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"
14 XBT_LOG_NEW_DEFAULT_CATEGORY(msg_chord,
15 "Messages specific for this msg example");
19 #define MAILBOX_NAME_SIZE 10
21 static int nb_bits = 24;
22 static int nb_keys = 0;
23 static int timeout = 50;
24 static int max_simulation_time = 1000;
25 static int periodic_stabilize_delay = 20;
26 static int periodic_fix_fingers_delay = 120;
27 static int periodic_check_predecessor_delay = 120;
28 static int periodic_lookup_delay = 10;
33 typedef struct finger {
35 char mailbox[MAILBOX_NAME_SIZE]; // string representation of the id
36 } s_finger_t, *finger_t;
43 char mailbox[MAILBOX_NAME_SIZE]; // my mailbox name (string representation of the id)
44 s_finger_t *fingers; // finger table, of size nb_bits (fingers[0] is my successor)
45 int pred_id; // predecessor id
46 char pred_mailbox[MAILBOX_NAME_SIZE]; // predecessor's mailbox name
47 int next_finger_to_fix; // index of the next finger to fix in fix_fingers()
48 msg_comm_t comm_receive; // current communication to receive
49 xbt_dynar_t comms; // current communications being sent
50 double last_change_date; // last time I changed a finger or my predecessor
54 * Types of tasks exchanged between nodes.
58 TASK_FIND_SUCCESSOR_ANSWER,
60 TASK_GET_PREDECESSOR_ANSWER,
62 TASK_SUCCESSOR_LEAVING,
63 TASK_PREDECESSOR_LEAVING
67 * Data attached with the tasks sent and received
69 typedef struct task_data {
70 e_task_type_t type; // type of task
71 int request_id; // id paramater (used by some types of tasks)
72 int request_finger; // finger parameter (used by some types of tasks)
73 int answer_id; // answer (used by some types of tasks)
74 char answer_to[MAILBOX_NAME_SIZE]; // mailbox to send an answer to (if any)
75 const char* issuer_host_name; // used for logging
76 } s_task_data_t, *task_data_t;
81 static void chord_initialize(void);
82 static int normalize(int id);
83 static int is_in_interval(int id, int start, int end);
84 static void get_mailbox(int host_id, char* mailbox);
85 static void task_data_destroy(task_data_t task_data);
86 static void print_finger_table(node_t node);
87 static void set_finger(node_t node, int finger_index, int id);
88 static void set_predecessor(node_t node, int predecessor_id);
91 static int node(int argc, char *argv[]);
92 static void handle_task(node_t node, msg_task_t task);
95 static void create(node_t node);
96 static int join(node_t node, int known_id);
97 static void leave(node_t node);
98 static int find_successor(node_t node, int id);
99 static int remote_find_successor(node_t node, int ask_to_id, int id);
100 static int remote_get_predecessor(node_t node, int ask_to_id);
101 static int closest_preceding_node(node_t node, int id);
102 static void stabilize(node_t node);
103 static void notify(node_t node, int predecessor_candidate_id);
104 static void remote_notify(node_t node, int notify_to, int predecessor_candidate_id);
105 static void fix_fingers(node_t node);
106 static void check_predecessor(node_t node);
107 static void random_lookup(node_t);
108 static void quit_notify(node_t node, int to);
111 * \brief Global initialization of the Chord simulation.
113 static void chord_initialize(void)
115 // compute the powers of 2 once for all
116 powers2 = xbt_new(int, nb_bits);
119 for (i = 0; i < nb_bits; i++) {
124 XBT_DEBUG("Sets nb_keys to %d", nb_keys);
128 * \brief Turns an id into an equivalent id in [0, nb_keys).
130 * \return the corresponding normalized id
132 static int normalize(int id)
134 // like id % nb_keys, but works with negatives numbers (and faster)
135 return id & (nb_keys - 1);
139 * \brief Returns whether a id belongs to the interval [start, end].
141 * The parameters are noramlized to make sure they are between 0 and nb_keys - 1).
