+++ /dev/null
-/* Copyright (c) 2010-2015. 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 "simgrid/msg.h"
-#include "simgrid/modelchecker.h"
-#include <xbt/RngStream.h>
-#include "src/mc/mc_replay.h" // FIXME: this is an internal header
-
-/** @addtogroup MSG_examples
- *
- * - <b>chord/chord.c: Classical Chord P2P protocol</b>
- * This example implements the well known Chord P2P protocol. Its main advantage is that it constitute a fully
- * working non-trivial example. In addition, its implementation is rather efficient, as demonstrated in
- * http://hal.inria.fr/inria-00602216/
- */
-
-
-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;
-
-static const double sleep_delay = 4.9999;
-
-extern long int smx_total_comms;
-
-/* Finger element. */
-typedef struct s_finger {
- int id;
- char mailbox[MAILBOX_NAME_SIZE]; // string representation of the id
-} s_finger_t, *finger_t;
-
-/* Node data. */
-typedef struct s_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
- double last_change_date; // last time I changed a finger or my predecessor
- RngStream stream; //RngStream for
-} 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,
- TASK_PREDECESSOR_ALIVE,
- TASK_PREDECESSOR_ALIVE_ANSWER
-} e_task_type_t;
-
-/* Data attached with the tasks sent and received */
-typedef struct s_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;
-static xbt_dynar_t host_list;
-
-// utility functions
-static void chord_exit(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_free(void* task);
-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, msg_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);
-
-/* \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;
- unsigned i;
- for (i = 0; i < nb_bits; i++) {
- powers2[i] = pow;
- pow = pow << 1;
- }
- nb_keys = pow;
- XBT_DEBUG("Sets nb_keys to %d", nb_keys);
-
- msg_host_t host;
- host_list = MSG_hosts_as_dynar();
- xbt_dynar_foreach(host_list, i, host) {
- char descr[512];
- RngStream stream;
- snprintf(descr, sizeof descr, "RngSream<%s>", MSG_host_get_name(host));
- stream = RngStream_CreateStream(descr);
- MSG_host_set_property_value(host, "stream", (char*)stream, NULL);
- }
-}
-
-static void chord_exit(void)
-{
- msg_host_t host;
- unsigned i;
- xbt_dynar_foreach(host_list, i, host) {
- RngStream stream = (RngStream)MSG_host_get_property_value(host, "stream");
- RngStream_DeleteStream(&stream);
- }
- xbt_dynar_free(&host_list);
-
- xbt_free(powers2);
-}
-
-/**
- * \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 an 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 a task.
- * \param task the MSG task to destroy
- */
-static void task_free(void* task)
-{
- // TODO add a parameter data_free_function to MSG_task_create?
- if(task != NULL){
- xbt_free(MSG_task_get_data(task));
- MSG_task_destroy(task);
- }
-}
-
-/**
- * \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;
- XBT_VERB("My finger table:");
- XBT_VERB("Start | Succ");
- for (i = 0; i < nb_bits; i++) {
- XBT_VERB(" %3d | %3d", (node->id + powers2[i]) % nb_keys, node->fingers[i].id);
- }
- XBT_VERB("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();
- XBT_DEBUG("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();
-
- XBT_DEBUG("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_active() || MC_record_replay_is_active()){
- periodic_stabilize_delay = 8;
- periodic_fix_fingers_delay = 8;
- periodic_check_predecessor_delay = 8;
- }
-
- double init_time = MSG_get_clock();
- msg_task_t task_received = NULL;
- int i;
- 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;
-
- int listen = 0;
- int no_op = 0;
- int sub_protocol = 0;
-
- xbt_assert(argc == 3 || argc == 5, "Wrong number of arguments for this node");
-
- // initialize my node
- s_node_t node = {0};
- node.id = xbt_str_parse_int(argv[1],"Invalid ID: %s");
- node.stream = (RngStream)MSG_host_get_property_value(MSG_host_self(), "stream");
- get_mailbox(node.id, node.mailbox);
- node.next_finger_to_fix = 0;
- 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 = xbt_str_parse_double(argv[2],"Invalid deadline: %s");
- create(&node);
- join_success = 1;
-
- } else {
- int known_id = xbt_str_parse_int(argv[2],"Invalid root ID: %s");
