X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/b69e984a013e4e9e2d98fc4013cd1721bf2f0245..0c43de62fbe4bfc243d6512296e09207e80bcd54:/src/simix/smx_synchro.c

diff --git a/src/simix/smx_synchro.c b/src/simix/smx_synchro.c
index 0139dee630..eebc903509 100644
--- a/src/simix/smx_synchro.c
+++ b/src/simix/smx_synchro.c
@@ -1,114 +1,239 @@
-/* 	$Id$	 */
-
-/* Copyright (c) 2007 Arnaud Legrand, Bruno Donnassolo.
-   All rights reserved.                                          */
+/* Copyright (c) 2007-2013. 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 "private.h"
+#include "smx_private.h"
 #include "xbt/log.h"
 
 
 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(simix_synchro, simix,
-				"Logging specific to SIMIX (synchronization)");
+                                "Logging specific to SIMIX (synchronization)");
+
+static smx_action_t SIMIX_synchro_wait(smx_host_t smx_host, double timeout);
+static void SIMIX_synchro_finish(smx_action_t action);
+static void _SIMIX_cond_wait(smx_cond_t cond, smx_mutex_t mutex, double timeout,
+                             smx_process_t issuer, smx_simcall_t simcall);
+static void _SIMIX_sem_wait(smx_sem_t sem, double timeout, smx_process_t issuer,
+                            smx_simcall_t simcall);
+
+/***************************** Synchro action *********************************/
+
+static smx_action_t SIMIX_synchro_wait(smx_host_t smx_host, double timeout)
+{
+  XBT_IN("(%p, %f)",smx_host,timeout);
+
+  smx_action_t action;
+  action = xbt_mallocator_get(simix_global->action_mallocator);
+  action->type = SIMIX_ACTION_SYNCHRO;
+  action->name = xbt_strdup("synchro");
+  action->synchro.sleep = 
+    surf_workstation_sleep(smx_host, timeout);
+
+  surf_action_set_data(action->synchro.sleep, action);
+  XBT_OUT();
+  return action;
+}
+
+void SIMIX_synchro_stop_waiting(smx_process_t process, smx_simcall_t simcall)
+{
+  XBT_IN("(%p, %p)",process,simcall);
+  switch (simcall->call) {
+
+    case SIMCALL_MUTEX_LOCK:
+      xbt_swag_remove(process, simcall_mutex_lock__get__mutex(simcall)->sleeping);
+      break;
+
+    case SIMCALL_COND_WAIT:
+      xbt_swag_remove(process, simcall_cond_wait__get__cond(simcall)->sleeping);
+      break;
+
+    case SIMCALL_COND_WAIT_TIMEOUT:
+      xbt_swag_remove(process, simcall_cond_wait_timeout__get__cond(simcall)->sleeping);
+      break;
 
+    case SIMCALL_SEM_ACQUIRE:
+      xbt_swag_remove(process, simcall_sem_acquire__get__sem(simcall)->sleeping);
+      break;
 
-/****************************** Synchronization *******************************/
+    case SIMCALL_SEM_ACQUIRE_TIMEOUT:
+      xbt_swag_remove(process, simcall_sem_acquire_timeout__get__sem(simcall)->sleeping);
+      break;
+
+    default:
+      THROW_IMPOSSIBLE;
+  }
+  XBT_OUT();
+}
+
+void SIMIX_synchro_destroy(smx_action_t action)
+{
+  XBT_IN("(%p)",action);
+  XBT_DEBUG("Destroying synchro %p", action);
+  xbt_assert(action->type == SIMIX_ACTION_SYNCHRO);
+  surf_action_unref(action->synchro.sleep);
+  xbt_free(action->name);
+  xbt_mallocator_release(simix_global->action_mallocator, action);
+  XBT_OUT();
+}
+
+void SIMIX_post_synchro(smx_action_t action)
+{
+  XBT_IN("(%p)",action);
+  xbt_assert(action->type == SIMIX_ACTION_SYNCHRO);
+  if (surf_action_get_state(action->synchro.sleep) == SURF_ACTION_FAILED)
+    action->state = SIMIX_FAILED;
+  else if(surf_action_get_state(action->synchro.sleep) == SURF_ACTION_DONE)
+    action->state = SIMIX_SRC_TIMEOUT;
+
+  SIMIX_synchro_finish(action);  
+  XBT_OUT();
+}
+
+static void SIMIX_synchro_finish(smx_action_t action)
+{
+  XBT_IN("(%p)",action);
+  smx_simcall_t simcall = xbt_fifo_shift(action->simcalls);
+
+  switch (action->state) {
+
+    case SIMIX_SRC_TIMEOUT:
+      SMX_EXCEPTION(simcall->issuer, timeout_error, 0, "Synchro's wait timeout");
+      break;
+
+    case SIMIX_FAILED:
+        simcall->issuer->context->iwannadie = 1;
+//      SMX_EXCEPTION(simcall->issuer, host_error, 0, "Host failed");
+      break;
+
+    default:
+      THROW_IMPOSSIBLE;
+      break;
+  }
 
