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Documentation fixups: some arguments got renamed, and the DTD did also
[simgrid.git] / src / msg / gos.c
index 8297d8f..ed5e702 100644 (file)
 #include "msg/private.h"
 #include "xbt/sysdep.h"
 #include "xbt/log.h"
-#include "msg_mailbox.h"
+#include "mailbox.h"
 
 
 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(msg_gos, msg,
                                "Logging specific to MSG (gos)");
 
-/** \defgroup msg_gos_functions MSG Operating System Functions
- *  \brief This section describes the functions that can be used
- *  by an agent for handling some task.
+/** \ingroup msg_gos_functions
+ *
+ * \brief Return the last value returned by a MSG function (except
+ * MSG_get_errno...).
  */
-
-MSG_error_t MSG_task_get_ext(m_task_t * task,
-                            m_channel_t channel,
-                            double max_duration,
-                            m_host_t host)
+MSG_error_t 
+MSG_get_errno(void)
 {
+       return PROCESS_GET_ERRNO();
+}
 
-  m_process_t process = MSG_process_self();
-  m_task_t t = NULL;
-  m_host_t h = NULL;
-  simdata_task_t t_simdata = NULL;
-  simdata_host_t h_simdata = NULL;
-  int first_time = 1;
-  xbt_fifo_item_t item = NULL;
-
-  smx_cond_t cond = NULL;      //conditional wait if the task isn't on the channel yet
-
-  CHECK_HOST();
-  xbt_assert1((channel >= 0)
-             && (channel < msg_global->max_channel), "Invalid channel %d",
-             channel);
-  /* Sanity check */
-  xbt_assert0(task, "Null pointer for the task storage");
-
-  if (*task)
-    CRITICAL0
-       ("MSG_task_get() was asked to write in a non empty task struct.");
-
-  /* Get the task */
-  h = MSG_host_self();
-  h_simdata = h->simdata;
-
-  DEBUG2("Waiting for a task on channel %d (%s)", channel, h->name);
-
-  SIMIX_mutex_lock(h->simdata->mutex);
-  while (1) {
-    if (xbt_fifo_size(h_simdata->mbox[channel]) > 0) {
-      if (!host) {
-       t = xbt_fifo_shift(h_simdata->mbox[channel]);
-       break;
-      } else {
-       xbt_fifo_foreach(h->simdata->mbox[channel], item, t, m_task_t) {
-         if (t->simdata->source == host)
-           break;
-       }
-       if (item) {
-         xbt_fifo_remove_item(h->simdata->mbox[channel], item);
-         break;
+/** \ingroup msg_gos_functions
+ * \brief Executes a task and waits for its termination.
+ *
+ * This function is used for describing the behavior of an agent. It
+ * takes only one parameter.
+ * \param task a #m_task_t to execute on the location on which the
+   agent is running.
+ * \return #MSG_FATAL if \a task is not properly initialized and
+ * #MSG_OK otherwise.
+ */
+MSG_error_t 
+MSG_task_execute(m_task_t task)
+{
+       simdata_task_t simdata = NULL;
+       m_process_t self = MSG_process_self();
+       CHECK_HOST();
+       
+       simdata = task->simdata;
+       xbt_assert0((!simdata->compute) && (task->simdata->using == 1),"This task is executed somewhere else. Go fix your code!");
+       
+       DEBUG1("Computing on %s", MSG_process_self()->simdata->m_host->name);
+       
+       simdata->using++;
+       SIMIX_mutex_lock(simdata->mutex);
+       simdata->compute = SIMIX_action_execute(SIMIX_host_self(), task->name, simdata->computation_amount);
+       SIMIX_action_set_priority(simdata->compute, simdata->priority);
+       
+       self->simdata->waiting_task = task;
+       SIMIX_register_action_to_condition(simdata->compute, simdata->cond);
+       SIMIX_cond_wait(simdata->cond, simdata->mutex);
+       SIMIX_unregister_action_to_condition(simdata->compute, simdata->cond);
+       self->simdata->waiting_task = NULL;
+       
+       SIMIX_mutex_unlock(simdata->mutex);
+       simdata->using--;
+       
+       if (SIMIX_action_get_state(task->simdata->compute) == SURF_ACTION_DONE) 
+       {
+               /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
+               SIMIX_action_destroy(task->simdata->compute);
+               simdata->computation_amount = 0.0;
+               simdata->comm = NULL;
+               simdata->compute = NULL;
+               MSG_RETURN(MSG_OK);
+       } 
+       else if(SIMIX_host_get_state(SIMIX_host_self()) == 0) 
+       {
+               /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
+               SIMIX_action_destroy(task->simdata->compute);
+               simdata->comm = NULL;
+               simdata->compute = NULL;
+               MSG_RETURN(MSG_HOST_FAILURE);
+       } 
+       else 
+       {
+               /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
+               SIMIX_action_destroy(task->simdata->compute);
+               simdata->comm = NULL;
+               simdata->compute = NULL;
+               MSG_RETURN(MSG_TASK_CANCELLED);
        }
-      }
-    }
-
-    if (max_duration > 0) {
-      if (!first_time) {
-       SIMIX_mutex_unlock(h->simdata->mutex);
-       h_simdata->sleeping[channel] = NULL;
-       SIMIX_cond_destroy(cond);
-       MSG_RETURN(MSG_TRANSFER_FAILURE);
-      }
-    }
-    xbt_assert1(!(h_simdata->sleeping[channel]),
-               "A process is already blocked on channel %d", channel);
-
-    cond = SIMIX_cond_init();
-    h_simdata->sleeping[channel] = cond;
-    if (max_duration > 0)
-      SIMIX_cond_wait_timeout(cond, h->simdata->mutex, max_duration);
-    else 
-      SIMIX_cond_wait(h_simdata->sleeping[channel], h->simdata->mutex);
-
-    if (SIMIX_host_get_state(h_simdata->smx_host) == 0)
-      MSG_RETURN(MSG_HOST_FAILURE);
+}
 
-    first_time = 0;
-  }
-  SIMIX_mutex_unlock(h->simdata->mutex);
+/** \ingroup m_task_management
+ * \brief Creates a new #m_task_t (a parallel one....).
+ *
+ * A constructor for #m_task_t taking six arguments and returning the 
+   corresponding object.
+ * \param name a name for the object. It is for user-level information
+   and can be NULL.
+ * \param host_nb the number of hosts implied in the parallel task.
+ * \param host_list an array of \p host_nb m_host_t.
+ * \param computation_amount an array of \p host_nb
+   doubles. computation_amount[i] is the total number of operations
+   that have to be performed on host_list[i].
+ * \param communication_amount an array of \p host_nb* \p host_nb doubles.
+ * \param data a pointer to any data may want to attach to the new
+   object.  It is for user-level information and can be NULL. It can
+   be retrieved with the function \ref MSG_task_get_data.
+ * \see m_task_t
+ * \return The new corresponding object.
+ */
+m_task_t 
+MSG_parallel_task_create(const char *name,int host_nb, const m_host_t * host_list, double *computation_amount, double *communication_amount, void *data)
+{
+       int i;
+       simdata_task_t simdata = xbt_new0(s_simdata_task_t, 1);
+       m_task_t task = xbt_new0(s_m_task_t, 1);
+       task->simdata = simdata;
+       
+       /* Task structure */
+       task->name = xbt_strdup(name);
+       task->data = data;
+       
+       /* Simulator Data */
+       simdata->computation_amount = 0;
+       simdata->message_size = 0;
+       simdata->cond = SIMIX_cond_init();
+       simdata->mutex = SIMIX_mutex_init();
+       simdata->compute = NULL;
+       simdata->comm = NULL;
+       simdata->rate = -1.0;
+       simdata->using = 1;
+       simdata->sender = NULL;
+       simdata->receiver = NULL;
+       simdata->source = NULL;
+       
+       simdata->host_nb = host_nb;
+       simdata->host_list = xbt_new0(smx_host_t, host_nb);
+       simdata->comp_amount = computation_amount;
+       simdata->comm_amount = communication_amount;
+       
+       for (i = 0; i < host_nb; i++)
+               simdata->host_list[i] = host_list[i]->simdata->smx_host;
+       
+       return task;
+}
 
