X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/3ebaa9f6d0886b21e5b01506f8136900f78e008e..b02ac1c736917a89bec0baa4de9afc17cd29777c:/examples/msg/chord/chord.c

diff --git a/examples/msg/chord/chord.c b/examples/msg/chord/chord.c
index a505f6c8c2..fe9ab9d15a 100644
--- a/examples/msg/chord/chord.c
+++ b/examples/msg/chord/chord.c
@@ -40,17 +40,28 @@ typedef struct node {
 } 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
-  // FIXME: remove successor_id and pred_id, request_id is enough
+  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)
+  const char* answer_to;                  // mailbox to send an answer to
+  const char* issuer_host_name;           // used for logging
 } s_task_data_t, *task_data_t;
 
 static int powers2[NB_BITS];
@@ -70,7 +81,7 @@ 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 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);
@@ -83,6 +94,9 @@ static void fix_fingers(node_t node);
 static void check_predecessor(node_t node);
 static void quit_notify(node_t node, int to);
 
+/**
+ * \brief Global initialization of the Chord simulation.
+ */
 static void chord_initialize(void)
 {
   // compute the powers of 2 once for all
@@ -95,7 +109,7 @@ static void chord_initialize(void)
 }
 
 /**
- * \brief Turns an id into an equivalent id in [0, NB_KEYS[
+ * \brief Turns an id into an equivalent id in [0, NB_KEYS).
  * \param id an id
  * \return the corresponding normalized id
  */
@@ -149,7 +163,6 @@ static int is_in_interval(int id, int start, int 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)
 {
@@ -184,7 +197,7 @@ 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);
+  DEBUG2("My new finger #%d is %d", finger_index, id);
 }
 
 /**
@@ -201,7 +214,7 @@ static void set_predecessor(node_t node, int predecessor_id)
     node->pred_mailbox = get_mailbox(predecessor_id);
   }
 
-  INFO1("My new predecessor is %d", predecessor_id);
+  DEBUG1("My new predecessor is %d", predecessor_id);
 }
 
 /**
@@ -215,9 +228,11 @@ int node(int argc, char *argv[])
 {
   double init_time = MSG_get_clock();
   m_task_t task = NULL;
+  m_task_t task_received = NULL;
   msg_comm_t comm_send = NULL;
   int i;
   int index;
+  int join_success = 0;
   double deadline;
   double next_stabilize_date = init_time + 10;
   double next_fix_fingers_date = init_time + 10;
@@ -239,6 +254,7 @@ int node(int argc, char *argv[])
   if (argc == 3) { // first ring
     deadline = atof(argv[2]);
     create(&node);
+    join_success = 1;
   }
   else {
     int known_id = atoi(argv[2]);
@@ -246,79 +262,85 @@ int node(int argc, char *argv[])
     deadline = atof(argv[4]);
 
     // sleep before starting
-    INFO1("Let's sleep during %f", sleep_time);
+    DEBUG1("Let's sleep during %f", sleep_time);
     MSG_process_sleep(sleep_time);
-    INFO0("Hey! Let's join the system.");
+    DEBUG0("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) {
 
-    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
-    }
+      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
+      }
 
-    if (!MSG_comm_test(node.comm_receive)) {
+      if (!MSG_comm_test(node.comm_receive)) {
 
-      // 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 if (MSG_get_clock() >= next_fix_fingers_date) {
-        fix_fingers(&node);
-        next_fix_fingers_date = MSG_get_clock() + 10;
-      }
-      else if (MSG_get_clock() >= next_check_predecessor_date) {
-        check_predecessor(&node);
-        next_check_predecessor_date = MSG_get_clock() + 10;
+        // 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 if (MSG_get_clock() >= next_fix_fingers_date) {
+          fix_fingers(&node);
+          next_fix_fingers_date = MSG_get_clock() + 10;
+        }
+        else if (MSG_get_clock() >= next_check_predecessor_date) {
+          check_predecessor(&node);
+          next_check_predecessor_date = MSG_get_clock() + 10;
+        }
+        else {
+          // nothing to do: sleep for a while
+          MSG_process_sleep(5);
+        }
       }
       else {
-	// nothing to do: sleep for a while
-        MSG_process_sleep(5);
-      }
-    }
-    else {
-      // a transfer has occured
+        // a transfer has occured
 