+  SIMIX_synchro_stop_waiting(simcall->issuer, simcall);
+  simcall->issuer->waiting_action = NULL;
+  SIMIX_synchro_destroy(action);
+  SIMIX_simcall_answer(simcall);
+  XBT_OUT();
+}
 /*********************************** Mutex ************************************/
 
+smx_mutex_t SIMIX_pre_mutex_init(smx_simcall_t simcall){
+  return SIMIX_mutex_init();
+}
 /**
  * \brief Initialize a mutex.
  *
- * Allocs and creates the data for the mutex. It have to be called before the utilisation of the mutex.
+ * Allocs and creates the data for the mutex.
  * \return A mutex
  */
-smx_mutex_t SIMIX_mutex_init()
+smx_mutex_t SIMIX_mutex_init(void)
 {
-  smx_mutex_t m = xbt_new0(s_smx_mutex_t, 1);
-  s_smx_process_t p;		/* useful to initialize sleeping swag */
-  /* structures initialization */
-  m->using = 0;
-  m->sleeping = xbt_swag_new(xbt_swag_offset(p, synchro_hookup));
-  return m;
+  XBT_IN("()");
+  s_smx_process_t p;            /* useful to initialize sleeping swag */
+
+  smx_mutex_t mutex = xbt_new0(s_smx_mutex_t, 1);
+  mutex->locked = 0;
+  mutex->sleeping = xbt_swag_new(xbt_swag_offset(p, synchro_hookup));
+  XBT_OUT();
+  return mutex;
 }
 
 /**
- * \brief Locks a mutex.
- *
- * Tries to lock a mutex, if the mutex isn't used yet, the process can continue its execution, else it'll be blocked here. You have to call #SIMIX_mutex_unlock to free the mutex.
- * \param mutex The mutex
+ * \brief Handles a mutex lock simcall.
+ * \param simcall the simcall
  */
-void SIMIX_mutex_lock(smx_mutex_t mutex)
+void SIMIX_pre_mutex_lock(smx_simcall_t simcall, smx_mutex_t mutex)
 {
-  smx_process_t self = SIMIX_process_self();
-  xbt_assert0((mutex != NULL), "Invalid parameters");
-
-
-  if (mutex->using) {
-    /* somebody using the mutex, block */
-    xbt_swag_insert(self, mutex->sleeping);
-    self->simdata->mutex = mutex;
-    /* wait for some process make the unlock and wake up me from mutex->sleeping */
-    xbt_context_yield();
-    self->simdata->mutex = NULL;
-
-    /* verify if the process was suspended */
-    while (self->simdata->suspended) {
-      xbt_context_yield();
-    }
-
-    mutex->using = 1;
+  XBT_IN("(%p)",simcall);
+  /* FIXME: check where to validate the arguments */
+  smx_action_t sync_act = NULL;
+  smx_process_t process = simcall->issuer;
+
+  if (mutex->locked) {
+    /* FIXME: check if the host is active ? */
+    /* Somebody using the mutex, use a synchro action to get host failures */
+    sync_act = SIMIX_synchro_wait(process->smx_host, -1);
+    xbt_fifo_push(sync_act->simcalls, simcall);
+    simcall->issuer->waiting_action = sync_act;
+    xbt_swag_insert(simcall->issuer, mutex->sleeping);   
   } else {
     /* mutex free */
-    mutex->using = 1;
+    mutex->locked = 1;
+    mutex->owner = simcall->issuer;
+    SIMIX_simcall_answer(simcall);
   }
-  return;
+  XBT_OUT();
 }
 
