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 #include "xbt/xbt_os_time.h"
16 XBT_LOG_NEW_DEFAULT_CATEGORY(msg_chord,
17 "Messages specific for this msg example");
21 #define MAILBOX_NAME_SIZE 10
23 static int nb_bits = 24;
24 static int nb_keys = 0;
25 static int timeout = 50;
26 static int max_simulation_time = 1000;
27 static int periodic_stabilize_delay = 20;
28 static int periodic_fix_fingers_delay = 120;
29 static int periodic_check_predecessor_delay = 120;
30 static int periodic_lookup_delay = 10;
32 extern long int smx_total_comms;
37 typedef struct finger {
39 char mailbox[MAILBOX_NAME_SIZE]; // string representation of the id
40 } s_finger_t, *finger_t;
47 char mailbox[MAILBOX_NAME_SIZE]; // my mailbox name (string representation of the id)
48 s_finger_t *fingers; // finger table, of size nb_bits (fingers[0] is my successor)
49 int pred_id; // predecessor id
50 char pred_mailbox[MAILBOX_NAME_SIZE]; // predecessor's mailbox name
51 int next_finger_to_fix; // index of the next finger to fix in fix_fingers()
52 msg_comm_t comm_receive; // current communication to receive
53 double last_change_date; // last time I changed a finger or my predecessor
57 * Types of tasks exchanged between nodes.
61 TASK_FIND_SUCCESSOR_ANSWER,
63 TASK_GET_PREDECESSOR_ANSWER,
65 TASK_SUCCESSOR_LEAVING,
66 TASK_PREDECESSOR_LEAVING
70 * Data attached with the tasks sent and received
72 typedef struct task_data {
73 e_task_type_t type; // type of task
74 int request_id; // id paramater (used by some types of tasks)
75 int request_finger; // finger parameter (used by some types of tasks)
76 int answer_id; // answer (used by some types of tasks)
77 char answer_to[MAILBOX_NAME_SIZE]; // mailbox to send an answer to (if any)
78 const char* issuer_host_name; // used for logging
79 } s_task_data_t, *task_data_t;
84 static void chord_initialize(void);
85 static int normalize(int id);
86 static int is_in_interval(int id, int start, int end);
87 static void get_mailbox(int host_id, char* mailbox);
88 static void task_free(void* task);
89 static void print_finger_table(node_t node);
90 static void set_finger(node_t node, int finger_index, int id);
91 static void set_predecessor(node_t node, int predecessor_id);
94 static int node(int argc, char *argv[]);
95 static void handle_task(node_t node, m_task_t task);
98 static void create(node_t node);
99 static int join(node_t node, int known_id);
100 static void leave(node_t node);
101 static int find_successor(node_t node, int id);
102 static int remote_find_successor(node_t node, int ask_to_id, int id);
103 static int remote_get_predecessor(node_t node, int ask_to_id);
104 static int closest_preceding_node(node_t node, int id);
105 static void stabilize(node_t node);
106 static void notify(node_t node, int predecessor_candidate_id);
107 static void remote_notify(node_t node, int notify_to, int predecessor_candidate_id);
108 static void fix_fingers(node_t node);
109 static void check_predecessor(node_t node);
110 static void random_lookup(node_t);
111 static void quit_notify(node_t node, int to);
114 * \brief Global initialization of the Chord simulation.
116 static void chord_initialize(void)
118 // compute the powers of 2 once for all
119 powers2 = xbt_new(int, nb_bits);
122 for (i = 0; i < nb_bits; i++) {
127 XBT_DEBUG("Sets nb_keys to %d", nb_keys);
131 * \brief Turns an id into an equivalent id in [0, nb_keys).
133 * \return the corresponding normalized id
135 static int normalize(int id)
137 // like id % nb_keys, but works with negatives numbers (and faster)
138 return id & (nb_keys - 1);
142 * \brief Returns whether a id belongs to the interval [start, end].