-      MSG_error_t status = MSG_comm_get_status(node.comm_receive);
-      MSG_comm_destroy(node.comm_receive);
-      node.comm_receive = NULL;
+        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.");
+        if (status != MSG_OK) {
+          DEBUG0("Failed to receive a task. Nevermind.");
+        }
+        else {
+          // the task was successfully received
+          handle_task(&node, task_received);
+        }
       }
-      else {
-        // the task was successfully received
-        handle_task(&node, task);
+
+      // see if some communications are finished
+      while ((index = MSG_comm_testany(node.comms)) != -1) {
+        comm_send = xbt_dynar_get_as(node.comms, index, msg_comm_t);
+        MSG_error_t status = MSG_comm_get_status(comm_send);
+        xbt_dynar_remove_at(node.comms, index, &comm_send);
+        DEBUG3("Communication %p is finished with status %d, dynar size is now %lu",
+            comm_send, status, xbt_dynar_length(node.comms));
+        MSG_comm_destroy(comm_send);
       }
     }
 
-    // see if some communications are finished
-    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));
+    // clean unfinished comms sent
+    unsigned int cursor;
+    xbt_dynar_foreach(node.comms, cursor, comm_send) {
+      task = MSG_comm_get_task(comm_send);
+      MSG_task_cancel(task);
+      xbt_free(MSG_task_get_data(task));
+      MSG_task_destroy(task);
       MSG_comm_destroy(comm_send);
+      // FIXME: the task is actually not destroyed because MSG thinks that the other side (whose process is dead) is still using it
     }
-  }
 
-  // clean unfinished comms sent
-  unsigned int cursor;
-  xbt_dynar_foreach(node.comms, cursor, comm_send) {
-    task = MSG_comm_get_task(comm_send);
-    MSG_task_cancel(task);
-    xbt_free(MSG_task_get_data(task));
-    MSG_task_destroy(task);
-    MSG_comm_destroy(comm_send);
+    // leave the ring
+    leave(&node);
   }
 
-  // leave the ring and stop the simulation
-  leave(&node);
+  // stop the simulation
   xbt_dynar_free(&node.comms);
   xbt_free(node.mailbox);
   xbt_free(node.pred_mailbox);
@@ -336,78 +358,86 @@ int node(int argc, char *argv[])
  */
 static void handle_task(node_t node, m_task_t task) {
 
+  DEBUG1("Handling task %p", task);
   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",
+  e_task_type_t type = task_data->type;
+
+  switch (type) {
+
+    case TASK_FIND_SUCCESSOR:
+      DEBUG2("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;
+        comm = MSG_task_isend(task, task_data->answer_to);
+        xbt_dynar_push(node->comms, &comm);
+        DEBUG3("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 {
+        // otherwise, forward the request to the closest preceding finger in my table
+        int closest = closest_preceding_node(node, task_data->request_id);
+        DEBUG2("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);
+      }
+      break;
 
-  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",
+    case TASK_GET_PREDECESSOR:
+      DEBUG1("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;
+      comm = MSG_task_isend(task, task_data->answer_to);
+      xbt_dynar_push(node->comms, &comm);
+      DEBUG3("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);
-    xbt_free(task_data);
-    MSG_task_destroy(task);
-  }
-
-  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);
-    xbt_free(task_data);
-    MSG_task_destroy(task);
-    /*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);
-    xbt_free(task_data);
-    MSG_task_destroy(task);
-    /* TODO
-    >> notify my new successor
-    >> update my table & predecessors table */
+      break;
+
+    case TASK_NOTIFY:
+      // someone is telling me that he may be my new predecessor
+      DEBUG1("Receiving a 'Notify' request from %s", task_data->issuer_host_name);
+      notify(node, task_data->request_id);
+      xbt_free(task_data);
+      MSG_task_destroy(task);
+      break;
+
+    case TASK_PREDECESSOR_LEAVING:
+      // my predecessor is about to quit
+      DEBUG1("Receiving a 'Predecessor Leaving' message from %s", task_data->issuer_host_name);
+      // modify my predecessor
+      set_predecessor(node, task_data->request_id);
+      xbt_free(task_data);
+      MSG_task_destroy(task);
+      /*TODO :
+      >> notify my new predecessor
+      >> send a notify_predecessors !!
+       */
+      break;
+
+    case TASK_SUCCESSOR_LEAVING:
+      // my successor is about to quit
+      DEBUG1("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);
+      xbt_free(task_data);
+      MSG_task_destroy(task);
+      /* TODO
+      >> notify my new successor
+      >> update my table & predecessors table */
+      break;
+
+    default:
+      CRITICAL1("Received an unexpected task: %d", type);
+      //xbt_abort();
   }
 }
 