+int SIMIX_pre_mutex_trylock(smx_simcall_t simcall, smx_mutex_t mutex){
+  return SIMIX_mutex_trylock(mutex, simcall->issuer);
+}	
 /**
  * \brief Tries to lock a mutex.
  *
- * Tries to lock a mutex, return 1 if the mutex is free, 0 else. This function does not block the process if the mutex is used.
+ * Tries to lock a mutex, return 1 if the mutex is unlocked, else 0.
+ * This function does not block and wait for the mutex to be unlocked.
  * \param mutex The mutex
+ * \param issuer The process that tries to acquire the mutex
  * \return 1 - mutex free, 0 - mutex used
  */
-int SIMIX_mutex_trylock(smx_mutex_t mutex)
+int SIMIX_mutex_trylock(smx_mutex_t mutex, smx_process_t issuer)
 {
-  xbt_assert0((mutex != NULL), "Invalid parameters");
-
-  if (mutex->using)
+  XBT_IN("(%p, %p)",mutex,issuer);
+  if (mutex->locked){
+    XBT_OUT();
     return 0;
-  else {
-    mutex->using = 1;
-    return 1;
   }
+
+  mutex->locked = 1;
+  mutex->owner = issuer;
+  XBT_OUT();
+  return 1;
 }
 
+void SIMIX_pre_mutex_unlock(smx_simcall_t simcall, smx_mutex_t mutex){
+   SIMIX_mutex_unlock(mutex, simcall->issuer);
+}
 /**
  * \brief Unlocks a mutex.
  *
- * Unlocks the mutex and wakes up a process blocked on it. If there are no process sleeping, only sets the mutex as free.
+ * Unlocks the mutex and gives it to a process waiting for it. 
+ * If the unlocker is not the owner of the mutex nothing happens.
+ * If there are no process waiting, it sets the mutex as free.
  * \param mutex The mutex
+ * \param issuer The process trying to unlock the mutex
  */
-void SIMIX_mutex_unlock(smx_mutex_t mutex)
+void SIMIX_mutex_unlock(smx_mutex_t mutex, smx_process_t issuer)
 {
-  smx_process_t p;		/*process to wake up */
+  XBT_IN("(%p, %p)",mutex,issuer);
+  smx_process_t p;              /*process to wake up */
 
-  xbt_assert0((mutex != NULL), "Invalid parameters");
+  /* If the mutex is not owned by the issuer do nothing */
+  if (issuer != mutex->owner){
+    XBT_OUT();
+    return;
+  }
 
   if (xbt_swag_size(mutex->sleeping) > 0) {
     p = xbt_swag_extract(mutex->sleeping);
-    mutex->using = 0;
-    xbt_swag_insert(p, simix_global->process_to_run);
+    SIMIX_synchro_destroy(p->waiting_action);
+    p->waiting_action = NULL;
+    mutex->owner = p;
+    SIMIX_simcall_answer(&p->simcall);
   } else {
     /* nobody to wake up */
-    mutex->using = 0;
+    mutex->locked = 0;
+    mutex->owner = NULL;
   }
-  return;
+  XBT_OUT();
 }
 
+void SIMIX_pre_mutex_destroy(smx_simcall_t simcall, smx_mutex_t mutex){
+  SIMIX_mutex_destroy(mutex);
+}
 /**
  * \brief Destroys a mutex.
  *
@@ -117,172 +242,152 @@ void SIMIX_mutex_unlock(smx_mutex_t mutex)
  */
 void SIMIX_mutex_destroy(smx_mutex_t mutex)
 {
-  if (mutex == NULL)
-    return;
-  else {
+  XBT_IN("(%p)",mutex);
+  if (mutex){
     xbt_swag_free(mutex->sleeping);
     xbt_free(mutex);
-    return;
   }
+  XBT_OUT();
 }
 
-/******************************** Conditional *********************************/
+/********************************* Condition **********************************/
 
