*/
typedef struct node {
int id; // my id
- 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
- char* pred_mailbox;
- xbt_dynar_t comms; // current communications to finish
+ char* pred_mailbox; // predecessor's mailbox name
+ xbt_dynar_t comms; // current communications pending
} 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
} s_task_data_t, *task_data_t;
// utility functions
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 bootstrap(node_t node, int known_id);
+static void leave(node_t node);
// Chord core
static int find_successor(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 notify(node_t node, int new_node_id);
+static void remote_notify(node_t node, int notify_id);
+static void stabilize(node_t node);
+static void quit_notify(node_t node, int to);
+
+// not implemented yet
static void remote_move_keys(node_t node, int take_from_id);
+
+// deprecated
+static void notify_predecessors(node_t node);
+static void initialize_finger_table(node_t data, int known_id);
+static void notify_predecessor_changed(node_t node, int predecessor_candidate_id);
+static void remote_notify_predecessor_changed(node_t node, int notify_to, int predecessor_candidate_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 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);
/**
* \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
+ */
+static void set_predecessor(node_t node, int predecessor_id)
+{
+ node->pred_id = predecessor_id;
+ xbt_free(node->pred_mailbox);
+ 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[])
{
+ double init_time = MSG_get_clock();
msg_comm_t comm = NULL;
int i;
char* mailbox;
+ double deadline;
+ double next_stabilize_date = init_time + 50;
- 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.mailbox = get_mailbox(node.id);
node.comms = xbt_dynar_new(sizeof(msg_comm_t), NULL);
- if (argc == 2) { // first ring
+ if (argc == 3) { // first ring
initialize_first_node(&node);
+ deadline = atof(argv[2]);
}
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);
join(&node, known_id);
}
- while (1) {
+ while ((MSG_get_clock() - init_time) < deadline) {
unsigned int cursor;
comm = NULL;
}
}
+ if (MSG_get_clock() >= next_stabilize_date) {
+ stabilize(&node);
+ next_stabilize_date = MSG_get_clock() + 50;
+ }
+
m_task_t task = NULL;
- MSG_error_t res = MSG_task_receive(&task, node.mailbox);
+ MSG_error_t res = MSG_task_receive_with_timeout(&task, node.mailbox, 45); // FIXME >> find the right timeout !!
- xbt_assert0(res == MSG_OK, "MSG_task_receive failed");
+ if (res == MSG_OK) // else check deadline condition and keep waiting for a task
+ {
// get data
const char* task_name = MSG_task_get_name(task);
xbt_free(mailbox);
}
}
- /*
- 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?
xbt_free(mailbox);
}
}
- /*
- else if (!strcmp(task_name, "Find Predecessor Answer")) {
+ else if (!strcmp(task_name, "Notify")) {
+ // someone may be my new neighboor
+ INFO1("Receiving a 'Notify' request from %s", task_data->issuer_host_name);
+ notify(&node, task_data->request_id);
}
- */
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);
}
- else if (!strcmp(task_name, "Notify")) {
+ else if (!strcmp(task_name, "Notify Predecessor Changed")) {
// 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);
+ INFO1("Receiving a 'Notify Predecessor Changed' request from %s", task_data->issuer_host_name);
+ notify_predecessor_changed(&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));
- }
+ 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);
}
+ return 1;
}
/**
{
INFO0("Create a new Chord ring...");
- // I am my own successor and predecessor
+ // I am my own successor, predecessor and fingers
int i;
for (i = 0; i < NB_BITS; i++) {
- node->fingers[i].id = node->id;
- node->fingers[i].mailbox = xbt_strdup(node->mailbox);
+ set_finger(node, i, node->id);
}
- node->pred_id = node->id;
- node->pred_mailbox = node->mailbox;
+ set_predecessor(node, node->id);
print_finger_table(node);
}
/**
- * \brief Makes the current node join the system, knowing the id of a node already in the system
+ * \brief Makes the current node join the system, 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 join(node_t node, int known_id)
{
- 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("Joining the system");
+ // find my predecessor and successor
+ int pred;
+ int suc = remote_find_predecessor(node, known_id, node->id);
+ do {
+ pred = suc;
+ suc = remote_find_successor(node, pred, pred);
+ } while (!is_in_interval(node->id, pred + 1, suc));
+
+ set_finger(node, 0, suc);
+ set_predecessor(node, pred);
+ remote_notify(node, pred);
+ remote_notify(node, suc);
+ bootstrap(node, suc);
+}
+
+/**
+ * \brief Notifies the current node that a node has just joined the network.
