X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/2807fde4fd1f59c230d69a934634c5dfb77905f2..dbc1a4923f295149f7b119e1650c69e768aaa5ee:/src/simdag/sd_task.cpp

diff --git a/src/simdag/sd_task.cpp b/src/simdag/sd_task.cpp
index 42b7142230..cc7d15ca63 100644
--- a/src/simdag/sd_task.cpp
+++ b/src/simdag/sd_task.cpp
@@ -1,345 +1,702 @@
-/* Copyright (c) 2006-2017. The SimGrid Team.
+/* Copyright (c) 2006-2021. 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 "simdag_private.hpp"
+#include "simgrid/kernel/routing/NetPoint.hpp"
 #include "src/surf/HostImpl.hpp"
 #include "src/surf/surf_interface.hpp"
 #include <algorithm>
 
 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(sd_task, sd, "Logging specific to SimDag (task)");
 
-/* Destroys the data memorized by SD_task_schedule. Task state must be SD_SCHEDULED or SD_RUNNABLE. */
-static void __SD_task_destroy_scheduling_data(SD_task_t task)
+namespace simgrid {
+
+template class xbt::Extendable<sd::Task>;
+
+namespace sd {
+
+Task* Task::create(const std::string& name, double amount, void* userdata)
 {
-  if (task->state != SD_SCHEDULED && task->state != SD_RUNNABLE)
-    THROWF(arg_error, 0, "Task '%s' must be SD_SCHEDULED or SD_RUNNABLE", SD_task_get_name(task));
+  auto task = new Task();
+  task->set_name(name);
+  task->set_amount(amount);
+  task->set_data(userdata);
+  task->allocation_ = new std::vector<sg_host_t>();
+  sd_global->initial_tasks.insert(task);
 
-  xbt_free(task->flops_amount);
-  xbt_free(task->bytes_amount);
-  task->bytes_amount = nullptr;
-  task->flops_amount = nullptr;
+  return task;
 }
 
-/**
- * \brief Creates a new task.
- *
- * \param name the name of the task (can be \c nullptr)
- * \param data the user data you want to associate with the task (can be \c nullptr)
- * \param amount amount of the task
- * \return the new task
- * \see SD_task_destroy()
- */
-SD_task_t SD_task_create(const char *name, void *data, double amount)
-{
-  SD_task_t task = xbt_new0(s_SD_task_t, 1);
-  task->kind = SD_TASK_NOT_TYPED;
-  task->state= SD_NOT_SCHEDULED;
-  sd_global->initial_tasks->insert(task);
-
-  task->marked = 0;
-  task->start_time = -1.0;
-  task->finish_time = -1.0;
-  task->surf_action = nullptr;
-  task->watch_points = 0;
-
-  task->inputs = new std::set<SD_task_t>();
-  task->outputs = new std::set<SD_task_t>();
-  task->predecessors = new std::set<SD_task_t>();
-  task->successors = new std::set<SD_task_t>();
-
-  task->data = data;
-  task->name = xbt_strdup(name);
-  task->amount = amount;
-  task->allocation = new std::vector<sg_host_t>();
-  task->rate = -1;
+Task* Task::create_comm_e2e(const std::string& name, double amount, void* userdata)
+{
+  auto task              = create(name, amount, userdata);
+  task->bytes_amount_    = xbt_new0(double, 4);
+  task->bytes_amount_[2] = amount;
+  task->set_kind(SD_TASK_COMM_E2E);
+
   return task;
 }
 
-static inline SD_task_t SD_task_create_sized(const char *name, void *data, double amount, int count)
+Task* Task::create_comp_seq(const std::string& name, double amount, void* userdata)
 {
-  SD_task_t task = SD_task_create(name, data, amount);
-  task->bytes_amount = xbt_new0(double, count * count);
-  task->flops_amount = xbt_new0(double, count);
+  auto task              = create(name, amount, userdata);
+  task->flops_amount_    = xbt_new0(double, 1);
+  task->flops_amount_[0] = amount;
+  task->set_kind(SD_TASK_COMP_SEQ);
+
   return task;
 }
 
