#include "msg/msg.h"
#include "xbt/log.h"
#include "xbt/asserts.h"
+#include "simgrid/modelchecker.h"
+
XBT_LOG_NEW_DEFAULT_CATEGORY(msg_chord,
"Messages specific for this msg example");
-#define NB_BITS 6
-#define NB_KEYS 64
+#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;
+
+extern long int smx_total_comms;
/**
* Finger element.
*/
typedef struct finger {
int id;
- char* mailbox;
+ char mailbox[MAILBOX_NAME_SIZE]; // string representation of the id
} s_finger_t, *finger_t;
/**
*/
typedef struct node {
int id; // my id
- char* mailbox;
- s_finger_t fingers[NB_BITS]; // finger table (fingers[0] is my successor)
+ 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;
- xbt_dynar_t comms; // current communications to finish
+ 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
} s_node_t, *node_t;
/**
- * Task data
+ * 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 {
- int request_id;
- int request_finger;
- int answer_id;
- const char* answer_to;
- const char* issuer_host_name; // used for logging
- int successor_id; // used when quitting
- int pred_id; // used when quitting
+ 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 void chord_exit(void);
static int normalize(int id);
static int is_in_interval(int id, int start, int end);
-static char* get_mailbox(int host_id);
+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[]);
-
-// initialization
-static void initialize_first_node(node_t node);
-static void initialize_finger_table(node_t data, int known_id);
-static void join(node_t node, int known_id);
-static void leave(node_t node);
+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 find_predecessor(node_t node, int id);
-static int remote_find_predecessor(node_t node, int ask_to_id, int id);
-static int closest_preceding_finger(node_t node, int id);
-static int remote_closest_preceding_finger(int ask_to_id, int id);
-static void notify_predecessors(node_t node);
-static void remote_move_keys(node_t node, int take_from_id);
-static void update_finger_table(node_t node, int candidate_id, int finger_index);
-static void remote_update_finger_table(node_t node, int ask_to_id, int candidate_id, int finger_index);
+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 stabilize(node_t node);
+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 Turns an id into an equivalent id in [0, NB_KEYS[
- * \param id an id
- * \return the corresponding normalized id
+ * \brief Global initialization of the Chord simulation.
*/
-static int normalize(int id) {
-
- // make sure id >= 0
- while (id < 0) {
- id += NB_KEYS;
+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;
}
- // make sure id < NB_KEYS
- id = id % NB_KEYS;
+ nb_keys = pow;
+ XBT_DEBUG("Sets nb_keys to %d", nb_keys);
+}
- return id;
+static void chord_exit(void)
+{
+ xbt_free(powers2);
}
/**
- * \brief Returns whether a id belongs to the interval [start, end].
+ * \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 CHORD_NB_KEYS - 1).
+ * 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]
* \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) {
-
+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;
+ end += nb_keys;
}
if (id < start) {
- id += NB_KEYS;
+ 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
- * \return the name of its mailbox
- * FIXME: free the memory
+ * \param mailbox pointer to where the mailbox name should be written
+ * (there must be enough space)
*/
-static char* get_mailbox(int node_id) {
+static void get_mailbox(int node_id, char* mailbox)
+{
+ snprintf(mailbox, MAILBOX_NAME_SIZE - 1, "%d", node_id);
+}
- return bprintf("mailbox%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?