144 * The parameters are noramlized to make sure they are between 0 and nb_keys - 1).
145 * 1 belongs to [62, 3]
146 * 1 does not belong to [3, 62]
147 * 63 belongs to [62, 3]
148 * 63 does not belong to [3, 62]
149 * 24 belongs to [21, 29]
150 * 24 does not belong to [29, 21]
152 * \param id id to check
153 * \param start lower bound
154 * \param end upper bound
155 * \return a non-zero value if id in in [start, end]
157 static int is_in_interval(int id, int start, int end)
160 start = normalize(start);
161 end = normalize(end);
163 // make sure end >= start and id >= start
176 * \brief Gets the mailbox name of a host given its chord id.
177 * \param node_id id of a node
178 * \param mailbox pointer to where the mailbox name should be written
179 * (there must be enough space)
181 static void get_mailbox(int node_id, char* mailbox)
183 snprintf(mailbox, MAILBOX_NAME_SIZE - 1, "%d", node_id);
187 * \brief Frees the memory used by a task.
188 * \param task the MSG task to destroy
190 static void task_free(void* task)
192 // TODO add a parameter data_free_function to MSG_task_create?
193 xbt_free(MSG_task_get_data(task));
194 MSG_task_destroy(task);
198 * \brief Displays the finger table of a node.
201 static void print_finger_table(node_t node)
203 if (XBT_LOG_ISENABLED(msg_chord, xbt_log_priority_verbose)) {
205 XBT_VERB("My finger table:");
206 XBT_VERB("Start | Succ ");
207 for (i = 0; i < nb_bits; i++) {
208 XBT_VERB(" %3d | %3d ", (node->id + powers2[i]) % nb_keys, node->fingers[i].id);
210 XBT_VERB("Predecessor: %d", node->pred_id);
215 * \brief Sets a finger of the current node.
216 * \param node the current node
217 * \param finger_index index of the finger to set (0 to nb_bits - 1)
218 * \param id the id to set for this finger
220 static void set_finger(node_t node, int finger_index, int id)
222 if (id != node->fingers[finger_index].id) {
223 node->fingers[finger_index].id = id;
224 get_mailbox(id, node->fingers[finger_index].mailbox);
225 node->last_change_date = MSG_get_clock();
226 XBT_DEBUG("My new finger #%d is %d", finger_index, id);
231 * \brief Sets the predecessor of the current node.
232 * \param node the current node
233 * \param id the id to predecessor, or -1 to unset the predecessor
235 static void set_predecessor(node_t node, int predecessor_id)
237 if (predecessor_id != node->pred_id) {
238 node->pred_id = predecessor_id;
240 if (predecessor_id != -1) {
241 get_mailbox(predecessor_id, node->pred_mailbox);
243 node->last_change_date = MSG_get_clock();
245 XBT_DEBUG("My new predecessor is %d", predecessor_id);
250 * \brief Node Function
253 * - the id of a guy I know in the system (except for the first node)
254 * - the time to sleep before I join (except for the first node)
256 int node(int argc, char *argv[])
258 /* Reduce the run size for the MC */
260 periodic_stabilize_delay = 8;
261 periodic_fix_fingers_delay = 8;
262 periodic_check_predecessor_delay = 8;
265 double init_time = MSG_get_clock();
266 m_task_t task_received = NULL;
268 int join_success = 0;
270 double next_stabilize_date = init_time + periodic_stabilize_delay;
271 double next_fix_fingers_date = init_time + periodic_fix_fingers_delay;
272 double next_check_predecessor_date = init_time + periodic_check_predecessor_delay;
273 double next_lookup_date = init_time + periodic_lookup_delay;
275 xbt_assert0(argc == 3 || argc == 5, "Wrong number of arguments for this node");
