X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/5e81488ae538e889c7b1819a3813057f36c404cc..1181daf8b93cd68576f32b6f8cb3c7cb28c7932e:/examples/msg/chord/chord.c

diff --git a/examples/msg/chord/chord.c b/examples/msg/chord/chord.c
index e69de29bb2..8718f6687f 100644
--- a/examples/msg/chord/chord.c
+++ b/examples/msg/chord/chord.c
@@ -0,0 +1,715 @@
+
+/* Copyright (c) 2010. The SimGrid Team.
+ * All rights reserved.                                                     */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
+#include <stdio.h>
+#include "msg/msg.h"
+#include "xbt/log.h"
+#include "xbt/asserts.h"
+XBT_LOG_NEW_DEFAULT_CATEGORY(msg_chord,
+                             "Messages specific for this msg example");
+
+#define NB_BITS 6
+#define NB_KEYS 64
+
+/**
+ * Finger element.
+ */
+typedef struct finger {
+  int id;
+  char* mailbox;
+} s_finger_t, *finger_t;
+
+/**
+ * Node data.
+ */
+typedef struct node {
+  int id;                                 // my id
+  char* mailbox;
+  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
+} s_node_t, *node_t;
+
+/**
+ * Task data
+ */
+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
+} s_task_data_t, *task_data_t;
+
+// utility functions
+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);
+
+// 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);
+
+// Chord core
+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 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 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
+ */
+static int normalize(int id) {
+
+  // make sure id >= 0
+  while (id < 0) {
+    id += NB_KEYS;
+  }
+  // make sure id < NB_KEYS
+  id = id % NB_KEYS;
+
+  return id;
+}
+
+/**
+ * \brief Returns whether a id belongs to the interval [start, end].
+ *
+ * The parameters are noramlized to make sure they are between 0 and CHORD_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
+ * \return the name of its mailbox
+ * FIXME: free the memory
+ */
+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) {
+
+  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;
+  }
+  INFO1("Predecessor: %d", node->pred_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[])
+{
+  double init_time = MSG_get_clock();
+  msg_comm_t comm = NULL;
+  int i;
+  char* mailbox;
+  double deadline;
+
+  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.comms = xbt_dynar_new(sizeof(msg_comm_t), NULL);
+
+
+  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);
+    MSG_process_sleep(sleep_time);
+    INFO0("Hey! Let's join the system.");
+
+    join(&node, known_id);
+  }
+
+  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);
+	MSG_comm_destroy(comm);
+      }
+    }
+
+    m_task_t task = NULL;
+    MSG_error_t res = MSG_task_receive_with_timeout(&task, node.mailbox,45); // FIXME >> find the right timeout !!
+
+    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);
+    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");
+        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);
+      }
+    }
+
+    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);
+      }
+    }
+
+    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")) {
+      // 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);
+  }
+  return 1;
+}
+
+/**
+ * \brief Initializes the current node as the first one of the system.
+ * \param node the current node
+ */
+static void initialize_first_node(node_t node)
+{
+  INFO0("Create a new Chord ring...");
+
+  // 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);
+  }
+  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
+ * \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 successor
+}
+
+/**
+ * \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);
+}
+
+/*
+ * \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);
+  }
+
+  node->pred_id = find_predecessor(node, node->id);
+  node->pred_mailbox = get_mailbox(node->pred_id);
+
+  INFO0("Finger table initialized!");
+  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
+ */
+static void notify_predecessors(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
+  }
+}
+
+/**
+ * \brief Tells the current node that a node may have became its new finger.
+ * \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
+ */
+static void update_finger_table(node_t node, int candidate_id, int finger_index)
+{
+  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
+    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);
+    }
+  }
+}
+
+/**
+ * \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);
+  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
+ */
+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_finger(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
+ */
+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());
+
+  // 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);
+
+  return successor;
+}
+
+
+/**
+ * \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;
+  }
+
+  if (is_in_interval(id, node->id + 1, node->fingers[0].id)) {
+    return node->id;
+  }
+  int ask_to = closest_preceding_finger(node, id);
+  return remote_find_predecessor(node, ask_to, id);
+}
+
+/**
+ * \brief Asks another node the predecessor 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 predecessor node
+ */
+static int remote_find_predecessor(node_t node, int ask_to, int id)
+{
+  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;
+}
+
+/**
+ * \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_finger(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) {
+
+  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);
+  }
+  remote_notify(node, node->fingers[0].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 == 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);
+    print_finger_table(node);
+  }
+  else {
+    INFO1("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->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);
+}
+
+/**
+ * \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
+ */
+static void remote_move_keys(node_t node, int take_from_id) {
+  // TODO
+}
+
+/**
+ * \brief Main function.
+ */
+int main(int argc, char *argv[])
+{
+  if (argc < 3) {
+    printf("Usage: %s 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);
+
+  const char* platform_file = argv[1];
+  const char* application_file = argv[2];
+
+  /* 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());
+
+  MSG_clean();
+
+  if (res == MSG_OK)
+    return 0;
+  else
+    return 1;
+}