-/** @brief create a end-to-end communication task that can then be auto-scheduled
+Task* Task::create_comp_par_amdahl(const std::string& name, double amount, void* userdata, double alpha)
+{
+  xbt_assert(alpha < 1. && alpha >= 0., "Invalid parameter: alpha must be in [0.;1.[");
+
+  auto task = create(name, amount, userdata);
+  task->set_alpha(alpha);
+  task->set_kind(SD_TASK_COMP_PAR_AMDAHL);
+
+  return task;
+}
+
+Task* Task::create_comm_par_mxn_1d_block(const std::string& name, double amount, void* userdata)
+{
+  auto task = create(name, amount, userdata);
+  task->set_kind(SD_TASK_COMM_PAR_MXN_1D_BLOCK);
+
+  return task;
+}
+
+void Task::distribute_comp_amdahl(int count)
+{
+  xbt_assert(kind_ == SD_TASK_COMP_PAR_AMDAHL,
+             "Task %s is not a SD_TASK_COMP_PAR_AMDAHL typed task."
+             "Cannot use this function.",
+             get_cname());
+  flops_amount_ = xbt_new0(double, count);
+  for (int i = 0; i < count; i++)
+    flops_amount_[i] = (alpha_ + (1 - alpha_) / count) * amount_;
+}
+
+void Task::build_MxN_1D_block_matrix(int src_nb, int dst_nb)
+{
+  xbt_assert(kind_ == SD_TASK_COMM_PAR_MXN_1D_BLOCK,
+             "Task %s is not a SD_TASK_COMM_PAR_MXN_1D_BLOCK typed task."
+             "Cannot use this function.",
+             get_cname());
+  xbt_free(bytes_amount_);
+  bytes_amount_ = xbt_new0(double, allocation_->size() * allocation_->size());
+
+  for (int i = 0; i < src_nb; i++) {
+    double src_start = i * amount_ / src_nb;
+    double src_end   = src_start + amount_ / src_nb;
+    for (int j = 0; j < dst_nb; j++) {
+      double dst_start = j * amount_ / dst_nb;
+      double dst_end   = dst_start + amount_ / dst_nb;
+      XBT_VERB("(%d->%d): (%.2f, %.2f)-> (%.2f, %.2f)", i, j, src_start, src_end, dst_start, dst_end);
+      bytes_amount_[i * (src_nb + dst_nb) + src_nb + j] = 0.0;
+      if ((src_end > dst_start) && (dst_end > src_start)) { /* There is something to send */
+        bytes_amount_[i * (src_nb + dst_nb) + src_nb + j] = std::min(src_end, dst_end) - std::max(src_start, dst_start);
+        XBT_VERB("==> %.2f", bytes_amount_[i * (src_nb + dst_nb) + src_nb + j]);
+      }
+    }
+  }
+}
+
+bool Task::is_parent_of(Task* task) const
+{
+  return (successors_.find(task) != successors_.end() || outputs_.find(task) != outputs_.end());
+}
+
+bool Task::is_child_of(Task* task) const
+{
+  return (inputs_.find(task) != inputs_.end() || predecessors_.find(task) != predecessors_.end());
+}
+
+void Task::set_amount(double amount)
+{
+  amount_ = amount;
+  if (kind_ == SD_TASK_COMP_SEQ)
+    flops_amount_[0] = amount;
+  if (kind_ == SD_TASK_COMM_E2E) {
+    bytes_amount_[2] = amount;
+  }
+}
+
+void Task::set_rate(double rate)
+{
+  xbt_assert(kind_ == SD_TASK_COMM_E2E, "The rate can be modified for end-to-end communications only.");
+  if (state_ < SD_RUNNING) {
+    rate_ = rate;
+  } else {
+    XBT_WARN("Task %p has started. Changing rate is ineffective.", this);
+  }
+}
+void Task::set_state(e_SD_task_state_t new_state)
+{
+  std::set<Task*>::iterator idx;
+  XBT_DEBUG("Set state of '%s' to %d", get_cname(), new_state);
+  if ((new_state == SD_NOT_SCHEDULED || new_state == SD_SCHEDULABLE) && state_ == SD_FAILED) {
+    sd_global->completed_tasks.erase(this);
+    sd_global->initial_tasks.insert(this);
+  }
+
+  if (new_state == SD_SCHEDULED && state_ == SD_RUNNABLE) {
+    sd_global->initial_tasks.insert(this);
+    sd_global->runnable_tasks.erase(this);
+  }
+
+  if (new_state == SD_RUNNABLE) {
+    idx = sd_global->initial_tasks.find(this);
+    if (idx != sd_global->initial_tasks.end()) {
+      sd_global->runnable_tasks.insert(*idx);
+      sd_global->initial_tasks.erase(idx);
+    }
+  }
+
+  if (new_state == SD_RUNNING)
+    sd_global->runnable_tasks.erase(this);
+
+  if (new_state == SD_DONE || new_state == SD_FAILED) {
+    sd_global->completed_tasks.insert(this);
+    start_time_ = surf_action_->get_start_time();
+    if (new_state == SD_DONE) {
+      finish_time_ = surf_action_->get_finish_time();
+#if SIMGRID_HAVE_JEDULE
+      jedule_log_sd_event(this);
+#endif
+    } else
+      finish_time_ = simgrid_get_clock();
+    surf_action_->unref();
+    surf_action_ = nullptr;
+    allocation_->clear();
+  }
+
+  state_ = new_state;
+
+  if (watch_points_ & new_state) {
+    XBT_VERB("Watch point reached with task '%s'!", get_cname());
+    sd_global->watch_point_reached = true;
+    unwatch(new_state); /* remove the watch point */
+  }
+}
+
+double Task::get_alpha() const
+{
+  xbt_assert(kind_ == SD_TASK_COMP_PAR_AMDAHL, "Alpha parameter is not defined for this kind of task");
+  return alpha_;
+}
+
+double Task::get_remaining_amount() const
+{
+  if (surf_action_)
+    return surf_action_->get_remains();
+  else
+    return (state_ == SD_DONE) ? 0 : amount_;
+}
+
+double Task::get_start_time() const
+{
+  if (surf_action_)
+    return surf_action_->get_start_time();
+  else
+    return start_time_;
+}
+
+double Task::get_finish_time() const
+{
+  if (surf_action_) /* should never happen as actions are destroyed right after their completion */
+    return surf_action_->get_finish_time();
+  else
+    return finish_time_;
+}
+
+void Task::set_sender_side_allocation(unsigned long count, const std::vector<s4u::Host*>* sender)
+{
+  for (unsigned long i = 0; i < count; i++)
+    allocation_->push_back(sender->at(i));
+}
+
+void Task::set_receiver_side_allocation(unsigned long count, const std::vector<s4u::Host*>* receiver)
+{
+  for (unsigned long i = 0; i < count; i++)
+    allocation_->insert(allocation_->begin() + i, receiver->at(i));
+}
+
+void Task::watch(e_SD_task_state_t state)
+{
+  if (state & SD_NOT_SCHEDULED)
+    throw std::invalid_argument("Cannot add a watch point for state SD_NOT_SCHEDULED");
+
+  watch_points_ = watch_points_ | state;
+}
+
+void Task::unwatch(e_SD_task_state_t state)
+{
+  xbt_assert(state != SD_NOT_SCHEDULED, "SimDag error: Cannot have a watch point for state SD_NOT_SCHEDULED");
+  watch_points_ = watch_points_ & ~state;
+}
+
+void Task::dump() const
+{
+  XBT_INFO("Displaying task %s", get_cname());
+  if (state_ == SD_RUNNABLE)
+    XBT_INFO("  - state: runnable");
+  else if (state_ < SD_RUNNABLE)
+    XBT_INFO("  - state: %s not runnable", __get_state_name(state_));
+  else
+    XBT_INFO("  - state: not runnable %s", __get_state_name(state_));
+
+  if (kind_ != 0) {
+    switch (kind_) {
+      case SD_TASK_COMM_E2E:
+        XBT_INFO("  - kind: end-to-end communication");
+        break;
+      case SD_TASK_COMP_SEQ:
+        XBT_INFO("  - kind: sequential computation");
+        break;
+      case SD_TASK_COMP_PAR_AMDAHL:
+        XBT_INFO("  - kind: parallel computation following Amdahl's law");
+        break;
+      case SD_TASK_COMM_PAR_MXN_1D_BLOCK:
+        XBT_INFO("  - kind: MxN data redistribution assuming 1D block distribution");
+        break;
+      default:
+        XBT_INFO("  - (unknown kind %d)", kind_);
+    }
+  }
+
+  XBT_INFO("  - amount: %.0f", amount_);
+  if (kind_ == SD_TASK_COMP_PAR_AMDAHL)
+    XBT_INFO("  - alpha: %.2f", alpha_);
+  XBT_INFO("  - Dependencies to satisfy: %lu", has_unsolved_dependencies());
+  if (has_unsolved_dependencies() > 0) {
+    XBT_INFO("  - pre-dependencies:");
+    for (auto const& it : predecessors_)
+      XBT_INFO("    %s", it->get_cname());
+
+    for (auto const& it : inputs_)
+      XBT_INFO("    %s", it->get_cname());
+  }
+  if (is_waited_by() > 0) {
+    XBT_INFO("  - post-dependencies:");
+
+    for (auto const& it : successors_)
+      XBT_INFO("    %s", it->get_cname());
+    for (auto const& it : outputs_)
+      XBT_INFO("    %s", it->get_cname());
+  }
+}
+
+void Task::released_by(Task* pred)
+{
+  predecessors_.erase(pred);
+  inputs_.erase(pred);
+  XBT_DEBUG("Release dependency on %s: %lu remain(s). Becomes schedulable if %zu=0", get_cname(),
+            has_unsolved_dependencies(), predecessors_.size());
+
+  if (state_ == SD_NOT_SCHEDULED && predecessors_.empty())
+    set_state(SD_SCHEDULABLE);
+
+  if (state_ == SD_SCHEDULED && has_unsolved_dependencies() == 0)
+    set_state(SD_RUNNABLE);
+
+  if (state_ == SD_RUNNABLE && not sd_global->watch_point_reached)
+    run();
+}
+
+void Task::produced_by(Task* pred)
+{
+  start_time_ = pred->get_finish_time();
+  predecessors_.erase(pred);
+  if (state_ == SD_SCHEDULED)
+    set_state(SD_RUNNABLE);
+  else
+    set_state(SD_SCHEDULABLE);
+
+  Task* comm_dst = *(successors_.begin());
+  if (comm_dst->get_state() == SD_NOT_SCHEDULED && comm_dst->get_predecessors().empty()) {
+    XBT_DEBUG("%s is a transfer, %s may be ready now if %zu=0", get_cname(), comm_dst->get_cname(),
+              comm_dst->get_predecessors().size());
+    comm_dst->set_state(SD_SCHEDULABLE);
+  }
+  if (state_ == SD_RUNNABLE && not sd_global->watch_point_reached)
+    run();
+}
+
+void Task::do_schedule()
+{
+  if (state_ > SD_SCHEDULABLE)
+    throw std::invalid_argument(simgrid::xbt::string_printf("Task '%s' has already been scheduled", get_cname()));
+
+  if (has_unsolved_dependencies() == 0)
+    set_state(SD_RUNNABLE);
+  else
+    set_state(SD_SCHEDULED);
+}
+
+void Task::schedule(const std::vector<s4u::Host*>& hosts, const double* flops_amount, const double* bytes_amount,
+                    double rate)
+{
+  unsigned long host_count = hosts.size();
+  rate_                    = rate;
+
+  if (flops_amount) {
+    flops_amount_ = static_cast<double*>(xbt_realloc(flops_amount_, sizeof(double) * host_count));
+    memcpy(flops_amount_, flops_amount, sizeof(double) * host_count);
+  } else {
+    xbt_free(flops_amount_);
+    flops_amount_ = nullptr;
+  }
+
+  unsigned long communication_nb = host_count * host_count;
+  if (bytes_amount) {
+    bytes_amount_ = static_cast<double*>(xbt_realloc(bytes_amount_, sizeof(double) * communication_nb));
+    memcpy(bytes_amount_, bytes_amount, sizeof(double) * communication_nb);
+  } else {
+    xbt_free(bytes_amount_);
+    bytes_amount_ = nullptr;
+  }
+
+  for (unsigned long i = 0; i < host_count; i++)
+    allocation_->push_back(hosts[i]);
+
+  do_schedule();
+}
+
+void Task::schedulev(const std::vector<s4u::Host*>& hosts)
+{
+  xbt_assert(kind_ == SD_TASK_COMP_SEQ || kind_ == SD_TASK_COMP_PAR_AMDAHL,
+             "Task %s is not typed. Cannot automatically schedule it.", get_cname());
+
+  for (unsigned long i = 0; i < hosts.size(); i++)
+    allocation_->push_back(hosts[i]);
+
+  XBT_VERB("Schedule computation task %s on %zu host(s)", get_cname(), allocation_->size());
+
+  if (kind_ == SD_TASK_COMP_SEQ) {
+    if (not flops_amount_) { /*This task has failed and is rescheduled. Reset the flops_amount*/
+      flops_amount_    = xbt_new0(double, 1);
+      flops_amount_[0] = amount_;
+    }
+    XBT_VERB("It costs %.f flops", flops_amount_[0]);
+  }
+
+  if (kind_ == SD_TASK_COMP_PAR_AMDAHL) {
+    distribute_comp_amdahl(hosts.size());
+    XBT_VERB("%.f flops will be distributed following Amdahl's Law", flops_amount_[0]);
+  }
+
+  do_schedule();
+
+  /* Iterate over all inputs and outputs to say where I am located (and start them if runnable) */
+  for (auto const& input : inputs_) {
+    unsigned long src_nb = input->get_allocation_size();
+    unsigned long dst_nb = hosts.size();
+    if (src_nb == 0)
+      XBT_VERB("Sender side of '%s' not scheduled. Set receiver side to '%s''s allocation", input->get_cname(),
+               get_cname());
+    input->set_sender_side_allocation(dst_nb, allocation_);
+
+    if (input->get_allocation_size() > allocation_->size()) {
+      if (kind_ == SD_TASK_COMP_PAR_AMDAHL)
+        input->build_MxN_1D_block_matrix(src_nb, dst_nb);
+
+      input->do_schedule();
+      XBT_VERB("Auto-Schedule Communication task '%s'. Send %.f bytes from %lu hosts to %lu hosts.", input->get_cname(),
+               input->get_amount(), src_nb, dst_nb);
+    }
+  }
+
+  for (auto const& output : outputs_) {
+    unsigned long src_nb = hosts.size();
+    unsigned long dst_nb = output->get_allocation_size();
+    if (dst_nb == 0)
+      XBT_VERB("Receiver side of '%s' not scheduled. Set sender side to '%s''s allocation", output->get_cname(),
+               get_cname());
+    output->set_receiver_side_allocation(src_nb, allocation_);
+
+    if (output->get_allocation_size() > allocation_->size()) {
+      if (kind_ == SD_TASK_COMP_PAR_AMDAHL)
+        output->build_MxN_1D_block_matrix(src_nb, dst_nb);
+
+      output->do_schedule();
+      XBT_VERB("Auto-Schedule Communication task %s. Send %.f bytes from %lu hosts to %lu hosts.", output->get_cname(),
+               output->get_amount(), src_nb, dst_nb);
+    }
+  }
+}
+
+void Task::unschedule()
+{
+  if (state_ == SD_NOT_SCHEDULED || state_ == SD_SCHEDULABLE)
+    throw std::invalid_argument(xbt::string_printf(
+        "Task %s: the state must be SD_SCHEDULED, SD_RUNNABLE, SD_RUNNING or SD_FAILED", get_cname()));
+
+  if (state_ == SD_SCHEDULED || state_ == SD_RUNNABLE) /* if the task is scheduled or runnable */ {
+    allocation_->clear();
+    if (kind_ == SD_TASK_COMP_PAR_AMDAHL || kind_ == SD_TASK_COMM_PAR_MXN_1D_BLOCK) {
+      /* Don't free scheduling data for typed tasks */
+      xbt_free(flops_amount_);
+      xbt_free(bytes_amount_);
+      bytes_amount_ = nullptr;
+      flops_amount_ = nullptr;
+    }
+  }
+
+  if (state_ == SD_RUNNING)
+    /* the task should become SD_FAILED */
+    surf_action_->cancel();
+  else {
+    if (has_unsolved_dependencies() == 0)
+      set_state(SD_SCHEDULABLE);
+    else
+      set_state(SD_NOT_SCHEDULED);
+  }
+  start_time_ = -1.0;
+}
+
+void Task::run()
+{
+  xbt_assert(state_ == SD_RUNNABLE, "Task '%s' is not runnable! Task state: %d", get_cname(), (int)state_);
+  xbt_assert(not allocation_->empty(), "Task '%s': host_list is empty!", get_cname());
+
+  XBT_VERB("Executing task '%s'", get_cname());
+
+  /* Beware! The scheduling data are now used by the surf action directly! no copy was done */
+  auto host_model = allocation_->front()->get_netpoint()->get_englobing_zone()->get_host_model();
+  surf_action_    = host_model->execute_parallel(*allocation_, flops_amount_, bytes_amount_, rate_);
+
+  surf_action_->set_data(this);
+
+  XBT_DEBUG("surf_action = %p", surf_action_);
+
+  set_state(SD_RUNNING);
+  sd_global->return_set.insert(this);
+}
+
+void Task::destroy()
+{
+  XBT_DEBUG("Destroying task %s...", get_cname());
+
+  /* First Remove all dependencies associated with the task. */
+  while (not predecessors_.empty())
+    SD_task_dependency_remove(*(predecessors_.begin()), this);
+  while (not inputs_.empty())
+    SD_task_dependency_remove(*(inputs_.begin()), this);
+  while (not successors_.empty())
+    SD_task_dependency_remove(this, *(successors_.begin()));
+  while (not outputs_.empty())
+    SD_task_dependency_remove(this, *(outputs_.begin()));
+
+  if (state_ == SD_SCHEDULED || state_ == SD_RUNNABLE) {
+    xbt_free(flops_amount_);
+    xbt_free(bytes_amount_);
+    bytes_amount_ = nullptr;
+    flops_amount_ = nullptr;
+  }
+
+  xbt_free(flops_amount_);
+  xbt_free(bytes_amount_);
+
+  delete allocation_;
+
+  if (surf_action_ != nullptr)
+    surf_action_->unref();
+
+  XBT_DEBUG("Task destroyed.");
+}
+} // namespace sd
+} // namespace simgrid
+
+/* **************************** Public C interface *************************** */
+
+/**
+ * @brief Creates a new task.
+ *
+ * @param name the name of the task (can be @c nullptr)
+ * @param data the user data you want to associate with the task (can be @c nullptr)
+ * @param amount amount of the task
+ * @return the new task
+ * @see SD_task_destroy()
+ */
+SD_task_t SD_task_create(const char* name, void* data, double amount)
+{
+  return simgrid::sd::Task::create(name, amount, data);
+}
+
+/** @brief create an end-to-end communication task that can then be auto-scheduled
  *
- * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This allows to specify the task costs at
+ * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This allows one to specify the task costs at
  * creation, and decouple them from the scheduling process where you just specify which resource should deliver the
  * mandatory power.
  *
  * A end-to-end communication must be scheduled on 2 hosts, and the amount specified at creation is sent from hosts[0]
  * to hosts[1].
  */
-SD_task_t SD_task_create_comm_e2e(const char *name, void *data, double amount)
+SD_task_t SD_task_create_comm_e2e(const char* name, void* data, double amount)
 {
-  SD_task_t res = SD_task_create_sized(name, data, amount, 2);
-  res->bytes_amount[2] = amount;
-  res->kind = SD_TASK_COMM_E2E;
-
-  return res;
+  return simgrid::sd::Task::create_comm_e2e(name, amount, data);
 }
 