@@ -417,7 +447,7 @@ static void handle_task(node_t node, m_task_t task) {
  */
 static void create(node_t node)
 {
-  INFO0("Create a new Chord ring...");
+  DEBUG0("Create a new Chord ring...");
   set_predecessor(node, -1); // -1 means that I have no predecessor
   print_finger_table(node);
 }
@@ -427,22 +457,23 @@ static void create(node_t 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 join(node_t node, int known_id)
+static int join(node_t node, int known_id)
 {
   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.");
-    }
-  } while (successor_id == -1);
+  int successor_id = remote_find_successor(node, known_id, node->id);
+  if (successor_id == -1) {
+    DEBUG0("Cannot join the ring.");
+  }
+  else {
+    set_finger(node, 0, successor_id);
+    print_finger_table(node);
+  }
 
-  set_finger(node, 0, successor_id);
-  print_finger_table(node);
+  return successor_id != -1;
 }
 
 /**
@@ -451,7 +482,7 @@ static void join(node_t node, int known_id)
  */
 static void leave(node_t node)
 {
-  INFO0("Well Guys! I Think it's time for me to quit ;)");
+  DEBUG0("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 ...
@@ -478,7 +509,7 @@ static void quit_notify(node_t node, int to)
     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";
+    req_data->type = TASK_PREDECESSOR_LEAVING;
   }
   else if (to == -1) {    // notify my predecessor
 
@@ -489,9 +520,9 @@ static void quit_notify(node_t node, int to)
     to_mailbox = node->pred_mailbox;
     INFO2("Telling my Predecessor %d about my departure via mailbox %s",
 	  node->pred_id, to_mailbox);
-    task_name = "Successor Leaving";
+    req_data->type = TASK_SUCCESSOR_LEAVING;
   }
-  m_task_t task = MSG_task_create(task_name, COMP_SIZE, COMM_SIZE, req_data);
+  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);
@@ -529,24 +560,26 @@ static int remote_find_successor(node_t node, int ask_to, int id)
   int stop = 0;
   char* mailbox = get_mailbox(ask_to);
   task_data_t req_data = xbt_new0(s_task_data_t, 1);
+  req_data->type = TASK_FIND_SUCCESSOR;
   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 id %d", ask_to, id);
-  m_task_t task = MSG_task_create("Find Successor", COMP_SIZE, COMM_SIZE, req_data);
+  m_task_t task = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
+  DEBUG3("Sending a 'Find Successor' request (task %p) to %d for id %d", task, ask_to, id);
   MSG_error_t res = MSG_task_send_with_timeout(task, mailbox, 50);
 
   if (res != MSG_OK) {
-    INFO2("Failed to send the 'Find Successor' request to %d for id %d", ask_to, id);
+    DEBUG2("Failed to send the 'Find Successor' request to %d for id %d", ask_to, id);
     MSG_task_destroy(task);
     xbt_free(req_data);
   }
   else {
 
     // receive the answer
-    INFO2("Sent a 'Find Successor' request to %d for key %d, waiting for the answer", ask_to, id);
+    DEBUG3("Sent a 'Find Successor' request (task %p) to %d for key %d, waiting for the answer",
+        task, ask_to, id);
 
     do {
       if (node->comm_receive == NULL) {
@@ -557,20 +590,20 @@ static int remote_find_successor(node_t node, int ask_to, int id)
       res = MSG_comm_wait(node->comm_receive, 50);
 
       if (res != MSG_OK) {
-	INFO1("Failed to receive the answer to my 'Find Successor' request: %d", res);
+        DEBUG2("Failed to receive the answer to my 'Find Successor' request (task %p): %d", task, res);
         stop = 1;
 //      MSG_comm_destroy(node->comm_receive);
       }
       else {
         task = MSG_comm_get_task(node->comm_receive);
-        INFO1("Received a task '%s'", MSG_task_get_name(task));
+        task_data_t ans_data = MSG_task_get_data(task);
 