+ * \param node the current node
+ * \param new_node_id id of the new node in the network
+ */
+static void notify(node_t node, int new_node_id)
+{
+ INFO1("A new node %d has joined the network, let's see if it is a neighboor", new_node_id);
+ if (is_in_interval(new_node_id, node->id + 1, node->fingers[0].id - 1)) {
+ // new_node_id is my new successor
+ set_finger(node, 0, new_node_id);
+ bootstrap(node, new_node_id);
+ }
+
+ if (is_in_interval(new_node_id, node->pred_id + 1, node->id - 1)) {
+ // new_node_id is my new predecessor
+ set_predecessor(node, new_node_id);
+ bootstrap(node, new_node_id);
+ }
+}
+
+/**
+ * \brief Notifies a remote node that the current node has just joined
+ * the network.
+ * \param node the current node
+ * \param notify_id id of the remote node to notify
+ */
+static void remote_notify(node_t node, int notify_id)
+{
+ task_data_t req_data = xbt_new0(s_task_data_t, 1);
+ req_data->request_id = node->id;
+ req_data->issuer_host_name = MSG_host_get_name(MSG_host_self());
+
+ // send a "Notify" request to notify_id
+ INFO2("Sending a 'Notify' request to %d because I have joined the network with id %d", notify_id, node->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);
+}
+
+/**
+* \brief Let the current node send queries to fill in its own finger table.
+* \param node the current node
+* \param ask_to_id id of a node to send queries to
+*/
+static void bootstrap(node_t node, int ask_to_id)
+{
+ INFO0("Filling my finger table");
+ int i, pred_id, succ_id;
+ int pow = 1;
+
+ for (i = 0; i < NB_BITS; i++)
+ {
+ pred_id = remote_find_successor(node, ask_to_id, pow);
+ do {
+ succ_id = pred_id;
+ pred_id = remote_find_predecessor(node, pred_id, pred_id);
+ } while (pred_id >= pow);
+
+ pow = pow << 1;
+ set_finger(node, i, succ_id);
+ }
+}
+
+/**
+ * \brief Makes the current node quit the system
+ * \param node the current node
+ */
+static void leave(node_t node)
+{
+ 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 = NULL;
+ 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";
+
+ }
+ 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);
+ xbt_dynar_push(node->comms, &comm);
}
/*
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);
+ set_finger(node, finger_index, candidate_id);
print_finger_table(node);
if (node->pred_id != node->id) { // FIXME: is this necessary?
/**
* \brief This function is called periodically. It checks the immediate
- * successor of the current node.
+ * successor and predecessor of the current node.
* \param node the current node
*/
-static void stabilize(node_t 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);
+static void stabilize(node_t node)
+{
+ INFO0("Stabilizing node");
+ int succ_id;
+ succ_id = node->pred_id;
+ succ_id = remote_find_successor(node, succ_id, succ_id);
+ if (is_in_interval(succ_id, node->pred_id + 1, node->id - 1)) {
+ set_predecessor(node, succ_id);
+ }
+ succ_id = node->fingers[0].id;
+ succ_id = remote_find_predecessor(node, succ_id, succ_id);
+ if (is_in_interval(succ_id, node->id + 1, node->fingers[0].id - 1)) {
+ set_finger(node, 0, succ_id);
}
- remote_notify(node, node->fingers[0].id, node->id);
}
/**
* \param node the current node
* \param candidate_id the possible new predecessor
*/
-static void notify(node_t node, int predecessor_candidate_id) {
+static void notify_predecessor_changed(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);
-
- INFO1("My new predecessor is %d", predecessor_candidate_id);
+ set_predecessor(node, predecessor_candidate_id);
print_finger_table(node);
}
else {
* \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) {
+static void remote_notify_predecessor_changed(node_t node, int notify_id, int predecessor_candidate_id) {
task_data_t req_data = xbt_new0(s_task_data_t, 1);
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);
+ INFO1("Sending a 'Notify Predecessor Changed' request to %d", notify_id);
+ m_task_t task = MSG_task_create("Notify Predecessor Changed", 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);