+smx_cond_t SIMIX_pre_cond_init(smx_simcall_t simcall){
+  return SIMIX_cond_init();
+}
 /**
  * \brief Initialize a condition.
  *
- * Allocs and creates the data for the condition. It have to be called before the utilisation of the condition.
+ * Allocates and creates the data for the condition.
+ * It have to be called before the use of the condition.
  * \return A condition
  */
-smx_cond_t SIMIX_cond_init()
+smx_cond_t SIMIX_cond_init(void)
 {
-  smx_cond_t cond = xbt_new0(s_smx_cond_t, 1);
+  XBT_IN("()");
   s_smx_process_t p;
-
+  smx_cond_t cond = xbt_new0(s_smx_cond_t, 1);
   cond->sleeping = xbt_swag_new(xbt_swag_offset(p, synchro_hookup));
-  cond->actions = xbt_fifo_new();
   cond->mutex = NULL;
+  XBT_OUT();
   return cond;
 }
 
 /**
- * \brief Signalizes a condition.
- *
- * Signalizes a condition and wakes up a sleping process. If there are no process sleeping, no action is done.
- * \param cond A condition
+ * \brief Handle a condition waiting simcall without timeouts
+ * \param simcall the simcall
  */
-void SIMIX_cond_signal(smx_cond_t cond)
+void SIMIX_pre_cond_wait(smx_simcall_t simcall, smx_cond_t cond, smx_mutex_t mutex)
 {
-  DEBUG1("Signal condition %p", cond);
-  xbt_assert0((cond != NULL), "Invalid parameters");
-  smx_process_t proc = NULL;
-
-  if (xbt_swag_size(cond->sleeping) >= 1) {
-    proc = xbt_swag_extract(cond->sleeping);
-    xbt_swag_insert(proc, simix_global->process_to_run);
-  }
+  XBT_IN("(%p)",simcall);
+  smx_process_t issuer = simcall->issuer;
 
-  return;
+  _SIMIX_cond_wait(cond, mutex, -1, issuer, simcall);
+  XBT_OUT();
 }
 
 /**
- * \brief Waits on a condition.
- *
- * Blocks a process until the signal is called. This functions frees the mutex associated and locks it after its execution.
- * \param cond A condition
- * \param mutex A mutex
+ * \brief Handle a condition waiting simcall with timeouts
+ * \param simcall the simcall
  */
-void SIMIX_cond_wait(smx_cond_t cond, smx_mutex_t mutex)
+void SIMIX_pre_cond_wait_timeout(smx_simcall_t simcall, smx_cond_t cond,
+		                 smx_mutex_t mutex, double timeout)
 {
-  smx_action_t act_sleep;
-  xbt_assert0((mutex != NULL), "Invalid parameters");
-
-  DEBUG1("Wait condition %p", cond);
-  cond->mutex = mutex;
-
-  SIMIX_mutex_unlock(mutex);
-  /* create an action null only if there are no actions already on the condition, usefull if the host crashs */
-  if (xbt_fifo_size(cond->actions) == 0) {
-    act_sleep = SIMIX_action_sleep(SIMIX_host_self(), -1);
-    SIMIX_register_action_to_condition(act_sleep, cond);
-    SIMIX_register_condition_to_action(act_sleep, cond);
-    __SIMIX_cond_wait(cond);
-    xbt_fifo_pop(act_sleep->cond_list);
-    SIMIX_action_destroy(act_sleep);
-  } else {
-    __SIMIX_cond_wait(cond);
-  }
-  /* get the mutex again */
-  SIMIX_mutex_lock(cond->mutex);
+  XBT_IN("(%p)",simcall);
+  smx_process_t issuer = simcall->issuer;
 
-  return;
+  _SIMIX_cond_wait(cond, mutex, timeout, issuer, simcall);
+  XBT_OUT();
 }
 
-xbt_fifo_t SIMIX_cond_get_actions(smx_cond_t cond)
-{
-  xbt_assert0((cond != NULL), "Invalid parameters");
-  return cond->actions;
-}
 