-  DEBUG1("OK, got a task (%s)", t->name);
-  /* clean conditional */
-  if (cond) {
-    SIMIX_cond_destroy(cond);
-    h_simdata->sleeping[channel] = NULL;
-  }
+MSG_error_t 
+MSG_parallel_task_execute(m_task_t task)
+{
+       simdata_task_t simdata = NULL;
+       m_process_t self = MSG_process_self();
+       CHECK_HOST();
+       
+       simdata = task->simdata;
+       
+       xbt_assert0((!simdata->compute) && (task->simdata->using == 1),"This task is executed somewhere else. Go fix your code!");
+       
+       xbt_assert0(simdata->host_nb,"This is not a parallel task. Go to hell.");
+       
+       DEBUG1("Computing on %s", MSG_process_self()->simdata->m_host->name);
+       
+       simdata->using++;
+       
+       SIMIX_mutex_lock(simdata->mutex);
+       simdata->compute =
+       SIMIX_action_parallel_execute(task->name, simdata->host_nb, simdata->host_list, simdata->comp_amount, simdata->comm_amount, 1.0, -1.0);
+       
+       self->simdata->waiting_task = task;
+       SIMIX_register_action_to_condition(simdata->compute, simdata->cond);
+       SIMIX_cond_wait(simdata->cond, simdata->mutex);
+       SIMIX_unregister_action_to_condition(simdata->compute, simdata->cond);
+       self->simdata->waiting_task = NULL;
+       
+       
+       SIMIX_mutex_unlock(simdata->mutex);
+       simdata->using--;
+       
+       if (SIMIX_action_get_state(task->simdata->compute) == SURF_ACTION_DONE) 
+       {
+               /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
+               SIMIX_action_destroy(task->simdata->compute);
+               simdata->computation_amount = 0.0;
+               simdata->comm = NULL;
+               simdata->compute = NULL;
+               MSG_RETURN(MSG_OK);
+       } 
+       else if(SIMIX_host_get_state(SIMIX_host_self()) == 0) 
+       {
+               /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
+               SIMIX_action_destroy(task->simdata->compute);
+               simdata->comm = NULL;
+               simdata->compute = NULL;
+               MSG_RETURN(MSG_HOST_FAILURE);
+       } 
+       else 
+       {
+               /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
+               SIMIX_action_destroy(task->simdata->compute);
+               simdata->comm = NULL;
+               simdata->compute = NULL;
+               MSG_RETURN(MSG_TASK_CANCELLED);
+       }
 
-  t_simdata = t->simdata;
-  t_simdata->receiver = process;
-  *task = t;
+}
 
-  SIMIX_mutex_lock(t_simdata->mutex);
 
-  /* Transfer */
-  /* create SIMIX action to the communication */
-  t_simdata->comm =
-      SIMIX_action_communicate(t_simdata->sender->simdata->m_host->
-                              simdata->smx_host,
-                              process->simdata->m_host->simdata->smx_host,
-                              t->name, t_simdata->message_size,
-                              t_simdata->rate);
-  /* if the process is suspend, create the action but stop its execution, it will be restart when the sender process resume */
-  if (MSG_process_is_suspended(t_simdata->sender)) {
-    DEBUG1("Process sender (%s) suspended", t_simdata->sender->name);
-    SIMIX_action_set_priority(t_simdata->comm, 0);
-  }
-  process->simdata->waiting_task = t;
-  SIMIX_register_action_to_condition(t_simdata->comm, t_simdata->cond);
-       while (1) {
-               SIMIX_cond_wait(t_simdata->cond, t_simdata->mutex);
-               if (SIMIX_action_get_state(t_simdata->comm) != SURF_ACTION_RUNNING)
-                       break;
+/** \ingroup msg_gos_functions
+ * \brief Sleep for the specified number of seconds
+ *
+ * Makes the current process sleep until \a time seconds have elapsed.
+ *
+ * \param nb_sec a number of second
+ */
+MSG_error_t 
+MSG_process_sleep(double nb_sec)
+{
+       smx_action_t act_sleep;
+       m_process_t proc = MSG_process_self();
+       smx_mutex_t mutex;
+       smx_cond_t cond;
+       
+       /* create action to sleep */
+       act_sleep = SIMIX_action_sleep(SIMIX_process_get_host(proc->simdata->s_process), nb_sec);
+       
+       mutex = SIMIX_mutex_init();
+       SIMIX_mutex_lock(mutex);
+       
+       /* create conditional and register action to it */
+       cond = SIMIX_cond_init();
+       
+       SIMIX_register_action_to_condition(act_sleep, cond);
+       SIMIX_cond_wait(cond, mutex);
+       SIMIX_unregister_action_to_condition(act_sleep, cond);
+       SIMIX_mutex_unlock(mutex);
+       
+       /* remove variables */
+       SIMIX_cond_destroy(cond);
+       SIMIX_mutex_destroy(mutex);
+       
+       if (SIMIX_action_get_state(act_sleep) == SURF_ACTION_DONE) 
+       {
+               if (SIMIX_host_get_state(SIMIX_host_self()) == SURF_CPU_OFF) 
+               {
+                       SIMIX_action_destroy(act_sleep);
+                       MSG_RETURN(MSG_HOST_FAILURE);
+               }
+       } 
+       else 
+       {
+               SIMIX_action_destroy(act_sleep);
+               MSG_RETURN(MSG_HOST_FAILURE);
        }
-  SIMIX_unregister_action_to_condition(t_simdata->comm, t_simdata->cond);
-  process->simdata->waiting_task = NULL;
-
-  /* the task has already finished and the pointer must be null */
-  if (t->simdata->sender) {
-    t->simdata->sender->simdata->waiting_task = NULL;
-    /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
-    //t->simdata->comm = NULL;
-    //t->simdata->compute = NULL;
-  }
-  /* for this process, don't need to change in get function */
-  t->simdata->receiver = NULL;
-  SIMIX_mutex_unlock(t_simdata->mutex);
+       
+       MSG_RETURN(MSG_OK);
+}
 
+/** \ingroup msg_gos_functions
+ * \brief Return the number of MSG tasks currently running on
+ * the host of the current running process.
+ */
+static int 
+MSG_get_msgload(void)
+{
+       xbt_die("not implemented yet");
+       return 0;
+}
 
-  if (SIMIX_action_get_state(t_simdata->comm) == SURF_ACTION_DONE) {
-    //t_simdata->comm = NULL;
-    SIMIX_action_destroy(t_simdata->comm);
-    t_simdata->comm = NULL;
-               t_simdata->using--;
-    MSG_RETURN(MSG_OK);
-  } else if (SIMIX_host_get_state(h_simdata->smx_host) == 0) {
-    //t_simdata->comm = NULL;
-    SIMIX_action_destroy(t_simdata->comm);
-    t_simdata->comm = NULL;
-               t_simdata->using--;
-    MSG_RETURN(MSG_HOST_FAILURE);
-  } else {
-    //t_simdata->comm = NULL;
-    SIMIX_action_destroy(t_simdata->comm);
-    t_simdata->comm = NULL;
-               t_simdata->using--;
-    MSG_RETURN(MSG_TRANSFER_FAILURE);
-  }
 
-}
 
 /** \ingroup msg_gos_functions
- * \brief Listen on a channel and wait for receiving a task.
+ * \brief Listen on \a channel and waits for receiving a task from \a host.
  *
- * It takes two parameters.
+ * It takes three parameters.
  * \param task a memory location for storing a #m_task_t. It will
    hold a task when this function will return. Thus \a task should not
    be equal to \c NULL and \a *task should be equal to \c NULL. If one of
@@ -178,18 +279,20 @@ MSG_error_t MSG_task_get_ext(m_task_t * task,
  * \param channel the channel on which the agent should be
    listening. This value has to be >=0 and < than the maximal
    number of channels fixed with MSG_set_channel_number().
+ * \param host the host that is to be watched.
  * \return #MSG_FATAL if \a task is equal to \c NULL, #MSG_WARNING
* if \a *task is not equal to \c NULL, and #MSG_OK otherwise.
  if \a *task is not equal to \c NULL, and #MSG_OK otherwise.
  */
-MSG_error_t MSG_task_get(m_task_t * task, m_channel_t channel)
+MSG_error_t 
+MSG_task_get_from_host(m_task_t * task, m_channel_t channel, m_host_t host)
 {
-  return MSG_task_get_with_time_out(task, channel, -1);
+       return MSG_task_get_ext(task, channel, -1, host);
 }
 