142 * 1 belongs to [62, 3]
143 * 1 does not belong to [3, 62]
144 * 63 belongs to [62, 3]
145 * 63 does not belong to [3, 62]
146 * 24 belongs to [21, 29]
147 * 24 does not belong to [29, 21]
149 * \param id id to check
150 * \param start lower bound
151 * \param end upper bound
152 * \return a non-zero value if id in in [start, end]
154 static int is_in_interval(int id, int start, int end)
157 start = normalize(start);
158 end = normalize(end);
160 // make sure end >= start and id >= start
173 * \brief Gets the mailbox name of a host given its chord id.
174 * \param node_id id of a node
175 * \param mailbox pointer to where the mailbox name should be written
176 * (there must be enough space)
178 static void get_mailbox(int node_id, char* mailbox)
180 snprintf(mailbox, MAILBOX_NAME_SIZE - 1, "%d", node_id);
184 * \brief Frees the memory used by some task data.
185 * \param task_data the task data to destroy
187 static void task_data_destroy(task_data_t task_data)
193 * \brief Displays the finger table of a node.
196 static void print_finger_table(node_t node)
198 if (XBT_LOG_ISENABLED(msg_chord, xbt_log_priority_verbose)) {
200 XBT_VERB("My finger table:");
201 XBT_VERB("Start | Succ ");
202 for (i = 0; i < nb_bits; i++) {
203 XBT_VERB(" %3d | %3d ", (node->id + powers2[i]) % nb_keys, node->fingers[i].id);
205 XBT_VERB("Predecessor: %d", node->pred_id);
210 * \brief Sets a finger of the current node.
211 * \param node the current node
212 * \param finger_index index of the finger to set (0 to nb_bits - 1)
213 * \param id the id to set for this finger
215 static void set_finger(node_t node, int finger_index, int id)
217 if (id != node->fingers[finger_index].id) {
218 node->fingers[finger_index].id = id;
219 get_mailbox(id, node->fingers[finger_index].mailbox);
220 node->last_change_date = MSG_get_clock();
221 XBT_DEBUG("My new finger #%d is %d", finger_index, id);
226 * \brief Sets the predecessor of the current node.
227 * \param node the current node
228 * \param id the id to predecessor, or -1 to unset the predecessor
230 static void set_predecessor(node_t node, int predecessor_id)
232 if (predecessor_id != node->pred_id) {
233 node->pred_id = predecessor_id;
235 if (predecessor_id != -1) {
236 get_mailbox(predecessor_id, node->pred_mailbox);
238 node->last_change_date = MSG_get_clock();
240 XBT_DEBUG("My new predecessor is %d", predecessor_id);
245 * \brief Node Function
248 * - the id of a guy I know in the system (except for the first node)
249 * - the time to sleep before I join (except for the first node)
251 int node(int argc, char *argv[])
253 /* Reduce the run size for the MC */
255 periodic_stabilize_delay = 8;
256 periodic_fix_fingers_delay = 8;
257 periodic_check_predecessor_delay = 8;
260 double init_time = MSG_get_clock();
261 msg_task_t task_received = NULL;
262 msg_comm_t comm_send = NULL;
265 int join_success = 0;
267 double next_stabilize_date = init_time + periodic_stabilize_delay;
268 double next_fix_fingers_date = init_time + periodic_fix_fingers_delay;
269 double next_check_predecessor_date = init_time + periodic_check_predecessor_delay;
270 double next_lookup_date = init_time + periodic_lookup_delay;
272 xbt_assert(argc == 3 || argc == 5, "Wrong number of arguments for this node");
274 // initialize my node
276 node.id = atoi(argv[1]);
277 get_mailbox(node.id, node.mailbox);
278 node.next_finger_to_fix = 0;
279 node.comms = xbt_dynar_new(sizeof(msg_comm_t), NULL);
280 node.fingers = xbt_new0(s_finger_t, nb_bits);
281 node.last_change_date = init_time;
283 for (i = 0; i < nb_bits; i++) {
284 node.fingers[i].id = -1;
285 set_finger(&node, i, node.id);