 /** @brief create a sequential computation task that can then be auto-scheduled
  *
- * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This allows to specify the task costs at
+ * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This allows one to specify the task costs at
  * creation, and decouple them from the scheduling process where you just specify which resource should deliver the
  * mandatory power.
  *
  * A sequential computation must be scheduled on 1 host, and the amount specified at creation to be run on hosts[0].
  *
- * \param name the name of the task (can be \c nullptr)
- * \param data the user data you want to associate with the task (can be \c nullptr)
- * \param flops_amount amount of compute work to be done by the task
- * \return the new SD_TASK_COMP_SEQ typed task
+ * @param name the name of the task (can be @c nullptr)
+ * @param data the user data you want to associate with the task (can be @c nullptr)
+ * @param flops_amount amount of compute work to be done by the task
+ * @return the new SD_TASK_COMP_SEQ typed task
  */
-SD_task_t SD_task_create_comp_seq(const char *name, void *data, double flops_amount)
+SD_task_t SD_task_create_comp_seq(const char* name, void* data, double flops_amount)
 {
-  SD_task_t res = SD_task_create_sized(name, data, flops_amount, 1);
-  res->flops_amount[0] = flops_amount;
-  res->kind = SD_TASK_COMP_SEQ;
-
-  return res;
+  return simgrid::sd::Task::create_comp_seq(name, flops_amount, data);
 }
 