 /** \ingroup msg_gos_functions
- * \brief Listen on a channel and wait for receiving a task with a timeout.
+ * \brief Listen on a channel and wait for receiving a task.
  *
- * It takes three parameters.
+ * It takes two parameters.
  * \param task a memory location for storing a #m_task_t. It will
    hold a task when this function will return. Thus \a task should not
    be equal to \c NULL and \a *task should be equal to \c NULL. If one of
@@ -197,22 +300,17 @@ MSG_error_t MSG_task_get(m_task_t * task, m_channel_t channel)
  * \param channel the channel on which the agent should be
    listening. This value has to be >=0 and < than the maximal
    number of channels fixed with MSG_set_channel_number().
- * \param max_duration the maximum time to wait for a task before giving
-    up. In such a case, #MSG_TRANSFER_FAILURE will be returned, \a task 
-    will not be modified and will still be
-    equal to \c NULL when returning. 
  * \return #MSG_FATAL if \a task is equal to \c NULL, #MSG_WARNING
  if \a *task is not equal to \c NULL, and #MSG_OK otherwise.
* if \a *task is not equal to \c NULL, and #MSG_OK otherwise.
  */
-MSG_error_t MSG_task_get_with_time_out(m_task_t * task,
-                                      m_channel_t channel,
-                                      double max_duration)
+MSG_error_t 
+MSG_task_get(m_task_t * task, m_channel_t channel)
 {
-  return MSG_task_get_ext(task, channel, max_duration, NULL);
+       return MSG_task_get_with_timeout(task, channel, -1);
 }
 
 /** \ingroup msg_gos_functions
- * \brief Listen on \a channel and waits for receiving a task from \a host.
+ * \brief Listen on a channel and wait for receiving a task with a timeout.
  *
  * It takes three parameters.
  * \param task a memory location for storing a #m_task_t. It will
@@ -222,184 +320,100 @@ MSG_error_t MSG_task_get_with_time_out(m_task_t * task,
  * \param channel the channel on which the agent should be
    listening. This value has to be >=0 and < than the maximal
    number of channels fixed with MSG_set_channel_number().
- * \param host the host that is to be watched.
+ * \param max_duration the maximum time to wait for a task before giving
+    up. In such a case, #MSG_TRANSFER_FAILURE will be returned, \a task 
+    will not be modified and will still be
+    equal to \c NULL when returning. 
  * \return #MSG_FATAL if \a task is equal to \c NULL, #MSG_WARNING
    if \a *task is not equal to \c NULL, and #MSG_OK otherwise.
  */
-MSG_error_t MSG_task_get_from_host(m_task_t * task, int channel,
-                                  m_host_t host)
+MSG_error_t 
+MSG_task_get_with_timeout(m_task_t * task, m_channel_t channel, double max_duration)
 {
-  return MSG_task_get_ext(task, channel, -1, host);
+  return MSG_task_get_ext(task, channel, max_duration, NULL);
 }
 
-/** \ingroup msg_gos_functions
- * \brief Test whether there is a pending communication on a channel.
- *
- * It takes one parameter.
- * \param channel the channel on which the agent should be
-   listening. This value has to be >=0 and < than the maximal
-   number of channels fixed with MSG_set_channel_number().
- * \return 1 if there is a pending communication and 0 otherwise
+/** \defgroup msg_gos_functions MSG Operating System Functions
+ *  \brief This section describes the functions that can be used
+ *  by an agent for handling some task.
  */
-int MSG_task_Iprobe(m_channel_t channel)
-{
-  m_host_t h = NULL;
-
-  xbt_assert1((channel >= 0)
-             && (channel < msg_global->max_channel), "Invalid channel %d",
-             channel);
-  CHECK_HOST();
-
-  DEBUG2("Probing on channel %d (%s)", channel, h->name);
 
-  h = MSG_host_self();
-  return (xbt_fifo_get_first_item(h->simdata->mbox[channel]) != NULL);
+MSG_error_t 
+MSG_task_get_ext(m_task_t * task, m_channel_t channel, double timeout,m_host_t host)
+{
+       xbt_assert1((channel >= 0) && (channel < msg_global->max_channel), "Invalid channel %d",channel);
+        
+       return MSG_mailbox_get_task_ext(MSG_mailbox_get_by_channel(MSG_host_self(), channel), task, host, timeout);
 }
 
-/** \ingroup msg_gos_functions
- * \brief Test whether there is a pending communication on a channel, and who sent it.
- *
- * It takes one parameter.
- * \param channel the channel on which the agent should be
-   listening. This value has to be >=0 and < than the maximal
-   number of channels fixed with MSG_set_channel_number().
- * \return -1 if there is no pending communication and the PID of the process who sent it otherwise
- */
-int MSG_task_probe_from(m_channel_t channel)
+MSG_error_t 
+MSG_task_receive_from_host(m_task_t * task, const char* alias, m_host_t host)
 {
-  m_host_t h = NULL;
-  xbt_fifo_item_t item;
-  m_task_t t;
-
-  xbt_assert1((channel >= 0)
-             && (channel < msg_global->max_channel), "Invalid channel %d",
-             channel);
-  CHECK_HOST();
-
-  h = MSG_host_self();
+       return MSG_task_receive_ext(task, alias, -1, host);
+}
 
-  DEBUG2("Probing on channel %d (%s)", channel, h->name);
+MSG_error_t 
+MSG_task_receive(m_task_t * task, const char* alias)
+{
+       return MSG_task_receive_with_timeout(task, alias, -1);  
+}
 
-  item = xbt_fifo_get_first_item(h->simdata->mbox[channel]);
-  if ((!item) || (!(t = xbt_fifo_get_item_content(item))))
-    return -1;
+MSG_error_t 
+MSG_task_receive_with_timeout(m_task_t * task, const char* alias, double timeout)
+{
+       return MSG_task_receive_ext(task, alias, timeout, NULL);                
+}
 
-  return MSG_process_get_PID(t->simdata->sender);
+MSG_error_t 
+MSG_task_receive_ext(m_task_t* task, const char* alias, double timeout, m_host_t host)
+{
+       return MSG_mailbox_get_task_ext(MSG_mailbox_get_by_alias(alias), task, host, timeout);
 }
 