277 // initialize my node
279 node.id = atoi(argv[1]);
280 get_mailbox(node.id, node.mailbox);
281 node.next_finger_to_fix = 0;
282 node.fingers = xbt_new0(s_finger_t, nb_bits);
283 node.last_change_date = init_time;
285 for (i = 0; i < nb_bits; i++) {
286 node.fingers[i].id = -1;
287 set_finger(&node, i, node.id);
290 if (argc == 3) { // first ring
291 deadline = atof(argv[2]);
296 int known_id = atoi(argv[2]);
297 //double sleep_time = atof(argv[3]);
298 deadline = atof(argv[4]);
301 // sleep before starting
302 XBT_DEBUG("Let's sleep during %f", sleep_time);
303 MSG_process_sleep(sleep_time);
305 XBT_DEBUG("Hey! Let's join the system.");
307 join_success = join(&node, known_id);
311 while (MSG_get_clock() < init_time + deadline
312 // && MSG_get_clock() < node.last_change_date + 1000
313 && MSG_get_clock() < max_simulation_time) {
315 if (node.comm_receive == NULL) {
316 task_received = NULL;
317 node.comm_receive = MSG_task_irecv(&task_received, node.mailbox);
318 // FIXME: do not make MSG_task_irecv() calls from several functions
321 if (!MSG_comm_test(node.comm_receive)) {
323 // no task was received: make some periodic calls
324 if (MSG_get_clock() >= next_stabilize_date) {
326 next_stabilize_date = MSG_get_clock() + periodic_stabilize_delay;
328 else if (MSG_get_clock() >= next_fix_fingers_date) {
330 next_fix_fingers_date = MSG_get_clock() + periodic_fix_fingers_delay;
332 else if (MSG_get_clock() >= next_check_predecessor_date) {
333 check_predecessor(&node);
334 next_check_predecessor_date = MSG_get_clock() + periodic_check_predecessor_delay;
336 else if (MSG_get_clock() >= next_lookup_date) {
337 random_lookup(&node);
338 next_lookup_date = MSG_get_clock() + periodic_lookup_delay;
341 // nothing to do: sleep for a while
342 MSG_process_sleep(5);
346 // a transfer has occured
348 MSG_error_t status = MSG_comm_get_status(node.comm_receive);
350 if (status != MSG_OK) {
351 XBT_DEBUG("Failed to receive a task. Nevermind.");
352 node.comm_receive = NULL;
355 // the task was successfully received
356 MSG_comm_destroy(node.comm_receive);
357 node.comm_receive = NULL;
358 handle_task(&node, task_received);
362 // see if some communications are finished
364 while ((index = MSG_comm_testany(node.comms)) != -1) {
365 comm_send = xbt_dynar_get_as(node.comms, index, msg_comm_t);
366 MSG_error_t status = MSG_comm_get_status(comm_send);
367 xbt_dynar_remove_at(node.comms, index, &comm_send);
368 XBT_DEBUG("Communication %p is finished with status %d, dynar size is now %lu",
369 comm_send, status, xbt_dynar_length(node.comms));
370 m_task_t task = MSG_comm_get_task(comm_send);
371 MSG_comm_destroy(comm_send);
372 if (status != MSG_OK) {
373 task_data_destroy(MSG_task_get_data(task));
374 MSG_task_destroy(task);
380 // clean unfinished comms sent
381 /* unsigned int cursor;
382 xbt_dynar_foreach(node.comms, cursor, comm_send) {
383 m_task_t task = MSG_comm_get_task(comm_send);
384 MSG_task_cancel(task);
385 task_data_destroy(MSG_task_get_data(task));
386 MSG_task_destroy(task);
387 MSG_comm_destroy(comm_send);
388 // FIXME: the task is actually not destroyed because MSG thinks that the other side (whose process is dead) is still using it
395 // stop the simulation
396 xbt_free(node.fingers);
397 XBT_INFO("Messages created: %lu", smx_total_comms);
402 * \brief This function is called when the current node receives a task.