 /** @brief create a parallel computation task that can then be auto-scheduled
  *
- * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This allows to specify the task costs at
+ * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This allows one to specify the task costs at
  * creation, and decouple them from the scheduling process where you just specify which resource should deliver the
  * mandatory power.
  *
  * A parallel computation can be scheduled on any number of host.
  * The underlying speedup model is Amdahl's law.
- * To be auto-scheduled, \see SD_task_distribute_comp_amdahl has to be called first.
- * \param name the name of the task (can be \c nullptr)
- * \param data the user data you want to associate with the task (can be \c nullptr)
- * \param flops_amount amount of compute work to be done by the task
- * \param alpha purely serial fraction of the work to be done (in [0.;1.[)
- * \return the new task
+ * To be auto-scheduled, @see SD_task_distribute_comp_amdahl has to be called first.
+ * @param name the name of the task (can be @c nullptr)
+ * @param data the user data you want to associate with the task (can be @c nullptr)
+ * @param flops_amount amount of compute work to be done by the task
+ * @param alpha purely serial fraction of the work to be done (in [0.;1.[)
+ * @return the new task
  */
-SD_task_t SD_task_create_comp_par_amdahl(const char *name, void *data, double flops_amount, double alpha)
+SD_task_t SD_task_create_comp_par_amdahl(const char* name, void* data, double flops_amount, double alpha)
 {
-  xbt_assert(alpha < 1. && alpha >= 0., "Invalid parameter: alpha must be in [0.;1.[");
-
-  SD_task_t res = SD_task_create(name, data, flops_amount);
-  res->alpha = alpha;
-  res->kind = SD_TASK_COMP_PAR_AMDAHL;
-
-  return res;
+  return simgrid::sd::Task::create_comp_par_amdahl(name, flops_amount, data, alpha);
 }
 
 /** @brief create a complex data redistribution task that can then be  auto-scheduled
  *
  * Auto-scheduling mean that the task can be used with SD_task_schedulev().
- * This allows to specify the task costs at creation, and decouple them from the scheduling process where you just
+ * This allows one to specify the task costs at creation, and decouple them from the scheduling process where you just
  * specify which resource should communicate.
  *
  * A data redistribution can be scheduled on any number of host.
- * The assumed distribution is a 1D block distribution. Each host owns the same share of the \see amount.
- * To be auto-scheduled, \see SD_task_distribute_comm_mxn_1d_block has to be  called first.
- * \param name the name of the task (can be \c nullptr)
- * \param data the user data you want to associate with the task (can be \c nullptr)
- * \param amount amount of data to redistribute by the task
- * \return the new task
+ * The assumed distribution is a 1D block distribution. Each host owns the same share of the @see amount.
+ * To be auto-scheduled, @see SD_task_distribute_comm_mxn_1d_block has to be  called first.
+ * @param name the name of the task (can be @c nullptr)
+ * @param data the user data you want to associate with the task (can be @c nullptr)
+ * @param amount amount of data to redistribute by the task
+ * @return the new task
  */
-SD_task_t SD_task_create_comm_par_mxn_1d_block(const char *name, void *data, double amount)
+SD_task_t SD_task_create_comm_par_mxn_1d_block(const char* name, void* data, double amount)
 {
-  SD_task_t res = SD_task_create(name, data, amount);
-  res->kind = SD_TASK_COMM_PAR_MXN_1D_BLOCK;
-
-  return res;
+  return simgrid::sd::Task::create_comm_par_mxn_1d_block(name, amount, data);
 }
 
 /**
- * \brief Destroys a task.
+ * @brief Destroys a task.
  *
  * The user data (if any) should have been destroyed first.
  *
- * \param task the task you want to destroy
- * \see SD_task_create()
+ * @param task the task you want to destroy
+ * @see SD_task_create()
  */
 void SD_task_destroy(SD_task_t task)
 {
-  XBT_DEBUG("Destroying task %s...", SD_task_get_name(task));
-
-  /* First Remove all dependencies associated with the task. */
-  while (not task->predecessors->empty())
-    SD_task_dependency_remove(*(task->predecessors->begin()), task);
-  while (not task->inputs->empty())
-    SD_task_dependency_remove(*(task->inputs->begin()), task);
-  while (not task->successors->empty())
-    SD_task_dependency_remove(task, *(task->successors->begin()));
-  while (not task->outputs->empty())
-    SD_task_dependency_remove(task, *(task->outputs->begin()));
-
-  if (task->state == SD_SCHEDULED || task->state == SD_RUNNABLE)
-    __SD_task_destroy_scheduling_data(task);
-
-  xbt_free(task->name);
-
-  if (task->surf_action != nullptr)
-    task->surf_action->unref();
-
-  delete task->allocation;
-  xbt_free(task->bytes_amount);
-  xbt_free(task->flops_amount);
-  delete task->inputs;
-  delete task->outputs;
-  delete task->predecessors;
-  delete task->successors;
-  xbt_free(task);
-
-  XBT_DEBUG("Task destroyed.");
+  task->destroy();
 }
 
 /**
- * \brief Returns the user data of a task
+ * @brief Returns the user data of a task
  *
- * \param task a task
- * \return the user data associated with this task (can be \c nullptr)
- * \see SD_task_set_data()
+ * @param task a task
+ * @return the user data associated with this task (can be @c nullptr)
+ * @see SD_task_set_data()
  */
-void *SD_task_get_data(SD_task_t task)
+void* SD_task_get_data(const_SD_task_t task)
 {
-  return task->data;
+  return task->get_data();
 }
 
 /**
- * \brief Sets the user data of a task
+ * @brief Sets the user data of a task
  *
- * The new data can be \c nullptr. The old data should have been freed first, if it was not \c nullptr.
+ * The new data can be @c nullptr. The old data should have been freed first, if it was not @c nullptr.
  *
- * \param task a task
- * \param data the new data you want to associate with this task
- * \see SD_task_get_data()
+ * @param task a task
+ * @param data the new data you want to associate with this task
+ * @see SD_task_get_data()
  */
-void SD_task_set_data(SD_task_t task, void *data)
+void SD_task_set_data(SD_task_t task, void* data)
 {
-  task->data = data;
+  task->set_data(data);
 }
 
 /**
- * \brief Sets the rate of a task
+ * @brief Sets the rate of a task
  *
  * This will change the network bandwidth a task can use. This rate  cannot be dynamically changed. Once the task has
  * started, this call is ineffective. This rate depends on both the nominal bandwidth on the route onto which the task
- * is scheduled (\see SD_task_get_current_bandwidth) and the amount of data to transfer.
+ * is scheduled (@see SD_task_get_current_bandwidth) and the amount of data to transfer.
  *
  * To divide the nominal bandwidth by 2, the rate then has to be :
  *    rate = bandwidth/(2*amount)
  *
- * \param task a \see SD_TASK_COMM_E2E task (end-to-end communication)
- * \param rate the new rate you want to associate with this task.
+ * @param task a @see SD_TASK_COMM_E2E task (end-to-end communication)
+ * @param rate the new rate you want to associate with this task.
  */
 void SD_task_set_rate(SD_task_t task, double rate)
 {
-  xbt_assert(task->kind == SD_TASK_COMM_E2E, "The rate can be modified for end-to-end communications only.");
-  if(task->state < SD_RUNNING) {
-    task->rate = rate;
-  } else {
-    XBT_WARN("Task %p has started. Changing rate is ineffective.", task);
-  }
+  task->set_rate(rate);
 }
 
