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 "mc/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, m_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 DEBUG1("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)
138 // make sure id < nb_keys
145 * \brief Returns whether a id belongs to the interval [start, end].
147 * The parameters are noramlized to make sure they are between 0 and nb_keys - 1).
148 * 1 belongs to [62, 3]
149 * 1 does not belong to [3, 62]
150 * 63 belongs to [62, 3]
151 * 63 does not belong to [3, 62]
152 * 24 belongs to [21, 29]
153 * 24 does not belong to [29, 21]
155 * \param id id to check
156 * \param start lower bound
157 * \param end upper bound
158 * \return a non-zero value if id in in [start, end]
160 static int is_in_interval(int id, int start, int end)
163 start = normalize(start);
164 end = normalize(end);
166 // make sure end >= start and id >= start
179 * \brief Gets the mailbox name of a host given its chord id.
180 * \param node_id id of a node
181 * \param mailbox pointer to where the mailbox name should be written
182 * (there must be enough space)
184 static void get_mailbox(int node_id, char* mailbox)
186 snprintf(mailbox, MAILBOX_NAME_SIZE - 1, "%d", node_id);
190 * \brief Frees the memory used by some task data.
191 * \param task_data the task data to destroy
193 static void task_data_destroy(task_data_t task_data)
199 * \brief Displays the finger table of a node.
202 static void print_finger_table(node_t node)
204 if (XBT_LOG_ISENABLED(msg_chord, xbt_log_priority_verbose)) {
206 VERB0("My finger table:");
207 VERB0("Start | Succ ");
208 for (i = 0; i < nb_bits; i++) {
209 VERB2(" %3d | %3d ", (node->id + powers2[i]) % nb_keys, node->fingers[i].id);
211 VERB1("Predecessor: %d", node->pred_id);
216 * \brief Sets a finger of the current node.
217 * \param node the current node
218 * \param finger_index index of the finger to set (0 to nb_bits - 1)
219 * \param id the id to set for this finger
221 static void set_finger(node_t node, int finger_index, int id)
223 if (id != node->fingers[finger_index].id) {
224 node->fingers[finger_index].id = id;
225 get_mailbox(id, node->fingers[finger_index].mailbox);
226 node->last_change_date = MSG_get_clock();
227 DEBUG2("My new finger #%d is %d", finger_index, id);
232 * \brief Sets the predecessor of the current node.
233 * \param node the current node
234 * \param id the id to predecessor, or -1 to unset the predecessor
236 static void set_predecessor(node_t node, int predecessor_id)
238 if (predecessor_id != node->pred_id) {
239 node->pred_id = predecessor_id;
241 if (predecessor_id != -1) {
242 get_mailbox(predecessor_id, node->pred_mailbox);
244 node->last_change_date = MSG_get_clock();
246 DEBUG1("My new predecessor is %d", predecessor_id);
251 * \brief Node Function
254 * - the id of a guy I know in the system (except for the first node)
255 * - the time to sleep before I join (except for the first node)
257 int node(int argc, char *argv[])
259 double init_time = MSG_get_clock();
260 m_task_t task_received = NULL;
261 msg_comm_t comm_send = NULL;
264 int join_success = 0;
266 double next_stabilize_date = init_time + periodic_stabilize_delay;
267 double next_fix_fingers_date = init_time + periodic_fix_fingers_delay;
268 double next_check_predecessor_date = init_time + periodic_check_predecessor_delay;
269 double next_lookup_date = init_time + periodic_lookup_delay;
271 xbt_assert0(argc == 3 || argc == 5, "Wrong number of arguments for this node");
273 // initialize my node
275 node.id = atoi(argv[1]);
276 get_mailbox(node.id, node.mailbox);
277 node.next_finger_to_fix = 0;
278 node.comms = xbt_dynar_new(sizeof(msg_comm_t), NULL);
279 node.fingers = xbt_new0(s_finger_t, nb_bits);