- //double sleep_time = atof(argv[3]);
- deadline = xbt_str_parse_double(argv[4],"Invalid deadline: %s");
-
- /*
- // sleep before starting
- XBT_DEBUG("Let's sleep during %f", sleep_time);
- MSG_process_sleep(sleep_time);
- */
- XBT_DEBUG("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
- }
-
- //XBT_INFO("Node %d is ring member : %d", node.id, is_ring_member(known_id, node.id) != -1);
-
- if (!MSG_comm_test(node.comm_receive)) {
-
- // no task was received: make some periodic calls
-
- if(MC_is_active() || MC_record_replay_is_active()){
- if(MC_is_active() && !MC_visited_reduction() && no_op){
- MC_cut();
- }
- if(listen == 0 && (sub_protocol = MC_random(0, 4)) > 0){
- if(sub_protocol == 1)
- stabilize(&node);
- else if(sub_protocol == 2)
- fix_fingers(&node);
- else if(sub_protocol == 3)
- check_predecessor(&node);
- else
- random_lookup(&node);
- listen = 1;
- }else{
- MSG_process_sleep(sleep_delay);
- if(!MC_visited_reduction())
- no_op = 1;
- }
- }else{
- 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(sleep_delay);
- }
- }
-
- } else {
- // a transfer has occurred
-
- msg_error_t status = MSG_comm_get_status(node.comm_receive);
-
- if (status != MSG_OK) {
- XBT_DEBUG("Failed to receive a task. Nevermind.");
- MSG_comm_destroy(node.comm_receive);
- 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);
- }
- }
- }
-
- if (node.comm_receive) {
- /* handle last task if any */
- if (MSG_comm_wait(node.comm_receive, 0) == MSG_OK)
- task_free(task_received);
- MSG_comm_destroy(node.comm_receive);
- node.comm_receive = NULL;
- }
-
- // leave the ring
- leave(&node);
- }
-
- // stop the simulation
- 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, msg_task_t task) {
-
- XBT_DEBUG("Handling task %p", task);
- 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:
- XBT_DEBUG("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;
- XBT_DEBUG("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);
- MSG_task_dsend(task, task_data->answer_to, task_free);
- }
- else {
- // otherwise, forward the request to the closest preceding finger in my table
- int closest = closest_preceding_node(node, task_data->request_id);
- XBT_DEBUG("Forwarding the 'Find Successor' request for id %d to my closest preceding finger %d",
- task_data->request_id, closest);
- get_mailbox(closest, mailbox);
- MSG_task_dsend(task, mailbox, task_free);
- }
- break;
-
- case TASK_GET_PREDECESSOR:
- XBT_DEBUG("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;
- XBT_DEBUG("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);
- MSG_task_dsend(task, task_data->answer_to, task_free);
- break;
-
- case TASK_NOTIFY:
- // someone is telling me that he may be my new predecessor
- XBT_DEBUG("Receiving a 'Notify' request from %s", task_data->issuer_host_name);
- notify(node, task_data->request_id);
- task_free(task);
- break;
-
- case TASK_PREDECESSOR_LEAVING:
- // my predecessor is about to quit
- XBT_DEBUG("Receiving a 'Predecessor Leaving' message from %s", task_data->issuer_host_name);
- // modify my predecessor
- set_predecessor(node, task_data->request_id);
- task_free(task);
- /*TODO :
- >> notify my new predecessor
- >> send a notify_predecessors !!
- */
- break;
-
- case TASK_SUCCESSOR_LEAVING:
- // my successor is about to quit
- XBT_DEBUG("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_free(task);
- /* TODO
- >> notify my new successor
- >> update my table & predecessors table */
- break;
-
- case TASK_FIND_SUCCESSOR_ANSWER:
- case TASK_GET_PREDECESSOR_ANSWER:
- case TASK_PREDECESSOR_ALIVE_ANSWER:
- XBT_DEBUG("Ignoring unexpected task of type %d (%p)", (int)type, task);
- task_free(task);
- break;
-
- case TASK_PREDECESSOR_ALIVE:
- XBT_DEBUG("Receiving a 'Predecessor Alive' request from %s", task_data->issuer_host_name);
- task_data->type = TASK_PREDECESSOR_ALIVE_ANSWER;
- XBT_DEBUG("Sending back a 'Predecessor Alive Answer' to %s (mailbox %s)",
- task_data->issuer_host_name,
- task_data->answer_to);
- MSG_task_dsend(task, task_data->answer_to, task_free);
- break;
-
- default:
- THROW_IMPOSSIBLE;
- }
-}
-
-/**
- * \brief Initializes the current node as the first one of the system.
