#define NB_BITS 6
#define NB_KEYS 64
+#define COMM_SIZE 10
+#define COMP_SIZE 0
/**
* Finger element.
*/
typedef struct finger {
int id;
- const char* mailbox;
+ char* mailbox;
} s_finger_t, *finger_t;
/**
*/
typedef struct node {
int id; // my id
- const char* mailbox;
+ char* mailbox; // my usual mailbox name
s_finger_t fingers[NB_BITS]; // finger table (fingers[0] is my successor)
int pred_id; // predecessor id
- const char* pred_mailbox;
- xbt_dynar_t comms; // current communications to finish
+ char* pred_mailbox; // 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
} s_node_t, *node_t;
/**
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
+ // FIXME: remove successor_id and pred_id, request_id is enough
} s_task_data_t, *task_data_t;
+static int powers2[NB_BITS];
+
// utility functions
+static void chord_initialize(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 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 handle_task(node_t node, m_task_t task);
// Chord core
+static void create(node_t node);
+static void 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 quit_notify(node_t node, int to);
+
+static void chord_initialize(void)
+{
+ // compute the powers of 2 once for all
+ int pow = 1;
+ int i;
+ for (i = 0; i < NB_BITS; i++) {
+ powers2[i] = pow;
+ pow = pow << 1;
+ }
+}
/**
* \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) {
-
+static int normalize(int id)
+{
// make sure id >= 0
while (id < 0) {
id += NB_KEYS;
}
-
// make sure id < NB_KEYS
id = id % NB_KEYS;
* \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);
* \return the name of its mailbox
* FIXME: free the memory
*/
-static char* get_mailbox(int node_id) {
-
+static char* get_mailbox(int node_id)
+{
return bprintf("mailbox%d", node_id);
}
* \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)
+{
int i;
int pow = 1;
INFO0("My finger table:");
INFO0("Start | Succ ");
for (i = 0; i < NB_BITS; i++) {
- INFO2(" %4d | %4d ", (node->id + pow) % NB_KEYS, node->fingers[i].id);
+ INFO2(" %3d | %3d ", (node->id + pow) % NB_KEYS, node->fingers[i].id);
pow = pow << 1;
}
INFO1("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)
+{
+ node->fingers[finger_index].id = id;
+ xbt_free(node->fingers[finger_index].mailbox);
+ node->fingers[finger_index].mailbox = get_mailbox(id);
+ INFO2("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)
+{
+ node->pred_id = predecessor_id;
+ xbt_free(node->pred_mailbox);
+
+ if (predecessor_id != -1) {
+ node->pred_mailbox = get_mailbox(predecessor_id);
+ }
+
+ INFO1("My new predecessor is %d", predecessor_id);
+}
+
/**
* \brief Node Function
* Arguments:
*/
int node(int argc, char *argv[])
{
- msg_comm_t comm = NULL;
+ double init_time = MSG_get_clock();
+ m_task_t task = NULL;
+ msg_comm_t comm_send = NULL;
+ int i;
+ double deadline;
+ double next_stabilize_date = init_time + 10;
+ double next_fix_fingers_date = init_time + 10;
+ double next_check_predecessor_date = init_time + 10;
- xbt_assert0(argc == 2 || argc == 4, "Wrong number of arguments for this node");
+ 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]);
node.mailbox = get_mailbox(node.id);
+ node.next_finger_to_fix = 0;
node.comms = xbt_dynar_new(sizeof(msg_comm_t), NULL);
- if (argc == 2) { // first ring
- initialize_first_node(&node);
+ for (i = 0; i < NB_BITS; i++) {
+ set_finger(&node, i, node.id);
+ }
+
+ if (argc == 3) { // first ring
+ deadline = atof(argv[2]);
+ create(&node);
}
else {
int known_id = atoi(argv[2]);
double sleep_time = atof(argv[3]);
+ deadline = atof(argv[4]);
// sleep before starting
- INFO1("Let's sleep >>%f", sleep_time);
+ INFO1("Let's sleep during %f", sleep_time);
MSG_process_sleep(sleep_time);
INFO0("Hey! Let's join the system.");
join(&node, known_id);
}
- while (1) {
+ while (MSG_get_clock() < init_time + deadline) {
- 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);
- }
+ // see if some communications are finished
+ int index;
+ while ((index = MSG_comm_testany(node.comms)) != -1) {
+ comm_send = xbt_dynar_get_as(node.comms, index, msg_comm_t);
+ xbt_dynar_remove_at(node.comms, index, &comm_send);