+
 /** \ingroup msg_gos_functions
- * \brief Wait for at most \a max_duration second for a task reception
-   on \a channel. 
- * \a PID is updated with the PID of the first process that triggered this event if any.
+ * \brief Put a task on a channel of an host and waits for the end of the
+ * transmission.
  *
- * It takes three parameters:
- * \param channel the channel on which the agent should be
-   listening. This value has to be >=0 and < than the maximal.
-   number of channels fixed with MSG_set_channel_number().
- * \param PID a memory location for storing an int.
- * \param max_duration the maximum time to wait for a task before
-    giving up. In the case of a reception, *\a PID will be updated
-    with the PID of the first process to send a task.
- * \return #MSG_HOST_FAILURE if the host is shut down in the meantime
-   and #MSG_OK otherwise.
+ * This function is used for describing the behavior of an agent. It
+ * takes three parameter.
+ * \param task a #m_task_t to send on another location. This task
+   will not be usable anymore when the function will return. There is
+   no automatic task duplication and you have to save your parameters
+   before calling this function. Tasks are unique and once it has been
+   sent to another location, you should not access it anymore. You do
+   not need to call MSG_task_destroy() but to avoid using, as an
+   effect of inattention, this task anymore, you definitely should
+   renitialize it with #MSG_TASK_UNINITIALIZED. Note that this task
+   can be transfered iff it has been correctly created with
+   MSG_task_create().
+ * \param dest the destination of the message
+ * \param channel the channel on which the agent should put this
+   task. This value has to be >=0 and < than the maximal number of
+   channels fixed with MSG_set_channel_number().
+ * \return #MSG_FATAL if \a task is not properly initialized and
+ * #MSG_OK otherwise. Returns #MSG_HOST_FAILURE if the host on which
+ * this function was called was shut down. Returns
+ * #MSG_TRANSFER_FAILURE if the transfer could not be properly done
+ * (network failure, dest failure)
  */
-MSG_error_t MSG_channel_select_from(m_channel_t channel,
-                                   double max_duration, int *PID)
+MSG_error_t 
+MSG_task_put(m_task_t task, m_host_t dest, m_channel_t channel)
 {
-  m_host_t h = NULL;
-  simdata_host_t h_simdata = NULL;
-  xbt_fifo_item_t item;
-  m_task_t t;
-  int first_time = 1;
-  smx_cond_t cond;
-
-  xbt_assert1((channel >= 0)
-             && (channel < msg_global->max_channel), "Invalid channel %d",
-             channel);
-  if (PID) {
-    *PID = -1;
-  }
-
-  if (max_duration == 0.0) {
-    *PID = MSG_task_probe_from(channel);
-    MSG_RETURN(MSG_OK);
-  } else {
-    CHECK_HOST();
-    h = MSG_host_self();
-    h_simdata = h->simdata;
-
-    DEBUG2("Probing on channel %d (%s)", channel, h->name);
-    while (!(item = xbt_fifo_get_first_item(h->simdata->mbox[channel]))) {
-      if (max_duration > 0) {
-       if (!first_time) {
-         MSG_RETURN(MSG_OK);
-       }
-      }
-      SIMIX_mutex_lock(h_simdata->mutex);
-      xbt_assert1(!(h_simdata->sleeping[channel]),
-                 "A process is already blocked on this channel %d",
-                 channel);
-      cond = SIMIX_cond_init();
-      h_simdata->sleeping[channel] = cond;     /* I'm waiting. Wake me up when you're ready */
-      if (max_duration > 0) {
-       SIMIX_cond_wait_timeout(cond, h_simdata->mutex, max_duration);
-      } else {
-       SIMIX_cond_wait(cond, h_simdata->mutex);
-      }
-      SIMIX_cond_destroy(cond);
-      SIMIX_mutex_unlock(h_simdata->mutex);
-      if (SIMIX_host_get_state(h_simdata->smx_host) == 0) {
-       MSG_RETURN(MSG_HOST_FAILURE);
-      }
-      h_simdata->sleeping[channel] = NULL;
-      first_time = 0;
-    }
-    if (!item || !(t = xbt_fifo_get_item_content(item))) {
-      MSG_RETURN(MSG_OK);
-    }
-    if (PID) {
-      *PID = MSG_process_get_PID(t->simdata->sender);
-    }
-    MSG_RETURN(MSG_OK);
-  }
+       return MSG_task_put_with_timeout(task, dest, channel, -1.0);
 }
 
-
 /** \ingroup msg_gos_functions
-
- * \brief Return the number of tasks waiting to be received on a \a
-   channel and sent by \a host.
+ * \brief Does exactly the same as MSG_task_put but with a bounded transmition 
+ * rate.
  *
- * It takes two parameters.
- * \param channel the channel on which the agent should be
-   listening. This value has to be >=0 and < than the maximal
-   number of channels fixed with MSG_set_channel_number().
- * \param host the host that is to be watched.
- * \return the number of tasks waiting to be received on \a channel
-   and sent by \a host.
+ * \sa MSG_task_put
  */
-int MSG_task_probe_from_host(int channel, m_host_t host)
+MSG_error_t
+MSG_task_put_bounded(m_task_t task, m_host_t dest, m_channel_t channel, double maxrate)
 {
-  xbt_fifo_item_t item;
-  m_task_t t;
-  int count = 0;
-  m_host_t h = NULL;
-
-  xbt_assert1((channel >= 0)
-             && (channel < msg_global->max_channel), "Invalid channel %d",
-             channel);
-  CHECK_HOST();
-  h = MSG_host_self();
-
-  DEBUG2("Probing on channel %d (%s)", channel, h->name);
-
-  xbt_fifo_foreach(h->simdata->mbox[channel], item, t, m_task_t) {
-    if (t->simdata->source == host)
-      count++;
-  }
-
-  return count;
+       task->simdata->rate = maxrate;
+       return MSG_task_put(task, dest, channel);
 }
 
 /** \ingroup msg_gos_functions \brief Put a task on a channel of an
@@ -422,7 +436,7 @@ int MSG_task_probe_from_host(int channel, m_host_t host)
  * \param channel the channel on which the agent should put this
    task. This value has to be >=0 and < than the maximal number of
    channels fixed with MSG_set_channel_number().
- * \param max_duration the maximum time to wait for a task before giving
+ * \param timeout the maximum time to wait for a task before giving
     up. In such a case, #MSG_TRANSFER_FAILURE will be returned, \a task 
     will not be modified 
  * \return #MSG_FATAL if \a task is not properly initialized and
@@ -431,599 +445,230 @@ int MSG_task_probe_from_host(int channel, m_host_t host)
    #MSG_TRANSFER_FAILURE if the transfer could not be properly done
    (network failure, dest failure, timeout...)
  */
-MSG_error_t MSG_task_put_with_timeout(m_task_t task, m_host_t dest,
-                                     m_channel_t channel,
-                                     double max_duration)
+MSG_error_t 
+MSG_task_put_with_timeout(m_task_t task, m_host_t dest, m_channel_t channel, double timeout)
 {
+       xbt_assert1((channel >= 0) && (channel < msg_global->max_channel), "Invalid channel %d", channel);
+       
+       return MSG_mailbox_put_with_timeout(MSG_mailbox_get_by_channel(dest, channel), task, timeout);
+}
 
+MSG_error_t 
+MSG_task_send(m_task_t task,const char* alias)
+{
+       return MSG_task_send_with_timeout(task, alias, -1);
+}
 
-  m_process_t process = MSG_process_self();
-  simdata_task_t task_simdata = NULL;
-  m_host_t local_host = NULL;
-  m_host_t remote_host = NULL;
-  CHECK_HOST();
-
-  xbt_assert1((channel >= 0)
-             && (channel < msg_global->max_channel), "Invalid channel %d",
-             channel);
-
-  task_simdata = task->simdata;
-  task_simdata->sender = process;
-  task_simdata->source = MSG_process_get_host(process);
-  xbt_assert0(task_simdata->using == 1,
-             "This task is still being used somewhere else. You cannot send it now. Go fix your code!");
-  task_simdata->comm = NULL;
-
-       task_simdata->using++;
-  local_host = ((simdata_process_t) process->simdata)->m_host;
-  remote_host = dest;
-
-  DEBUG4("Trying to send a task (%g kB) from %s to %s on channel %d",
-        task->simdata->message_size / 1000, local_host->name,
-        remote_host->name, channel);
-
-  SIMIX_mutex_lock(remote_host->simdata->mutex);
-  xbt_fifo_push(((simdata_host_t) remote_host->simdata)->
-               mbox[channel], task);
-
-
-  if (remote_host->simdata->sleeping[channel]) {
-    DEBUG0("Somebody is listening. Let's wake him up!");
-    SIMIX_cond_signal(remote_host->simdata->sleeping[channel]);
-  }
-  SIMIX_mutex_unlock(remote_host->simdata->mutex);
-
-  process->simdata->put_host = dest;
-  process->simdata->put_channel = channel;
-  SIMIX_mutex_lock(task->simdata->mutex);
-  // DEBUG4("Task sent (%g kB) from %s to %s on channel %d, waiting...", task->simdata->message_size/1000,local_host->name, remote_host->name, channel);
-
-  process->simdata->waiting_task = task;
-  if (max_duration > 0) {
-    xbt_ex_t e;
-               double time;
-               double time_elapsed;
-               time = SIMIX_get_clock();
-    TRY {
-               /*verify if the action that ends is the correct. Call the wait_timeout with the new time. If the timeout occurs, an exception is raised */
-                       while (1) {
-                       time_elapsed = SIMIX_get_clock() - time;
-                               SIMIX_cond_wait_timeout(task->simdata->cond, task->simdata->mutex,
-                                               max_duration-time_elapsed);
-                               if ((task->simdata->comm != NULL) &&
-                                               (SIMIX_action_get_state(task->simdata->comm) != SURF_ACTION_RUNNING))
-                                       break;
-                       }
-    } CATCH(e) {
-      if(e.category==timeout_error) {
-       xbt_ex_free(e);
-       /* verify if the timeout happened and the communication didn't started yet */
-       if (task->simdata->comm == NULL) {
-         process->simdata->waiting_task = NULL;
-         xbt_fifo_remove(((simdata_host_t) remote_host->simdata)->
-                         mbox[channel], task);
-         if (task->simdata->receiver) {
-           task->simdata->receiver->simdata->waiting_task = NULL;
-         }
-         task->simdata->sender = NULL;
-         SIMIX_mutex_unlock(task->simdata->mutex);
-         MSG_RETURN(MSG_TRANSFER_FAILURE);
-       }
-      } else {
-       RETHROW;
-      }
-    }
-  } else {
-               while (1) {
-                       SIMIX_cond_wait(task->simdata->cond, task->simdata->mutex);
-                       if (SIMIX_action_get_state(task->simdata->comm) != SURF_ACTION_RUNNING)
-                               break;
-               }
-  }
-
-  DEBUG1("Action terminated %s", task->name);
-  process->simdata->waiting_task = NULL;
-  /* the task has already finished and the pointer must be null */
-  if (task->simdata->receiver) {
-    task->simdata->receiver->simdata->waiting_task = NULL;
-    /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
-    //      task->simdata->comm = NULL;
-    //task->simdata->compute = NULL;
-  }
-  task->simdata->sender = NULL;
-  SIMIX_mutex_unlock(task->simdata->mutex);
 