+ 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) {
+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);
+ }
+}
- int i;
- int pow = 1;
- INFO0("My finger table:");
- INFO0("Start | Succ ");
- for (i = 0; i < NB_BITS; i++) {
- INFO2(" %3d | %3d ", (node->id + pow) % NB_KEYS, node->fingers[i].id);
- pow = pow << 1;
+/**
+ * \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);
}
- INFO1("Predecessor: %d", node->pred_id);
}
/**
*/
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();
- msg_comm_t comm = NULL;
+ m_task_t task_received = NULL;
int i;
- char* mailbox;
+ 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");
+ xbt_assert(argc == 3 || argc == 5, "Wrong number of arguments for this node");
// initialize my node
s_node_t node = {0};
node.id = atoi(argv[1]);
- node.mailbox = get_mailbox(node.id);
- node.comms = xbt_dynar_new(sizeof(msg_comm_t), NULL);
-
+ 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
- initialize_first_node(&node);
deadline = atof(argv[2]);
+ create(&node);
+ join_success = 1;
}
else {
int known_id = atoi(argv[2]);
- double sleep_time = atof(argv[3]);
+ //double sleep_time = atof(argv[3]);
deadline = atof(argv[4]);
+ /*
// sleep before starting
- INFO1("Let's sleep >>%f", sleep_time);
+ XBT_DEBUG("Let's sleep during %f", sleep_time);
MSG_process_sleep(sleep_time);
- INFO0("Hey! Let's join the system.");
+ */
+ XBT_DEBUG("Hey! Let's join the system.");
- join(&node, known_id);
+ join_success = join(&node, known_id);
}
- while ((MSG_get_clock( )- init_time) < deadline) {
+ if (join_success) {
+ while (MSG_get_clock() < init_time + deadline
+// && MSG_get_clock() < node.last_change_date + 1000
+ && MSG_get_clock() < max_simulation_time) {
- unsigned int cursor;
- comm = NULL;
- xbt_dynar_foreach(node.comms, cursor, comm) {
- if (MSG_comm_test(comm)) { // FIXME: try with MSG_comm_testany instead
- xbt_dynar_cursor_rm(node.comms, &cursor);
- MSG_comm_destroy(comm);
+ 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
}
- }
- m_task_t task = NULL;
- MSG_error_t res = MSG_task_receive_with_timeout(&task, node.mailbox,45); // FIXME >> find the right timeout !!
+ if (!MSG_comm_test(node.comm_receive)) {
- if(res == MSG_OK) // else check deadline condition and keep waiting for a task
- {
+ // 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);
+ }
+ }
- // get data
- const char* task_name = MSG_task_get_name(task);
- task_data_t task_data = (task_data_t) MSG_task_get_data(task);
+ if (node.comm_receive && MSG_comm_test(node.comm_receive)) {
- if (!strcmp(task_name, "Find Successor")) {
- INFO2("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->answer_id = node.fingers[0].id;
- MSG_task_set_name(task, "Find Successor Answer");
- INFO3("Sending back a 'Find Successor' Answer to %s: the successor of %d is %d", task_data->issuer_host_name, 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_finger(&node, task_data->request_id);
- INFO2("Forwarding 'Find Successor' request for id %d to my closest preceding finger %d", task_data->request_id, closest);
- mailbox = get_mailbox(closest);
- comm = MSG_task_isend(task, mailbox);
- xbt_dynar_push(node.comms, &comm);
- xbt_free(mailbox);
- }
- }
+ // a transfer has occured
- else if (!strcmp(task_name, "Find Predecessor")) {
- INFO2("Receiving a 'Find Predecessor' Request from %s for id %d", task_data->issuer_host_name, task_data->request_id);
- // am I the predecessor?
- if (is_in_interval(task_data->request_id, node.id + 1, node.fingers[0].id)) {
- task_data->answer_id = node.id;
- MSG_task_set_name(task, "Find Predecessor Answer");
- INFO3("Sending back a 'Find Predecessor' Answer to %s: the predecessor of %d is %d", task_data->issuer_host_name, 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_finger(&node, task_data->request_id);
- INFO2("Forwarding 'Find Predecessor' request for id %d to my closest preceding finger %d", task_data->request_id, closest);
- mailbox = get_mailbox(closest);
- comm = MSG_task_isend(task, mailbox);
- xbt_dynar_push(node.comms, &comm);
- xbt_free(mailbox);
+ 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);
+ }
}
}
- else if (!strcmp(task_name, "Update Finger")) {
- // someone is telling me that he may be my new finger
- INFO1("Receiving an 'Update Finger' request from %s", task_data->issuer_host_name);
- update_finger_table(&node, task_data->request_id, task_data->request_finger);
+ if (node.comm_receive) {
+ MSG_comm_destroy(node.comm_receive);
+ node.comm_receive = NULL;
}
- else if (!strcmp(task_name, "Notify")) {
- // someone is telling me that he may be my new predecessor
- INFO1("Receiving a 'Notify' request from %s", task_data->issuer_host_name);
- notify(&node, task_data->request_id);
- }
- else if (!strcmp(task_name, "Predecessor Leaving")) {
- // my predecessor is about quitting
- INFO1("Receiving a 'quite notify' from %s", task_data->issuer_host_name);
- // modify my predecessor
- node.pred_id = task_data->pred_id;
- node.pred_mailbox = get_mailbox(node.id);
- /*TODO :
- >> notify my new predecessor
- >> send a notify_predecessors !!