+ DEBUG3("Communication %p is finished with status %d, dynar size is now %lu",
+ comm_send, MSG_comm_get_status(comm_send), xbt_dynar_length(node.comms));
+ MSG_comm_destroy(comm_send);
}
- m_task_t task = NULL;
- MSG_error_t res = MSG_task_receive(&task, node.mailbox);
-
- xbt_assert0(res == MSG_OK, "MSG_task_receive failed");
+ if (node.comm_receive == NULL) {
+ task = NULL;
+ node.comm_receive = MSG_task_irecv(&task, node.mailbox);
+ // FIXME: do not make MSG_task_irecv() calls from several functions
+ }
- // 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 (!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);
+ // no task was received: make some periodic calls
+ if (MSG_get_clock() >= next_stabilize_date) {
+ stabilize(&node);
+ next_stabilize_date = MSG_get_clock() + 10;
}
- 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);
- comm = MSG_task_isend(task, get_mailbox(closest));
- xbt_dynar_push(node.comms, &comm);
+ else if (MSG_get_clock() >= next_fix_fingers_date) {
+ fix_fingers(&node);
+ next_fix_fingers_date = MSG_get_clock() + 10;
}
- }
- /*
- else if (!strcmp(task_name, "Find Successor Answer")) {
-
- }
- */
- 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 if (MSG_get_clock() >= next_check_predecessor_date) {
+ check_predecessor(&node);
+ next_check_predecessor_date = MSG_get_clock() + 10;
}
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);
- comm = MSG_task_isend(task, get_mailbox(closest));
- xbt_dynar_push(node.comms, &comm);
+ // nothing to do: sleep for a while
+ MSG_process_sleep(1);
}
}
- /*
- else if (!strcmp(task_name, "Find Predecessor Answer")) {
+ else {
+ // a transfer has occured
- }
- */
- else if (!strcmp(task_name, "Update Finger")) {
- // someone is telling me that he may be my new finger
- INFO1("Receving an 'Update Finger' from %s", task_data->issuer_host_name);
- update_finger_table(&node, task_data->request_id, task_data->request_finger);
- }
- else if (!strcmp(task_name, "Notify")) {
- // someone is telling me that he may be my new predecessor
- INFO1("Receving an 'Notify' from %s", task_data->issuer_host_name);
- notify(&node, task_data->request_id);
- }
- /*
- else if (!strcmp(task_name, "Fix Fingers"))
- {
- int i;
- for (i = KEY_BITS - 1 ; i >= 0; i--)
- {
- data->fingers[i] = find_finger_elem(data,(data->id)+pow(2,i-1));
+ MSG_error_t status = MSG_comm_get_status(node.comm_receive);
+ MSG_comm_destroy(node.comm_receive);
+ node.comm_receive = NULL;
+
+ if (status != MSG_OK) {
+ INFO0("Failed to receive a task. Nevermind.");
+ }
+ else {
+ // the task was successfully received
+ handle_task(&node, task);
}
}
- */
}
+ // leave the ring and stop the 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);
+ }
+ 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
*/
-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 = node->mailbox;
+ msg_comm_t comm = NULL;
+ char* mailbox = NULL;
+ const char* task_name = MSG_task_get_name(task);
+ task_data_t task_data = (task_data_t) MSG_task_get_data(task);
+
+ 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");
+ comm = MSG_task_isend(task, task_data->answer_to);
+ xbt_dynar_push(node->comms, &comm);
+ 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);
+ }
+ else {
+ // otherwise, forward the request to the closest preceding finger in my table
+ int closest = closest_preceding_node(node, task_data->request_id);
+ INFO2("Forwarding the '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);
+ }
+ }
+
+ else if (!strcmp(task_name, "Get Predecessor")) {
+ INFO1("Receiving a 'Get Predecessor' request from %s", task_data->issuer_host_name);
+ task_data->answer_id = node->pred_id;
+ MSG_task_set_name(task, "Get Predecessor Answer");
+ comm = MSG_task_isend(task, task_data->answer_to);
+ xbt_dynar_push(node->comms, &comm);
+ INFO3("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);
+ }
+
+ 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 to quit
+ INFO1("Receiving a 'Predecessor Leaving' message from %s", task_data->issuer_host_name);
+ // modify my predecessor
+ set_predecessor(node, task_data->pred_id);
+ /*TODO :
+ >> notify my new predecessor
+ >> send a notify_predecessors !!