288 if (argc == 3) { // first ring
289 deadline = atof(argv[2]);
294 int known_id = atoi(argv[2]);
295 //double sleep_time = atof(argv[3]);
296 deadline = atof(argv[4]);
299 // sleep before starting
300 XBT_DEBUG("Let's sleep during %f", sleep_time);
301 MSG_process_sleep(sleep_time);
303 XBT_DEBUG("Hey! Let's join the system.");
305 join_success = join(&node, known_id);
309 while (MSG_get_clock() < init_time + deadline
310 // && MSG_get_clock() < node.last_change_date + 1000
311 && MSG_get_clock() < max_simulation_time) {
313 if (node.comm_receive == NULL) {
314 task_received = NULL;
315 node.comm_receive = MSG_task_irecv(&task_received, node.mailbox);
316 // FIXME: do not make MSG_task_irecv() calls from several functions
319 if (!MSG_comm_test(node.comm_receive)) {
321 // no task was received: make some periodic calls
322 if (MSG_get_clock() >= next_stabilize_date) {
324 next_stabilize_date = MSG_get_clock() + periodic_stabilize_delay;
326 else if (MSG_get_clock() >= next_fix_fingers_date) {
328 next_fix_fingers_date = MSG_get_clock() + periodic_fix_fingers_delay;
330 else if (MSG_get_clock() >= next_check_predecessor_date) {
331 check_predecessor(&node);
332 next_check_predecessor_date = MSG_get_clock() + periodic_check_predecessor_delay;
334 else if (MSG_get_clock() >= next_lookup_date) {
335 random_lookup(&node);
336 next_lookup_date = MSG_get_clock() + periodic_lookup_delay;
339 // nothing to do: sleep for a while
340 MSG_process_sleep(5);
344 // a transfer has occured
346 msg_error_t status = MSG_comm_get_status(node.comm_receive);
348 if (status != MSG_OK) {
349 XBT_DEBUG("Failed to receive a task. Nevermind.");
350 node.comm_receive = NULL;
353 // the task was successfully received
354 MSG_comm_destroy(node.comm_receive);
355 node.comm_receive = NULL;
356 handle_task(&node, task_received);
360 // see if some communications are finished
361 while ((index = MSG_comm_testany(node.comms)) != -1) {
362 comm_send = xbt_dynar_get_as(node.comms, index, msg_comm_t);
363 msg_error_t status = MSG_comm_get_status(comm_send);
364 xbt_dynar_remove_at(node.comms, index, &comm_send);
365 XBT_DEBUG("Communication %p is finished with status %d, dynar size is now %lu",
366 comm_send, status, xbt_dynar_length(node.comms));
367 msg_task_t task = MSG_comm_get_task(comm_send);
368 MSG_comm_destroy(comm_send);
369 if (status != MSG_OK) {
370 task_data_destroy(MSG_task_get_data(task));
371 MSG_task_destroy(task);
376 // clean unfinished comms sent
377 /* unsigned int cursor;
378 xbt_dynar_foreach(node.comms, cursor, comm_send) {
379 msg_task_t task = MSG_comm_get_task(comm_send);
380 MSG_task_cancel(task);
381 task_data_destroy(MSG_task_get_data(task));
382 MSG_task_destroy(task);
383 MSG_comm_destroy(comm_send);
384 // FIXME: the task is actually not destroyed because MSG thinks that the other side (whose process is dead) is still using it
391 // stop the simulation
392 xbt_dynar_free(&node.comms);
393 xbt_free(node.fingers);
398 * \brief This function is called when the current node receives a task.
399 * \param node the current node
400 * \param task the task to handle (don't touch it then:
401 * it will be destroyed, reused or forwarded)
403 static void handle_task(node_t node, msg_task_t task) {
405 XBT_DEBUG("Handling task %p", task);
406 msg_comm_t comm = NULL;
407 char mailbox[MAILBOX_NAME_SIZE];
408 task_data_t task_data = (task_data_t) MSG_task_get_data(task);
409 e_task_type_t type = task_data->type;
413 case TASK_FIND_SUCCESSOR:
414 XBT_DEBUG("Receiving a 'Find Successor' request from %s for id %d",
415 task_data->issuer_host_name, task_data->request_id);
416 // is my successor the successor?
