2 /* Copyright (c) 2010. The SimGrid Team.
3 * All rights reserved. */
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. */
11 #include "xbt/asserts.h"
12 #include "simgrid/modelchecker.h"
13 #include "chord_liveness.h"
16 /** @addtogroup MSG_examples
18 * - <b>chord/chord.c: Classical Chord P2P protocol</b>
19 * This example implements the well known Chord P2P protocol. Its
20 * main advantage is that it constitute a fully working non-trivial
21 * example. In addition, its implementation is rather efficient, as
22 * demonstrated in http://hal.inria.fr/inria-00602216/
26 XBT_LOG_NEW_DEFAULT_CATEGORY(chord_liveness,
27 "Messages specific for this example");
31 #define MAILBOX_NAME_SIZE 10
33 static int nb_bits = 24;
34 static int nb_keys = 0;
35 static int timeout = 50;
36 static int max_simulation_time = 1000;
37 static int periodic_stabilize_delay = 20;
38 static int periodic_fix_fingers_delay = 120;
39 static int periodic_check_predecessor_delay = 120;
40 static int periodic_lookup_delay = 10;
42 //extern long int smx_total_comms;
47 typedef struct s_finger {
49 char mailbox[MAILBOX_NAME_SIZE]; // string representation of the id
50 } s_finger_t, *finger_t;
55 typedef struct s_node {
57 char mailbox[MAILBOX_NAME_SIZE]; // my mailbox name (string representation of the id)
58 s_finger_t *fingers; // finger table, of size nb_bits (fingers[0] is my successor)
59 int pred_id; // predecessor id
60 char pred_mailbox[MAILBOX_NAME_SIZE]; // predecessor's mailbox name
61 int next_finger_to_fix; // index of the next finger to fix in fix_fingers()
62 msg_comm_t comm_receive; // current communication to receive
63 double last_change_date; // last time I changed a finger or my predecessor
67 * Types of tasks exchanged between nodes.
71 TASK_FIND_SUCCESSOR_ANSWER,
73 TASK_GET_PREDECESSOR_ANSWER,
75 TASK_SUCCESSOR_LEAVING,
76 TASK_PREDECESSOR_LEAVING
80 * Data attached with the tasks sent and received
82 typedef struct s_task_data {
83 e_task_type_t type; // type of task
84 int request_id; // id paramater (used by some types of tasks)
85 int request_finger; // finger parameter (used by some types of tasks)
86 int answer_id; // answer (used by some types of tasks)
87 char answer_to[MAILBOX_NAME_SIZE]; // mailbox to send an answer to (if any)
88 const char* issuer_host_name; // used for logging
89 } s_task_data_t, *task_data_t;
94 static void chord_initialize(void);
95 static void chord_exit(void);
96 static int normalize(int id);
97 static int is_in_interval(int id, int start, int end);
98 static void get_mailbox(int host_id, char* mailbox);
99 static void task_free(void* task);
100 static void print_finger_table(node_t node);
101 static void set_finger(node_t node, int finger_index, int id);
102 static void set_predecessor(node_t node, int predecessor_id);
105 static int node(int argc, char *argv[]);
106 static void handle_task(node_t node, msg_task_t task);
109 static void create(node_t node);
110 static int join(node_t node, int known_id);
111 static void leave(node_t node);
112 static int find_successor(node_t node, int id);
113 static int remote_find_successor(node_t node, int ask_to_id, int id);
114 static int remote_get_predecessor(node_t node, int ask_to_id);
115 static int closest_preceding_node(node_t node, int id);
116 static void stabilize(node_t node);
117 static void notify(node_t node, int predecessor_candidate_id);
118 static void remote_notify(node_t node, int notify_to, int predecessor_candidate_id);
119 static void fix_fingers(node_t node);
120 static void check_predecessor(node_t node);
121 static void random_lookup(node_t);
122 static void quit_notify(node_t node);
124 /* Global variable corresponding to atomic proposition */
128 * \brief Global initialization of the Chord simulation.