-void __SIMIX_cond_wait(smx_cond_t cond)
+static void _SIMIX_cond_wait(smx_cond_t cond, smx_mutex_t mutex, double timeout,
+                             smx_process_t issuer, smx_simcall_t simcall)
 {
-  smx_process_t self = SIMIX_process_self();
-  xbt_assert0((cond != NULL), "Invalid parameters");
+  XBT_IN("(%p, %p, %f, %p,%p)",cond,mutex,timeout,issuer,simcall);
+  smx_action_t sync_act = NULL;
 
-  /* process status */
+  XBT_DEBUG("Wait condition %p", cond);
 
-  self->simdata->cond = cond;
-  xbt_swag_insert(self, cond->sleeping);
-  xbt_context_yield();
-  self->simdata->cond = NULL;
-  while (self->simdata->suspended) {
-    xbt_context_yield();
+  /* If there is a mutex unlock it */
+  /* FIXME: what happens if the issuer is not the owner of the mutex? */
+  if (mutex != NULL) {
+    cond->mutex = mutex;
+    SIMIX_mutex_unlock(mutex, issuer);
   }
-  return;
 
+  sync_act = SIMIX_synchro_wait(issuer->smx_host, timeout);
+  xbt_fifo_unshift(sync_act->simcalls, simcall);
+  issuer->waiting_action = sync_act;
+  xbt_swag_insert(simcall->issuer, cond->sleeping);   
+  XBT_OUT();
 }
 
+void SIMIX_pre_cond_signal(smx_simcall_t simcall, smx_cond_t cond){
+  SIMIX_cond_signal(cond);
+}
 /**
- * \brief Waits on a condition with timeout.
+ * \brief Signalizes a condition.
  *
- * Same behavior of #SIMIX_cond_wait, but waits a maximum time and throws an timeout_error if it happens.
+ * Signalizes a condition and wakes up a sleeping process. 
+ * If there are no process sleeping, no action is done.
  * \param cond A condition
- * \param mutex A mutex
- * \param max_duration Timeout time
  */
-void SIMIX_cond_wait_timeout(smx_cond_t cond, smx_mutex_t mutex,
-			     double max_duration)
+void SIMIX_cond_signal(smx_cond_t cond)
 {
-  xbt_assert0((mutex != NULL), "Invalid parameters");
-  smx_action_t act_sleep;
+  XBT_IN("(%p)",cond);
+  smx_process_t proc = NULL;
+  smx_mutex_t mutex = NULL;
+  smx_simcall_t simcall = NULL;
 
-  DEBUG1("Timed wait condition %p", cond);
-  cond->mutex = mutex;
+  XBT_DEBUG("Signal condition %p", cond);
 
-  SIMIX_mutex_unlock(mutex);
-  if (max_duration >= 0) {
-    act_sleep = SIMIX_action_sleep(SIMIX_host_self(), max_duration);
-    SIMIX_register_action_to_condition(act_sleep, cond);
-    SIMIX_register_condition_to_action(act_sleep, cond);
-    __SIMIX_cond_wait(cond);
-    xbt_fifo_remove(act_sleep->cond_list, cond);
-    if (SIMIX_action_get_state(act_sleep) == SURF_ACTION_DONE) {
-      SIMIX_action_destroy(act_sleep);
-      THROW0(timeout_error, 0, "Condition timeout");
-    } else {
-      SIMIX_action_destroy(act_sleep);
-    }
+  /* If there are processes waiting for the condition choose one and try 
+     to make it acquire the mutex */
+  if ((proc = xbt_swag_extract(cond->sleeping))) {
 
-  } else
-    __SIMIX_cond_wait(cond);
+    /* Destroy waiter's synchro action */
+    SIMIX_synchro_destroy(proc->waiting_action);
+    proc->waiting_action = NULL;
 
-  /* get the mutex again */
-  SIMIX_mutex_lock(cond->mutex);
+    /* Now transform the cond wait simcall into a mutex lock one */
+    simcall = &proc->simcall;
+    if(simcall->call == SIMCALL_COND_WAIT)
+      mutex = simcall_cond_wait__get__mutex(simcall);
+    else
+      mutex = simcall_cond_wait_timeout__get__mutex(simcall);
+    simcall->call = SIMCALL_MUTEX_LOCK;
 
