From 9635b325d92f922d52509d83a146803501b49f8f Mon Sep 17 00:00:00 2001 From: Marion Guthmuller Date: Mon, 8 Oct 2012 21:25:21 +0200 Subject: [PATCH] version of chord before use MSG_task_dsend --- examples/msg/chord/chord_before_dsend.c | 946 ++++++++++++++++++++++++ 1 file changed, 946 insertions(+) create mode 100644 examples/msg/chord/chord_before_dsend.c diff --git a/examples/msg/chord/chord_before_dsend.c b/examples/msg/chord/chord_before_dsend.c new file mode 100644 index 0000000000..8f7b2f543a --- /dev/null +++ b/examples/msg/chord/chord_before_dsend.c @@ -0,0 +1,946 @@ + +/* Copyright (c) 2010. The SimGrid Team. + * All rights reserved. */ + +/* This program is free software; you can redistribute it and/or modify it + * under the terms of the license (GNU LGPL) which comes with this package. */ + +#include +#include "msg/msg.h" +#include "xbt/log.h" +#include "xbt/asserts.h" +#include "mc/modelchecker.h" +#include "mc/mc.h" +XBT_LOG_NEW_DEFAULT_CATEGORY(msg_chord, + "Messages specific for this msg example"); + +#define COMM_SIZE 10 +#define COMP_SIZE 0 +#define MAILBOX_NAME_SIZE 10 + +static int nb_bits = 24; +static int nb_keys = 0; +static int timeout = 50; +static int max_simulation_time = 1000; +static int periodic_stabilize_delay = 20; +static int periodic_fix_fingers_delay = 120; +static int periodic_check_predecessor_delay = 120; +static int periodic_lookup_delay = 10; + +/** + * Finger element. + */ +typedef struct finger { + int id; + char mailbox[MAILBOX_NAME_SIZE]; // string representation of the id +} s_finger_t, *finger_t; + +/** + * Node data. + */ +typedef struct node { + int id; // my id + char mailbox[MAILBOX_NAME_SIZE]; // my mailbox name (string representation of the id) + s_finger_t *fingers; // finger table, of size nb_bits (fingers[0] is my successor) + int pred_id; // predecessor id + char pred_mailbox[MAILBOX_NAME_SIZE]; // predecessor's mailbox name + int next_finger_to_fix; // index of the next finger to fix in fix_fingers() + msg_comm_t comm_receive; // current communication to receive + xbt_dynar_t comms; // current communications being sent + double last_change_date; // last time I changed a finger or my predecessor +} s_node_t, *node_t; + +/** + * Types of tasks exchanged between nodes. + */ +typedef enum { + TASK_FIND_SUCCESSOR, + TASK_FIND_SUCCESSOR_ANSWER, + TASK_GET_PREDECESSOR, + TASK_GET_PREDECESSOR_ANSWER, + TASK_NOTIFY, + TASK_SUCCESSOR_LEAVING, + TASK_PREDECESSOR_LEAVING +} e_task_type_t; + +/** + * Data attached with the tasks sent and received + */ +typedef struct task_data { + e_task_type_t type; // type of task + int request_id; // id paramater (used by some types of tasks) + int request_finger; // finger parameter (used by some types of tasks) + int answer_id; // answer (used by some types of tasks) + char answer_to[MAILBOX_NAME_SIZE]; // mailbox to send an answer to (if any) + const char* issuer_host_name; // used for logging +} s_task_data_t, *task_data_t; + +static int *powers2; + +// utility functions +static void chord_initialize(void); +static int normalize(int id); +static int is_in_interval(int id, int start, int end); +static void get_mailbox(int host_id, char* mailbox); +static void task_data_destroy(task_data_t task_data); +static void print_finger_table(node_t node); +static void set_finger(node_t node, int finger_index, int id); +static void set_predecessor(node_t node, int predecessor_id); + +// process functions +static int node(int argc, char *argv[]); +static void handle_task(node_t node, m_task_t task); + +// Chord core +static void create(node_t node); +static int join(node_t node, int known_id); +static void leave(node_t node); +static int find_successor(node_t node, int id); +static int remote_find_successor(node_t node, int ask_to_id, int id); +static int remote_get_predecessor(node_t node, int ask_to_id); +static int closest_preceding_node(node_t node, int id); +static void stabilize(node_t node); +static void notify(node_t node, int predecessor_candidate_id); +static void remote_notify(node_t node, int notify_to, int predecessor_candidate_id); +static