130 static void chord_initialize(void)
132 // compute the powers of 2 once for all
133 powers2 = xbt_new(int, nb_bits);
136 for (i = 0; i < nb_bits; i++) {
141 XBT_DEBUG("Sets nb_keys to %d", nb_keys);
144 static void chord_exit(void)
150 * \brief Turns an id into an equivalent id in [0, nb_keys).
152 * \return the corresponding normalized id
154 static int normalize(int id)
156 // like id % nb_keys, but works with negatives numbers (and faster)
157 return id & (nb_keys - 1);
161 * \brief Returns whether an id belongs to the interval [start, end].
163 * The parameters are noramlized to make sure they are between 0 and nb_keys - 1).
164 * 1 belongs to [62, 3]
165 * 1 does not belong to [3, 62]
166 * 63 belongs to [62, 3]
167 * 63 does not belong to [3, 62]
168 * 24 belongs to [21, 29]
169 * 24 does not belong to [29, 21]
171 * \param id id to check
172 * \param start lower bound
173 * \param end upper bound
174 * \return a non-zero value if id in in [start, end]
176 static int is_in_interval(int id, int start, int end)
179 start = normalize(start);
180 end = normalize(end);
182 // make sure end >= start and id >= start
195 * \brief Gets the mailbox name of a host given its chord id.
196 * \param node_id id of a node
197 * \param mailbox pointer to where the mailbox name should be written
198 * (there must be enough space)
200 static void get_mailbox(int node_id, char* mailbox)
202 snprintf(mailbox, MAILBOX_NAME_SIZE - 1, "%d", node_id);
206 * \brief Frees the memory used by a task.
207 * \param task the MSG task to destroy
209 static void task_free(void* task)
211 // TODO add a parameter data_free_function to MSG_task_create?
212 xbt_free(MSG_task_get_data(task));
213 MSG_task_destroy(task);
218 * \brief Displays the finger table of a node.
221 static void print_finger_table(node_t node)
223 if (XBT_LOG_ISENABLED(chord_liveness, xbt_log_priority_verbose)) {
225 XBT_VERB("My finger table:");
226 XBT_VERB("Start | Succ ");
227 for (i = 0; i < nb_bits; i++) {
228 XBT_VERB(" %3d | %3d ", (node->id + powers2[i]) % nb_keys, node->fingers[i].id);
230 XBT_VERB("Predecessor: %d", node->pred_id);
235 * \brief Sets a finger of the current node.
236 * \param node the current node
237 * \param finger_index index of the finger to set (0 to nb_bits - 1)
238 * \param id the id to set for this finger
240 static void set_finger(node_t node, int finger_index, int id)
242 if (id != node->fingers[finger_index].id) {
243 node->fingers[finger_index].id = id;
244 get_mailbox(id, node->fingers[finger_index].mailbox);
245 node->last_change_date = MSG_get_clock();
246 XBT_DEBUG("My new finger #%d is %d", finger_index, id);
251 * \brief Sets the predecessor of the current node.