-  if (SIMIX_action_get_state(task->simdata->comm) == SURF_ACTION_DONE) {
-    MSG_RETURN(MSG_OK);
-  } else if (SIMIX_host_get_state(local_host->simdata->smx_host) == 0) {
-    MSG_RETURN(MSG_HOST_FAILURE);
-  } else {
-    MSG_RETURN(MSG_TRANSFER_FAILURE);
-  }
+MSG_error_t 
+MSG_task_send_bounded(m_task_t task, const char* alias, double maxrate)
+{
+       task->simdata->rate = maxrate;
+       return MSG_task_send(task, alias);
 }
 
-/** \ingroup msg_gos_functions
- * \brief Put a task on a channel of an host and waits for the end of the
- * transmission.
- *
- * This function is used for describing the behavior of an agent. It
- * takes three parameter.
- * \param task a #m_task_t to send on another location. This task
-   will not be usable anymore when the function will return. There is
-   no automatic task duplication and you have to save your parameters
-   before calling this function. Tasks are unique and once it has been
-   sent to another location, you should not access it anymore. You do
-   not need to call MSG_task_destroy() but to avoid using, as an
-   effect of inattention, this task anymore, you definitely should
-   renitialize it with #MSG_TASK_UNINITIALIZED. Note that this task
-   can be transfered iff it has been correctly created with
-   MSG_task_create().
- * \param dest the destination of the message
- * \param channel the channel on which the agent should put this
-   task. This value has to be >=0 and < than the maximal number of
-   channels fixed with MSG_set_channel_number().
- * \return #MSG_FATAL if \a task is not properly initialized and
- * #MSG_OK otherwise. Returns #MSG_HOST_FAILURE if the host on which
- * this function was called was shut down. Returns
- * #MSG_TRANSFER_FAILURE if the transfer could not be properly done
- * (network failure, dest failure)
- */
-MSG_error_t MSG_task_put(m_task_t task, m_host_t dest, m_channel_t channel)
+                                   
+MSG_error_t 
+MSG_task_send_with_timeout(m_task_t task, const char* alias, double timeout)
 {
-  return MSG_task_put_with_timeout(task, dest, channel, -1.0);
+       return MSG_mailbox_put_with_timeout(MSG_mailbox_get_by_alias(alias), task, timeout);
 }
 
-/** \ingroup msg_gos_functions
- * \brief Does exactly the same as MSG_task_put but with a bounded transmition 
- * rate.
- *
- * \sa MSG_task_put
- */
-MSG_error_t MSG_task_put_bounded(m_task_t task,
-                                m_host_t dest, m_channel_t channel,
-                                double max_rate)
+int 
+MSG_task_listen(const char* alias)
 {
-  MSG_error_t res = MSG_OK;
-  task->simdata->rate = max_rate;
-  res = MSG_task_put(task, dest, channel);
-  return (res);
+       CHECK_HOST();
+       
+       return !MSG_mailbox_is_empty(MSG_mailbox_get_by_alias(alias));
 }
 
 /** \ingroup msg_gos_functions
- * \brief Executes a task and waits for its termination.
+ * \brief Test whether there is a pending communication on a channel.
  *
- * This function is used for describing the behavior of an agent. It
- * takes only one parameter.
- * \param task a #m_task_t to execute on the location on which the
-   agent is running.
- * \return #MSG_FATAL if \a task is not properly initialized and
- * #MSG_OK otherwise.
+ * It takes one parameter.
+ * \param channel the channel on which the agent should be
+   listening. This value has to be >=0 and < than the maximal
+   number of channels fixed with MSG_set_channel_number().
+ * \return 1 if there is a pending communication and 0 otherwise
  */
-MSG_error_t MSG_task_execute(m_task_t task)
+int 
+MSG_task_Iprobe(m_channel_t channel)
 {
-  simdata_task_t simdata = NULL;
-  m_process_t self = MSG_process_self();
+  xbt_assert1((channel >= 0) && (channel < msg_global->max_channel), "Invalid channel %d", channel);
+  
   CHECK_HOST();
-
-  simdata = task->simdata;
-  xbt_assert0((!simdata->compute) && (task->simdata->using == 1),
-             "This task is executed somewhere else. Go fix your code!");
-
-  DEBUG1("Computing on %s", MSG_process_self()->simdata->m_host->name);
-  simdata->using++;
-  SIMIX_mutex_lock(simdata->mutex);
-  simdata->compute =
-      SIMIX_action_execute(SIMIX_host_self(), task->name,
-                          simdata->computation_amount);
-  SIMIX_action_set_priority(simdata->compute, simdata->priority);
-
-  self->simdata->waiting_task = task;
-  SIMIX_register_action_to_condition(simdata->compute, simdata->cond);
-  SIMIX_cond_wait(simdata->cond, simdata->mutex);
-  SIMIX_unregister_action_to_condition(simdata->compute, simdata->cond);
-  self->simdata->waiting_task = NULL;
-
-  SIMIX_mutex_unlock(simdata->mutex);
-  simdata->using--;
-
-  if (SIMIX_action_get_state(task->simdata->compute) == SURF_ACTION_DONE) {
-    /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
-    SIMIX_action_destroy(task->simdata->compute);
-    simdata->computation_amount = 0.0;
-    simdata->comm = NULL;
-    simdata->compute = NULL;
-    MSG_RETURN(MSG_OK);
-  } else if (SIMIX_host_get_state(SIMIX_host_self()) == 0) {
-    /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
-    SIMIX_action_destroy(task->simdata->compute);
-    simdata->comm = NULL;
-    simdata->compute = NULL;
-    MSG_RETURN(MSG_HOST_FAILURE);
-  } else {
-    /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
-    SIMIX_action_destroy(task->simdata->compute);
-    simdata->comm = NULL;
-    simdata->compute = NULL;
-    MSG_RETURN(MSG_TASK_CANCELLED);
-  }
+  
+  return !MSG_mailbox_is_empty(MSG_mailbox_get_by_channel(MSG_host_self(), channel));
 }
 