 /**
- * \brief Returns the state of a task
+ * @brief Returns the state of a task
  *
- * \param task a task
- * \return the current \ref e_SD_task_state_t "state" of this task:
+ * @param task a task
+ * @return the current @ref e_SD_task_state_t "state" of this task:
  * #SD_NOT_SCHEDULED, #SD_SCHEDULED, #SD_RUNNABLE, #SD_RUNNING, #SD_DONE or #SD_FAILED
- * \see e_SD_task_state_t
- */
-e_SD_task_state_t SD_task_get_state(SD_task_t task)
-{
-  return task->state;
-}
-
-/* Changes the state of a task. Updates the sd_global->watch_point_reached flag.
+ * @see e_SD_task_state_t
  */
-void SD_task_set_state(SD_task_t task, e_SD_task_state_t new_state)
+e_SD_task_state_t SD_task_get_state(const_SD_task_t task)
 {
-  std::set<SD_task_t>::iterator idx;
-  XBT_DEBUG("Set state of '%s' to %d", task->name, new_state);
-  if ((new_state == SD_NOT_SCHEDULED || new_state == SD_SCHEDULABLE) && task->state == SD_FAILED){
-    sd_global->completed_tasks->erase(task);
-    sd_global->initial_tasks->insert(task);
-  }
-
-  if (new_state == SD_SCHEDULED && task->state == SD_RUNNABLE){
-    sd_global->initial_tasks->insert(task);
-    sd_global->runnable_tasks->erase(task);
-  }
-
-  if (new_state == SD_RUNNABLE){
-    idx = sd_global->initial_tasks->find(task);
-    if (idx != sd_global->initial_tasks->end()) {
-      sd_global->runnable_tasks->insert(*idx);
-      sd_global->initial_tasks->erase(idx);
-    }
-  }
-
-  if (new_state == SD_RUNNING)
-    sd_global->runnable_tasks->erase(task);
-
-  if (new_state == SD_DONE || new_state == SD_FAILED){
-    sd_global->completed_tasks->insert(task);
-    task->start_time = task->surf_action->getStartTime();
-    if (new_state == SD_DONE){
-      task->finish_time = task->surf_action->getFinishTime();
-#if SIMGRID_HAVE_JEDULE
-      jedule_log_sd_event(task);
-#endif
-    } else
-      task->finish_time = surf_get_clock();
-    task->surf_action->unref();
-    task->surf_action = nullptr;
-    task->allocation->clear();
-  }
-
-  task->state = new_state;
-
-  if (task->watch_points & new_state) {
-    XBT_VERB("Watch point reached with task '%s'!", task->name);
-    sd_global->watch_point_reached = true;
-    SD_task_unwatch(task, new_state);   /* remove the watch point */
-  }
+  return task->get_state();
 }
-
 /**
- * \brief Returns the name of a task
+ * @brief Returns the name of a task
  *
- * \param task a task
- * \return the name of this task (can be \c nullptr)
+ * @param task a task
+ * @return the name of this task (can be @c nullptr)
  */
-const char *SD_task_get_name(SD_task_t task)
+const char* SD_task_get_name(const_SD_task_t task)
 {
-  return task->name;
+  return task->get_cname();
 }
 
 /** @brief Allows to change the name of a task */
-void SD_task_set_name(SD_task_t task, const char *name)
+void SD_task_set_name(SD_task_t task, const char* name)
 {
-  xbt_free(task->name);
-  task->name = xbt_strdup(name);
+  task->set_name(name);
 }
 
 /** @brief Returns the dynar of the parents of a task
  *
- * \param task a task
- * \return a newly allocated dynar comprising the parents of this task
+ * @param task a task
+ * @return a newly allocated dynar comprising the parents of this task
  */
 
-xbt_dynar_t SD_task_get_parents(SD_task_t task)
+xbt_dynar_t SD_task_get_parents(const_SD_task_t task)
 {
   xbt_dynar_t parents = xbt_dynar_new(sizeof(SD_task_t), nullptr);
 
-  for (auto const& it : *task->predecessors)
+  for (auto const& it : task->get_predecessors())
     xbt_dynar_push(parents, &it);
-  for (auto const& it : *task->inputs)
+  for (auto const& it : task->get_inputs())
     xbt_dynar_push(parents, &it);
 
   return parents;
@@ -347,53 +704,53 @@ xbt_dynar_t SD_task_get_parents(SD_task_t task)
 
 /** @brief Returns the dynar of the parents of a task
  *
- * \param task a task
- * \return a newly allocated dynar comprising the parents of this task
+ * @param task a task
+ * @return a newly allocated dynar comprising the parents of this task
  */
-xbt_dynar_t SD_task_get_children(SD_task_t task)
+xbt_dynar_t SD_task_get_children(const_SD_task_t task)
 {
   xbt_dynar_t children = xbt_dynar_new(sizeof(SD_task_t), nullptr);
 
-  for (auto const& it : *task->successors)
+  for (auto const& it : task->get_successors())
     xbt_dynar_push(children, &it);
-  for (auto const& it : *task->outputs)
+  for (auto const& it : task->get_outputs())
     xbt_dynar_push(children, &it);
 
   return children;
 }
 
 /**
- * \brief Returns the number of workstations involved in a task
+ * @brief Returns the number of workstations involved in a task
  *
  * Only call this on already scheduled tasks!
- * \param task a task
+ * @param task a task
  */
-int SD_task_get_workstation_count(SD_task_t task)
+int SD_task_get_workstation_count(const_SD_task_t task)
 {
-  return task->allocation->size();
+  return static_cast<int>(task->get_allocation_size());
 }
 
 /**
- * \brief Returns the list of workstations involved in a task
+ * @brief Returns the list of workstations involved in a task
  *
  * Only call this on already scheduled tasks!
- * \param task a task
+ * @param task a task
  */
-sg_host_t *SD_task_get_workstation_list(SD_task_t task)
+sg_host_t* SD_task_get_workstation_list(const_SD_task_t task)
 {
-  return task->allocation->data();
+  return task->get_allocation()->data();
 }
 
 /**
- * \brief Returns the total amount of work contained in a task
+ * @brief Returns the total amount of work contained in a task
  *
- * \param task a task
- * \return the total amount of work (computation or data transfer) for this task
- * \see SD_task_get_remaining_amount()
+ * @param task a task
+ * @return the total amount of work (computation or data transfer) for this task
+ * @see SD_task_get_remaining_amount()
  */
-double SD_task_get_amount(SD_task_t task)
+double SD_task_get_amount(const_SD_task_t task)
 {
-  return task->amount;
+  return task->get_amount();
 }
 
 /** @brief Sets the total amount of work of a task
@@ -401,283 +758,222 @@ double SD_task_get_amount(SD_task_t task)
  * bytes_amount arrays respectively. Nothing more than modifying task->amount is done for parallel  typed tasks
  * (COMP_PAR_AMDAHL and COMM_PAR_MXN_1D_BLOCK) as the distribution of the amount of work is done at scheduling time.
  *
- * \param task a task
- * \param amount the new amount of work to execute
+ * @param task a task
+ * @param amount the new amount of work to execute
  */
 void SD_task_set_amount(SD_task_t task, double amount)
 {
-  task->amount = amount;
-  if (task->kind == SD_TASK_COMP_SEQ)
-    task->flops_amount[0] = amount;
-  if (task->kind == SD_TASK_COMM_E2E)
-    task->bytes_amount[2] = amount;
+  task->set_amount(amount);
 }
 
 /**
- * \brief Returns the alpha parameter of a SD_TASK_COMP_PAR_AMDAHL task
+ * @brief Returns the alpha parameter of a SD_TASK_COMP_PAR_AMDAHL task
  *
- * \param task a parallel task assuming Amdahl's law as speedup model
- * \return the alpha parameter (serial part of a task in percent) for this task
+ * @param task a parallel task assuming Amdahl's law as speedup model
+ * @return the alpha parameter (serial part of a task in percent) for this task
  */
-double SD_task_get_alpha(SD_task_t task)
+double SD_task_get_alpha(const_SD_task_t task)
 {
-  xbt_assert(SD_task_get_kind(task) == SD_TASK_COMP_PAR_AMDAHL, "Alpha parameter is not defined for this kind of task");
-  return task->alpha;
+  return task->get_alpha();
 }
 
 /**
- * \brief Returns the remaining amount work to do till the completion of a task
+ * @brief Returns the remaining amount work to do till the completion of a task
  *
- * \param task a task
- * \return the remaining amount of work (computation or data transfer) of this task
- * \see SD_task_get_amount()
+ * @param task a task
+ * @return the remaining amount of work (computation or data transfer) of this task
+ * @see SD_task_get_amount()
  */
-double SD_task_get_remaining_amount(SD_task_t task)
+double SD_task_get_remaining_amount(const_SD_task_t task)
 {
-  if (task->surf_action)
-    return task->surf_action->getRemains();
-  else
-    return (task->state == SD_DONE) ? 0 : task->amount;
+  return task->get_remaining_amount();
 }
 
-e_SD_task_kind_t SD_task_get_kind(SD_task_t task)
+e_SD_task_kind_t SD_task_get_kind(const_SD_task_t task)
 {
-  return task->kind;
+  return task->get_kind();
 }
 