252 * \param node the current node
253 * \param id the id to predecessor, or -1 to unset the predecessor
255 static void set_predecessor(node_t node, int predecessor_id)
257 if (predecessor_id != node->pred_id) {
258 node->pred_id = predecessor_id;
260 if (predecessor_id != -1) {
261 get_mailbox(predecessor_id, node->pred_mailbox);
263 node->last_change_date = MSG_get_clock();
265 XBT_DEBUG("My new predecessor is %d", predecessor_id);
270 * \brief Node Function
273 * - the id of a guy I know in the system (except for the first node)
274 * - the time to sleep before I join (except for the first node)
276 int node(int argc, char *argv[])
278 /* Reduce the run size for the MC */
280 periodic_stabilize_delay = 8;
281 periodic_fix_fingers_delay = 8;
282 periodic_check_predecessor_delay = 8;
285 double init_time = MSG_get_clock();
286 msg_task_t task_received = NULL;
288 int join_success = 0;
290 double next_stabilize_date = init_time + periodic_stabilize_delay;
291 double next_fix_fingers_date = init_time + periodic_fix_fingers_delay;
292 double next_check_predecessor_date = init_time + periodic_check_predecessor_delay;
293 double next_lookup_date = init_time + periodic_lookup_delay;
295 xbt_assert(argc == 3 || argc == 5, "Wrong number of arguments for this node");
297 // initialize my node
299 node.id = atoi(argv[1]);
300 get_mailbox(node.id, node.mailbox);
301 node.next_finger_to_fix = 0;
302 node.fingers = xbt_new0(s_finger_t, nb_bits);
303 node.last_change_date = init_time;
305 for (i = 0; i < nb_bits; i++) {
306 node.fingers[i].id = -1;
307 set_finger(&node, i, node.id);
310 if (argc == 3) { // first ring
311 deadline = atof(argv[2]);
316 int known_id = atoi(argv[2]);
317 //double sleep_time = atof(argv[3]);
318 deadline = atof(argv[4]);
321 // sleep before starting
322 XBT_DEBUG("Let's sleep during %f", sleep_time);
323 MSG_process_sleep(sleep_time);
325 XBT_DEBUG("Hey! Let's join the system.");
327 join_success = join(&node, known_id);
330 XBT_INFO("Node %d joined the ring", node.id);
338 while (MSG_get_clock() < init_time + deadline
339 // && MSG_get_clock() < node.last_change_date + 1000
340 && MSG_get_clock() < max_simulation_time) {
342 if (node.comm_receive == NULL) {
343 task_received = NULL;
344 node.comm_receive = MSG_task_irecv(&task_received, node.mailbox);
345 // FIXME: do not make MSG_task_irecv() calls from several functions
348 if (!MSG_comm_test(node.comm_receive)) {
350 // no task was received: make some periodic calls
351 if (MSG_get_clock() >= next_stabilize_date) {
353 next_stabilize_date = MSG_get_clock() + periodic_stabilize_delay;
355 else if (MSG_get_clock() >= next_fix_fingers_date) {
357 next_fix_fingers_date = MSG_get_clock() + periodic_fix_fingers_delay;
359 else if (MSG_get_clock() >= next_check_predecessor_date) {
360 check_predecessor(&node);
361 next_check_predecessor_date = MSG_get_clock() + periodic_check_predecessor_delay;
363 else if (MSG_get_clock() >= next_lookup_date) {
364 random_lookup(&node);
365 next_lookup_date = MSG_get_clock() + periodic_lookup_delay;
368 // nothing to do: sleep for a while
369 MSG_process_sleep(5);
373 if (node.comm_receive) {
375 XBT_INFO("A transfer has occured");
379 // a transfer has occured
381 msg_error_t status = MSG_comm_get_status(node.comm_receive);
383 if (status != MSG_OK) {
384 XBT_INFO("Failed to receive a task. Nevermind.");
385 MSG_comm_destroy(node.comm_receive);
386 node.comm_receive = NULL;
389 // the task was successfully received
390 XBT_INFO("The task was successfully received by node %d", node.id);
391 MSG_comm_destroy(node.comm_receive);
392 node.comm_receive = NULL;
393 handle_task(&node, task_received);
399 if (node.comm_receive) {
400 MSG_comm_destroy(node.comm_receive);
401 node.comm_receive = NULL;
408 // stop the simulation
409 xbt_free(node.fingers);
414 * \brief This function is called when the current node receives a task.
415 * \param node the current node
416 * \param task the task to handle (don't touch it then:
417 * it will be destroyed, reused or forwarded)
419 static void handle_task(node_t node, msg_task_t task) {
421 XBT_DEBUG("Handling task %p", task);
422 char mailbox[MAILBOX_NAME_SIZE];
423 task_data_t task_data = (task_data_t) MSG_task_get_data(task);
424 e_task_type_t type = task_data->type;
428 case TASK_FIND_SUCCESSOR:
429 XBT_DEBUG("Receiving a 'Find Successor' request from %s for id %d",
430 task_data->issuer_host_name, task_data->request_id);
431 // is my successor the successor?