- */
- }
- else if (!strcmp(task_name, "Successor Leaving")) {
- // my successor is about quitting
- INFO1("Receiving a 'quite notify' from %s", task_data->issuer_host_name);
- // modify my successor FIXME : this should be implicit ?
- node.fingers[0].id = task_data->successor_id;
- node.fingers[0].mailbox = get_mailbox(node.fingers[0].id);
- /* TODO
- >> notify my new successor
- >> update my table & predecessors table */
- }
- }
- }
- // leave the ring and quit simulation
- leave(&node);
- xbt_dynar_free(&node.comms);
- xbt_free(node.mailbox);
- xbt_free(node.pred_mailbox);
- for (i = 0; i < NB_BITS - 1; i++) {
- xbt_free(node.fingers[i].mailbox);
+ // leave the ring
+ leave(&node);
}
+
+ // stop the simulation
+ xbt_free(node.fingers);
+ return 0;
}
/**
- * \brief Initializes the current node as the first one of the system.
+ * \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 initialize_first_node(node_t node)
-{
- INFO0("Create a new Chord ring...");
+static void handle_task(node_t node, m_task_t task) {
- // I am my own successor and predecessor
- int i;
- for (i = 0; i < NB_BITS; i++) {
- node->fingers[i].id = node->id;
- node->fingers[i].mailbox = xbt_strdup(node->mailbox);
+ 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:
+ XBT_DEBUG("Ignoring unexpected task of type %d (%p)", type, task);
+ task_free(task);
+ break;
}
- node->pred_id = node->id;
- node->pred_mailbox = node->mailbox;
- print_finger_table(node);
}
/**
- * \brief Makes the current node join the system, knowing the id of a node already in the system
+ * \brief Initializes the current node as the first one of the system.
* \param node the current node
- * \param known_id id of a node already in the system
*/
-static void join(node_t node, int known_id)
+static void create(node_t node)
{
- initialize_finger_table(node, known_id); // determine my fingers, asking to known_id
- remote_notify(node, node->fingers[0].id, node->id); // tell my successor that I'm his new predecessor
- notify_predecessors(node); // tell others that I may have became their finger
- remote_move_keys(node, node->fingers[0].id); // take some key-value pairs from my successor
+ 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 quit the system
+ * \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 void leave(node_t node)
+static int join(node_t node, int known_id)
{
- INFO0("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 Notify msg to tell my successor||predecessor about my departure
- * \param node the current node
- */
-static void quit_notify(node_t node, int to)
-{
- 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());
- const char *task_name = NULL;
- const char* to_mailbox;
- if( to == 1) // notify my successor
- {
- to_mailbox = node->fingers[0].mailbox;
- INFO1("Telling my Successor about my departure via mailbox %s", to_mailbox);
- task_name = "Predecessor Leaving";
+ XBT_INFO("Joining the ring with id %d, knowing node %d", node->id, known_id);
+ set_predecessor(node, -1); // no predecessor (yet)
- }
- else if(to == -1) // notify my predecessor
- {
- to_mailbox = node->pred_mailbox;
- INFO1("Telling my Predecessor about my departure via mailbox %s",to_mailbox);
- task_name = "Predecessor Leaving";
- }
- m_task_t task = MSG_task_create(task_name, 1000, 5000, req_data);
- //char* mailbox = get_mailbox(to_mailbox);
- msg_comm_t comm = MSG_task_isend(task, to_mailbox);
-}
-
-/*
- * \brief Initializes my finger table, knowing the id of a node already in the system.
