_state_interleave_process(initial_state, process);
438       if(mc_reduce_kind != e_mc_reduce_none)
439         break;
440     }
441   }
442
443   xbt_fifo_unshift(mc_stack_safety, initial_state);
444
445   /* To ensure the soundness of DPOR, we have to keep a list of 
446      processes which are still enabled at each step of the exploration. 
447      If max depth is reached, we interleave them in the state in which they have 
448      been enabled for the first time. */
449   xbt_swag_foreach(process, simix_global->process_list){
450     if(MC_process_is_enabled(process)){
451       char *key = bprintf("%lu", process->pid);
452       char *data = bprintf("%d", xbt_fifo_size(mc_stack_safety));
453       xbt_dict_set(first_enabled_state, key, data, NULL);
454       xbt_free(key);
455     }
456   }
457
458   MC_UNSET_RAW_MEM;
459
460   if(raw_mem_set)
461     MC_SET_RAW_MEM;
462   else
463     MC_UNSET_RAW_MEM;
464   
465 }
466
467
468 /** \brief Model-check the application using a DFS exploration
469  *         with DPOR (Dynamic Partial Order Reductions)
470  */
471 void MC_dpor(void)
472 {
473
474   char *req_str = NULL;
475   int value;
476   smx_simcall_t req = NULL, prev_req = NULL;
477   mc_state_t state = NULL, prev_state = NULL, next_state = NULL, restored_state=NULL;
478   smx_process_t process = NULL;
479   xbt_fifo_item_t item = NULL;
480   mc_state_t state_test = NULL;
481   int pos;
482   int visited_state = -1;
483   int enabled = 0;
484   int interleave_size = 0;
485   int comm_pattern = 0;
486
487   while (xbt_fifo_size(mc_stack_safety) > 0) {
488
489     /* Get current state */
490     state = (mc_state_t) 
491       xbt_fifo_get_item_content(xbt_fifo_get_first_item(mc_stack_safety));
492
493     XBT_DEBUG("**************************************************");
494     XBT_DEBUG("Exploration depth=%d (state=%p, num %d)(%u interleave, user_max_depth %d, first_enabled_state size : %d)",
495               xbt_fifo_size(mc_stack_safety), state, state->num,
496               MC_state_interleave_size(state), user_max_depth_reached, xbt_dict_size(first_enabled_state));
497       
498     interleave_size = MC_state_interleave_size(state);
499
500     /* Update statistics */
501     mc_stats->visited_states++;
502
503     /* If there are processes to interleave and the maximum depth has not been reached
504        then perform one step of the exploration algorithm */
505     if (xbt_fifo_size(mc_stack_safety) <= _sg_mc_max_depth && !user_max_depth_reached &&
506         (req = MC_state_get_request(state, &value)) && visited_state == -1) {
507
508       /* Debug information */
509       if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
510         req_str = MC_request_to_string(req, value);
511         XBT_DEBUG("Execute: %s", req_str);
512         xbt_free(req_str);
513       }
514       
515       MC_SET_RAW_MEM;
516       if(dot_output != NULL)
517         req_str = MC_request_get_dot_output(req, value);
518       MC_UNSET_RAW_MEM;
519
520       MC_state_set_executed_request(state, req, value);
521       mc_stats->executed_transitions++;
522
523       MC_SET_RAW_MEM;
524       char *key = bprintf("%lu", req->issuer->pid);
525       xbt_dict_remove(first_enabled_state, key); 
526       xbt_free(key);
527       MC_UNSET_RAW_MEM;
528       
529       if(_sg_mc_comms_determinism || _sg_mc_send_determinism){
530         if(req->call == SIMCALL_COMM_ISEND)
531           comm_pattern = 1;
532         else if(req->call == SIMCALL_COMM_IRECV)
533           comm_pattern = 2;
534       }
535
536       /* Answer the request */
537       SIMIX_simcall_pre(req, value); /* After this call req is no longer usefull */
538
539       if(_sg_mc_comms_determinism || _sg_mc_send_determinism){
540         MC_SET_RAW_MEM;
541         if(comm_pattern != 0){
542           if(!initial_state_safety->initial_communications_pattern_done)
543             get_comm_pattern(initial_communications_pattern, req, comm_pattern);
544           else
545             get_comm_pattern(communications_pattern, req, comm_pattern);
546         }
547         MC_UNSET_RAW_MEM; 
548         comm_pattern = 0;
549       }
550
551       /* Wait for requests (schedules processes) */
552       MC_wait_for_requests();
553
554       /* Create the new expanded state */
555       MC_SET_RAW_MEM;
556
557       next_state = MC_state_new();
558
559       if((visited_state = is_visited_state()) == -1){
560      
561         /* Get an enabled process and insert it in the interleave set of the next state */
562         xbt_swag_foreach(process, simix_global->process_list){
563           if(MC_process_is_enabled(process)){
564             MC_state_interleave_process(next_state, process);
565             if(mc_reduce_kind != e_mc_reduce_none)
566               break;
567           }
568         }
569
570         if(_sg_mc_checkpoint && ((xbt_fifo_size(mc_stack_safety) + 1) % _sg_mc_checkpoint == 0)){
571           next_state->system_state = MC_take_snapshot(next_state->num);
572         }
573
574         if(dot_output != NULL)
575           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, next_state->num, req_str);
576
577       }else{
578
579         if(dot_output != NULL)