432 if (is_in_interval(task_data->request_id, node->id + 1, node->fingers[0].id)) {
433 task_data->type = TASK_FIND_SUCCESSOR_ANSWER;
434 task_data->answer_id = node->fingers[0].id;
435 XBT_DEBUG("Sending back a 'Find Successor Answer' to %s (mailbox %s): the successor of %d is %d",
436 task_data->issuer_host_name,
437 task_data->answer_to,
438 task_data->request_id, task_data->answer_id);
439 MSG_task_dsend(task, task_data->answer_to, task_free);
442 // otherwise, forward the request to the closest preceding finger in my table
443 int closest = closest_preceding_node(node, task_data->request_id);
444 XBT_DEBUG("Forwarding the 'Find Successor' request for id %d to my closest preceding finger %d",
445 task_data->request_id, closest);
446 get_mailbox(closest, mailbox);
447 MSG_task_dsend(task, mailbox, task_free);
451 case TASK_GET_PREDECESSOR:
452 XBT_DEBUG("Receiving a 'Get Predecessor' request from %s", task_data->issuer_host_name);
453 task_data->type = TASK_GET_PREDECESSOR_ANSWER;
454 task_data->answer_id = node->pred_id;
455 XBT_DEBUG("Sending back a 'Get Predecessor Answer' to %s via mailbox '%s': my predecessor is %d",
456 task_data->issuer_host_name,
457 task_data->answer_to, task_data->answer_id);
458 MSG_task_dsend(task, task_data->answer_to, task_free);
462 // someone is telling me that he may be my new predecessor
463 XBT_DEBUG("Receiving a 'Notify' request from %s", task_data->issuer_host_name);
464 notify(node, task_data->request_id);
468 case TASK_PREDECESSOR_LEAVING:
469 // my predecessor is about to quit
470 XBT_DEBUG("Receiving a 'Predecessor Leaving' message from %s", task_data->issuer_host_name);
471 // modify my predecessor
472 set_predecessor(node, task_data->request_id);
475 >> notify my new predecessor
476 >> send a notify_predecessors !!
480 case TASK_SUCCESSOR_LEAVING:
481 // my successor is about to quit
482 XBT_DEBUG("Receiving a 'Successor Leaving' message from %s", task_data->issuer_host_name);
483 // modify my successor FIXME : this should be implicit ?
484 set_finger(node, 0, task_data->request_id);
487 >> notify my new successor
488 >> update my table & predecessors table */
491 case TASK_FIND_SUCCESSOR_ANSWER:
492 case TASK_GET_PREDECESSOR_ANSWER:
493 XBT_DEBUG("Ignoring unexpected task of type %d (%p)", (int)type, task);
500 * \brief Initializes the current node as the first one of the system.
501 * \param node the current node
503 static void create(node_t node)
505 XBT_DEBUG("Create a new Chord ring...");
506 set_predecessor(node, -1); // -1 means that I have no predecessor
507 print_finger_table(node);
511 * \brief Makes the current node join the ring, knowing the id of a node
512 * already in the ring
513 * \param node the current node
514 * \param known_id id of a node already in the ring
515 * \return 1 if the join operation succeeded, 0 otherwise
517 static int join(node_t node, int known_id)
519 XBT_INFO("Joining the ring with id %d, knowing node %d", node->id, known_id);
520 set_predecessor(node, -1); // no predecessor (yet)
524 for (i = 0; i < nb_bits; i++) {
525 set_finger(node, i, known_id);
529 int successor_id = remote_find_successor(node, known_id, node->id);
530 if (successor_id == -1) {
531 XBT_INFO("Cannot join the ring.");
534 set_finger(node, 0, successor_id);
535 print_finger_table(node);
538 return successor_id != -1;
542 * \brief Makes the current node quit the system
543 * \param node the current node
545 static void leave(node_t node)
547 XBT_DEBUG("Well Guys! I Think it's time for me to quit ;)");
552 * \brief Notifies the successor and the predecessor of the current node
554 * \param node the current node
556 static void quit_notify(node_t node)
558 char mailbox[MAILBOX_NAME_SIZE];
559 //send the PREDECESSOR_LEAVING to our successor
560 task_data_t req_data = xbt_new0(s_task_data_t,1);
561 req_data->type = TASK_PREDECESSOR_LEAVING;
562 req_data->request_id = node->pred_id;