+/** \ingroup msg_gos_functions
 
-/** \ingroup m_task_management
* \brief Creates a new #m_task_t (a parallel one....).
+ * \brief Return the number of tasks waiting to be received on a \a
  channel and sent by \a host.
  *
- * A constructor for #m_task_t taking six arguments and returning the 
-   corresponding object.
- * \param name a name for the object. It is for user-level information
-   and can be NULL.
- * \param host_nb the number of hosts implied in the parallel task.
- * \param host_list an array of \p host_nb m_host_t.
- * \param computation_amount an array of \p host_nb
-   doubles. computation_amount[i] is the total number of operations
-   that have to be performed on host_list[i].
- * \param communication_amount an array of \p host_nb* \p host_nb doubles.
- * \param data a pointer to any data may want to attach to the new
-   object.  It is for user-level information and can be NULL. It can
-   be retrieved with the function \ref MSG_task_get_data.
- * \see m_task_t
- * \return The new corresponding object.
+ * It takes two parameters.
+ * \param channel the channel on which the agent should be
+   listening. This value has to be >=0 and < than the maximal
+   number of channels fixed with MSG_set_channel_number().
+ * \param host the host that is to be watched.
+ * \return the number of tasks waiting to be received on \a channel
+   and sent by \a host.
  */
-m_task_t MSG_parallel_task_create(const char *name,
-                                 int host_nb,
-                                 const m_host_t * host_list,
-                                 double *computation_amount,
-                                 double *communication_amount, void *data)
+int 
+MSG_task_probe_from_host(int channel, m_host_t host)
 {
-  int i;
-  simdata_task_t simdata = xbt_new0(s_simdata_task_t, 1);
-  m_task_t task = xbt_new0(s_m_task_t, 1);
-  task->simdata = simdata;
-
-  /* Task structure */
-  task->name = xbt_strdup(name);
-  task->data = data;
-
-  /* Simulator Data */
-  simdata->computation_amount = 0;
-  simdata->message_size = 0;
-  simdata->cond = SIMIX_cond_init();
-  simdata->mutex = SIMIX_mutex_init();
-  simdata->compute = NULL;
-  simdata->comm = NULL;
-  simdata->rate = -1.0;
-  simdata->using = 1;
-  simdata->sender = NULL;
-  simdata->receiver = NULL;
-  simdata->source = NULL;
-
-  simdata->host_nb = host_nb;
-  simdata->host_list = xbt_new0(smx_host_t, host_nb);
-  simdata->comp_amount = computation_amount;
-  simdata->comm_amount = communication_amount;
-
-  for (i = 0; i < host_nb; i++)
-    simdata->host_list[i] = host_list[i]->simdata->smx_host;
-
-  return task;
-
+       xbt_assert1((channel >= 0) && (channel < msg_global->max_channel), "Invalid channel %d", channel);
+       
+       CHECK_HOST();
+       
+       return MSG_mailbox_get_count_host_waiting_tasks(MSG_mailbox_get_by_channel(MSG_host_self(), channel),host);     
+       
 }
 
-
-MSG_error_t MSG_parallel_task_execute(m_task_t task)
+int 
+MSG_task_listen_from_host(const char* alias, m_host_t host)
 {
-  simdata_task_t simdata = NULL;
-  m_process_t self = MSG_process_self();
-  CHECK_HOST();
-
-  simdata = task->simdata;
-  xbt_assert0((!simdata->compute) && (task->simdata->using == 1),
-             "This task is executed somewhere else. Go fix your code!");
-
-  xbt_assert0(simdata->host_nb,
-             "This is not a parallel task. Go to hell.");
-
-  DEBUG1("Computing on %s", MSG_process_self()->simdata->m_host->name);
-  simdata->using++;
-  SIMIX_mutex_lock(simdata->mutex);
-  simdata->compute =
-      SIMIX_action_parallel_execute(task->name, simdata->host_nb,
-                                   simdata->host_list,
-                                   simdata->comp_amount,
-                                   simdata->comm_amount, 1.0, -1.0);
-
-  self->simdata->waiting_task = task;
-  SIMIX_register_action_to_condition(simdata->compute, simdata->cond);
-  SIMIX_cond_wait(simdata->cond, simdata->mutex);
-  SIMIX_unregister_action_to_condition(simdata->compute, simdata->cond);
-  self->simdata->waiting_task = NULL;
-
-
-  SIMIX_mutex_unlock(simdata->mutex);
-  simdata->using--;
-
-  if (SIMIX_action_get_state(task->simdata->compute) == SURF_ACTION_DONE) {
-    /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
-    SIMIX_action_destroy(task->simdata->compute);
-    simdata->computation_amount = 0.0;
-    simdata->comm = NULL;
-    simdata->compute = NULL;
-    MSG_RETURN(MSG_OK);
-  } else if (SIMIX_host_get_state(SIMIX_host_self()) == 0) {
-    /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
-    SIMIX_action_destroy(task->simdata->compute);
-    simdata->comm = NULL;
-    simdata->compute = NULL;
-    MSG_RETURN(MSG_HOST_FAILURE);
-  } else {
-    /* action ended, set comm and compute = NULL, the actions is already destroyed in the main function */
-    SIMIX_action_destroy(task->simdata->compute);
-    simdata->comm = NULL;
-    simdata->compute = NULL;
-    MSG_RETURN(MSG_TASK_CANCELLED);
-  }
-
+       CHECK_HOST();
+       
+       return MSG_mailbox_get_count_host_waiting_tasks(MSG_mailbox_get_by_alias(alias),host);          
 }
 
-
 /** \ingroup msg_gos_functions
- * \brief Sleep for the specified number of seconds
- *
- * Makes the current process sleep until \a time seconds have elapsed.
+ * \brief Test whether there is a pending communication on a channel, and who sent it.
  *
- * \param nb_sec a number of second
+ * It takes one parameter.
+ * \param channel the channel on which the agent should be
+   listening. This value has to be >=0 and < than the maximal
+   number of channels fixed with MSG_set_channel_number().
+ * \return -1 if there is no pending communication and the PID of the process who sent it otherwise
  */
-MSG_error_t MSG_process_sleep(double nb_sec)
+int 
+MSG_task_probe_from(m_channel_t channel)
 {
-  smx_action_t act_sleep;
-  m_process_t proc = MSG_process_self();
-  smx_mutex_t mutex;
-  smx_cond_t cond;
-  /* create action to sleep */
-  act_sleep =
-      SIMIX_action_sleep(SIMIX_process_get_host(proc->simdata->s_process),
-                        nb_sec);
+       m_task_t task;
 
-  mutex = SIMIX_mutex_init();
-  SIMIX_mutex_lock(mutex);
-  /* create conditional and register action to it */
-  cond = SIMIX_cond_init();
+       CHECK_HOST();
+       
+       xbt_assert1((channel >= 0) && (channel < msg_global->max_channel), "Invalid channel %d", channel);
 
-  SIMIX_register_action_to_condition(act_sleep, cond);
-  SIMIX_cond_wait(cond, mutex);
-  SIMIX_unregister_action_to_condition(act_sleep, cond);
-  SIMIX_mutex_unlock(mutex);
+       if(NULL == (task = MSG_mailbox_get_head(MSG_mailbox_get_by_channel(MSG_host_self(), channel))))
+               return -1;
 
-  /* remove variables */
-  SIMIX_cond_destroy(cond);
-  SIMIX_mutex_destroy(mutex);
+       return MSG_process_get_PID(task->simdata->sender);
+}
 
-  if (SIMIX_action_get_state(act_sleep) == SURF_ACTION_DONE) {
-    if (SIMIX_host_get_state(SIMIX_host_self()) == SURF_CPU_OFF) {
-      SIMIX_action_destroy(act_sleep);
-      MSG_RETURN(MSG_HOST_FAILURE);
-    }
-  } else {
-    SIMIX_action_destroy(act_sleep);
-    MSG_RETURN(MSG_HOST_FAILURE);
-  }
+int
+MSG_task_listen_from(const char* alias)
+{
+       m_task_t task;
 
+       CHECK_HOST();
 
-  MSG_RETURN(MSG_OK);
-}
+       if(NULL == (task = MSG_mailbox_get_head(MSG_mailbox_get_by_alias(alias))))
+               return -1;
 