- * \param node the current node
- * \param known_id id of a node already in the system
- */
-static void initialize_finger_table(node_t node, int known_id)
-{
- int my_id = node->id;
+ /*
int i;
- int pow = 1; // 2^i
-
- INFO0("Initializing my finger table...");
-
- // ask known_id who is my immediate successor
- node->fingers[0].id = remote_find_successor(node, known_id, my_id + 1);
- node->fingers[0].mailbox = get_mailbox(node->fingers[0].id);
-
- // find all other fingers
- for (i = 0; i < NB_BITS - 1; i++) {
-
- pow = pow << 1; // equivalent to pow = pow * 2
- if (is_in_interval(my_id + pow, my_id, node->fingers[i].id - 1)) {
- // I already have the info for this finger
- node->fingers[i + 1].id = node->fingers[i].id;
- }
- else {
- // I don't have the info, ask the only guy I know
- node->fingers[i + 1].id = remote_find_successor(node, known_id, my_id + pow);
- }
- node->fingers[i + 1].mailbox = get_mailbox(node->fingers[i + 1].id);
+ for (i = 0; i < nb_bits; i++) {
+ set_finger(node, i, known_id);
}
+ */
- node->pred_id = find_predecessor(node, node->id);
- node->pred_mailbox = get_mailbox(node->pred_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);
+ }
- INFO0("Finger table initialized!");
- print_finger_table(node);
+ return successor_id != -1;
}
/**
- * \brief Notifies some nodes that the current node may have became their finger.
- * \param node the current node, which has just joined the system
+ * \brief Makes the current node quit the system
+ * \param node the current node
*/
-static void notify_predecessors(node_t node)
+static void leave(node_t node)
{
- int i, pred_id;
- int pow = 1;
- for (i = 0; i < NB_BITS; i++) {
- // find the closest node whose finger #i can be me
- pred_id = find_predecessor(node, node->id - pow + 1); // note: no "+1" in the article!
- if (pred_id != node->id) {
- remote_update_finger_table(node, pred_id, node->id, i);
- }
- pow = pow << 1; // pow = pow * 2
- }
+ XBT_DEBUG("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 Tells the current node that a node may have became its new finger.
+/*
+ * \brief Notifies the successor or the predecessor of the current node
+ * of the departure
* \param node the current node
- * \param candidate_id id of the node that may be a new finger of the current node
- * \param finger_index index of the finger to update
+ * \param to 1 to notify the successor, -1 to notify the predecessor
+ * FIXME: notify both nodes with only one call
*/
-static void update_finger_table(node_t node, int candidate_id, int finger_index)
+static void quit_notify(node_t node, int to)
{
- int pow = 1;
- int i;
- for (i = 0; i < finger_index; i++) {
- pow = pow << 1;
+ /* 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;
+ XBT_INFO("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 (is_in_interval(candidate_id, node->id + pow, node->fingers[finger_index].id - 1)) {
- if (is_in_interval(candidate_id, node->id, node->fingers[finger_index].id - 1)) {
-// INFO3("Candidate %d is between %d and %d!", candidate_id, node->id + pow, node->fingers[finger_index].id - 1);
- // candidate_id is my new finger
- xbt_free(node->fingers[finger_index].mailbox);
- node->fingers[finger_index].id = candidate_id;
- node->fingers[finger_index].mailbox = get_mailbox(candidate_id);
- INFO2("My new finger #%d is %d", finger_index, candidate_id);
- print_finger_table(node);
-
- if (node->pred_id != node->id) { // FIXME: is this necessary?