580           fprintf(dot_output, "\"%d\" -> \"%d\" [%s];\n", state->num, visited_state, req_str);
581
582       }
583
584       xbt_fifo_unshift(mc_stack_safety, next_state);
585
586       /* Insert in dict all enabled processes, if not included yet */
587       xbt_swag_foreach(process, simix_global->process_list){
588         if(MC_process_is_enabled(process)){
589           char *key = bprintf("%lu", process->pid);
590           if(xbt_dict_get_or_null(first_enabled_state, key) == NULL){
591             char *data = bprintf("%d", xbt_fifo_size(mc_stack_safety));
592             xbt_dict_set(first_enabled_state, key, data, NULL); 
593           }
594           xbt_free(key);
595         }
596       }
597       
598       if(dot_output != NULL)
599         xbt_free(req_str);
600
601       MC_UNSET_RAW_MEM;
602
603       /* Let's loop again */
604
605       /* The interleave set is empty or the maximum depth is reached, let's back-track */
606     } else {
607
608       if((xbt_fifo_size(mc_stack_safety) > _sg_mc_max_depth) || user_max_depth_reached || visited_state != -1){  
609
610         if(user_max_depth_reached && visited_state == -1)
611           XBT_DEBUG("User max depth reached !");
612         else if(visited_state == -1)
613           XBT_WARN("/!\\ Max depth reached ! /!\\ ");
614
615         visited_state = -1;
616
617         /* Interleave enabled processes in the state in which they have been enabled for the first time */
618         xbt_swag_foreach(process, simix_global->process_list){
619           if(MC_process_is_enabled(process)){
620             char *key = bprintf("%lu", process->pid);
621             enabled = (int)strtoul(xbt_dict_get_or_null(first_enabled_state, key), 0, 10);
622             xbt_free(key);
623             int cursor = xbt_fifo_size(mc_stack_safety);
624             xbt_fifo_foreach(mc_stack_safety, item, state_test, mc_state_t){
625               if(cursor-- == enabled){ 
626                 if(!MC_state_process_is_done(state_test, process) && state_test->num != state->num){ 
627                   XBT_DEBUG("Interleave process %lu in state %d", process->pid, state_test->num);
628                   MC_state_interleave_process(state_test, process);
629                   break;
630                 }
631               }
632             }
633           }
634         }
635
636       }else{
637
638         XBT_DEBUG("There are no more processes to interleave. (depth %d)", xbt_fifo_size(mc_stack_safety) + 1);
639
640       }
641
642       MC_SET_RAW_MEM;
643
644       if(_sg_mc_comms_determinism || _sg_mc_send_determinism){
645         if(initial_state_safety->initial_communications_pattern_done){
646           if(interleave_size == 0){ /* if (interleave_size > 0), process interleaved but not enabled => "incorrect" path, determinism not evaluated */
647             //print_communications_pattern(communications_pattern);
648             deterministic_pattern(initial_communications_pattern, communications_pattern);
649             if(initial_state_safety->comm_deterministic == 0 && _sg_mc_comms_determinism){
650               XBT_INFO("****************************************************");
651               XBT_INFO("***** Non-deterministic communications pattern *****");
652               XBT_INFO("****************************************************");
653               XBT_INFO("Initial communications pattern:");
654               print_communications_pattern(initial_communications_pattern);
655               XBT_INFO("Communications pattern counter-example:");
656               print_communications_pattern(communications_pattern);
657               MC_print_statistics(mc_stats);
658               return;
659             }else if(initial_state_safety->send_deterministic == 0 && _sg_mc_send_determinism){
660               XBT_INFO("****************************************************");
661               XBT_INFO("***** Non-send-deterministic communications pattern *****");
662               XBT_INFO("****************************************************");
663               XBT_INFO("Initial communications pattern:");
664               print_communications_pattern(initial_communications_pattern);
665               XBT_INFO("Communications pattern counter-example:");
666               print_communications_pattern(communications_pattern);
667               MC_print_statistics(mc_stats);
668               return;
669             }
670           }
671         }else{
672           initial_state_safety->initial_communications_pattern_done = 1;
673         }
674       }
675
676       /* Trash the current state, no longer needed */
677       xbt_fifo_shift(mc_stack_safety);
678       MC_state_delete(state);
679       XBT_DEBUG("Delete state %d at depth %d", state->num, xbt_fifo_size(mc_stack_safety) + 1);
680
681       MC_UNSET_RAW_MEM;        
682       
683       /* Check for deadlocks */
684       if(MC_deadlock_check()){
685         MC_show_deadlock(NULL);
686         return;
687       }
688
689       MC_SET_RAW_MEM;
690       /* Traverse the stack backwards until a state with a non empty interleave
691          set is found, deleting all the states that have it empty in the way.