 /** @brief Displays debugging information about a task */
-void SD_task_dump(SD_task_t task)
+void SD_task_dump(const_SD_task_t task)
 {
-  XBT_INFO("Displaying task %s", SD_task_get_name(task));
-  if (task->state == SD_RUNNABLE)
-    XBT_INFO("  - state: runnable");
-  else if (task->state < SD_RUNNABLE)
-    XBT_INFO("  - state: %s not runnable", __get_state_name(task->state));
-  else
-    XBT_INFO("  - state: not runnable %s", __get_state_name(task->state));
+  task->dump();
+}
 
-  if (task->kind != 0) {
-    switch (task->kind) {
+/** @brief Dumps the task in dotty formalism into the FILE* passed as second argument */
+void SD_task_dotty(const_SD_task_t task, void* out)
+{
+  auto* fout = static_cast<FILE*>(out);
+  fprintf(fout, "  T%p [label=\"%.20s\"", task, task->get_cname());
+  switch (task->get_kind()) {
     case SD_TASK_COMM_E2E:
-      XBT_INFO("  - kind: end-to-end communication");
+    case SD_TASK_COMM_PAR_MXN_1D_BLOCK:
+      fprintf(fout, ", shape=box");
       break;
     case SD_TASK_COMP_SEQ:
-      XBT_INFO("  - kind: sequential computation");
-      break;
     case SD_TASK_COMP_PAR_AMDAHL:
-      XBT_INFO("  - kind: parallel computation following Amdahl's law");
-      break;
-    case SD_TASK_COMM_PAR_MXN_1D_BLOCK:
-      XBT_INFO("  - kind: MxN data redistribution assuming 1D block distribution");
+      fprintf(fout, ", shape=circle");
       break;
     default:
-      XBT_INFO("  - (unknown kind %d)", task->kind);
-    }
-  }
-
-  XBT_INFO("  - amount: %.0f", SD_task_get_amount(task));
-  if (task->kind == SD_TASK_COMP_PAR_AMDAHL)
-    XBT_INFO("  - alpha: %.2f", task->alpha);
-  XBT_INFO("  - Dependencies to satisfy: %zu", task->inputs->size()+ task->predecessors->size());
-  if ((task->inputs->size()+ task->predecessors->size()) > 0) {
-    XBT_INFO("  - pre-dependencies:");
-    for (auto const& it : *task->predecessors)
-      XBT_INFO("    %s", it->name);
-
-    for (auto const& it : *task->inputs)
-      XBT_INFO("    %s", it->name);
-  }
-  if ((task->outputs->size() + task->successors->size()) > 0) {
-    XBT_INFO("  - post-dependencies:");
-
-    for (auto const& it : *task->successors)
-      XBT_INFO("    %s", it->name);
-    for (auto const& it : *task->outputs)
-      XBT_INFO("    %s", it->name);
-  }
-}
-
-/** @brief Dumps the task in dotty formalism into the FILE* passed as second argument */
-void SD_task_dotty(SD_task_t task, void *out)
-{
-  FILE *fout = static_cast<FILE*>(out);
-  fprintf(fout, "  T%p [label=\"%.20s\"", task, task->name);
-  switch (task->kind) {
-  case SD_TASK_COMM_E2E:
-  case SD_TASK_COMM_PAR_MXN_1D_BLOCK:
-    fprintf(fout, ", shape=box");
-    break;
-  case SD_TASK_COMP_SEQ:
-  case SD_TASK_COMP_PAR_AMDAHL:
-    fprintf(fout, ", shape=circle");
-    break;
-  default:
-    xbt_die("Unknown task type!");
+      xbt_die("Unknown task type!");
   }
   fprintf(fout, "];\n");
-  for (auto const& it : *task->predecessors)
+  for (auto const& it : task->get_predecessors())
     fprintf(fout, " T%p -> T%p;\n", it, task);
-  for (auto const& it : *task->inputs)
+  for (auto const& it : task->get_inputs())
     fprintf(fout, " T%p -> T%p;\n", it, task);
 }
 
 /**
- * \brief Adds a dependency between two tasks
+ * @brief Adds a dependency between two tasks
  *
- * \a dst will depend on \a src, ie \a dst will not start before \a src is finished.
- * Their \ref e_SD_task_state_t "state" must be #SD_NOT_SCHEDULED, #SD_SCHEDULED or #SD_RUNNABLE.
+ * @a dst will depend on @a src, ie @a dst will not start before @a src is finished.
+ * Their @ref e_SD_task_state_t "state" must be #SD_NOT_SCHEDULED, #SD_SCHEDULED or #SD_RUNNABLE.
  *
- * \param name the name of the new dependency (can be \c nullptr)
- * \param data the user data you want to associate with this dependency (can be \c nullptr)
- * \param src the task which must be executed first
- * \param dst the task you want to make depend on \a src
- * \see SD_task_dependency_remove()
+ * @param src the task which must be executed first
+ * @param dst the task you want to make depend on @a src
+ * @see SD_task_dependency_remove()
  */
-void SD_task_dependency_add(const char *name, void *data, SD_task_t src, SD_task_t dst)
+void SD_task_dependency_add(SD_task_t src, SD_task_t dst)
 {
   if (src == dst)
-    THROWF(arg_error, 0, "Cannot add a dependency between task '%s' and itself", SD_task_get_name(src));
+    throw std::invalid_argument(
+        simgrid::xbt::string_printf("Cannot add a dependency between task '%s' and itself", SD_task_get_name(src)));
 
-  if (src->state == SD_DONE || src->state == SD_FAILED)
-    THROWF(arg_error, 0, "Task '%s' must be SD_NOT_SCHEDULED, SD_SCHEDULABLE, SD_SCHEDULED, SD_RUNNABLE, or SD_RUNNING",
-           src->name);
+  if (src->get_state() == SD_DONE || src->get_state() == SD_FAILED)
+    throw std::invalid_argument(simgrid::xbt::string_printf(
+        "Task '%s' must be SD_NOT_SCHEDULED, SD_SCHEDULABLE, SD_SCHEDULED, SD_RUNNABLE, or SD_RUNNING",
+        src->get_cname()));
 
-  if (dst->state == SD_DONE || dst->state == SD_FAILED || dst->state == SD_RUNNING)
-    THROWF(arg_error, 0, "Task '%s' must be SD_NOT_SCHEDULED, SD_SCHEDULABLE, SD_SCHEDULED, or SD_RUNNABLE",
-           dst->name);
+  if (dst->get_state() == SD_DONE || dst->get_state() == SD_FAILED || dst->get_state() == SD_RUNNING)
+    throw std::invalid_argument(simgrid::xbt::string_printf(
+        "Task '%s' must be SD_NOT_SCHEDULED, SD_SCHEDULABLE, SD_SCHEDULED, or SD_RUNNABLE", dst->get_cname()));
 
-  if (dst->inputs->find(src) != dst->inputs->end() || src->outputs->find(dst) != src->outputs->end() ||
-      src->successors->find(dst) != src->successors->end() || dst->predecessors->find(src) != dst->predecessors->end())
-    THROWF(arg_error, 0, "A dependency already exists between task '%s' and task '%s'", src->name, dst->name);
+  if (dst->is_child_of(src) || src->is_parent_of(dst))
+    throw std::invalid_argument(simgrid::xbt::string_printf(
+        "A dependency already exists between task '%s' and task '%s'", src->get_cname(), dst->get_cname()));
 
-  XBT_DEBUG("SD_task_dependency_add: src = %s, dst = %s", src->name, dst->name);
+  XBT_DEBUG("SD_task_dependency_add: src = %s, dst = %s", src->get_cname(), dst->get_cname());
 
-  if (src->kind == SD_TASK_COMM_E2E || src->kind == SD_TASK_COMM_PAR_MXN_1D_BLOCK){
-    if (dst->kind == SD_TASK_COMP_SEQ || dst->kind == SD_TASK_COMP_PAR_AMDAHL)
-        dst->inputs->insert(src);
+  if (src->get_kind() == SD_TASK_COMM_E2E || src->get_kind() == SD_TASK_COMM_PAR_MXN_1D_BLOCK) {
+    if (dst->get_kind() == SD_TASK_COMP_SEQ || dst->get_kind() == SD_TASK_COMP_PAR_AMDAHL)
+      dst->add_input(src);
     else
-      dst->predecessors->insert(src);
-    src->successors->insert(dst);
+      dst->add_predecessor(src);
+    src->add_successor(dst);
   } else {
-    if (dst->kind == SD_TASK_COMM_E2E|| dst->kind == SD_TASK_COMM_PAR_MXN_1D_BLOCK)
-      src->outputs->insert(dst);
+    if (dst->get_kind() == SD_TASK_COMM_E2E || dst->get_kind() == SD_TASK_COMM_PAR_MXN_1D_BLOCK)
+      src->add_output(dst);
     else
-      src->successors->insert(dst);
-    dst->predecessors->insert(src);
+      src->add_successor(dst);
+    dst->add_predecessor(src);
   }
 