- // my predecessor may be concerned too
- remote_update_finger_table(node, node->pred_id, candidate_id, finger_index);
+ if (node->pred_id == -1) {
+ return;
}
- }
-}
-
-/**
- * \brief Tells a remote node that a node may have became its new finger.
- * \param ask_to_id id of the remote node to update
- * \param candidate_id id of the node that may be a new finger of the remote node
- * \param finger_index index of the finger to update
- */
-static void remote_update_finger_table(node_t node, int ask_to_id, int candidate_id, int finger_index)
-{
- task_data_t req_data = xbt_new0(s_task_data_t, 1);
- req_data->request_id = candidate_id;
- req_data->request_finger = finger_index;
- req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
- // send a "Update Finger" request to ask_to_id
- INFO3("Sending an 'Update Finger' request to %d: his finger #%d may be %d now", ask_to_id, finger_index, candidate_id);
- m_task_t task = MSG_task_create("Update Finger", 1000, 5000, req_data);
- char* mailbox = get_mailbox(ask_to_id);
- msg_comm_t comm = MSG_task_isend(task, mailbox);
+ to_mailbox = node->pred_mailbox;
+ XBT_INFO("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);
- xbt_free(mailbox);
+ */
}
/**
* \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
+ * \return the id of the successor node, or -1 if the request failed
*/
static int find_successor(node_t node, int id)
{
}
// otherwise, ask the closest preceding finger in my table
- int closest = closest_preceding_finger(node, id);
+ int closest = closest_preceding_node(node, id);
return remote_find_successor(node, closest, 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
+ * \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)
{
- s_task_data_t req_data;
- char* mailbox = bprintf("%s Find Successor", node->mailbox);
- req_data.request_id = id;
- req_data.answer_to = mailbox;
- req_data.issuer_host_name = MSG_host_get_name(MSG_host_self());
+ 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
- INFO2("Sending a 'Find Successor' request to %d for key %d", ask_to, id);
- m_task_t task = MSG_task_create("Find Successor", 1000, 5000, &req_data);
- MSG_task_send(task, get_mailbox(ask_to));
-
- // receive the answer
- task = NULL;
- MSG_task_receive(&task, req_data.answer_to);
- task_data_t ans_data;
- ans_data = MSG_task_get_data(task);
- int successor = ans_data->answer_id;
- xbt_free(mailbox);
- INFO2("Received the answer to my Find Successor request: the successor of key %d is %d", id, successor);
+ m_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 {
- return successor;
-}
+ // 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) {
+ m_task_t task_received = NULL;
+ node->comm_receive = MSG_task_irecv(&task_received, node->mailbox);
+ }
-/**
- * \brief Makes the current node find the predecessor node of an id.
- * \param node the current node
- * \param id the id to find
- * \return the id of the predecessor node
- */
-static int find_predecessor(node_t node, int id)
-{
- if (node->id == node->fingers[0].id) {
- // I am the only node in the system
- return node->id;
- }
+ res = MSG_comm_wait(node->comm_receive, timeout);
- if (is_in_interval(id, node->id + 1, node->fingers[0].id)) {
- return node->id;
+ if (res != MSG_OK) {
+ XBT_DEBUG("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);
+ XBT_DEBUG("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
+ 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);
}
- int ask_to = closest_preceding_finger(node, id);
- return remote_find_predecessor(node, ask_to, id);
+
+ return successor;
}
/**
- * \brief Asks another node the predecessor node of an id.
+ * \brief Asks another node its predecessor.