417 if (is_in_interval(task_data->request_id, node->id + 1, node->fingers[0].id)) {
418 task_data->type = TASK_FIND_SUCCESSOR_ANSWER;
419 task_data->answer_id = node->fingers[0].id;
420 XBT_DEBUG("Sending back a 'Find Successor Answer' to %s (mailbox %s): the successor of %d is %d",
421 task_data->issuer_host_name,
422 task_data->answer_to,
423 task_data->request_id, task_data->answer_id);
424 comm = MSG_task_isend(task, task_data->answer_to);
425 xbt_dynar_push(node->comms, &comm);
428 // otherwise, forward the request to the closest preceding finger in my table
429 int closest = closest_preceding_node(node, task_data->request_id);
430 XBT_DEBUG("Forwarding the 'Find Successor' request for id %d to my closest preceding finger %d",
431 task_data->request_id, closest);
432 get_mailbox(closest, mailbox);
433 comm = MSG_task_isend(task, mailbox);
434 xbt_dynar_push(node->comms, &comm);
438 case TASK_GET_PREDECESSOR:
439 XBT_DEBUG("Receiving a 'Get Predecessor' request from %s", task_data->issuer_host_name);
440 task_data->type = TASK_GET_PREDECESSOR_ANSWER;
441 task_data->answer_id = node->pred_id;
442 XBT_DEBUG("Sending back a 'Get Predecessor Answer' to %s via mailbox '%s': my predecessor is %d",
443 task_data->issuer_host_name,
444 task_data->answer_to, task_data->answer_id);
445 comm = MSG_task_isend(task, task_data->answer_to);
446 xbt_dynar_push(node->comms, &comm);
450 // someone is telling me that he may be my new predecessor
451 XBT_DEBUG("Receiving a 'Notify' request from %s", task_data->issuer_host_name);
452 notify(node, task_data->request_id);
453 task_data_destroy(task_data);
454 MSG_task_destroy(task);
457 case TASK_PREDECESSOR_LEAVING:
458 // my predecessor is about to quit
459 XBT_DEBUG("Receiving a 'Predecessor Leaving' message from %s", task_data->issuer_host_name);
460 // modify my predecessor
461 set_predecessor(node, task_data->request_id);
462 task_data_destroy(task_data);
463 MSG_task_destroy(task);
465 >> notify my new predecessor
466 >> send a notify_predecessors !!
470 case TASK_SUCCESSOR_LEAVING:
471 // my successor is about to quit
472 XBT_DEBUG("Receiving a 'Successor Leaving' message from %s", task_data->issuer_host_name);
473 // modify my successor FIXME : this should be implicit ?
474 set_finger(node, 0, task_data->request_id);
475 task_data_destroy(task_data);
476 MSG_task_destroy(task);
478 >> notify my new successor
479 >> update my table & predecessors table */
482 case TASK_FIND_SUCCESSOR_ANSWER:
483 case TASK_GET_PREDECESSOR_ANSWER:
484 XBT_DEBUG("Ignoring unexpected task of type %d (%p)", type, task);
485 task_data_destroy(task_data);
486 MSG_task_destroy(task);
492 * \brief Initializes the current node as the first one of the system.