563 get_mailbox(node->id, req_data->answer_to);
564 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
566 msg_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
567 XBT_DEBUG("Sending a 'PREDECESSOR_LEAVING' to my successor %d",node->fingers[0].id);
568 MSG_task_send_with_timeout(task_sent, node->fingers[0].mailbox, timeout);
570 //send the SUCCESSOR_LEAVING to our predecessor
571 get_mailbox(node->pred_id, mailbox);
572 task_data_t req_data_s = xbt_new0(s_task_data_t,1);
573 req_data_s->type = TASK_SUCCESSOR_LEAVING;
574 req_data_s->request_id = node->fingers[0].id;
575 req_data_s->request_id = node->pred_id;
576 get_mailbox(node->id, req_data_s->answer_to);
577 req_data_s->issuer_host_name = MSG_host_get_name(MSG_host_self());
579 msg_task_t task_sent_s = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data_s);
580 XBT_DEBUG("Sending a 'SUCCESSOR_LEAVING' to my predecessor %d",node->pred_id);
581 MSG_task_send_with_timeout(task_sent_s, mailbox, timeout);
586 * \brief Makes the current node find the successor node of an id.
587 * \param node the current node
588 * \param id the id to find
589 * \return the id of the successor node, or -1 if the request failed
591 static int find_successor(node_t node, int id)
593 // is my successor the successor?
594 if (is_in_interval(id, node->id + 1, node->fingers[0].id)) {
595 return node->fingers[0].id;
598 // otherwise, ask the closest preceding finger in my table
599 int closest = closest_preceding_node(node, id);
600 return remote_find_successor(node, closest, id);
604 * \brief Asks another node the successor node of an id.
605 * \param node the current node
606 * \param ask_to the node to ask to
607 * \param id the id to find
608 * \return the id of the successor node, or -1 if the request failed
610 static int remote_find_successor(node_t node, int ask_to, int id)
614 char mailbox[MAILBOX_NAME_SIZE];
615 get_mailbox(ask_to, mailbox);
616 task_data_t req_data = xbt_new0(s_task_data_t, 1);
617 req_data->type = TASK_FIND_SUCCESSOR;
618 req_data->request_id = id;
619 get_mailbox(node->id, req_data->answer_to);
620 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
622 // send a "Find Successor" request to ask_to_id
623 msg_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
624 XBT_DEBUG("Sending a 'Find Successor' request (task %p) to %d for id %d", task_sent, ask_to, id);
625 msg_error_t res = MSG_task_send_with_timeout(task_sent, mailbox, timeout);
628 XBT_DEBUG("Failed to send the 'Find Successor' request (task %p) to %d for id %d",
629 task_sent, ask_to, id);
630 task_free(task_sent);
634 // receive the answer
635 XBT_DEBUG("Sent a 'Find Successor' request (task %p) to %d for key %d, waiting for the answer",
636 task_sent, ask_to, id);
639 if (node->comm_receive == NULL) {
640 msg_task_t task_received = NULL;
641 node->comm_receive = MSG_task_irecv(&task_received, node->mailbox);
644 res = MSG_comm_wait(node->comm_receive, timeout);
647 XBT_DEBUG("Failed to receive the answer to my 'Find Successor' request (task %p): %d",
648 task_sent, (int)res);
650 MSG_comm_destroy(node->comm_receive);
651 node->comm_receive = NULL;
654 msg_task_t task_received = MSG_comm_get_task(node->comm_receive);
655 XBT_DEBUG("Received a task (%p)", task_received);
656 task_data_t ans_data = MSG_task_get_data(task_received);
658 if (MC_is_active()) {
659 // the model-checker is expected to find a counter-example here.
661 // As you can see in the test right below, task_received is not always equal to task_sent
662 // (as messages from differing round can interleave). But the previous version of this code
663 // wrongly assumed that, leading to problems. But this only occured on large platforms,
664 // leading to hardly usable traces. So we used the model-checker to track down the issue,
665 // and we came down to this test, that explained the bug in a snap.