void fix_fingers(node_t node); +static void check_predecessor(node_t node); +static void random_lookup(node_t); +static void quit_notify(node_t node, int to); + +/** + * \brief Global initialization of the Chord simulation. + */ +static void chord_initialize(void) +{ + // compute the powers of 2 once for all + powers2 = xbt_new(int, nb_bits); + int pow = 1; + int i; + for (i = 0; i < nb_bits; i++) { + powers2[i] = pow; + pow = pow << 1; + } + nb_keys = pow; + DEBUG1("Sets nb_keys to %d", nb_keys); +} + +/** + * \brief Turns an id into an equivalent id in [0, nb_keys). + * \param id an id + * \return the corresponding normalized id + */ +static int normalize(int id) +{ + // like id % nb_keys, but works with negatives numbers (and faster) + return id & (nb_keys - 1); +} + +/** + * \brief Returns whether a id belongs to the interval [start, end]. + * + * The parameters are noramlized to make sure they are between 0 and nb_keys - 1). + * 1 belongs to [62, 3] + * 1 does not belong to [3, 62] + * 63 belongs to [62, 3] + * 63 does not belong to [3, 62] + * 24 belongs to [21, 29] + * 24 does not belong to [29, 21] + * + * \param id id to check + * \param start lower bound + * \param end upper bound + * \return a non-zero value if id in in [start, end] + */ +static int is_in_interval(int id, int start, int end) +{ + id = normalize(id); + start = normalize(start); + end = normalize(end); + + // make sure end >= start and id >= start + if (end < start) { + end += nb_keys; + } + + if (id < start) { + id += nb_keys; + } + + return id <= end; +} + +/** + * \brief Gets the mailbox name of a host given its chord id. + * \param node_id id of a node + * \param mailbox pointer to where the mailbox name should be written + * (there must be enough space) + */ +static void get_mailbox(int node_id, char* mailbox) +{ + snprintf(mailbox, MAILBOX_NAME_SIZE - 1, "%d", node_id); +} + +/** + * \brief Frees the memory used by some task data. + * \param task_data the task data to destroy + */ +static void task_data_destroy(task_data_t task_data) +{ + xbt_free(task_data); +} + +/** + * \brief Displays the finger table of a node. + * \param node a node + */ +static void print_finger_table(node_t node) +{ + if (XBT_LOG_ISENABLED(msg_chord, xbt_log_priority_verbose)) { + int i; + VERB0("My finger table:"); + VERB0("Start | Succ "); + for (i = 0; i < nb_bits; i++) { + VERB2(" %3d | %3d ", (node->id + powers2[i]) % nb_keys, node->fingers[i].id); + } + VERB1("Predecessor: %d", node->pred_id); + } +} + +/** + * \brief Sets a finger of the current node. + * \param node the current node + * \param finger_index index of the finger to set (0 to nb_bits - 1) + * \param id the id to set for this finger + */ +static void set_finger(node_t node, int finger_index, int id) +{ + if (id != node->fingers[finger_index].id) { + node->fingers[finger_index].id = id; + get_mailbox(id, node->fingers[finger_index].mailbox); + node->last_change_date = MSG_get_clock(); + DEBUG2("My new finger #%d is %d", finger_index, id); + } +} + +/** + * \brief Sets the predecessor of the current node. + * \param node the current node + * \param id the id to predecessor, or -1 to unset the predecessor + */ +static void set_predecessor(node_t node, int predecessor_id) +{ + if (predecessor_id != node->pred_id) { + node->pred_id = predecessor_id; + + if (predecessor_id != -1) { + get_mailbox(predecessor_id, node->pred_mailbox); + } + node->last_change_date = MSG_get_clock(); + + DEBUG1("My new predecessor is %d", predecessor_id); + } +} + +/** + * \brief Node Function + * Arguments: + * - my id + * - the id of a guy I know in the system (except for the first node) + * - the time to sleep before I join (except for the first node) + */ +int node(int argc, char *argv[]) +{ + /* Reduce the run size for the MC */ + if(MC_IS_ENABLED){ + periodic_stabilize_delay = 8; + periodic_fix_fingers_delay = 8; + periodic_check_predecessor_delay = 8; + } + + double init_time = MSG_get_clock(); + m_task_t task_received = NULL; + msg_comm_t comm_send = NULL; + int i; + int index; + int join_success = 0; + double