493 * \param node the current node
495 static void create(node_t node)
497 XBT_DEBUG("Create a new Chord ring...");
498 set_predecessor(node, -1); // -1 means that I have no predecessor
499 print_finger_table(node);
503 * \brief Makes the current node join the ring, knowing the id of a node
504 * already in the ring
505 * \param node the current node
506 * \param known_id id of a node already in the ring
507 * \return 1 if the join operation succeeded, 0 otherwise
509 static int join(node_t node, int known_id)
511 XBT_INFO("Joining the ring with id %d, knowing node %d", node->id, known_id);
512 set_predecessor(node, -1); // no predecessor (yet)
514 int successor_id = remote_find_successor(node, known_id, node->id);
515 if (successor_id == -1) {
516 XBT_INFO("Cannot join the ring.");
519 set_finger(node, 0, successor_id);
520 print_finger_table(node);
523 return successor_id != -1;
527 * \brief Makes the current node quit the system
528 * \param node the current node
530 static void leave(node_t node)
532 XBT_DEBUG("Well Guys! I Think it's time for me to quit ;)");
533 quit_notify(node, 1); // notify to my successor ( >>> 1 );
534 quit_notify(node, -1); // notify my predecessor ( >>> -1);
539 * \brief Notifies the successor or the predecessor of the current node
541 * \param node the current node
542 * \param to 1 to notify the successor, -1 to notify the predecessor
543 * FIXME: notify both nodes with only one call
545 static void quit_notify(node_t node, int to)
548 task_data_t req_data = xbt_new0(s_task_data_t, 1);
549 req_data->request_id = node->id;
550 req_data->successor_id = node->fingers[0].id;
551 req_data->pred_id = node->pred_id;
552 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
553 req_data->answer_to = NULL;
554 const char* task_name = NULL;
555 const char* to_mailbox = NULL;
556 if (to == 1) { // notify my successor
557 to_mailbox = node->fingers[0].mailbox;
558 INFO2("Telling my Successor %d about my departure via mailbox %s",
559 node->fingers[0].id, to_mailbox);
560 req_data->type = TASK_PREDECESSOR_LEAVING;
562 else if (to == -1) { // notify my predecessor
564 if (node->pred_id == -1) {
568 to_mailbox = node->pred_mailbox;
569 INFO2("Telling my Predecessor %d about my departure via mailbox %s",
570 node->pred_id, to_mailbox);
571 req_data->type = TASK_SUCCESSOR_LEAVING;
573 msg_task_t task = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
574 //char* mailbox = get_mailbox(to_mailbox);
575 msg_comm_t comm = MSG_task_isend(task, to_mailbox);
576 xbt_dynar_push(node->comms, &comm);
581 * \brief Makes the current node find the successor node of an id.
582 * \param node the current node
583 * \param id the id to find
584 * \return the id of the successor node, or -1 if the request failed
586 static int find_successor(node_t node, int id)
588 // is my successor the successor?
589 if (is_in_interval(id, node->id + 1, node->fingers[0].id)) {
590 return node->fingers[0].id;
593 // otherwise, ask the closest preceding finger in my table
594 int closest = closest_preceding_node(node, id);
595 return remote_find_successor(node, closest, id);
599 * \brief Asks another node the successor node of an id.
600 * \param node the current node
601 * \param ask_to the node to ask to
602 * \param id the id to find
603 * \return the id of the successor node, or -1 if the request failed
605 static int remote_find_successor(node_t node, int ask_to, int id)
609 char mailbox[MAILBOX_NAME_SIZE];
610 get_mailbox(ask_to, mailbox);
611 task_data_t req_data = xbt_new0(s_task_data_t, 1);
612 req_data->type = TASK_FIND_SUCCESSOR;
613 req_data->request_id = id;
614 get_mailbox(node->id, req_data->answer_to);
615 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
617 // send a "Find Successor" request to ask_to_id
618 msg_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
619 XBT_DEBUG("Sending a 'Find Successor' request (task %p) to %d for id %d", task_sent, ask_to, id);
620 msg_error_t res = MSG_task_send_with_timeout(task_sent, mailbox, timeout);
623 XBT_DEBUG("Failed to send the 'Find Successor' request (task %p) to %d for id %d",
624 task_sent, ask_to, id);
625 MSG_task_destroy(task_sent);
626 task_data_destroy(req_data);
630 // receive the answer
631 XBT_DEBUG("Sent a 'Find Successor' request (task %p) to %d for key %d, waiting for the answer",
632 task_sent, ask_to, id);
635 if (node->comm_receive == NULL) {
636 msg_task_t task_received = NULL;
637 node->comm_receive = MSG_task_irecv(&task_received, node->mailbox);
640 res = MSG_comm_wait(node->comm_receive, timeout);
643 XBT_DEBUG("Failed to receive the answer to my 'Find Successor' request (task %p): %d",
646 MSG_comm_destroy(node->comm_receive);
647 node->comm_receive = NULL;
650 msg_task_t task_received = MSG_comm_get_task(node->comm_receive);
651 XBT_DEBUG("Received a task (%p)", task_received);
652 task_data_t ans_data = MSG_task_get_data(task_received);
655 MC_assert(task_received == task_sent);
658 if (task_received != task_sent) {
659 // this is not the expected answer
660 MSG_comm_destroy(node->comm_receive);
661 node->comm_receive = NULL;
662 handle_task(node, task_received);
665 // this is our answer
666 XBT_DEBUG("Received the answer to my 'Find Successor' request for id %d (task %p): the successor of key %d is %d",
667 ans_data->request_id, task_received, id, ans_data->answer_id);
668 successor = ans_data->answer_id;
670 MSG_comm_destroy(node->comm_receive);
671 node->comm_receive = NULL;
672 MSG_task_destroy(task_received);
673 task_data_destroy(req_data);
683 * \brief Asks another node its predecessor.