280 node.last_change_date = init_time;
282 for (i = 0; i < nb_bits; i++) {
283 node.fingers[i].id = -1;
284 set_finger(&node, i, node.id);
287 if (argc == 3) { // first ring
288 deadline = atof(argv[2]);
293 int known_id = atoi(argv[2]);
294 //double sleep_time = atof(argv[3]);
295 deadline = atof(argv[4]);
298 // sleep before starting
299 DEBUG1("Let's sleep during %f", sleep_time);
300 MSG_process_sleep(sleep_time);
302 DEBUG0("Hey! Let's join the system.");
304 join_success = join(&node, known_id);
308 while (MSG_get_clock() < init_time + deadline
309 // && MSG_get_clock() < node.last_change_date + 1000
310 && MSG_get_clock() < max_simulation_time) {
312 if (node.comm_receive == NULL) {
313 task_received = NULL;
314 node.comm_receive = MSG_task_irecv(&task_received, node.mailbox);
315 // FIXME: do not make MSG_task_irecv() calls from several functions
318 if (!MSG_comm_test(node.comm_receive)) {
320 // no task was received: make some periodic calls
321 if (MSG_get_clock() >= next_stabilize_date) {
323 next_stabilize_date = MSG_get_clock() + periodic_stabilize_delay;
325 else if (MSG_get_clock() >= next_fix_fingers_date) {
327 next_fix_fingers_date = MSG_get_clock() + periodic_fix_fingers_delay;
329 else if (MSG_get_clock() >= next_check_predecessor_date) {
330 check_predecessor(&node);
331 next_check_predecessor_date = MSG_get_clock() + periodic_check_predecessor_delay;
333 else if (MSG_get_clock() >= next_lookup_date) {
334 random_lookup(&node);
335 next_lookup_date = MSG_get_clock() + periodic_lookup_delay;
338 // nothing to do: sleep for a while
339 MSG_process_sleep(5);
343 // a transfer has occured
345 MSG_error_t status = MSG_comm_get_status(node.comm_receive);
347 if (status != MSG_OK) {
348 DEBUG0("Failed to receive a task. Nevermind.");
349 node.comm_receive = NULL;
352 // the task was successfully received
353 MSG_comm_destroy(node.comm_receive);
354 node.comm_receive = NULL;
355 handle_task(&node, task_received);
359 // see if some communications are finished
360 while ((index = MSG_comm_testany(node.comms)) != -1) {
361 comm_send = xbt_dynar_get_as(node.comms, index, msg_comm_t);
362 MSG_error_t status = MSG_comm_get_status(comm_send);
363 xbt_dynar_remove_at(node.comms, index, &comm_send);
364 DEBUG3("Communication %p is finished with status %d, dynar size is now %lu",
365 comm_send, status, xbt_dynar_length(node.comms));
366 m_task_t task = MSG_comm_get_task(comm_send);
367 MSG_comm_destroy(comm_send);
368 if (status != MSG_OK) {
369 task_data_destroy(MSG_task_get_data(task));
370 MSG_task_destroy(task);
375 // clean unfinished comms sent
376 /* unsigned int cursor;
377 xbt_dynar_foreach(node.comms, cursor, comm_send) {
378 m_task_t task = MSG_comm_get_task(comm_send);
379 MSG_task_cancel(task);
380 task_data_destroy(MSG_task_get_data(task));
381 MSG_task_destroy(task);
382 MSG_comm_destroy(comm_send);
383 // FIXME: the task is actually not destroyed because MSG thinks that the other side (whose process is dead) is still using it
390 // stop the simulation
391 xbt_dynar_free(&node.comms);
392 xbt_free(node.fingers);
397 * \brief This function is called when the current node receives a task.
398 * \param node the current node
399 * \param task the task to handle (don't touch it then:
400 * it will be destroyed, reused or forwarded)
402 static void handle_task(node_t node, m_task_t task) {
404 DEBUG1("Handling task %p", task);
405 msg_comm_t comm = NULL;
406 char mailbox[MAILBOX_NAME_SIZE];
407 task_data_t task_data = (task_data_t) MSG_task_get_data(task);
408 e_task_type_t type = task_data->type;
412 case TASK_FIND_SUCCESSOR:
413 DEBUG2("Receiving a 'Find Successor' request from %s for id %d",
414 task_data->issuer_host_name, task_data->request_id);
415 // is my successor the successor?