   /* if the task was runnable, the task goes back to SD_SCHEDULED because of the new dependency*/
-  if (dst->state == SD_RUNNABLE) {
-    XBT_DEBUG("SD_task_dependency_add: %s was runnable and becomes scheduled!", dst->name);
-    SD_task_set_state(dst, SD_SCHEDULED);
+  if (dst->get_state() == SD_RUNNABLE) {
+    XBT_DEBUG("SD_task_dependency_add: %s was runnable and becomes scheduled!", dst->get_cname());
+    dst->set_state(SD_SCHEDULED);
   }
 }
 
 /**
- * \brief Indicates whether there is a dependency between two tasks.
+ * @brief Indicates whether there is a dependency between two tasks.
  *
- * \param src a task
- * \param dst a task depending on \a src
+ * @param src a task
+ * @param dst a task depending on @a src
  *
  * If src is nullptr, checks whether dst has any pre-dependency.
  * If dst is nullptr, checks whether src has any post-dependency.
  */
-int SD_task_dependency_exists(SD_task_t src, SD_task_t dst)
+int SD_task_dependency_exists(const_SD_task_t src, SD_task_t dst)
 {
   xbt_assert(src != nullptr || dst != nullptr, "Invalid parameter: both src and dst are nullptr");
 
-  if (src) {
-    if (dst) {
-      return (src->successors->find(dst) != src->successors->end() || src->outputs->find(dst) != src->outputs->end());
-    } else {
-      return src->successors->size() + src->outputs->size();
-    }
-  } else {
-    return dst->predecessors->size() + dst->inputs->size();
-  }
-  return 0;
+  if (src)
+    if (dst)
+      return src->is_parent_of(dst);
+    else
+      return static_cast<int>(src->is_waited_by());
+  else
+    return static_cast<int>(dst->has_unsolved_dependencies());
 }
 
 /**
- * \brief Remove a dependency between two tasks
+ * @brief Remove a dependency between two tasks
  *
- * \param src a task
- * \param dst a task depending on \a src
- * \see SD_task_dependency_add()
+ * @param src a task
+ * @param dst a task depending on @a src
+ * @see SD_task_dependency_add()
  */
 void SD_task_dependency_remove(SD_task_t src, SD_task_t dst)
 {
-  XBT_DEBUG("SD_task_dependency_remove: src = %s, dst = %s", SD_task_get_name(src), SD_task_get_name(dst));
+  XBT_DEBUG("SD_task_dependency_remove: src = %s, dst = %s", src->get_cname(), dst->get_cname());
 
-  if (src->successors->find(dst) == src->successors->end() && src->outputs->find(dst) == src->outputs->end())
-    THROWF(arg_error, 0, "No dependency found between task '%s' and '%s': task '%s' is not a successor of task '%s'",
-           src->name, dst->name, dst->name, src->name);
+  if (not src->is_parent_of(dst))
+    throw std::invalid_argument(simgrid::xbt::string_printf(
+        "No dependency found between task '%s' and '%s': task '%s' is not a successor of task '%s'", src->get_cname(),
+        dst->get_cname(), dst->get_cname(), src->get_cname()));
 
-  if (src->kind == SD_TASK_COMM_E2E || src->kind == SD_TASK_COMM_PAR_MXN_1D_BLOCK){
-    if (dst->kind == SD_TASK_COMP_SEQ || dst->kind == SD_TASK_COMP_PAR_AMDAHL)
-      dst->inputs->erase(src);
+  if (src->get_kind() == SD_TASK_COMM_E2E || src->get_kind() == SD_TASK_COMM_PAR_MXN_1D_BLOCK) {
+    if (dst->get_kind() == SD_TASK_COMP_SEQ || dst->get_kind() == SD_TASK_COMP_PAR_AMDAHL)
+      dst->rm_input(src);
     else
-      dst->predecessors->erase(src);
-    src->successors->erase(dst);
+      dst->rm_predecessor(src);
+    src->rm_successor(dst);
   } else {
-    if (dst->kind == SD_TASK_COMM_E2E|| dst->kind == SD_TASK_COMM_PAR_MXN_1D_BLOCK)
-      src->outputs->erase(dst);
+    if (dst->get_kind() == SD_TASK_COMM_E2E || dst->get_kind() == SD_TASK_COMM_PAR_MXN_1D_BLOCK)
+      src->rm_output(dst);
     else
-      src->successors->erase(dst);
-    dst->predecessors->erase(src);
+      src->rm_successor(dst);
+    dst->rm_predecessor(src);
   }
 
   /* if the task was scheduled and dependencies are satisfied, we can make it runnable */
-  if (dst->predecessors->empty() && dst->inputs->empty() && dst->state == SD_SCHEDULED)
-    SD_task_set_state(dst, SD_RUNNABLE);
+  if (dst->has_unsolved_dependencies() == 0 && dst->get_state() == SD_SCHEDULED)
+    dst->set_state(SD_RUNNABLE);
 }
 
 /**
- * \brief Adds a watch point to a task
+ * @brief Adds a watch point to a task
  *
- * SD_simulate() will stop as soon as the \ref e_SD_task_state_t "state" of this task becomes the one given in argument.
+ * SD_simulate() will stop as soon as the @ref e_SD_task_state_t "state" of this task becomes the one given in argument.
  * The watch point is then automatically removed.
  *
- * \param task a task
- * \param state the \ref e_SD_task_state_t "state" you want to watch (cannot be #SD_NOT_SCHEDULED)
- * \see SD_task_unwatch()
+ * @param task a task
+ * @param state the @ref e_SD_task_state_t "state" you want to watch (cannot be #SD_NOT_SCHEDULED)
+ * @see SD_task_unwatch()
  */
 void SD_task_watch(SD_task_t task, e_SD_task_state_t state)
 {
-  if (state & SD_NOT_SCHEDULED)
-    THROWF(arg_error, 0, "Cannot add a watch point for state SD_NOT_SCHEDULED");
-
-  task->watch_points = task->watch_points | state;
+  task->watch(state);
 }
 
 /**
- * \brief Removes a watch point from a task
+ * @brief Removes a watch point from a task
  *
- * \param task a task
- * \param state the \ref e_SD_task_state_t "state" you no longer want to watch
- * \see SD_task_watch()
+ * @param task a task
+ * @param state the @ref e_SD_task_state_t "state" you no longer want to watch
+ * @see SD_task_watch()
  */
 void SD_task_unwatch(SD_task_t task, e_SD_task_state_t state)
 {
-  xbt_assert(state != SD_NOT_SCHEDULED, "SimDag error: Cannot have a watch point for state SD_NOT_SCHEDULED");
-  task->watch_points = task->watch_points & ~state;
+  task->unwatch(state);
 }
 