-  return;
+    SIMIX_pre_mutex_lock(simcall, mutex);
+  }
+  XBT_OUT();
 }
 
+void SIMIX_pre_cond_broadcast(smx_simcall_t simcall, smx_cond_t cond){
+  SIMIX_cond_broadcast(cond);
+}
 /**
  * \brief Broadcasts a condition.
  *
- * Signalizes a condition and wakes up ALL sleping process. If there are no process sleeping, no action is done.
+ * Signal ALL processes waiting on a condition.
+ * If there are no process waiting, no action is done.
  * \param cond A condition
  */
 void SIMIX_cond_broadcast(smx_cond_t cond)
 {
-  xbt_assert0((cond != NULL), "Invalid parameters");
-  smx_process_t proc = NULL;
-  smx_process_t proc_next = NULL;
+  XBT_IN("(%p)",cond);
+  XBT_DEBUG("Broadcast condition %p", cond);
 
-  DEBUG1("Broadcast condition %p", cond);
-  xbt_swag_foreach_safe(proc, proc_next, cond->sleeping) {
-    xbt_swag_remove(proc, cond->sleeping);
-    xbt_swag_insert(proc, simix_global->process_to_run);
+  /* Signal the condition until nobody is waiting on it */
+  while (xbt_swag_size(cond->sleeping)) {
+    SIMIX_cond_signal(cond);
   }
-
-  return;
+  XBT_OUT();
 }
 
+void SIMIX_pre_cond_destroy(smx_simcall_t simcall, smx_cond_t cond){
+  SIMIX_cond_destroy(cond);
+}
 /**
  * \brief Destroys a contidion.
  *
@@ -291,54 +396,134 @@ void SIMIX_cond_broadcast(smx_cond_t cond)
  */
 void SIMIX_cond_destroy(smx_cond_t cond)
 {
-  DEBUG1("Destroy condition %p", cond);
-  if (cond == NULL)
-    return;
-  else {
-    xbt_fifo_item_t item = NULL;
-    smx_action_t action = NULL;
+  XBT_IN("(%p)",cond);
+  XBT_DEBUG("Destroy condition %p", cond);
 
-    xbt_assert0(xbt_swag_size(cond->sleeping) == 0,
-		"Cannot destroy conditional since someone is still using it");
-    xbt_swag_free(cond->sleeping);
+  if (cond != NULL) {
+    xbt_assert(xbt_swag_size(cond->sleeping) == 0,
+                "Cannot destroy conditional since someone is still using it");
 
-    xbt_fifo_foreach(cond->actions, item, action, smx_action_t) {
-      SIMIX_unregister_condition_to_action(action, cond);
-    }
-    xbt_fifo_free(cond->actions);
+    xbt_swag_free(cond->sleeping);
     xbt_free(cond);
-    return;
   }
+  XBT_OUT();
 }
 