416 if (is_in_interval(task_data->request_id, node->id + 1, node->fingers[0].id)) {
417 task_data->type = TASK_FIND_SUCCESSOR_ANSWER;
418 task_data->answer_id = node->fingers[0].id;
419 DEBUG4("Sending back a 'Find Successor Answer' to %s (mailbox %s): the successor of %d is %d",
420 task_data->issuer_host_name,
421 task_data->answer_to,
422 task_data->request_id, task_data->answer_id);
423 comm = MSG_task_isend(task, task_data->answer_to);
424 xbt_dynar_push(node->comms, &comm);
427 // otherwise, forward the request to the closest preceding finger in my table
428 int closest = closest_preceding_node(node, task_data->request_id);
429 DEBUG2("Forwarding the 'Find Successor' request for id %d to my closest preceding finger %d",
430 task_data->request_id, closest);
431 get_mailbox(closest, mailbox);
432 comm = MSG_task_isend(task, mailbox);
433 xbt_dynar_push(node->comms, &comm);
437 case TASK_GET_PREDECESSOR:
438 DEBUG1("Receiving a 'Get Predecessor' request from %s", task_data->issuer_host_name);
439 task_data->type = TASK_GET_PREDECESSOR_ANSWER;
440 task_data->answer_id = node->pred_id;
441 DEBUG3("Sending back a 'Get Predecessor Answer' to %s via mailbox '%s': my predecessor is %d",
442 task_data->issuer_host_name,
443 task_data->answer_to, task_data->answer_id);
444 comm = MSG_task_isend(task, task_data->answer_to);
445 xbt_dynar_push(node->comms, &comm);
449 // someone is telling me that he may be my new predecessor
450 DEBUG1("Receiving a 'Notify' request from %s", task_data->issuer_host_name);
451 notify(node, task_data->request_id);
452 task_data_destroy(task_data);
453 MSG_task_destroy(task);
456 case TASK_PREDECESSOR_LEAVING:
457 // my predecessor is about to quit
458 DEBUG1("Receiving a 'Predecessor Leaving' message from %s", task_data->issuer_host_name);
459 // modify my predecessor
460 set_predecessor(node, task_data->request_id);
461 task_data_destroy(task_data);
462 MSG_task_destroy(task);
464 >> notify my new predecessor
465 >> send a notify_predecessors !!
469 case TASK_SUCCESSOR_LEAVING:
470 // my successor is about to quit
471 DEBUG1("Receiving a 'Successor Leaving' message from %s", task_data->issuer_host_name);
472 // modify my successor FIXME : this should be implicit ?
473 set_finger(node, 0, task_data->request_id);
474 task_data_destroy(task_data);
475 MSG_task_destroy(task);
477 >> notify my new successor
478 >> update my table & predecessors table */
481 case TASK_FIND_SUCCESSOR_ANSWER:
482 case TASK_GET_PREDECESSOR_ANSWER:
483 DEBUG2("Ignoring unexpected task of type %d (%p)", type, task);
484 task_data_destroy(task_data);
485 MSG_task_destroy(task);
491 * \brief Initializes the current node as the first one of the system.