684 * \param node the current node
685 * \param ask_to the node to ask to
686 * \return the id of its predecessor node, or -1 if the request failed
687 * (or if the node does not know its predecessor)
689 static int remote_get_predecessor(node_t node, int ask_to)
691 int predecessor_id = -1;
693 char mailbox[MAILBOX_NAME_SIZE];
694 get_mailbox(ask_to, mailbox);
695 task_data_t req_data = xbt_new0(s_task_data_t, 1);
696 req_data->type = TASK_GET_PREDECESSOR;
697 get_mailbox(node->id, req_data->answer_to);
698 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
700 // send a "Get Predecessor" request to ask_to_id
701 XBT_DEBUG("Sending a 'Get Predecessor' request to %d", ask_to);
702 msg_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
703 msg_error_t res = MSG_task_send_with_timeout(task_sent, mailbox, timeout);
706 XBT_DEBUG("Failed to send the 'Get Predecessor' request (task %p) to %d",
708 MSG_task_destroy(task_sent);
709 task_data_destroy(req_data);
713 // receive the answer
714 XBT_DEBUG("Sent 'Get Predecessor' request (task %p) to %d, waiting for the answer on my mailbox '%s'",
715 task_sent, ask_to, req_data->answer_to);
718 if (node->comm_receive == NULL) { // FIXME simplify this
719 msg_task_t task_received = NULL;
720 node->comm_receive = MSG_task_irecv(&task_received, node->mailbox);
723 res = MSG_comm_wait(node->comm_receive, timeout);
726 XBT_DEBUG("Failed to receive the answer to my 'Get Predecessor' request (task %p): %d",
729 MSG_comm_destroy(node->comm_receive);
730 node->comm_receive = NULL;
733 msg_task_t task_received = MSG_comm_get_task(node->comm_receive);
734 task_data_t ans_data = MSG_task_get_data(task_received);
737 MC_assert(task_received == task_sent);
740 if (task_received != task_sent) {
741 MSG_comm_destroy(node->comm_receive);
742 node->comm_receive = NULL;
743 handle_task(node, task_received);
746 XBT_DEBUG("Received the answer to my 'Get Predecessor' request (task %p): the predecessor of node %d is %d",
747 task_received, ask_to, ans_data->answer_id);
748 predecessor_id = ans_data->answer_id;
750 MSG_comm_destroy(node->comm_receive);
751 node->comm_receive = NULL;
752 MSG_task_destroy(task_received);
753 task_data_destroy(req_data);
759 return predecessor_id;
763 * \brief Returns the closest preceding finger of an id
764 * with respect to the finger table of the current node.
765 * \param node the current node
766 * \param id the id to find
767 * \return the closest preceding finger of that id
769 int closest_preceding_node(node_t node, int id)
772 for (i = nb_bits - 1; i >= 0; i--) {
773 if (is_in_interval(node->fingers[i].id, node->id + 1, id - 1)) {
774 return node->fingers[i].id;
781 * \brief This function is called periodically. It checks the immediate
782 * successor of the current node.