- * \param node the current node
- */
-static void create(node_t node)
-{
- XBT_DEBUG("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)
-{
- XBT_INFO("Joining the ring with id %d, knowing node %d", node->id, known_id);
- set_predecessor(node, -1); // no predecessor (yet)
-
- /*
- int i;
- for (i = 0; i < nb_bits; i++) {
- set_finger(node, i, known_id);
- }
- */
-
- int successor_id = remote_find_successor(node, known_id, node->id);
- if (successor_id == -1) {
- XBT_INFO("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)
-{
- XBT_DEBUG("Well Guys! I Think it's time for me to quit ;)");
- quit_notify(node);
-}
-
-/**
- * \brief Notifies the successor and the predecessor of the current node
- * of the departure
- * \param node the current node
- */
-static void quit_notify(node_t node)
-{
- char mailbox[MAILBOX_NAME_SIZE];
- //send the PREDECESSOR_LEAVING to our successor
- task_data_t req_data = xbt_new0(s_task_data_t,1);
- req_data->type = TASK_PREDECESSOR_LEAVING;
- req_data->request_id = node->pred_id;
- get_mailbox(node->id, req_data->answer_to);
- req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
-
- msg_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
- XBT_DEBUG("Sending a 'PREDECESSOR_LEAVING' to my successor %d",node->fingers[0].id);
- if (MSG_task_send_with_timeout(task_sent, node->fingers[0].mailbox, timeout)==
- MSG_TIMEOUT) {
- XBT_DEBUG("Timeout expired when sending a 'PREDECESSOR_LEAVING' to my successor %d",
- node->fingers[0].id);
- task_free(task_sent);
- }
-
- //send the SUCCESSOR_LEAVING to our predecessor
- get_mailbox(node->pred_id, mailbox);
- task_data_t req_data_s = xbt_new0(s_task_data_t,1);
- req_data_s->type = TASK_SUCCESSOR_LEAVING;
- req_data_s->request_id = node->fingers[0].id;
- req_data_s->request_id = node->pred_id;
- get_mailbox(node->id, req_data_s->answer_to);
- req_data_s->issuer_host_name = MSG_host_get_name(MSG_host_self());
-
- msg_task_t task_sent_s = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data_s);
- XBT_DEBUG("Sending a 'SUCCESSOR_LEAVING' to my predecessor %d",node->pred_id);
- if (MSG_task_send_with_timeout(task_sent_s, mailbox, timeout)==
- MSG_TIMEOUT) {
- XBT_DEBUG("Timeout expired when sending a 'SUCCESSOR_LEAVING' to my predecessor %d",
- node->pred_id);
- task_free(task_sent_s);
- }
-
-}
-
-/**
- * \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
- msg_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
- XBT_DEBUG("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) {
- XBT_DEBUG("Failed to send the 'Find Successor' request (task %p) to %d for id %d",
- task_sent, ask_to, id);
- task_free(task_sent);
- }
- else {
-
- // receive the answer
- XBT_DEBUG("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) {
- msg_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) {
- XBT_DEBUG("Failed to receive the answer to my 'Find Successor' request (task %p): %d",
- task_sent, (int)res);
- stop = 1;
- MSG_comm_destroy(node->comm_receive);
- node->comm_receive = NULL;
- }
- else {
- msg_task_t task_received = MSG_comm_get_task(node->comm_receive);
- XBT_DEBUG("Received a task (%p)", task_received);
- task_data_t ans_data = MSG_task_get_data(task_received);
-
- // Once upon a time, our code assumed that here, task_received != task_sent all the time
- //
- // This assumption is wrong (as messages from differing round can interleave), leading to a bug in our code.
- // We failed to find this bug directly, as it only occured on large platforms, leading to hardly usable traces.
- // Instead, we used the model-checker to track down the issue by adding the following test here in the code:
- // if (MC_is_active()) {
- // MC_assert(task_received == task_sent);
- // }
- // That explained the bug in a snap, with a very cool example and everything.