692          For each deleted state, check if the request that has generated it 
693          (from it's predecesor state), depends on any other previous request 
694          executed before it. If it does then add it to the interleave set of the
695          state that executed that previous request. */
696       
697       while ((state = xbt_fifo_shift(mc_stack_safety)) != NULL) {
698         if(mc_reduce_kind != e_mc_reduce_none){
699           req = MC_state_get_internal_request(state);
700           xbt_fifo_foreach(mc_stack_safety, item, prev_state, mc_state_t) {
701             if(MC_request_depend(req, MC_state_get_internal_request(prev_state))){
702               if(XBT_LOG_ISENABLED(mc_dpor, xbt_log_priority_debug)){
703                 XBT_DEBUG("Dependent Transitions:");
704                 prev_req = MC_state_get_executed_request(prev_state, &value);
705                 req_str = MC_request_to_string(prev_req, value);
706                 XBT_DEBUG("%s (state=%d)", req_str, prev_state->num);
707                 xbt_free(req_str);
708                 prev_req = MC_state_get_executed_request(state, &value);
709                 req_str = MC_request_to_string(prev_req, value);
710                 XBT_DEBUG("%s (state=%d)", req_str, state->num);
711                 xbt_free(req_str);              
712               }
713
714               if(!MC_state_process_is_done(prev_state, req->issuer))
715                 MC_state_interleave_process(prev_state, req->issuer);
716               else
717                 XBT_DEBUG("Process %p is in done set", req->issuer);
718
719               break;
720
721             }else if(req->issuer == MC_state_get_internal_request(prev_state)->issuer){
722
723               XBT_DEBUG("Simcall %d and %d with same issuer", req->call, MC_state_get_internal_request(prev_state)->call);
724               break;
725
726             }else{
727
728               XBT_DEBUG("Simcall %d, process %lu (state %d) and simcall %d, process %lu (state %d) are independant", req->call, req->issuer->pid, state->num, MC_state_get_internal_request(prev_state)->call, MC_state_get_internal_request(prev_state)->issuer->pid, prev_state->num);
729
730             }
731           }
732         }
733              
734         if (MC_state_interleave_size(state) && xbt_fifo_size(mc_stack_safety) < _sg_mc_max_depth) {
735           /* We found a back-tracking point, let's loop */
736           XBT_DEBUG("Back-tracking to state %d at depth %d", state->num, xbt_fifo_size(mc_stack_safety) + 1);
737           if(_sg_mc_checkpoint){
738             if(state->system_state != NULL){
739               MC_restore_snapshot(state->system_state);
740               xbt_fifo_unshift(mc_stack_safety, state);
741               MC_UNSET_RAW_MEM;
742             }else{
743               pos = xbt_fifo_size(mc_stack_safety);
744               item = xbt_fifo_get_first_item(mc_stack_safety);
745               while(pos>0){
746                 restored_state = (mc_state_t) xbt_fifo_get_item_content(item);
747                 if(restored_state->system_state != NULL){
748                   break;
749                 }else{
750                   item = xbt_fifo_get_next_item(item);
751                   pos--;
752                 }
753               }
754               MC_restore_snapshot(restored_state->system_state);
755               xbt_fifo_unshift(mc_stack_safety, state);
756               MC_UNSET_RAW_MEM;
757               MC_replay(mc_stack_safety, pos);
758             }
759           }else{
760             xbt_fifo_unshift(mc_stack_safety, state);
761             MC_UNSET_RAW_MEM;
762             MC_replay(mc_stack_safety, -1);
763           }
764           XBT_DEBUG("Back-tracking to state %d at depth %d done", state->num, xbt_fifo_size(mc_stack_safety));
765           break;
766         } else {
767           req = MC_state_get_internal_request(state);
768           if(_sg_mc_comms_determinism){
769             if(req->call == SIMCALL_COMM_ISEND || req->call == SIMCALL_COMM_IRECV){
770               if(!xbt_dynar_is_empty(communications_pattern))
771                 xbt_dynar_remove_at(communications_pattern, xbt_dynar_length(communications_pattern) - 1, NULL);
772             }
773           }
774           XBT_DEBUG("Delete state %d at depth %d", state->num, xbt_fifo_size(mc_stack_safety) + 1); 
775           MC_state_delete(state);
776         }
777       }
778       MC_UNSET_RAW_MEM;
779     }
780   }
781   MC_print_statistics(mc_stats);
782   MC_UNSET_RAW_MEM;  
783
784   return;
785 }
786
787
788
789