783 * \param node the current node
785 static void stabilize(node_t node)
787 XBT_DEBUG("Stabilizing node");
789 // get the predecessor of my immediate successor
791 int successor_id = node->fingers[0].id;
792 if (successor_id != node->id) {
793 candidate_id = remote_get_predecessor(node, successor_id);
796 candidate_id = node->pred_id;
799 // this node is a candidate to become my new successor
800 if (candidate_id != -1
801 && is_in_interval(candidate_id, node->id + 1, successor_id - 1)) {
802 set_finger(node, 0, candidate_id);
804 if (successor_id != node->id) {
805 remote_notify(node, successor_id, node->id);
810 * \brief Notifies the current node that its predecessor may have changed.
811 * \param node the current node
812 * \param candidate_id the possible new predecessor
814 static void notify(node_t node, int predecessor_candidate_id) {
816 if (node->pred_id == -1
817 || is_in_interval(predecessor_candidate_id, node->pred_id + 1, node->id - 1)) {
819 set_predecessor(node, predecessor_candidate_id);
820 print_finger_table(node);
823 XBT_DEBUG("I don't have to change my predecessor to %d", predecessor_candidate_id);
828 * \brief Notifies a remote node that its predecessor may have changed.
829 * \param node the current node
830 * \param notify_id id of the node to notify
831 * \param candidate_id the possible new predecessor
833 static void remote_notify(node_t node, int notify_id, int predecessor_candidate_id) {
835 task_data_t req_data = xbt_new0(s_task_data_t, 1);
836 req_data->type = TASK_NOTIFY;
837 req_data->request_id = predecessor_candidate_id;
838 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
840 // send a "Notify" request to notify_id
841 msg_task_t task = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
842 XBT_DEBUG("Sending a 'Notify' request (task %p) to %d", task, notify_id);
843 char mailbox[MAILBOX_NAME_SIZE];
844 get_mailbox(notify_id, mailbox);
845 msg_comm_t comm = MSG_task_isend(task, mailbox);
846 xbt_dynar_push(node->comms, &comm);
850 * \brief This function is called periodically.
851 * It refreshes the finger table of the current node.
852 * \param node the current node
854 static void fix_fingers(node_t node) {
856 XBT_DEBUG("Fixing fingers");
857 int i = node->next_finger_to_fix;
858 int id = find_successor(node, node->id + powers2[i]);
861 if (id != node->fingers[i].id) {
862 set_finger(node, i, id);
863 print_finger_table(node);
865 node->next_finger_to_fix = (i + 1) % nb_bits;
870 * \brief This function is called periodically.
871 * It checks whether the predecessor has failed
872 * \param node the current node
874 static void check_predecessor(node_t node)
876 XBT_DEBUG("Checking whether my predecessor is alive");
881 * \brief Performs a find successor request to a random id.
882 * \param node the current node
884 static void random_lookup(node_t node)
886 int id = 1337; // TODO pick a pseudorandom id
887 XBT_DEBUG("Making a lookup request for id %d", id);
888 find_successor(node, id);
892 * \brief Main function.
894 int main(int argc, char *argv[])
897 printf("Usage: %s [-nb_bits=n] [-timeout=t] platform_file deployment_file\n", argv[0]);
898 printf("example: %s ../msg_platform.xml chord.xml\n", argv[0]);
902 MSG_init(&argc, argv);
904 char **options = &argv[1];
905 while (!strncmp(options[0], "-", 1)) {
907 int length = strlen("-nb_bits=");
908 if (!strncmp(options[0], "-nb_bits=", length) && strlen(options[0]) > length) {
909 nb_bits = atoi(options[0] + length);
910 XBT_DEBUG("Set nb_bits to %d", nb_bits);
914 length = strlen("-timeout=");
915 if (!strncmp(options[0], "-timeout=", length) && strlen(options[0]) > length) {
916 timeout = atoi(options[0] + length);
917 XBT_DEBUG("Set timeout to %d", timeout);
920 xbt_assert(0, "Invalid chord option '%s'", options[0]);
926 const char* platform_file = options[0];
927 const char* application_file = options[1];
931 MSG_create_environment(platform_file);
933 MSG_function_register("node", node);
934 MSG_launch_application(application_file);
936 msg_error_t res = MSG_main();
937 XBT_INFO("Simulation time: %g", MSG_get_clock());