* \param node the current node
* \param ask_to the node to ask to
- * \param id the id to find
- * \return the id of the predecessor node
+ * \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_find_predecessor(node_t node, int ask_to, int id)
+static int remote_get_predecessor(node_t node, int ask_to)
{
- s_task_data_t req_data;
- char* mailbox = bprintf("%s Find Predecessor", node->mailbox);
- req_data.request_id = id;
- req_data.answer_to = mailbox;
- req_data.issuer_host_name = MSG_host_get_name(MSG_host_self());
-
- // send a "Find Predecessor" request to ask_to
- INFO2("Sending a 'Find Predecessor' request to %d for key %d", ask_to, id);
- m_task_t task = MSG_task_create("Find Predecessor", 1000, 5000, &req_data);
- MSG_task_send(task, get_mailbox(ask_to));
-
- // receive the answer
- task = NULL;
- MSG_task_receive(&task, req_data.answer_to);
- task_data_t ans_data;
- ans_data = MSG_task_get_data(task);
- int predecessor = ans_data->answer_id;
- xbt_free(mailbox);
- INFO2("Received the answer to my 'Find Predecessor' request: the predecessor of key %d is %d", id, predecessor);
-
- return predecessor;
+ 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);
+ 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) {
+ 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
+ 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) {
+ XBT_DEBUG("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 {
+ 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;
}
/**
* \param id the id to find
* \return the closest preceding finger of that id
*/
-int closest_preceding_finger(node_t node, int id)
+int closest_preceding_node(node_t node, int id)
{
int i;
- for (i = NB_BITS - 1; i >= 0; 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;
}
* successor of the current node.
* \param node the current node
*/
-static void stabilize(node_t node) {
+static void stabilize(node_t node)
+{
+ XBT_DEBUG("Stabilizing node");
- int x = find_predecessor(node, node->fingers[0].id);
- if (is_in_interval(x, node->id + 1, node->fingers[0].id)) {
- xbt_free(node->fingers[0].mailbox);
- node->fingers[0].id = x;
- node->fingers[0].mailbox = get_mailbox(x);
+ // 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);
}
- remote_notify(node, node->fingers[0].id, node->id);
}
/**
*/
static void notify(node_t node, int predecessor_candidate_id) {
- if (node->pred_id == node->id
- || is_in_interval(predecessor_candidate_id, node->pred_id, node->id)) {
-
- node->pred_id = predecessor_candidate_id;
- node->pred_mailbox = get_mailbox(predecessor_candidate_id);
+ if (node->pred_id == -1
+ || is_in_interval(predecessor_candidate_id, node->pred_id + 1, node->id - 1)) {
- INFO1("My new predecessor is %d", predecessor_candidate_id);
+ set_predecessor(node, predecessor_candidate_id);
print_finger_table(node);
}
else {
- INFO1("I don't have to change my predecessor to %d", predecessor_candidate_id);
+ XBT_DEBUG("I don't have to change my predecessor to %d", predecessor_candidate_id);
}
}
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
- INFO1("Sending a 'Notify' request to %d", notify_id);
- m_task_t task = MSG_task_create("Notify", 1000, 5000, req_data);
- char* mailbox = get_mailbox(notify_id);
- msg_comm_t comm = MSG_task_isend(task, mailbox);
- xbt_dynar_push(node->comms, &comm);
- xbt_free(mailbox);
+ m_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 Asks a node to take some of its keys.
- * \param node the current node, which has just joined the system
- * \param take_from_id id of a node who may have keys to give to the current node
+ * \brief This function is called periodically.
+ * It refreshes the finger table of the current node.
+ * \param node the current node
*/
-static void remote_move_keys(node_t node, int take_from_id) {
+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");
// 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
+ XBT_DEBUG("Making a lookup request for id %d", id);
+ find_successor(node, id);
+}
+
/**
* \brief Main function.
*/
int main(int argc, char *argv[])
{
+ MSG_global_init(&argc, argv);
if (argc < 3) {
- printf("Usage: %s platform_file deployment_file\n", argv[0]);
+ 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);
+ XBT_DEBUG("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);
+ 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];
- const char* platform_file = argv[1];
- const char* application_file = argv[2];
+ chord_initialize();
- /* MSG_config("workstation/model","KCCFLN05"); */
- 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());
+ XBT_CRITICAL("Messages created: %ld", smx_total_comms);
+ XBT_INFO("Simulated time: %g", MSG_get_clock());
MSG_clean();
+ chord_exit();
if (res == MSG_OK)
return 0;