deadline; + double next_stabilize_date = init_time + periodic_stabilize_delay; + double next_fix_fingers_date = init_time + periodic_fix_fingers_delay; + double next_check_predecessor_date = init_time + periodic_check_predecessor_delay; + double next_lookup_date = init_time + periodic_lookup_delay; + + xbt_assert0(argc == 3 || argc == 5, "Wrong number of arguments for this node"); + + // initialize my node + s_node_t node = {0}; + node.id = atoi(argv[1]); + get_mailbox(node.id, node.mailbox); + node.next_finger_to_fix = 0; + node.comms = xbt_dynar_new(sizeof(msg_comm_t), NULL); + node.fingers = xbt_new0(s_finger_t, nb_bits); + node.last_change_date = init_time; + + for (i = 0; i < nb_bits; i++) { + node.fingers[i].id = -1; + set_finger(&node, i, node.id); + } + + if (argc == 3) { // first ring + deadline = atof(argv[2]); + create(&node); + join_success = 1; + } + else { + int known_id = atoi(argv[2]); + //double sleep_time = atof(argv[3]); + deadline = atof(argv[4]); + + /* + // sleep before starting + DEBUG1("Let's sleep during %f", sleep_time); + MSG_process_sleep(sleep_time); + */ + DEBUG0("Hey! Let's join the system."); + + join_success = join(&node, known_id); + } + + if (join_success) { + while (MSG_get_clock() < init_time + deadline +// && MSG_get_clock() < node.last_change_date + 1000 + && MSG_get_clock() < max_simulation_time) { + + if (node.comm_receive == NULL) { + task_received = NULL; + node.comm_receive = MSG_task_irecv(&task_received, node.mailbox); + // FIXME: do not make MSG_task_irecv() calls from several functions + } + + if (!MSG_comm_test(node.comm_receive)) { + + // no task was received: make some periodic calls + if (MSG_get_clock() >= next_stabilize_date) { + stabilize(&node); + next_stabilize_date = MSG_get_clock() + periodic_stabilize_delay; + } + else if (MSG_get_clock() >= next_fix_fingers_date) { + fix_fingers(&node); + next_fix_fingers_date = MSG_get_clock() + periodic_fix_fingers_delay; + } + else if (MSG_get_clock() >= next_check_predecessor_date) { + check_predecessor(&node); + next_check_predecessor_date = MSG_get_clock() + periodic_check_predecessor_delay; + } + else if (MSG_get_clock() >= next_lookup_date) { + random_lookup(&node); + next_lookup_date = MSG_get_clock() + periodic_lookup_delay; + } + else { + // nothing to do: sleep for a while + MSG_process_sleep(5); + } + } + else { + // a transfer has occured + + MSG_error_t status = MSG_comm_get_status(node.comm_receive); + + if (status != MSG_OK) { + DEBUG0("Failed to receive a task. Nevermind."); + node.comm_receive = NULL; + } + else { + // the task was successfully received + MSG_comm_destroy(node.comm_receive); + node.comm_receive = NULL; + handle_task(&node, task_received); + } + } + + // see if some communications are finished + while ((index = MSG_comm_testany(node.comms)) != -1) { + comm_send = xbt_dynar_get_as(node.comms, index, msg_comm_t); + MSG_error_t status = MSG_comm_get_status(comm_send); + xbt_dynar_remove_at(node.comms, index, &comm_send); + DEBUG3("Communication %p is finished with status %d, dynar size is now %lu", + comm_send, status, xbt_dynar_length(node.comms)); + m_task_t task = MSG_comm_get_task(comm_send); + MSG_comm_destroy(comm_send); + if (status != MSG_OK) { + task_data_destroy(MSG_task_get_data(task)); + MSG_task_destroy(task); + } + } + } + + // clean unfinished comms sent + /* unsigned int cursor; + xbt_dynar_foreach(node.comms, cursor, comm_send) { + m_task_t task = MSG_comm_get_task(comm_send); + MSG_task_cancel(task); + task_data_destroy(MSG_task_get_data(task)); + MSG_task_destroy(task); + MSG_comm_destroy(comm_send); + // FIXME: the task is actually not destroyed because MSG thinks that the other side (whose process is dead) is still using it + }*/ + + // leave the ring + leave(&node); + } + + // stop the simulation + xbt_dynar_free(&node.comms); + xbt_free(node.fingers); + return 0; +} + +/** + * \brief This function is called when the current node receives a task. + * \param node the current node + * \param task the task to handle (don't touch it then: + * it will be destroyed, reused or forwarded) + */ +static void handle_task(node_t node, m_task_t task) { + + DEBUG1("Handling task %p", task); + msg_comm_t comm = NULL; + char mailbox[MAILBOX_NAME_SIZE]; + task_data_t task_data = (task_data_t) MSG_task_get_data(task); + e_task_type_t type = task_data->type; + + switch (type) { + + case TASK_FIND_SUCCESSOR: + DEBUG2("Receiving a 'Find Successor' request from %s for id %d", + task_data->issuer_host_name, task_data->request_id); + // is my successor the successor? + if (is_in_interval(task_data->request_id, node->id + 1, node->fingers[0].id)) { + task_data->type = TASK_FIND_SUCCESSOR_ANSWER; + task_data->answer_id = node->fingers[0].id; + DEBUG4("Sending back a 'Find Successor Answer' to %s (mailbox %s): the successor of %d is %d", + task_data->issuer_host_name, + task_data->answer_to, + task_data->request_id, task_data->answer_id); + comm = MSG_task_isend(task, task_data->answer_to); + xbt_dynar_push(node->comms, &comm); + } + else { + // otherwise, forward the request to the closest preceding finger in my table + int closest = closest_preceding_node(node, task_data->request_id); + DEBUG2("Forwarding the 'Find Successor' request for id %d to my closest preceding finger %d", + task_data->request_id, closest); + get_mailbox(closest, mailbox); + comm = MSG_task_isend(task, mailbox); + xbt_dynar_push(node->comms, &comm); + } + break; + + case TASK_GET_PREDECESSOR: + DEBUG1("Receiving a 'Get Predecessor' request from %s", task_data->issuer_host_name); + task_data->type = TASK_GET_PREDECESSOR_ANSWER; + task_data->answer_id = node->pred_id; + DEBUG3("Sending back a 'Get Predecessor Answer' to %s via mailbox '%s': my predecessor is %d", + task_data->issuer_host_name, + task_data->answer_to, task_data->answer_id); + comm = MSG_task_isend(task, task_data->answer_to); + xbt_dynar_push(node->comms, &comm); + break; + + case TASK_NOTIFY: + // someone is telling me that he may be my new predecessor + DEBUG1("Receiving a 'Notify' request from %s", task_data->issuer_host_name); + notify(node, task_data->request_id); + task_data_destroy(task_data); + MSG_task_destroy(task); + break; + + case TASK_PREDECESSOR_LEAVING: + // my predecessor is about to quit + DEBUG1("Receiving a 'Predecessor Leaving' message from %s", task_data->issuer_host_name); + // modify my predecessor + set_predecessor(node, task_data->request_id); + task_data_destroy(task_data); + MSG_task_destroy(task); + /*TODO : + >> notify my new predecessor + >> send a notify_predecessors !! + */ + break; + + case TASK_SUCCESSOR_LEAVING: + // my successor is about to quit + DEBUG1("Receiving a 'Successor Leaving' message from %s", task_data->issuer_host_name); + // modify my successor FIXME : this should be implicit ? + set_finger(node, 0, task_data->request_id); + task_data_destroy(task_data); + MSG_task_destroy(task); + /* TODO + >> notify my new successor + >> update my table & predecessors table */ + break; + + case TASK_FIND_SUCCESSOR_ANSWER: + case TASK_GET_PREDECESSOR_ANSWER: + DEBUG2("Ignoring unexpected task of type %d (%p)", type, task); + task_data_destroy(task_data); + MSG_task_destroy(task); + break; + } +} + +/** + * \brief Initializes the current node as the first one of the system. + * \param node the current node + */ +static void create(node_t node) +{ + DEBUG0("Create a new Chord ring..."); + set_predecessor(node, -1); // -1 means that I have no predecessor + print_finger_table(node); +} + +/** + * \brief Makes the current node join the ring, knowing the id of a node + * already in the ring + * \param node the current node + * \param known_id id of a node already in the ring + * \return 1 if the join operation succeeded, 0 otherwise + */ +static int join(node_t node, int known_id) +{ + INFO2("Joining the ring with id %d, knowing node %d", node->id, known_id); + set_predecessor(node, -1); // no predecessor (yet) + + int successor_id = remote_find_successor(node, known_id, node->id); + if (successor_id == -1) { + INFO0("Cannot join the ring."); + } + else { + set_finger(node, 0, successor_id); + print_finger_table(node); + } + + return successor_id != -1; +} + +/** + * \brief Makes the current node quit the system + * \param node the current node + */ +static void leave(node_t node) +{ + DEBUG0("Well Guys! I Think it's time for me to quit ;)"); + quit_notify(node, 1); // notify to my successor ( >>> 1 ); + quit_notify(node, -1); // notify my predecessor ( >>> -1); + // TODO ... +} + +/* + * \brief Notifies the successor or the predecessor of the current node + * of the departure + * \param node the current node + * \param to 1 to notify the successor, -1 to notify the predecessor + * FIXME: notify both nodes with only one call + */ +static void quit_notify(node_t node, int to) +{ + /* TODO + task_data_t req_data = xbt_new0(s_task_data_t, 1); + req_data->request_id = node->id; + req_data->successor_id = node->fingers[0].id; + req_data->pred_id = node->pred_id; + req_data->issuer_host_name = MSG_host_get_name(MSG_host_self()); + req_data->answer_to = NULL; + const char* task_name = NULL; + const char* to_mailbox = NULL; + if (to == 1) { // notify my successor + to_mailbox = node->fingers[0].mailbox; + INFO2("Telling my Successor %d about my departure via mailbox %s", + node->fingers[0].id, to_mailbox); + req_data->type = TASK_PREDECESSOR_LEAVING; + } + else if (to == -1) { // notify my predecessor + + if (node->pred_id == -1) { + return; + } + + to_mailbox = node->pred_mailbox; + INFO2("Telling my Predecessor %d about my departure via mailbox %s", + node->pred_id, to_mailbox); + req_data->type = TASK_SUCCESSOR_LEAVING; + } + m_task_t task = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data); + //char* mailbox = get_mailbox(to_mailbox); + msg_comm_t comm = MSG_task_isend(task, to_mailbox); + xbt_dynar_push(node->comms, &comm); + */ +} + +/** + * \brief Makes the current node find the successor node of an id. + * \param node the current node + * \param id the id to find + * \return the id of the successor node, or -1 if the request failed + */ +static int find_successor(node_t node, int id) +{ + // is my successor the successor? + if (is_in_interval(id, node->id + 1, node->fingers[0].id)) { + return node->fingers[0].id; + } + + // otherwise, ask the closest preceding finger in my table + int closest = closest_preceding_node(node, id); + return remote_find_successor(node, closest, id); +} + +/** + * \brief Asks another node the successor node of an id. + * \param node the current node + * \param ask_to the node to ask to + * \param id the id to find + * \return the id of the successor node, or -1 if the request failed + */ +static int remote_find_successor(node_t node, int ask_to, int id) +{ + int successor = -1; + int stop = 0; + char mailbox[MAILBOX_NAME_SIZE]; + get_mailbox(ask_to, mailbox); + task_data_t req_data = xbt_new0(s_task_data_t, 1); + req_data->type = TASK_FIND_SUCCESSOR; + req_data->request_id = id; + get_mailbox(node->id, req_data->answer_to); + req_data->issuer_host_name = MSG_host_get_name(MSG_host_self()); + + // send a "Find Successor" request to ask_to_id + m_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data); + DEBUG3("Sending a 'Find Successor' request (task %p) to %d for id %d", task_sent, ask_to, id); + MSG_error_t res = MSG_task_send_with_timeout(task_sent, mailbox, timeout); + + if (res != MSG_OK) { + DEBUG3("Failed to send the 'Find Successor' request (task %p) to %d for id %d", + task_sent, ask_to, id); + MSG_task_destroy(task_sent); + task_data_destroy(req_data); + } + else { + + // receive the answer + DEBUG3("Sent a 'Find Successor' request (task %p) to %d for key %d, waiting for the answer", + task_sent, ask_to, id); + + do { + if (node->comm_receive == NULL) { + m_task_t task_received = NULL; + node->comm_receive = MSG_task_irecv(&task_received, node->mailbox); + } + + res = MSG_comm_wait(node->comm_receive, timeout); + + if (res != MSG_OK) { + DEBUG2("Failed to receive the answer to my 'Find Successor' request (task %p): %d", + task_sent, res); + stop = 1; + MSG_comm_destroy(node->comm_receive); + node->comm_receive = NULL; + } + else { + m_task_t task_received = MSG_comm_get_task(node->comm_receive); + DEBUG1("Received a task (%p)", task_received); + task_data_t ans_data = MSG_task_get_data(task_received); + + if (MC_IS_ENABLED) { + MC_assert(task_received == task_sent); + } + + if (task_received != task_sent) { + // this is not the expected answer + MSG_comm_destroy(node->comm_receive); + node->comm_receive = NULL; + handle_task(node, task_received); + } + else { + // this is our answer + DEBUG4("Received the answer to my 'Find Successor' request for id %d (task %p): the successor of key %d is %d", + ans_data->request_id, task_received, id, ans_data->answer_id); + successor = ans_data->answer_id; + stop = 1; + MSG_comm_destroy(node->comm_receive); + node->comm_receive = NULL; + MSG_task_destroy(task_received); + task_data_destroy(req_data); + } + } + } while (!stop); + } + + return successor; +} + +/** + * \brief Asks another node its predecessor. + * \param node the current node + * \param ask_to the node to ask to + * \return the id of its predecessor node, or -1 if the request failed + * (or if the node does not know its predecessor) + */ +static int remote_get_predecessor(node_t node, int ask_to) +{ + int predecessor_id = -1; + int stop = 0; + char mailbox[MAILBOX_NAME_SIZE]; + get_mailbox(ask_to, mailbox); + task_data_t req_data = xbt_new0(s_task_data_t, 1); + req_data->type = TASK_GET_PREDECESSOR; + get_mailbox(node->id, req_data->answer_to); + req_data->issuer_host_name = MSG_host_get_name(MSG_host_self()); + + // send a "Get Predecessor" request to ask_to_id + DEBUG1("Sending a 'Get Predecessor' request to %d", ask_to); + m_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data); + MSG_error_t res = MSG_task_send_with_timeout(task_sent, mailbox, timeout); + + if (res != MSG_OK) { + DEBUG2("Failed to send the 'Get Predecessor' request (task %p) to %d", + task_sent, ask_to); + MSG_task_destroy(task_sent); + task_data_destroy(req_data); + } + else { + + // receive the answer + DEBUG3("Sent 'Get Predecessor' request (task %p) to %d, waiting for the answer on my mailbox '%s'", + task_sent, ask_to, req_data->answer_to); + + do { + if (node->comm_receive == NULL) { // FIXME simplify this + m_task_t task_received = NULL; + node->comm_receive = MSG_task_irecv(&task_received, node->mailbox); + } + + res = MSG_comm_wait(node->comm_receive, timeout); + + if (res != MSG_OK) { + DEBUG2("Failed to receive the answer to my 'Get Predecessor' request (task %p): %d", + task_sent, res); + stop = 1; + MSG_comm_destroy(node->comm_receive); + node->comm_receive = NULL; + } + else { + m_task_t task_received = MSG_comm_get_task(node->comm_receive); + task_data_t ans_data = MSG_task_get_data(task_received); + + if (MC_IS_ENABLED) { + MC_assert(task_received == task_sent); + } + + if (task_received != task_sent) { + MSG_comm_destroy(node->comm_receive); + node->comm_receive = NULL; + handle_task(node, task_received); + } + else { + DEBUG3("Received the answer to my 'Get Predecessor' request (task %p): the predecessor of node %d is %d", + task_received, ask_to, ans_data->answer_id); + predecessor_id = ans_data->answer_id; + stop = 1; + MSG_comm_destroy(node->comm_receive); + node->comm_receive = NULL; + MSG_task_destroy(task_received); + task_data_destroy(req_data); + } + } + } while (!stop); + } + + return predecessor_id; +} + +/** + * \brief Returns the closest preceding finger of an id + * with respect to the finger table of the current node. + * \param node the current node + * \param id the id to find + * \return the closest preceding finger of that id + */ +int closest_preceding_node(node_t node, int id) +{ + int i; + for (i = nb_bits - 1; i >= 0; i--) { + if (is_in_interval(node->fingers[i].id, node->id + 1, id - 1)) { + return node->fingers[i].id; + } + } + return node->id; +} + +/** + * \brief This function is called periodically. It checks the immediate + * successor of the current node. + * \param node the current node + */ +static void stabilize(node_t node) +{ + DEBUG0("Stabilizing node"); + + // get the predecessor of my immediate successor + int candidate_id; + int successor_id = node->fingers[0].id; + if (successor_id != node->id) { + candidate_id = remote_get_predecessor(node, successor_id); + } + else { + candidate_id = node->pred_id; + } + + // this node is a candidate to become my new successor + if (candidate_id != -1 + && is_in_interval(candidate_id, node->id + 1, successor_id - 1)) { + set_finger(node, 0, candidate_id); + } + if (successor_id != node->id) { + remote_notify(node, successor_id, node->id); + } +} + +/** + * \brief Notifies the current node that its predecessor may have changed. + * \param node the current node + * \param candidate_id the possible new predecessor + */ +static void notify(node_t node, int predecessor_candidate_id) { + + if (node->pred_id == -1 + || is_in_interval(predecessor_candidate_id, node->pred_id + 1, node->id - 1)) { + + set_predecessor(node, predecessor_candidate_id); + print_finger_table(node); + } + else { + DEBUG1("I don't have to change my predecessor to %d", predecessor_candidate_id); + } +} + +/** + * \brief Notifies a remote node that its predecessor may have changed. + * \param node the current node + * \param notify_id id of the node to notify + * \param candidate_id the possible new predecessor + */ +static void remote_notify(node_t node, int notify_id, int predecessor_candidate_id) { + + task_data_t req_data = xbt_new0(s_task_data_t, 1); + req_data->type = TASK_NOTIFY; + req_data->request_id = predecessor_candidate_id; + req_data->issuer_host_name = MSG_host_get_name(MSG_host_self()); + + // send a "Notify" request to notify_id + m_task_t task = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data); + DEBUG2("Sending a 'Notify' request (task %p) to %d", task, notify_id); + char mailbox[MAILBOX_NAME_SIZE]; + get_mailbox(notify_id, mailbox); + msg_comm_t comm = MSG_task_isend(task, mailbox); + xbt_dynar_push(node->comms, &comm); +} + +/** + * \brief This function is called periodically. + * It refreshes the finger table of the current node. + * \param node the current node + */ +static void fix_fingers(node_t node) { + + DEBUG0("Fixing fingers"); + int i = node->next_finger_to_fix; + int id = find_successor(node, node->id + powers2[i]); + if (id != -1) { + + if (id != node->fingers[i].id) { + set_finger(node, i, id); + print_finger_table(node); + } + node->next_finger_to_fix = (i + 1) % nb_bits; + } +} + +/** + * \brief This function is called periodically. + * It checks whether the predecessor has failed + * \param node the current node + */ +static void check_predecessor(node_t node) +{ + DEBUG0("Checking whether my predecessor is alive"); + // TODO +} + +/** + * \brief Performs a find successor request to a random id. + * \param node the current node + */ +static void random_lookup(node_t node) +{ + int id = 1337; // TODO pick a pseudorandom id + DEBUG1("Making a lookup request for id %d", id); + find_successor(node, id); +} + +/** + * \brief Main function. + */ +int main(int argc, char *argv[]) +{ + if (argc < 3) { + printf("Usage: %s [-nb_bits=n] [-timeout=t] platform_file deployment_file\n", argv[0]); + printf("example: %s ../msg_platform.xml chord.xml\n", argv[0]); + exit(1); + } + + MSG_global_init(&argc, argv); + + char **options = &argv[1]; + while (!strncmp(options[0], "-", 1)) { + + int length = strlen("-nb_bits="); + if (!strncmp(options[0], "-nb_bits=", length) && strlen(options[0]) > length) { + nb_bits = atoi(options[0] + length); + DEBUG1("Set nb_bits to %d", nb_bits); + } + else { + + length = strlen("-timeout="); + if (!strncmp(options[0], "-timeout=", length) && strlen(options[0]) > length) { + timeout = atoi(options[0] + length); + DEBUG1("Set timeout to %d", timeout); + } + else { + xbt_assert1(0, "Invalid chord option '%s'", options[0]); + } + } + options++; + } + + const char* platform_file = options[0]; + const char* application_file = options[1]; + + chord_initialize(); + + MSG_set_channel_number(0); + MSG_create_environment(platform_file); + + MSG_function_register("node", node); + MSG_launch_application(application_file); + + MSG_error_t res = MSG_main(); + INFO1("Simulation time: %g", MSG_get_clock()); + + MSG_clean(); + + if (res == MSG_OK) + return 0; + else + return 1; +} -- 2.20.1