403 * \param node the current node
404 * \param task the task to handle (don't touch it then:
405 * it will be destroyed, reused or forwarded)
407 static void handle_task(node_t node, m_task_t task) {
409 XBT_DEBUG("Handling task %p", task);
410 char mailbox[MAILBOX_NAME_SIZE];
411 task_data_t task_data = (task_data_t) MSG_task_get_data(task);
412 e_task_type_t type = task_data->type;
416 case TASK_FIND_SUCCESSOR:
417 XBT_DEBUG("Receiving a 'Find Successor' request from %s for id %d",
418 task_data->issuer_host_name, task_data->request_id);
419 // is my successor the successor?
420 if (is_in_interval(task_data->request_id, node->id + 1, node->fingers[0].id)) {
421 task_data->type = TASK_FIND_SUCCESSOR_ANSWER;
422 task_data->answer_id = node->fingers[0].id;
423 XBT_DEBUG("Sending back a 'Find Successor Answer' to %s (mailbox %s): the successor of %d is %d",
424 task_data->issuer_host_name,
425 task_data->answer_to,
426 task_data->request_id, task_data->answer_id);
427 MSG_task_dsend(task, task_data->answer_to, task_free);
430 // otherwise, forward the request to the closest preceding finger in my table
431 int closest = closest_preceding_node(node, task_data->request_id);
432 XBT_DEBUG("Forwarding the 'Find Successor' request for id %d to my closest preceding finger %d",
433 task_data->request_id, closest);
434 get_mailbox(closest, mailbox);
435 MSG_task_dsend(task, mailbox, task_free);
439 case TASK_GET_PREDECESSOR:
440 XBT_DEBUG("Receiving a 'Get Predecessor' request from %s", task_data->issuer_host_name);
441 task_data->type = TASK_GET_PREDECESSOR_ANSWER;
442 task_data->answer_id = node->pred_id;
443 XBT_DEBUG("Sending back a 'Get Predecessor Answer' to %s via mailbox '%s': my predecessor is %d",
444 task_data->issuer_host_name,
445 task_data->answer_to, task_data->answer_id);
446 MSG_task_dsend(task, task_data->answer_to, task_free);
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);
456 case TASK_PREDECESSOR_LEAVING:
457 // my predecessor is about to quit
458 XBT_DEBUG("Receiving a 'Predecessor Leaving' message from %s", task_data->issuer_host_name);
459 // modify my predecessor
460 set_predecessor(node, task_data->request_id);
463 >> notify my new predecessor
464 >> send a notify_predecessors !!
468 case TASK_SUCCESSOR_LEAVING:
469 // my successor is about to quit
470 XBT_DEBUG("Receiving a 'Successor Leaving' message from %s", task_data->issuer_host_name);
471 // modify my successor FIXME : this should be implicit ?
472 set_finger(node, 0, task_data->request_id);
475 >> notify my new successor
476 >> update my table & predecessors table */
479 case TASK_FIND_SUCCESSOR_ANSWER:
480 case TASK_GET_PREDECESSOR_ANSWER:
481 XBT_DEBUG("Ignoring unexpected task of type %d (%p)", type, task);
488 * \brief Initializes the current node as the first one of the system.