-        if (strcmp(MSG_task_get_name(task), "Find Successor Answer")) {
+        if (ans_data->type != TASK_FIND_SUCCESSOR_ANSWER) {
           handle_task(node, task);
         }
         else {
-          INFO2("This is the answer to my 'Find Successor' request: the successor of key %d is %d", id, successor);
-          task_data_t ans_data = MSG_task_get_data(task);
+          DEBUG3("Received the answer to my 'Find Successor' request (task %p): the successor of key %d is %d",
+              task, id, successor);
           successor = ans_data->answer_id;
           stop = 1;
           MSG_task_destroy(task);
@@ -598,23 +631,24 @@ static int remote_get_predecessor(node_t node, int ask_to)
   int stop = 0;
   char* mailbox = get_mailbox(ask_to);
   task_data_t req_data = xbt_new0(s_task_data_t, 1);
+  req_data->type = TASK_GET_PREDECESSOR;
   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);
+  DEBUG1("Sending a 'Get Predecessor' request to %d", ask_to);
+  m_task_t task = MSG_task_create(NULL, COMP_SIZE, COMM_SIZE, req_data);
   MSG_error_t res = MSG_task_send_with_timeout(task, mailbox, 50);
 
   if (res != MSG_OK) {
-    INFO1("Failed to send the 'Get Predecessor' request to %d", ask_to);
+    DEBUG1("Failed to send the 'Get Predecessor' request to %d", ask_to);
     MSG_task_destroy(task);
     xbt_free(req_data);
   }
   else {
 
     // receive the answer
-    INFO2("Sent 'Get Predecessor' request to %d, waiting for the answer on my mailbox '%s'", ask_to, req_data->answer_to);
+    DEBUG2("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
@@ -625,20 +659,19 @@ static int remote_get_predecessor(node_t node, int ask_to)
       res = MSG_comm_wait(node->comm_receive, 50);
 
       if (res != MSG_OK) {
-        INFO1("Failed to receive the answer to my 'Get Predecessor' request: %d", res);
+        DEBUG1("Failed to receive the answer to my 'Get Predecessor' request: %d", res);
         stop = 1;
 //        MSG_comm_destroy(node->comm_receive);
       }
       else {
         task = MSG_comm_get_task(node->comm_receive);
-        INFO1("Received a task '%s'", MSG_task_get_name(task));
+        task_data_t ans_data = MSG_task_get_data(task);
 
-        if (strcmp(MSG_task_get_name(task), "Get Predecessor Answer")) {
+        if (ans_data->type != TASK_GET_PREDECESSOR_ANSWER) {
           handle_task(node, task);
         }
         else {
-          INFO2("This is the answer to my 'Get Predecessor' request: the predecessor of node %d is %d", ask_to, predecessor_id);
-          task_data_t ans_data = MSG_task_get_data(task);
+          DEBUG2("Received the answer to my 'Get Predecessor' request: the predecessor of node %d is %d", ask_to, predecessor_id);
           predecessor_id = ans_data->answer_id;
           stop = 1;
           MSG_task_destroy(task);
@@ -678,7 +711,7 @@ int closest_preceding_node(node_t node, int id)
  */
 static void stabilize(node_t node)
 {
-  INFO0("Stabilizing node");
+  DEBUG0("Stabilizing node");
 
   // get the predecessor of my immediate successor
   int candidate_id;
@@ -714,7 +747,7 @@ static void notify(node_t node, int predecessor_candidate_id) {
     print_finger_table(node);
   }
   else {
-    INFO1("I don't have to change my predecessor to %d", predecessor_candidate_id);
+    DEBUG1("I don't have to change my predecessor to %d", predecessor_candidate_id);
   }
 }
 
@@ -727,12 +760,13 @@ static void notify(node_t node, int 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", COMP_SIZE, COMM_SIZE, req_data);
+  DEBUG1("Sending a 'Notify' request to %d", notify_id);
+  m_task_t task = MSG_task_create(NULL, 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);
@@ -746,7 +780,7 @@ static void remote_notify(node_t node, int notify_id, int predecessor_candidate_
  */
 static void fix_fingers(node_t node) {
 
-  INFO0("Fixing fingers");
+  DEBUG0("Fixing fingers");
   int i = node->next_finger_to_fix;
   int id = find_successor(node, node->id + powers2[i]);
   if (id != -1) {
@@ -766,7 +800,7 @@ static void fix_fingers(node_t node) {
  */
 static void check_predecessor(node_t node)
 {
-  INFO0("Checking whether my predecessor is alive");
+  DEBUG0("Checking whether my predecessor is alive");
   // TODO
 }