666 //MC_assert(task_received == task_sent);
669 if (task_received != task_sent) {
670 // this is not the expected answer
671 MSG_comm_destroy(node->comm_receive);
672 node->comm_receive = NULL;
673 handle_task(node, task_received);
676 // this is our answer
677 XBT_DEBUG("Received the answer to my 'Find Successor' request for id %d (task %p): the successor of key %d is %d",
678 ans_data->request_id, task_received, id, ans_data->answer_id);
679 successor = ans_data->answer_id;
681 MSG_comm_destroy(node->comm_receive);
682 node->comm_receive = NULL;
683 task_free(task_received);
693 * \brief Asks another node its predecessor.
694 * \param node the current node
695 * \param ask_to the node to ask to
696 * \return the id of its predecessor node, or -1 if the request failed
697 * (or if the node does not know its predecessor)
699 static int remote_get_predecessor(node_t node, int ask_to)
701 int predecessor_id = -1;
703 char mailbox[MAILBOX_NAME_SIZE];
704 get_mailbox(ask_to, mailbox);
705 task_data_t req_data = xbt_new0(s_task_data_t, 1);
706 req_data->type = TASK_GET_PREDECESSOR;
707 get_mailbox(node->id, req_data->answer_to);
708 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
710 // send a "Get Predecessor" request to ask_to_id
711 XBT_DEBUG("Sending a 'Get Predecessor' request to %d", ask_to);
712 msg_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
713 msg_error_t res = MSG_task_send_with_timeout(task_sent, mailbox, timeout);
716 XBT_DEBUG("Failed to send the 'Get Predecessor' request (task %p) to %d",
718 task_free(task_sent);
722 // receive the answer
723 XBT_DEBUG("Sent 'Get Predecessor' request (task %p) to %d, waiting for the answer on my mailbox '%s'",
724 task_sent, ask_to, req_data->answer_to);
727 if (node->comm_receive == NULL) { // FIXME simplify this
728 msg_task_t task_received = NULL;
729 node->comm_receive = MSG_task_irecv(&task_received, node->mailbox);
732 res = MSG_comm_wait(node->comm_receive, timeout);
735 XBT_DEBUG("Failed to receive the answer to my 'Get Predecessor' request (task %p): %d",
736 task_sent, (int)res);
738 MSG_comm_destroy(node->comm_receive);
739 node->comm_receive = NULL;
742 msg_task_t task_received = MSG_comm_get_task(node->comm_receive);
743 task_data_t ans_data = MSG_task_get_data(task_received);
745 /*if (MC_is_active()) {
746 MC_assert(task_received == task_sent);
749 if (task_received != task_sent) {
750 MSG_comm_destroy(node->comm_receive);
751 node->comm_receive = NULL;
752 handle_task(node, task_received);
755 XBT_DEBUG("Received the answer to my 'Get Predecessor' request (task %p): the predecessor of node %d is %d",
756 task_received, ask_to, ans_data->answer_id);
757 predecessor_id = ans_data->answer_id;
759 MSG_comm_destroy(node->comm_receive);
760 node->comm_receive = NULL;
761 task_free(task_received);
767 return predecessor_id;
771 * \brief Returns the closest preceding finger of an id
772 * with respect to the finger table of the current node.
773 * \param node the current node
774 * \param id the id to find
775 * \return the closest preceding finger of that id
777 int closest_preceding_node(node_t node, int id)
780 for (i = nb_bits - 1; i >= 0; i--) {
781 if (is_in_interval(node->fingers[i].id, node->id + 1, id - 1)) {
782 return node->fingers[i].id;
789 * \brief This function is called periodically. It checks the immediate
790 * successor of the current node.
791 * \param node the current node
793 static void stabilize(node_t node)
795 XBT_DEBUG("Stabilizing node");
797 // get the predecessor of my immediate successor
799 int successor_id = node->fingers[0].id;
800 if (successor_id != node->id) {
801 candidate_id = remote_get_predecessor(node, successor_id);
804 candidate_id = node->pred_id;
807 // this node is a candidate to become my new successor
808 if (candidate_id != -1
809 && is_in_interval(candidate_id, node->id + 1, successor_id - 1)) {
810 set_finger(node, 0, candidate_id);
812 if (successor_id != node->id) {
813 remote_notify(node, successor_id, node->id);
818 * \brief Notifies the current node that its predecessor may have changed.