489 * \param node the current node
491 static void create(node_t node)
493 XBT_DEBUG("Create a new Chord ring...");
494 set_predecessor(node, -1); // -1 means that I have no predecessor
495 print_finger_table(node);
499 * \brief Makes the current node join the ring, knowing the id of a node
500 * already in the ring
501 * \param node the current node
502 * \param known_id id of a node already in the ring
503 * \return 1 if the join operation succeeded, 0 otherwise
505 static int join(node_t node, int known_id)
507 XBT_INFO("Joining the ring with id %d, knowing node %d", node->id, known_id);
508 set_predecessor(node, -1); // no predecessor (yet)
512 for (i = 0; i < nb_bits; i++) {
513 set_finger(node, i, known_id);
517 int successor_id = remote_find_successor(node, known_id, node->id);
518 if (successor_id == -1) {
519 XBT_INFO("Cannot join the ring.");
522 set_finger(node, 0, successor_id);
523 print_finger_table(node);
526 return successor_id != -1;
530 * \brief Makes the current node quit the system
531 * \param node the current node
533 static void leave(node_t node)
535 XBT_DEBUG("Well Guys! I Think it's time for me to quit ;)");
536 quit_notify(node, 1); // notify to my successor ( >>> 1 );
537 quit_notify(node, -1); // notify my predecessor ( >>> -1);
542 * \brief Notifies the successor or the predecessor of the current node
544 * \param node the current node
545 * \param to 1 to notify the successor, -1 to notify the predecessor
546 * FIXME: notify both nodes with only one call
548 static void quit_notify(node_t node, int to)
551 task_data_t req_data = xbt_new0(s_task_data_t, 1);
552 req_data->request_id = node->id;
553 req_data->successor_id = node->fingers[0].id;
554 req_data->pred_id = node->pred_id;
555 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
556 req_data->answer_to = NULL;
557 const char* task_name = NULL;
558 const char* to_mailbox = NULL;
559 if (to == 1) { // notify my successor
560 to_mailbox = node->fingers[0].mailbox;
561 XBT_INFO("Telling my Successor %d about my departure via mailbox %s",
562 node->fingers[0].id, to_mailbox);
563 req_data->type = TASK_PREDECESSOR_LEAVING;
565 else if (to == -1) { // notify my predecessor
567 if (node->pred_id == -1) {
571 to_mailbox = node->pred_mailbox;
572 XBT_INFO("Telling my Predecessor %d about my departure via mailbox %s",
573 node->pred_id, to_mailbox);
574 req_data->type = TASK_SUCCESSOR_LEAVING;
576 m_task_t task = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
577 //char* mailbox = get_mailbox(to_mailbox);
578 msg_comm_t comm = MSG_task_isend(task, to_mailbox);
579 xbt_dynar_push(node->comms, &comm);
584 * \brief Makes the current node find the successor node of an id.
585 * \param node the current node
586 * \param id the id to find
587 * \return the id of the successor node, or -1 if the request failed
589 static int find_successor(node_t node, int id)
591 // is my successor the successor?
592 if (is_in_interval(id, node->id + 1, node->fingers[0].id)) {
593 return node->fingers[0].id;
596 // otherwise, ask the closest preceding finger in my table
597 int closest = closest_preceding_node(node, id);
598 return remote_find_successor(node, closest, id);
602 * \brief Asks another node the successor node of an id.
603 * \param node the current node
604 * \param ask_to the node to ask to
605 * \param id the id to find
606 * \return the id of the successor node, or -1 if the request failed
608 static int remote_find_successor(node_t node, int ask_to, int id)
612 char mailbox[MAILBOX_NAME_SIZE];
613 get_mailbox(ask_to, mailbox);
614 task_data_t req_data = xbt_new0(s_task_data_t, 1);
615 req_data->type = TASK_FIND_SUCCESSOR;
616 req_data->request_id = id;
617 get_mailbox(node->id, req_data->answer_to);
618 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
620 // send a "Find Successor" request to ask_to_id
621 m_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
622 XBT_DEBUG("Sending a 'Find Successor' request (task %p) to %d for id %d", task_sent, ask_to, id);
623 MSG_error_t res = MSG_task_send_with_timeout(task_sent, mailbox, timeout);
626 XBT_DEBUG("Failed to send the 'Find Successor' request (task %p) to %d for id %d",
627 task_sent, ask_to, id);
628 task_free(task_sent);
632 // receive the answer
633 XBT_DEBUG("Sent a 'Find Successor' request (task %p) to %d for key %d, waiting for the answer",
634 task_sent, ask_to, id);
637 if (node->comm_receive == NULL) {
638 m_task_t task_received = NULL;
639 node->comm_receive = MSG_task_irecv(&task_received, node->mailbox);
642 res = MSG_comm_wait(node->comm_receive, timeout);
645 XBT_DEBUG("Failed to receive the answer to my 'Find Successor' request (task %p): %d",
648 MSG_comm_destroy(node->comm_receive);
649 node->comm_receive = NULL;
652 m_task_t task_received = MSG_comm_get_task(node->comm_receive);
653 XBT_DEBUG("Received a task (%p)", task_received);
654 task_data_t ans_data = MSG_task_get_data(task_received);
657 MC_assert(task_received == task_sent);
660 if (task_received != task_sent) {
661 // this is not the expected answer
662 MSG_comm_destroy(node->comm_receive);
663 node->comm_receive = NULL;
664 handle_task(node, task_received);
667 // this is our answer
668 XBT_DEBUG("Received the answer to my 'Find Successor' request for id %d (task %p): the successor of key %d is %d",
669 ans_data->request_id, task_received, id, ans_data->answer_id);
670 successor = ans_data->answer_id;
672 MSG_comm_destroy(node->comm_receive);
673 node->comm_receive = NULL;
674 task_free(task_received);
684 * \brief Asks another node its predecessor.