492 * \param node the current node
494 static void create(node_t node)
496 DEBUG0("Create a new Chord ring...");
497 set_predecessor(node, -1); // -1 means that I have no predecessor
498 print_finger_table(node);
502 * \brief Makes the current node join the ring, knowing the id of a node
503 * already in the ring
504 * \param node the current node
505 * \param known_id id of a node already in the ring
506 * \return 1 if the join operation succeeded, 0 otherwise
508 static int join(node_t node, int known_id)
510 INFO2("Joining the ring with id %d, knowing node %d", node->id, known_id);
511 set_predecessor(node, -1); // no predecessor (yet)
513 int successor_id = remote_find_successor(node, known_id, node->id);
514 if (successor_id == -1) {
515 INFO0("Cannot join the ring.");
518 set_finger(node, 0, successor_id);
519 print_finger_table(node);
522 return successor_id != -1;
526 * \brief Makes the current node quit the system
527 * \param node the current node
529 static void leave(node_t node)
531 DEBUG0("Well Guys! I Think it's time for me to quit ;)");
532 quit_notify(node, 1); // notify to my successor ( >>> 1 );
533 quit_notify(node, -1); // notify my predecessor ( >>> -1);
538 * \brief Notifies the successor or the predecessor of the current node
540 * \param node the current node
541 * \param to 1 to notify the successor, -1 to notify the predecessor
542 * FIXME: notify both nodes with only one call
544 static void quit_notify(node_t node, int to)
547 task_data_t req_data = xbt_new0(s_task_data_t, 1);
548 req_data->request_id = node->id;
549 req_data->successor_id = node->fingers[0].id;
550 req_data->pred_id = node->pred_id;
551 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
552 req_data->answer_to = NULL;
553 const char* task_name = NULL;
554 const char* to_mailbox = NULL;
555 if (to == 1) { // notify my successor
556 to_mailbox = node->fingers[0].mailbox;
557 INFO2("Telling my Successor %d about my departure via mailbox %s",
558 node->fingers[0].id, to_mailbox);
559 req_data->type = TASK_PREDECESSOR_LEAVING;
561 else if (to == -1) { // notify my predecessor
563 if (node->pred_id == -1) {
567 to_mailbox = node->pred_mailbox;
568 INFO2("Telling my Predecessor %d about my departure via mailbox %s",
569 node->pred_id, to_mailbox);
570 req_data->type = TASK_SUCCESSOR_LEAVING;
572 m_task_t task = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
573 //char* mailbox = get_mailbox(to_mailbox);
574 msg_comm_t comm = MSG_task_isend(task, to_mailbox);
575 xbt_dynar_push(node->comms, &comm);
580 * \brief Makes the current node find the successor node of an id.
581 * \param node the current node
582 * \param id the id to find
583 * \return the id of the successor node, or -1 if the request failed
585 static int find_successor(node_t node, int id)
587 // is my successor the successor?
588 if (is_in_interval(id, node->id + 1, node->fingers[0].id)) {
589 return node->fingers[0].id;
592 // otherwise, ask the closest preceding finger in my table
593 int closest = closest_preceding_node(node, id);
594 return remote_find_successor(node, closest, id);
598 * \brief Asks another node the successor node of an id.
599 * \param node the current node
600 * \param ask_to the node to ask to
601 * \param id the id to find
602 * \return the id of the successor node, or -1 if the request failed
604 static int remote_find_successor(node_t node, int ask_to, int id)
608 char mailbox[MAILBOX_NAME_SIZE];
609 get_mailbox(ask_to, mailbox);
610 task_data_t req_data = xbt_new0(s_task_data_t, 1);
611 req_data->type = TASK_FIND_SUCCESSOR;
612 req_data->request_id = id;
613 get_mailbox(node->id, req_data->answer_to);
614 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
616 // send a "Find Successor" request to ask_to_id
617 m_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
618 DEBUG3("Sending a 'Find Successor' request (task %p) to %d for id %d", task_sent, ask_to, id);
619 MSG_error_t res = MSG_task_send_with_timeout(task_sent, mailbox, timeout);
622 DEBUG3("Failed to send the 'Find Successor' request (task %p) to %d for id %d",
623 task_sent, ask_to, id);
624 MSG_task_destroy(task_sent);
625 task_data_destroy(req_data);
629 // receive the answer
630 DEBUG3("Sent a 'Find Successor' request (task %p) to %d for key %d, waiting for the answer",
631 task_sent, ask_to, id);
634 if (node->comm_receive == NULL) {
635 m_task_t task_received = NULL;
636 node->comm_receive = MSG_task_irecv(&task_received, node->mailbox);
639 res = MSG_comm_wait(node->comm_receive, timeout);
642 DEBUG2("Failed to receive the answer to my 'Find Successor' request (task %p): %d",
645 MSG_comm_destroy(node->comm_receive);
646 node->comm_receive = NULL;
649 m_task_t task_received = MSG_comm_get_task(node->comm_receive);
650 DEBUG1("Received a task (%p)", task_received);
651 task_data_t ans_data = MSG_task_get_data(task_received);
654 MC_assert(task_received == task_sent);
657 if (task_received != task_sent) {
658 // this is not the expected answer
659 MSG_comm_destroy(node->comm_receive);
660 node->comm_receive = NULL;
661 handle_task(node, task_received);
664 // this is our answer
665 DEBUG4("Received the answer to my 'Find Successor' request for id %d (task %p): the successor of key %d is %d",
666 ans_data->request_id, task_received, id, ans_data->answer_id);
667 successor = ans_data->answer_id;
669 MSG_comm_destroy(node->comm_receive);
670 node->comm_receive = NULL;
671 MSG_task_destroy(task_received);
672 task_data_destroy(req_data);
682 * \brief Asks another node its predecessor.