+ */
+ }
+
+ else if (!strcmp(task_name, "Successor Leaving")) {
+ // my successor is about to quit
+ INFO1("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->successor_id);
+ /* TODO
+ >> notify my new successor
+ >> update my table & predecessors table */
}
- 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 sucessor
+ INFO0("Create a new Chord ring...");
+ set_predecessor(node, -1); // -1 means that I have no predecessor
+ print_finger_table(node);
}
-/*
- * \brief Initializes my finger table, knowing the id of a node already in 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 system
+ * \param known_id id of a node already in the ring
*/
-static void initialize_finger_table(node_t node, int known_id)
+static void join(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);
+ INFO2("Joining the ring with id %d, knowing node %d", node->id, known_id);
+ set_predecessor(node, -1); // no predecessor (yet)
+
+ int successor_id;
+ do {
+ successor_id = remote_find_successor(node, known_id, node->id);
+ if (successor_id == -1) {
+ INFO0("I really want to join the ring. Let's try again.");
}
- node->fingers[i + 1].mailbox = get_mailbox(node->fingers[i + 1].id);
- }
-
- node->pred_id = find_predecessor(node, node->id);
- node->pred_mailbox = get_mailbox(node->pred_id);
+ } while (successor_id == -1);
- INFO0("Finger table initialized!");
+ set_finger(node, 0, successor_id);
print_finger_table(node);
}
/**
- * \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
- }
+ 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 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;
- }
-
- // 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
- 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);
+ 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 = 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);
+ task_name = "Predecessor Leaving";
- 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);
- }
}
-}
+ else if (to == -1) // notify my predecessor
+ {
+ 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());
+ to_mailbox = node->pred_mailbox;
+ INFO2("Telling my Predecessor %d about my departure via mailbox %s",
+ node->pred_id, to_mailbox);
+ task_name = "Predecessor Leaving";
- // 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);
- msg_comm_t comm = MSG_task_isend(task, get_mailbox(ask_to_id));
+ }
+ m_task_t task = MSG_task_create(task_name, 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
+ * \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 received_answer = 0;
+ task_data_t req_data = xbt_new0(s_task_data_t, 1);
+ req_data->request_id = id;
+ req_data->answer_to = node->mailbox;
+ 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 = MSG_task_create("Find Successor", COMP_SIZE, COMM_SIZE, req_data);
+ MSG_error_t res = MSG_task_send_with_timeout(task, get_mailbox(ask_to), 200);
- return successor;
-}
+ if (res == MSG_OK) {
-/**
- * \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;
- }
+ // receive the answer
+ INFO2("Sent a 'Find Successor' request to %d for key %d, waiting for the answer", ask_to, id);
- if (is_in_interval(id, node->id + 1, node->fingers[0].id)) {
- return node->id;
+ do {
+ if (node->comm_receive == NULL) {
+ task = NULL;
+ node->comm_receive = MSG_task_irecv(&task, node->mailbox);
+ }
+
+ res = MSG_comm_wait(node->comm_receive, 50);
+
+ if (res != MSG_OK) {
+ INFO1("Failed to receive the answer: %d", res);
+ }
+ else {
+ task = MSG_comm_get_task(node->comm_receive);