685 * \param node the current node
686 * \param ask_to the node to ask to
687 * \return the id of its predecessor node, or -1 if the request failed
688 * (or if the node does not know its predecessor)
690 static int remote_get_predecessor(node_t node, int ask_to)
692 int predecessor_id = -1;
694 char mailbox[MAILBOX_NAME_SIZE];
695 get_mailbox(ask_to, mailbox);
696 task_data_t req_data = xbt_new0(s_task_data_t, 1);
697 req_data->type = TASK_GET_PREDECESSOR;
698 get_mailbox(node->id, req_data->answer_to);
699 req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
701 // send a "Get Predecessor" request to ask_to_id
702 XBT_DEBUG("Sending a 'Get Predecessor' request to %d", ask_to);
703 m_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
704 MSG_error_t res = MSG_task_send_with_timeout(task_sent, mailbox, timeout);
707 XBT_DEBUG("Failed to send the 'Get Predecessor' request (task %p) to %d",
709 task_free(task_sent);
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 m_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 m_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 task_free(task_received);
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 XBT_DEBUG("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 XBT_DEBUG("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 XBT_DEBUG("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_task_dsend(task, mailbox, task_free);
848 * \brief This function is called periodically.
849 * It refreshes the finger table of the current node.
850 * \param node the current node
852 static void fix_fingers(node_t node) {
854 XBT_DEBUG("Fixing fingers");
855 int i = node->next_finger_to_fix;
856 int id = find_successor(node, node->id + powers2[i]);
859 if (id != node->fingers[i].id) {
860 set_finger(node, i, id);
861 print_finger_table(node);
863 node->next_finger_to_fix = (i + 1) % nb_bits;
868 * \brief This function is called periodically.
869 * It checks whether the predecessor has failed
870 * \param node the current node
872 static void check_predecessor(node_t node)
874 XBT_DEBUG("Checking whether my predecessor is alive");
879 * \brief Performs a find successor request to a random id.
880 * \param node the current node
882 static void random_lookup(node_t node)
884 int id = 1337; // TODO pick a pseudorandom id
885 XBT_DEBUG("Making a lookup request for id %d", id);
886 find_successor(node, id);
890 * \brief Main function.
892 int main(int argc, char *argv[])
894 xbt_os_timer_t timer = xbt_os_timer_new();
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_global_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_die("Invalid chord option '%s'", options[0]);
926 const char* platform_file = options[0];
927 const char* application_file = options[1];
931 MSG_set_channel_number(0);
932 MSG_create_environment(platform_file);
934 MSG_function_register("node", node);
935 MSG_launch_application(application_file);
937 xbt_os_timer_start(timer);
938 MSG_error_t res = MSG_main();
939 xbt_os_timer_stop(timer);
940 XBT_CRITICAL("Simulation time %lf", xbt_os_timer_elapsed(timer));
941 XBT_INFO("Simulated time: %g", MSG_get_clock());