683 * \param node the current node
684 * \param ask_to the node to ask to
685 * \return the id of its predecessor node, or -1 if the request failed
686 * (or if the node does not know its predecessor)
688 static int remote_get_predecessor(node_t node, int ask_to)
690 int predecessor_id = -1;
692 char mailbox[MAILBOX_NAME_SIZE];
693 get_mailbox(ask_to, mailbox);
694 task_data_t req_data = xbt_new0(s_task_data_t, 1);
695 req_data->type = TASK_GET_PREDECESSOR;
696 get_mailbox(node->id, req_data->answer_to);
697 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
699 // send a "Get Predecessor" request to ask_to_id
700 DEBUG1("Sending a 'Get Predecessor' request to %d", ask_to);
701 m_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
702 MSG_error_t res = MSG_task_send_with_timeout(task_sent, mailbox, timeout);
705 DEBUG2("Failed to send the 'Get Predecessor' request (task %p) to %d",
707 MSG_task_destroy(task_sent);
708 task_data_destroy(req_data);
712 // receive the answer
713 DEBUG3("Sent 'Get Predecessor' request (task %p) to %d, waiting for the answer on my mailbox '%s'",
714 task_sent, ask_to, req_data->answer_to);
717 if (node->comm_receive == NULL) { // FIXME simplify this
718 m_task_t task_received = NULL;
719 node->comm_receive = MSG_task_irecv(&task_received, node->mailbox);
722 res = MSG_comm_wait(node->comm_receive, timeout);
725 DEBUG2("Failed to receive the answer to my 'Get Predecessor' request (task %p): %d",
728 MSG_comm_destroy(node->comm_receive);
729 node->comm_receive = NULL;
732 m_task_t task_received = MSG_comm_get_task(node->comm_receive);
733 task_data_t ans_data = MSG_task_get_data(task_received);
736 MC_assert(task_received == task_sent);
739 if (task_received != task_sent) {
740 MSG_comm_destroy(node->comm_receive);
741 node->comm_receive = NULL;
742 handle_task(node, task_received);
745 DEBUG3("Received the answer to my 'Get Predecessor' request (task %p): the predecessor of node %d is %d",
746 task_received, ask_to, ans_data->answer_id);
747 predecessor_id = ans_data->answer_id;
749 MSG_comm_destroy(node->comm_receive);
750 node->comm_receive = NULL;
751 MSG_task_destroy(task_received);
752 task_data_destroy(req_data);
758 return predecessor_id;
762 * \brief Returns the closest preceding finger of an id
763 * with respect to the finger table of the current node.
764 * \param node the current node
765 * \param id the id to find
766 * \return the closest preceding finger of that id
768 int closest_preceding_node(node_t node, int id)
771 for (i = nb_bits - 1; i >= 0; i--) {
772 if (is_in_interval(node->fingers[i].id, node->id + 1, id - 1)) {
773 return node->fingers[i].id;
780 * \brief This function is called periodically. It checks the immediate
781 * successor of the current node.