- //
- // This MC_assert is now desactivated as the case is now properly handled in our code and we don't want the
- // MC to fail any further under that condition, but this comment is here to as a memorial for this first
- // brillant victory of the model-checking in the SimGrid community :)
-
- if (task_received != task_sent ||
- ans_data->type != TASK_FIND_SUCCESSOR_ANSWER) {
- // 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
- XBT_DEBUG("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;
- task_free(task_received);
- }
- }
- } 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
- XBT_DEBUG("Sending a 'Get Predecessor' request to %d", ask_to);
- msg_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) {
- XBT_DEBUG("Failed to send the 'Get Predecessor' request (task %p) to %d",
- task_sent, ask_to);
- task_free(task_sent);
- }
- else {
-
- // receive the answer
- XBT_DEBUG("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
- msg_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) {
- XBT_DEBUG("Failed to receive the answer to my 'Get Predecessor' request (task %p): %d",
- task_sent, (int)res);
- stop = 1;
- MSG_comm_destroy(node->comm_receive);
- node->comm_receive = NULL;
- }
- else {
- msg_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_active()) {
- MC_assert(task_received == task_sent);
- }*/
-
- if (task_received != task_sent ||
- ans_data->type != TASK_GET_PREDECESSOR_ANSWER) {
- MSG_comm_destroy(node->comm_receive);
- node->comm_receive = NULL;
- handle_task(node, task_received);
- }
- else {
- XBT_DEBUG("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;
- task_free(task_received);
- }
- }
- } 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)
-{
- XBT_DEBUG("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 {
- XBT_DEBUG("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
- msg_task_t task = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
- XBT_DEBUG("Sending a 'Notify' request (task %p) to %d", task, notify_id);
- char mailbox[MAILBOX_NAME_SIZE];
- get_mailbox(notify_id, mailbox);
- MSG_task_dsend(task, mailbox, task_free);
- }
-
-/**
- * \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) {
-
- XBT_DEBUG("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)
-{
- XBT_DEBUG("Checking whether my predecessor is alive");
-
- if(node->pred_id == -1)
- return;
-
- int stop = 0;
-
- char mailbox[MAILBOX_NAME_SIZE];
- get_mailbox(node->pred_id, mailbox);
- task_data_t req_data = xbt_new0(s_task_data_t,1);
- req_data->type = TASK_PREDECESSOR_ALIVE;
- req_data->request_id = node->pred_id;
- get_mailbox(node->id, req_data->answer_to);
- req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
-
- msg_task_t task_sent = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
- XBT_DEBUG("Sending a 'Predecessor Alive' request to my predecessor %d", node->pred_id);
-
- msg_error_t res = MSG_task_send_with_timeout(task_sent, mailbox, timeout);
-
- if (res != MSG_OK) {
- XBT_DEBUG("Failed to send the 'Predecessor Alive' request (task %p) to %d", task_sent, node->pred_id);
- task_free(task_sent);
- }else{
-
- // receive the answer
- XBT_DEBUG("Sent 'Predecessor Alive' request (task %p) to %d, waiting for the answer on my mailbox '%s'",
- task_sent, node->pred_id, req_data->answer_to);
-
- do {
- if (node->comm_receive == NULL) { // FIXME simplify this
- msg_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) {
- XBT_DEBUG("Failed to receive the answer to my 'Predecessor Alive' request (task %p): %d",
- task_sent, (int)res);
- stop = 1;
- MSG_comm_destroy(node->comm_receive);
- node->comm_receive = NULL;
- node->pred_id = -1;
- }else {
- msg_task_t task_received = MSG_comm_get_task(node->comm_receive);
- if (task_received != task_sent) {
- MSG_comm_destroy(node->comm_receive);
- node->comm_receive = NULL;
- handle_task(node, task_received);
- }else{
- XBT_DEBUG("Received the answer to my 'Predecessor Alive' request (task %p) : my predecessor %d is alive",
- task_received, node->pred_id);
- stop = 1;
- MSG_comm_destroy(node->comm_receive);
- node->comm_receive = NULL;
- task_free(task_received);
- }
- }
- } while (!stop);
- }
-}
-
-/**
- * \brief Performs a find successor request to a random id.
- * \param node the current node
- */
-static void random_lookup(node_t node)
-{
- int random_index = RngStream_RandInt (node->stream, 0, nb_bits - 1);
- int random_id = node->fingers[random_index].id;
- XBT_DEBUG("Making a lookup request for id %d", random_id);
- int res = find_successor(node, random_id);
- XBT_DEBUG("The successor of node %d is %d", random_id, res);
-
-}
-
-int main(int argc, char *argv[])
-{
- MSG_init(&argc, argv);
- xbt_assert(argc > 2,
- "Usage: %s [-nb_bits=n] [-timeout=t] platform_file deployment_file\n"
- "\tExample: %s ../msg_platform.xml chord.xml\n", argv[0], argv[0]);
-
- 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 = xbt_str_parse_int(options[0] + length, "Invalid nb_bits parameter: %s");
- XBT_DEBUG("Set nb_bits to %d", nb_bits);
- }
- else {
-
- length = strlen("-timeout=");
- if (!strncmp(options[0], "-timeout=", length) && strlen(options[0]) > length) {
- timeout = xbt_str_parse_int(options[0] + length, "Invalid timeout parameter: %s");
- XBT_DEBUG("Set timeout to %d", timeout);
- }
- else {
- xbt_die("Invalid chord option '%s'", options[0]);
- }
- }
- options++;
- }
-
- const char* platform_file = options[0];
- const char* application_file = options[1];
-
- MSG_create_environment(platform_file);
-
- chord_initialize();
-
- MSG_function_register("node", node);
- MSG_launch_application(application_file);
-
- msg_error_t res = MSG_main();
- XBT_CRITICAL("Messages created: %ld", smx_total_comms);
- XBT_INFO("Simulated time: %g", MSG_get_clock());
-
- chord_exit();
-
- return res != MSG_OK;
-}