819 * \param node the current node
820 * \param candidate_id the possible new predecessor
822 static void notify(node_t node, int predecessor_candidate_id) {
824 if (node->pred_id == -1
825 || is_in_interval(predecessor_candidate_id, node->pred_id + 1, node->id - 1)) {
827 set_predecessor(node, predecessor_candidate_id);
828 print_finger_table(node);
831 XBT_DEBUG("I don't have to change my predecessor to %d", predecessor_candidate_id);
836 * \brief Notifies a remote node that its predecessor may have changed.
837 * \param node the current node
838 * \param notify_id id of the node to notify
839 * \param candidate_id the possible new predecessor
841 static void remote_notify(node_t node, int notify_id, int predecessor_candidate_id) {
843 task_data_t req_data = xbt_new0(s_task_data_t, 1);
844 req_data->type = TASK_NOTIFY;
845 req_data->request_id = predecessor_candidate_id;
846 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
848 // send a "Notify" request to notify_id
849 msg_task_t task = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
850 XBT_DEBUG("Sending a 'Notify' request (task %p) to %d", task, notify_id);
851 char mailbox[MAILBOX_NAME_SIZE];
852 get_mailbox(notify_id, mailbox);
853 MSG_task_dsend(task, mailbox, task_free);
857 * \brief This function is called periodically.
858 * It refreshes the finger table of the current node.
859 * \param node the current node
861 static void fix_fingers(node_t node) {
863 XBT_DEBUG("Fixing fingers");
864 int i = node->next_finger_to_fix;
865 int id = find_successor(node, node->id + powers2[i]);
868 if (id != node->fingers[i].id) {
869 set_finger(node, i, id);
870 print_finger_table(node);
872 node->next_finger_to_fix = (i + 1) % nb_bits;
877 * \brief This function is called periodically.
878 * It checks whether the predecessor has failed
879 * \param node the current node
881 static void check_predecessor(node_t node)
883 XBT_DEBUG("Checking whether my predecessor is alive");
888 * \brief Performs a find successor request to a random id.
889 * \param node the current node
891 static void random_lookup(node_t node)
893 int id = 1337; // TODO pick a pseudorandom id
894 XBT_DEBUG("Making a lookup request for id %d", id);
895 find_successor(node, id);
904 * \brief Main function.
906 int main(int argc, char *argv[])
908 MSG_init(&argc, argv);
910 printf("Usage: %s [-nb_bits=n] [-timeout=t] platform_file deployment_file\n", argv[0]);
911 printf("example: %s ../msg_platform.xml chord.xml\n", argv[0]);
915 char **options = &argv[0];
916 while (!strncmp(options[0], "-", 1)) {
918 int length = strlen("-nb_bits=");
919 if (!strncmp(options[0], "-nb_bits=", length) && strlen(options[0]) > length) {
920 nb_bits = atoi(options[0] + length);
921 XBT_DEBUG("Set nb_bits to %d", nb_bits);
925 length = strlen("-timeout=");
926 if (!strncmp(options[0], "-timeout=", length) && strlen(options[0]) > length) {
927 timeout = atoi(options[0] + length);
928 XBT_DEBUG("Set timeout to %d", timeout);
931 xbt_die("Invalid chord option '%s'", options[0]);
937 //const char* platform_file = options[0];
938 //const char* application_file = options[1];
942 MSG_config("model-check/property","promela_chord_liveness");
943 MC_automaton_new_propositional_symbol("join", &predJoin);
945 MSG_create_environment("../../msg_platform.xml");
947 MSG_function_register("node", node);
948 MSG_launch_application("deploy_chord_liveness.xml");
950 msg_error_t res = MSG_main();
951 //XBT_CRITICAL("Messages created: %ld", smx_total_comms);
952 XBT_INFO("Simulated time: %g", MSG_get_clock());