-/**
- * 	\brief Set a condition to an action
+/******************************** Semaphores **********************************/
+#define SMX_SEM_NOLIMIT 99999
+smx_sem_t SIMIX_pre_sem_init(smx_simcall_t simcall, unsigned int value){
+  return SIMIX_sem_init(value);
+}
+/** @brief Initialize a semaphore */
+smx_sem_t SIMIX_sem_init(unsigned int value)
+{
+  XBT_IN("(%u)",value);
+  s_smx_process_t p;
+
+  smx_sem_t sem = xbt_new0(s_smx_sem_t, 1);
+  sem->sleeping = xbt_swag_new(xbt_swag_offset(p, synchro_hookup));
+  sem->value = value;
+  XBT_OUT();
+  return sem;
+}
+
+void SIMIX_pre_sem_destroy(smx_simcall_t simcall, smx_sem_t sem){
+  SIMIX_sem_destroy(sem);
+}
+/** @brief Destroys a semaphore */
+void SIMIX_sem_destroy(smx_sem_t sem)
+{
+  XBT_IN("(%p)",sem);
+  XBT_DEBUG("Destroy semaphore %p", sem);
+  if (sem != NULL) {
+    xbt_assert(xbt_swag_size(sem->sleeping) == 0,
+                "Cannot destroy semaphore since someone is still using it");
+    xbt_swag_free(sem->sleeping);
+    xbt_free(sem);
+  }
+  XBT_OUT();
+}
+
+void SIMIX_pre_sem_release(smx_simcall_t simcall, smx_sem_t sem){
+  SIMIX_sem_release(sem);
+}
+/** @brief release the semaphore
  *
- * 	Creates the "link" between an action and a condition. You have to call this function when you create an action and want to wait its ending. 
- *	\param action SIMIX action
- *	\param cond SIMIX cond
+ * Unlock a process waiting on the semaphore.
+ * If no one was blocked, the semaphore capacity is increased by 1.
  */
-void SIMIX_register_condition_to_action(smx_action_t action,
-					smx_cond_t cond)
+void SIMIX_sem_release(smx_sem_t sem)
+{
+  XBT_IN("(%p)",sem);
+  smx_process_t proc;
+
+  XBT_DEBUG("Sem release semaphore %p", sem);
+  if ((proc = xbt_swag_extract(sem->sleeping))) {
+    SIMIX_synchro_destroy(proc->waiting_action);
+    proc->waiting_action = NULL;
+    SIMIX_simcall_answer(&proc->simcall);
+  } else if (sem->value < SMX_SEM_NOLIMIT) {
+    sem->value++;
+  }
+  XBT_OUT();
+}
+
+/** @brief Returns true if acquiring this semaphore would block */
+int SIMIX_sem_would_block(smx_sem_t sem)
+{
+  XBT_IN("(%p)",sem);
+  XBT_OUT();
+  return (sem->value <= 0);
+}
+
+int SIMIX_pre_sem_get_capacity(smx_simcall_t simcall, smx_sem_t sem){
+  return SIMIX_sem_get_capacity(sem);
+}
+/** @brief Returns the current capacity of the semaphore */
+int SIMIX_sem_get_capacity(smx_sem_t sem)
 {
-  xbt_assert0((action != NULL) && (cond != NULL), "Invalid parameters");
+  XBT_IN("(%p)",sem);
+  XBT_OUT();
+  return sem->value;
+}
 
-  DEBUG2("Register condition %p to action %p", cond, action);
-  xbt_fifo_push(action->cond_list, cond);
+static void _SIMIX_sem_wait(smx_sem_t sem, double timeout, smx_process_t issuer,
+                            smx_simcall_t simcall)
+{
+  XBT_IN("(%p, %f, %p, %p)",sem,timeout,issuer,simcall);
+  smx_action_t sync_act = NULL;
+
+  XBT_DEBUG("Wait semaphore %p (timeout:%f)", sem, timeout);
+  if (sem->value <= 0) {
+    sync_act = SIMIX_synchro_wait(issuer->smx_host, timeout);
+    xbt_fifo_unshift(sync_act->simcalls, simcall);
+    issuer->waiting_action = sync_act;
+    xbt_swag_insert(issuer, sem->sleeping);
+  } else {
+    sem->value--;
+    SIMIX_simcall_answer(simcall);
+  }
+  XBT_OUT();
 }
 
 /**
- * 	\brief Unset a condition to an action
- *
- * 	Destroys the "link" between an action and a condition. 
- *	\param action SIMIX action
- *	\param cond SIMIX cond
+ * \brief Handles a sem acquire simcall without timeout.
+ * \param simcall the simcall
  */
-void SIMIX_unregister_condition_to_action(smx_action_t action,
-					  smx_cond_t cond)
+void SIMIX_pre_sem_acquire(smx_simcall_t simcall, smx_sem_t sem)
 {
-  xbt_assert0((action != NULL) && (cond != NULL), "Invalid parameters");
+  XBT_IN("(%p)",simcall);
+  _SIMIX_sem_wait(sem, -1, simcall->issuer, simcall);
+  XBT_OUT();
+}
 
-  while (xbt_fifo_remove(action->cond_list, cond)) {
-  }
+/**
+ * \brief Handles a sem acquire simcall with timeout.
+ * \param simcall the simcall
+ */
+void SIMIX_pre_sem_acquire_timeout(smx_simcall_t simcall, smx_sem_t sem, double timeout)
+{
+  XBT_IN("(%p)",simcall);
+  _SIMIX_sem_wait(sem, timeout, simcall->issuer, simcall);  
+  XBT_OUT();
 }