-/** \ingroup msg_gos_functions
- * \brief Return the number of MSG tasks currently running on
- * the host of the current running process.
- */
-static int MSG_get_msgload(void)
-{
-  xbt_die("not implemented yet");
-  return 0;
+       return MSG_process_get_PID(task->simdata->sender);
 }
 
 /** \ingroup msg_gos_functions
+ * \brief Wait for at most \a max_duration second for a task reception
+   on \a channel. 
+ * \a PID is updated with the PID of the first process that triggered this event if any.
  *
- * \brief Return the last value returned by a MSG function (except
- * MSG_get_errno...).
+ * It takes three parameters:
+ * \param channel the channel on which the agent should be
+   listening. This value has to be >=0 and < than the maximal.
+   number of channels fixed with MSG_set_channel_number().
+ * \param PID a memory location for storing an int.
+ * \param timeout the maximum time to wait for a task before
+    giving up. In the case of a reception, *\a PID will be updated
+    with the PID of the first process to send a task.
+ * \return #MSG_HOST_FAILURE if the host is shut down in the meantime
+   and #MSG_OK otherwise.
  */
-MSG_error_t MSG_get_errno(void)
-{
-  return PROCESS_GET_ERRNO();
-}
-
 MSG_error_t 
-MSG_task_receive_ext(m_task_t* task, const char* alias, double timeout, m_host_t host)
+MSG_channel_select_from(m_channel_t channel,double timeout, int *PID)
 {
-       m_process_t process = MSG_process_self();
-       m_task_t t = NULL;
        m_host_t h = NULL;
-       simdata_task_t t_simdata = NULL;
        simdata_host_t h_simdata = NULL;
+       m_task_t t;
        int first_time = 1;
-       xbt_fifo_item_t item = NULL;
-       
-       smx_cond_t cond = NULL; //conditional wait if the task isn't on the channel yet
-       
-       /* get the mailbox from the alias (if the mailbox doesn't exist, create it) */
-       msg_mailbox_t mailbox = MSG_mailbox_get_by_alias(alias);
-       
-       CHECK_HOST();
-       
-       /* Sanity check */
-       xbt_assert0(task, "Null pointer for the task storage");
-       
-       if (*task)
-               CRITICAL0("MSG_task_get() was asked to write in a non empty task struct.");
-       
-       /* Get the task */
-       h = MSG_host_self();
-       h_simdata = h->simdata;
+       smx_cond_t cond;
+       msg_mailbox_t mailbox;
        
-       DEBUG2("Waiting for a task on channel aliased by %s (%s)", alias, h->name);
+       xbt_assert1((channel >= 0) && (channel < msg_global->max_channel), "Invalid channel %d",channel);
        
-       SIMIX_mutex_lock(h->simdata->mutex);
+       if(PID) 
+       {
+               *PID = -1;
+       }
        
-       while (1) 
+       if (timeout == 0.0) 
+       {
+               *PID = MSG_task_probe_from(channel);
+               MSG_RETURN(MSG_OK);
+       } 
+       else 
        {
-               /* if the mailbox is empty (has no task */
-               if(!MSG_mailbox_is_empty(mailbox))
+               CHECK_HOST();
+               h = MSG_host_self();
+               h_simdata = h->simdata;
+               
+               mailbox = MSG_mailbox_get_by_channel(MSG_host_self(), channel); 
+               
+               while(MSG_mailbox_is_empty(mailbox))
                {
-                       if(!host) 
+                       if(timeout > 0) 
+                       {
+                               if (!first_time) 
+                               {
+                                       MSG_RETURN(MSG_OK);
+                               }
+                       }
+                       
+                       SIMIX_mutex_lock(h_simdata->mutex);
+                       
+                       xbt_assert1(!MSG_mailbox_get_cond(mailbox),"A process is already blocked on this channel %d",channel);
+                       
+                       cond = SIMIX_cond_init();
+                       
+                       MSG_mailbox_set_cond(mailbox, cond);
+                       
+                       if (timeout > 0) 
                        {
-                               /* pop the head of the mailbox */
-                               t = MSG_mailbox_pop_head(mailbox);
-                               break;
+                               SIMIX_cond_wait_timeout(cond, h_simdata->mutex, timeout);
                        } 
                        else 
                        {
-                               /* get the first task of the host */
-                               if(NULL != (t = MSG_mailbox_get_first_host_task(mailbox,host)))
-                                       break;
+                               SIMIX_cond_wait(cond, h_simdata->mutex);
                        }
-               }
-       
-               if(timeout > 0) 
-               {
-                       if (!first_time
+                       
+                       SIMIX_cond_destroy(cond);
+                       SIMIX_mutex_unlock(h_simdata->mutex);
+                       
+                       if (SIMIX_host_get_state(h_simdata->smx_host) == 0
                        {
-                               SIMIX_mutex_unlock(h->simdata->mutex);
-                               /* set the simix condition of the mailbox to NULL */
-                               MSG_mailbox_set_cond(mailbox, NULL);
-                               SIMIX_cond_destroy(cond);
-                               MSG_RETURN(MSG_TRANSFER_FAILURE);
+                               MSG_RETURN(MSG_HOST_FAILURE);
                        }
+                       
+                       MSG_mailbox_set_cond(mailbox,NULL);
+                       first_time = 0;
                }
                
-               xbt_assert1(!MSG_mailbox_get_cond(mailbox),"A process is already blocked on the channel aliased by %s", alias);
-               
-               cond = SIMIX_cond_init();
-               
-               /* set the condition of the mailbox */
-               MSG_mailbox_set_cond(mailbox, cond);
-               
-               if (timeout > 0)
-                       SIMIX_cond_wait_timeout(cond, h->simdata->mutex, timeout);
-               else 
-                       SIMIX_cond_wait(MSG_mailbox_get_cond(mailbox), h->simdata->mutex);
-                       
-       
-               if (SIMIX_host_get_state(h_simdata->smx_host) == 0)
-                       MSG_RETURN(MSG_HOST_FAILURE);
-       
-               first_time = 0;
-       }
-       
-       SIMIX_mutex_unlock(h->simdata->mutex);
-       
-       DEBUG1("OK, got a task (%s)", t->name);
-       /* clean conditional */
-       if (cond) 
-       {
-               SIMIX_cond_destroy(cond);
+               if(NULL == (t = MSG_mailbox_get_head(mailbox)))
+                       MSG_RETURN(MSG_OK);
+                               
                
-               MSG_mailbox_set_cond(mailbox,NULL);
-       }
-       
-       t_simdata = t->simdata;
-       t_simdata->receiver = process;
-       *task = t;
-       
-       SIMIX_mutex_lock(t_simdata->mutex);
-       
-       /* Transfer */
-       /* create SIMIX action to the communication */
-       t_simdata->comm = SIMIX_action_communicate(
-                                                                                               t_simdata->sender->simdata->m_host->simdata->smx_host,
-                                                                                               process->simdata->m_host->simdata->smx_host,
-                                                                                               t->name, 
-                                                                                               t_simdata->message_size,
-                                                                                               t_simdata->rate
-                                                                                       );
-       
-       /* if the process is suspend, create the action but stop its execution, it will be restart when the sender process resume */
-       if (MSG_process_is_suspended(t_simdata->sender)) 
-       {
-               DEBUG1("Process sender (%s) suspended", t_simdata->sender->name);
-               SIMIX_action_set_priority(t_simdata->comm, 0);
-       }
-       
-       process->simdata->waiting_task = t;
-       SIMIX_register_action_to_condition(t_simdata->comm, t_simdata->cond);
-       
-       while (1) 
-       {
-               SIMIX_cond_wait(t_simdata->cond, t_simdata->mutex);
+               if (PID) 
+               {
+                       *PID = MSG_process_get_PID(t->simdata->sender);
+               }
                