782 * \param node the current node
784 static void stabilize(node_t node)
786 DEBUG0("Stabilizing node");
788 // get the predecessor of my immediate successor
790 int successor_id = node->fingers[0].id;
791 if (successor_id != node->id) {
792 candidate_id = remote_get_predecessor(node, successor_id);
795 candidate_id = node->pred_id;
798 // this node is a candidate to become my new successor
799 if (candidate_id != -1
800 && is_in_interval(candidate_id, node->id + 1, successor_id - 1)) {
801 set_finger(node, 0, candidate_id);
803 if (successor_id != node->id) {
804 remote_notify(node, successor_id, node->id);
809 * \brief Notifies the current node that its predecessor may have changed.
810 * \param node the current node
811 * \param candidate_id the possible new predecessor
813 static void notify(node_t node, int predecessor_candidate_id) {
815 if (node->pred_id == -1
816 || is_in_interval(predecessor_candidate_id, node->pred_id + 1, node->id - 1)) {
818 set_predecessor(node, predecessor_candidate_id);
819 print_finger_table(node);
822 DEBUG1("I don't have to change my predecessor to %d", predecessor_candidate_id);
827 * \brief Notifies a remote node that its predecessor may have changed.
828 * \param node the current node
829 * \param notify_id id of the node to notify
830 * \param candidate_id the possible new predecessor
832 static void remote_notify(node_t node, int notify_id, int predecessor_candidate_id) {
834 task_data_t req_data = xbt_new0(s_task_data_t, 1);
835 req_data->type = TASK_NOTIFY;
836 req_data->request_id = predecessor_candidate_id;
837 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
839 // send a "Notify" request to notify_id
840 m_task_t task = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
841 DEBUG2("Sending a 'Notify' request (task %p) to %d", task, notify_id);
842 char mailbox[MAILBOX_NAME_SIZE];
843 get_mailbox(notify_id, mailbox);
844 msg_comm_t comm = MSG_task_isend(task, mailbox);
845 xbt_dynar_push(node->comms, &comm);
849 * \brief This function is called periodically.
850 * It refreshes the finger table of the current node.
851 * \param node the current node
853 static void fix_fingers(node_t node) {
855 DEBUG0("Fixing fingers");
856 int i = node->next_finger_to_fix;
857 int id = find_successor(node, node->id + powers2[i]);
860 if (id != node->fingers[i].id) {
861 set_finger(node, i, id);
862 print_finger_table(node);
864 node->next_finger_to_fix = (i + 1) % nb_bits;
869 * \brief This function is called periodically.
870 * It checks whether the predecessor has failed
871 * \param node the current node
873 static void check_predecessor(node_t node)
875 DEBUG0("Checking whether my predecessor is alive");
880 * \brief Performs a find successor request to a random id.
881 * \param node the current node
883 static void random_lookup(node_t node)
885 int id = 1337; // TODO pick a pseudorandom id
886 DEBUG1("Making a lookup request for id %d", id);
887 find_successor(node, id);
891 * \brief Main function.
893 int main(int argc, char *argv[])
896 printf("Usage: %s [-nb_bits=n] [-timeout=t] platform_file deployment_file\n", argv[0]);
897 printf("example: %s ../msg_platform.xml chord.xml\n", argv[0]);
901 MSG_global_init(&argc, argv);
903 char **options = &argv[1];
904 while (!strncmp(options[0], "-", 1)) {
906 int length = strlen("-nb_bits=");
907 if (!strncmp(options[0], "-nb_bits=", length) && strlen(options[0]) > length) {
908 nb_bits = atoi(options[0] + length);
909 DEBUG1("Set nb_bits to %d", nb_bits);
913 length = strlen("-timeout=");
914 if (!strncmp(options[0], "-timeout=", length) && strlen(options[0]) > length) {
915 timeout = atoi(options[0] + length);
916 DEBUG1("Set timeout to %d", timeout);
919 xbt_assert1(0, "Invalid chord option '%s'", options[0]);
925 const char* platform_file = options[0];
926 const char* application_file = options[1];
930 MSG_set_channel_number(0);
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 INFO1("Simulation time: %g", MSG_get_clock());