+ INFO1("Received a task '%s'", MSG_task_get_name(task));
+
+ if (strcmp(MSG_task_get_name(task), "Find Successor Answer")) {
+ handle_task(node, task);
+ }
+ else {
+ task_data_t ans_data = MSG_task_get_data(task);
+ successor = ans_data->answer_id;
+ received_answer = 1;
+ INFO2("This is the answer to my 'Find Successor' request: the successor of key %d is %d", id, successor);
+ }
+ MSG_comm_destroy(node->comm_receive);
+ node->comm_receive = NULL;
+// MSG_task_destroy(task);
+ }
+ } while (!received_answer);
}
- 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);
+ int predecessor_id = -1;
+ int received_answer = 0;
+ task_data_t req_data = xbt_new0(s_task_data_t, 1);
+ req_data->answer_to = node->mailbox;
+ req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
+
+ // send a "Get Predecessor" request to ask_to_id
+ INFO1("Sending a 'Get Predecessor' request to %d", ask_to);
+ m_task_t task = MSG_task_create("Get Predecessor", COMP_SIZE, COMM_SIZE, req_data);
+ MSG_error_t res = MSG_task_send_with_timeout(task, get_mailbox(ask_to), 200);
- return predecessor;
+ if (res == MSG_OK) {
+
+ // receive the answer
+ INFO2("Sent 'Get Predecessor' request to %d, waiting for the answer on my mailbox '%s'", ask_to, req_data->answer_to);
+
+ do {
+ if (node->comm_receive == NULL) { // FIXME simplify this
+ task = NULL;
+ node->comm_receive = MSG_task_irecv(&task, node->mailbox);
+ }
+
+ res = MSG_comm_wait(node->comm_receive, 50);
+
+ if (res != MSG_OK) {
+ INFO1("Failed to receive the answer: %d", res);
+ }
+ else {
+ task = MSG_comm_get_task(node->comm_receive);
+ INFO1("Received a task '%s'", MSG_task_get_name(task));
+
+ if (strcmp(MSG_task_get_name(task), "Get Predecessor Answer")) {
+ handle_task(node, task);
+ }
+ else {
+ task_data_t ans_data = MSG_task_get_data(task);
+ predecessor_id = ans_data->answer_id;
+ received_answer = 1;
+ INFO2("This is the answer to my 'Get Predecessor' request: the predecessor of node %d is %d", ask_to, predecessor_id);
+ }
+ MSG_comm_destroy(node->comm_receive);
+ node->comm_receive = NULL;
+// MSG_task_destroy(task);
+ }
+ } while (!received_answer);
+ }
+
+ 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--) {
* successor of the current node.
* \param node the current node
*/
-static void stabilize(node_t node) {
+static void stabilize(node_t node)
+{
+ INFO0("Stabilizing node");
- int x = find_predecessor(node, node->fingers[0].id);
- if (is_in_interval(x, node->id + 1, node->fingers[0].id)) {
- 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 {
// 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);
- msg_comm_t comm = MSG_task_isend(task, get_mailbox(notify_id));
+ m_task_t task = MSG_task_create("Notify", COMP_SIZE, COMM_SIZE, 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);
+}
+
+/**
+ * \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) {
+
+ INFO0("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 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 checks whether the predecessor has failed
+ * \param node the current node
*/
-static void remote_move_keys(node_t node, int take_from_id) {
+static void check_predecessor(node_t node)
+{
+ INFO0("Checking whether my predecessor is alive");
// TODO
}
exit(1);
}
- MSG_global_init(&argc, argv);
-
const char* platform_file = argv[1];
const char* application_file = argv[2];
- /* MSG_config("workstation/model","KCCFLN05"); */
+ chord_initialize();
+
+ MSG_global_init(&argc, argv);
MSG_set_channel_number(0);
MSG_create_environment(platform_file);