-               if (SIMIX_action_get_state(t_simdata->comm) != SURF_ACTION_RUNNING)
-                       break;
-       }
-       
-       SIMIX_unregister_action_to_condition(t_simdata->comm, t_simdata->cond);
-               process->simdata->waiting_task = NULL;
-       
-       /* the task has already finished and the pointer must be null */
-       if (t->simdata->sender) 
-       {
-               t->simdata->sender->simdata->waiting_task = NULL;
-       }
-       
-       /* for this process, don't need to change in get function */
-       t->simdata->receiver = NULL;
-       SIMIX_mutex_unlock(t_simdata->mutex);
-       
-       
-       if (SIMIX_action_get_state(t_simdata->comm) == SURF_ACTION_DONE) 
-       {
-               SIMIX_action_destroy(t_simdata->comm);
-               t_simdata->comm = NULL;
-               t_simdata->using--;
                MSG_RETURN(MSG_OK);
-       } 
-       else if (SIMIX_host_get_state(h_simdata->smx_host) == 0) 
-       {
-               SIMIX_action_destroy(t_simdata->comm);
-               t_simdata->comm = NULL;
-               t_simdata->using--;
-               MSG_RETURN(MSG_HOST_FAILURE);
-       } 
-       else 
-       {
-               SIMIX_action_destroy(t_simdata->comm);
-               t_simdata->comm = NULL;
-               t_simdata->using--;
-               MSG_RETURN(MSG_TRANSFER_FAILURE);
        }
 }
 
-MSG_error_t 
-MSG_task_receive_with_time_out(m_task_t * task, const char* alias, double timeout)
-{
-       return MSG_task_receive_ext(task, alias, timeout, NULL);                
-}
-                            
-MSG_error_t 
-MSG_task_receive(m_task_t * task, const char* alias)
-{
-       return MSG_task_receive_with_time_out(task, alias, -1); 
-}
-
-int 
-MSG_task_listen(const char* alias)
-{
-       CHECK_HOST();
-       
-       DEBUG2("Probing on channel aliased by %s (%s)", alias, MSG_host_self()->name);
-       
-       return !MSG_mailbox_is_empty(MSG_mailbox_get_by_alias(alias));
-}
-
-int 
-MSG_task_listen_from_host(const char* alias, m_host_t host)
-{
-
-       return MSG_mailbox_get_count_host_tasks(MSG_mailbox_get_by_alias(alias),host);
-                       
-}
 
 MSG_error_t 
 MSG_alias_select_from(const char* alias, double timeout, int* PID)
@@ -1106,179 +751,8 @@ MSG_alias_select_from(const char* alias, double timeout, int* PID)
                MSG_RETURN(MSG_OK);
        }
 }
-                                   
-MSG_error_t 
-MSG_task_send_with_timeout(m_task_t task, const char* alias, double timeout)
-{
-       m_process_t process = MSG_process_self();
-       const char* hostname;
-       simdata_task_t task_simdata = NULL;
-       m_host_t local_host = NULL;
-       m_host_t remote_host = NULL;
-       smx_cond_t cond = NULL;
-       
-       /* get the mailbox from the alias (if the mailbox doesn't exist, create it) */
-       msg_mailbox_t mailbox = MSG_mailbox_get_by_alias(alias);
-
-       CHECK_HOST();
-       
-       task_simdata = task->simdata;
-       task_simdata->sender = process;
-       task_simdata->source = MSG_process_get_host(process);
-       
-       xbt_assert0(task_simdata->using == 1,"This task is still being used somewhere else. You cannot send it now. Go fix your code!");
-       
-       task_simdata->comm = NULL;
-       
-       task_simdata->using++;
-       local_host = ((simdata_process_t) process->simdata)->m_host;
-       
-       /* get the host name containing the mailbox */
-       hostname = MSG_mailbox_get_hostname(mailbox);
-
-       remote_host = MSG_get_host_by_name(hostname);
-
-       if(NULL == remote_host)
-               THROW1(not_found_error,0,"Host %s not fount", hostname);
-
-
-       DEBUG4("Trying to send a task (%g kB) from %s to %s on the channel aliased by the alias %s",task->simdata->message_size / 1000, local_host->name,remote_host->name, MSG_mailbox_get_alias(mailbox));
-       
-       SIMIX_mutex_lock(remote_host->simdata->mutex);
-
-       /* put the task in the mailbox */
-       MSG_mailbox_put(mailbox,task);
-       
-       if(NULL != (cond = MSG_mailbox_get_cond(mailbox)))
-       {
-               DEBUG0("Somebody is listening. Let's wake him up!");
-               SIMIX_cond_signal(cond);
-       }
-
-       
-       
-       SIMIX_mutex_unlock(remote_host->simdata->mutex);
-       
-       SIMIX_mutex_lock(task->simdata->mutex);
-
-       process->simdata->waiting_task = task;
-       
-       if(timeout > 0) 
-       {
-               xbt_ex_t e;
-               double time;
-               double time_elapsed;
-               time = SIMIX_get_clock();
-               
-               TRY 
-               {
-                       /*verify if the action that ends is the correct. Call the wait_timeout with the new time. If the timeout occurs, an exception is raised */
-                       while (1) 
-                       {
-                               time_elapsed = SIMIX_get_clock() - time;
-                               SIMIX_cond_wait_timeout(task->simdata->cond, task->simdata->mutex,timeout - time_elapsed);
-                               
-                               if ((task->simdata->comm != NULL) && (SIMIX_action_get_state(task->simdata->comm) != SURF_ACTION_RUNNING))
-                                       break;
-                       }
-               } 
-               CATCH(e) 
-               {
-                       if(e.category==timeout_error) 
-                       {
-                               xbt_ex_free(e);
-                               /* verify if the timeout happened and the communication didn't started yet */
-                               if (task->simdata->comm == NULL) 
-                               {
-                                       process->simdata->waiting_task = NULL;
-                                       
-                                       /* remove the task from the mailbox */
-                                       MSG_mailbox_remove(mailbox,task);
-                                       
-                                       if (task->simdata->receiver) 
-                                       {
-                                               task->simdata->receiver->simdata->waiting_task = NULL;
-                                       }
-                                       
-                                       task->simdata->sender = NULL;
-                                       
-                                       SIMIX_mutex_unlock(task->simdata->mutex);
-                                       MSG_RETURN(MSG_TRANSFER_FAILURE);
-                               }
-                       } 
-                       else 
-                       {
-                               RETHROW;
-                       }
-               }
-       } 
-       else 
-       {
-               while (1) 
-               {
-                       SIMIX_cond_wait(task->simdata->cond, task->simdata->mutex);
-                       
-                       if (SIMIX_action_get_state(task->simdata->comm) != SURF_ACTION_RUNNING)
-                               break;
-               }
-       }
-       
-       DEBUG1("Action terminated %s", task->name);
-       process->simdata->waiting_task = NULL;
-       
-       /* the task has already finished and the pointer must be null */
-       if (task->simdata->receiver) 
-       {
-               task->simdata->receiver->simdata->waiting_task = NULL;
-       }
-       
-       task->simdata->sender = NULL;
-       SIMIX_mutex_unlock(task->simdata->mutex);
-
-       
-       if (SIMIX_action_get_state(task->simdata->comm) == SURF_ACTION_DONE)
-       {
-               MSG_RETURN(MSG_OK);
-       } 
-       else if (SIMIX_host_get_state(local_host->simdata->smx_host) == 0) 
-       {
-               MSG_RETURN(MSG_HOST_FAILURE);
-       } 
-       else 
-       {
-               MSG_RETURN(MSG_TRANSFER_FAILURE);
-       }
-}
-
-MSG_error_t 
-MSG_task_send(m_task_t task,const char* alias)
-{
-       return MSG_task_send_with_timeout(task, alias, -1);
-}
 
 
-MSG_error_t 
-MSG_task_send_bounded(m_task_t task, const char* alias, double rate)
-{
-       task->simdata->rate = rate;
-       return MSG_task_send(task, alias);
-}
-
-int
-MSG_task_listen_from(const char* alias)
-{
-       m_host_t h = NULL;
-       m_task_t t;
-
-       CHECK_HOST();
 
-       h = MSG_host_self();
 
-       DEBUG2("Probing on alias %s(%s)", alias, h->name);
-
-       if(NULL == (t = MSG_mailbox_get_head(MSG_mailbox_get_by_alias(alias))))
-               return -1;
-
-       return MSG_process_get_PID(t->simdata->sender);
-}