 /**
- * \brief Returns an approximative estimation of the execution time of a task.
+ * @brief Returns an approximative estimation of the execution time of a task.
  *
  * The estimation is very approximative because the value returned is the time the task would take if it was executed
  * now and if it was the only task.
  *
- * \param task the task to evaluate
- * \param host_count number of hosts on which the task would be executed
- * \param host_list the hosts on which the task would be executed
- * \param flops_amount computation amount for each host(i.e., an array of host_count doubles)
- * \param bytes_amount communication amount between each pair of hosts (i.e., a matrix of host_count*host_count doubles)
- * \see SD_schedule()
+ * @param host_count number of hosts on which the task would be executed
+ * @param host_list the hosts on which the task would be executed
+ * @param flops_amount computation amount for each host(i.e., an array of host_count doubles)
+ * @param bytes_amount communication amount between each pair of hosts (i.e., a matrix of host_count*host_count doubles)
+ * @see SD_schedule()
  */
-double SD_task_get_execution_time(SD_task_t task, int host_count, const sg_host_t *host_list,
-                                  const double *flops_amount, const double *bytes_amount)
+double SD_task_get_execution_time(const_SD_task_t /*task*/, int host_count, const sg_host_t* host_list,
+                                  const double* flops_amount, const double* bytes_amount)
 {
   xbt_assert(host_count > 0, "Invalid parameter");
   double max_time = 0.0;
@@ -686,13 +982,13 @@ double SD_task_get_execution_time(SD_task_t task, int host_count, const sg_host_
   for (int i = 0; i < host_count; i++) {
     double time = 0.0;
     if (flops_amount != nullptr)
-      time = flops_amount[i] / host_list[i]->getSpeed();
+      time = flops_amount[i] / host_list[i]->get_speed();
 
     if (bytes_amount != nullptr)
       for (int j = 0; j < host_count; j++)
         if (bytes_amount[i * host_count + j] != 0)
-          time += (sg_host_route_latency(host_list[i], host_list[j]) +
-                   bytes_amount[i * host_count + j] / sg_host_route_bandwidth(host_list[i], host_list[j]));
+          time += (sg_host_get_route_latency(host_list[i], host_list[j]) +
+                   bytes_amount[i * host_count + j] / sg_host_get_route_bandwidth(host_list[i], host_list[j]));
 
     if (time > max_time)
       max_time = time;
@@ -700,267 +996,99 @@ double SD_task_get_execution_time(SD_task_t task, int host_count, const sg_host_
   return max_time;
 }
 
-static inline void SD_task_do_schedule(SD_task_t task)
-{
-  if (SD_task_get_state(task) > SD_SCHEDULABLE)
-    THROWF(arg_error, 0, "Task '%s' has already been scheduled", SD_task_get_name(task));
-
-  if (task->predecessors->empty() && task->inputs->empty())
-    SD_task_set_state(task, SD_RUNNABLE);
-  else
-    SD_task_set_state(task, SD_SCHEDULED);
-}
-
 /**
- * \brief Schedules a task
+ * @brief Schedules a task
  *
  * The task state must be #SD_NOT_SCHEDULED.
- * Once scheduled, a task is executed as soon as possible in \see SD_simulate, i.e. when its dependencies are satisfied.
- *
- * \param task the task you want to schedule
- * \param host_count number of hosts on which the task will be executed
- * \param host_list the hosts on which the task will be executed
- * \param flops_amount computation amount for each hosts (i.e., an array of host_count doubles)
- * \param bytes_amount communication amount between each pair of hosts (i.e., a matrix of host_count*host_count doubles)
- * \param rate task execution speed rate
- * \see SD_task_unschedule()
+ * Once scheduled, a task is executed as soon as possible in @see SD_simulate, i.e. when its dependencies are satisfied.
+ *
+ * @param task the task you want to schedule
+ * @param host_count number of hosts on which the task will be executed
+ * @param host_list the hosts on which the task will be executed
+ * @param flops_amount computation amount for each hosts (i.e., an array of host_count doubles)
+ * @param bytes_amount communication amount between each pair of hosts (i.e., a matrix of host_count*host_count doubles)
+ * @param rate task execution speed rate
+ * @see SD_task_unschedule()
  */
-void SD_task_schedule(SD_task_t task, int host_count, const sg_host_t * host_list,
-                      const double *flops_amount, const double *bytes_amount, double rate)
+void SD_task_schedule(SD_task_t task, int host_count, const sg_host_t* host_list, const double* flops_amount,
+                      const double* bytes_amount, double rate)
 {
   xbt_assert(host_count > 0, "host_count must be positive");
+  std::vector<sg_host_t> hosts(host_count);
 
-  task->rate = rate;
-
-  if (flops_amount) {
-    task->flops_amount = static_cast<double*>(xbt_realloc(task->flops_amount, sizeof(double) * host_count));
-    memcpy(task->flops_amount, flops_amount, sizeof(double) * host_count);
-  } else {
-    xbt_free(task->flops_amount);
-    task->flops_amount = nullptr;
-  }
-
-  int communication_nb = host_count * host_count;
-  if (bytes_amount) {
-    task->bytes_amount = static_cast<double*>(xbt_realloc(task->bytes_amount, sizeof(double) * communication_nb));
-    memcpy(task->bytes_amount, bytes_amount, sizeof(double) * communication_nb);
-  } else {
-    xbt_free(task->bytes_amount);
-    task->bytes_amount = nullptr;
-  }
-
-  for(int i =0; i<host_count; i++)
-    task->allocation->push_back(host_list[i]);
+  for (int i = 0; i < host_count; i++)
+    hosts[i] = host_list[i];
 
-  SD_task_do_schedule(task);
+  task->schedule(hosts, flops_amount, bytes_amount, rate);
 }
 
 /**
- * \brief Unschedules a task
+ * @brief Unschedules a task
  *
  * The task state must be #SD_SCHEDULED, #SD_RUNNABLE, #SD_RUNNING or #SD_FAILED.
  * If you call this function, the task state becomes #SD_NOT_SCHEDULED.
  * Call SD_task_schedule() to schedule it again.
  *
- * \param task the task you want to unschedule
- * \see SD_task_schedule()
+ * @param task the task you want to unschedule
+ * @see SD_task_schedule()
  */
 void SD_task_unschedule(SD_task_t task)
 {
-  if (task->state == SD_NOT_SCHEDULED || task->state == SD_SCHEDULABLE)
-    THROWF(arg_error, 0, "Task %s: the state must be SD_SCHEDULED, SD_RUNNABLE, SD_RUNNING or SD_FAILED", task->name);
-
-  if ((task->state == SD_SCHEDULED || task->state == SD_RUNNABLE) /* if the task is scheduled or runnable */
-      && ((task->kind == SD_TASK_COMP_PAR_AMDAHL) || (task->kind == SD_TASK_COMM_PAR_MXN_1D_BLOCK))) {
-          /* Don't free scheduling data for typed tasks */
-    __SD_task_destroy_scheduling_data(task);
-    task->allocation->clear();
-  }
-
-  if (SD_task_get_state(task) == SD_RUNNING)
-    /* the task should become SD_FAILED */
-    task->surf_action->cancel();
-  else {
-    if (task->predecessors->empty() && task->inputs->empty())
-      SD_task_set_state(task, SD_SCHEDULABLE);
-    else
-      SD_task_set_state(task, SD_NOT_SCHEDULED);
-  }
-  task->start_time = -1.0;
-}
-
-/* Runs a task. */
-void SD_task_run(SD_task_t task)
-{
-  xbt_assert(task->state == SD_RUNNABLE, "Task '%s' is not runnable! Task state: %d", task->name, (int) task->state);
-  xbt_assert(task->allocation != nullptr, "Task '%s': host_list is nullptr!", task->name);
-
-  XBT_VERB("Executing task '%s'", task->name);
-
-  /* Copy the elements of the task into the action */
-  int host_nb = task->allocation->size();
-  sg_host_t* hosts = new sg_host_t[host_nb];
-  std::copy_n(task->allocation->begin(), host_nb, hosts);
-
-  double* flops_amount = new double[host_nb]();
-  double* bytes_amount = new double[host_nb * host_nb]();
-
-  if(task->flops_amount)
-    std::copy_n(task->flops_amount, host_nb, flops_amount);
-  if(task->bytes_amount)
-    std::copy_n(task->bytes_amount, host_nb * host_nb, bytes_amount);
-
-  task->surf_action = surf_host_model->executeParallelTask(host_nb, hosts, flops_amount, bytes_amount, task->rate);
-
-  task->surf_action->setData(task);
-
-  XBT_DEBUG("surf_action = %p", task->surf_action);
-
-  __SD_task_destroy_scheduling_data(task);      /* now the scheduling data are not useful anymore */
-  SD_task_set_state(task, SD_RUNNING);
-  sd_global->return_set->insert(task);
+  task->unschedule();
 }
 
 /**
- * \brief Returns the start time of a task
+ * @brief Returns the start time of a task
  *
  * The task state must be SD_RUNNING, SD_DONE or SD_FAILED.
  *
- * \param task: a task
- * \return the start time of this task
+ * @param task: a task
+ * @return the start time of this task
  */
-double SD_task_get_start_time(SD_task_t task)
+double SD_task_get_start_time(const_SD_task_t task)
 {
-  if (task->surf_action)
-    return task->surf_action->getStartTime();
-  else
-    return task->start_time;
+  return task->get_start_time();
 }
 
 /**
- * \brief Returns the finish time of a task
+ * @brief Returns the finish time of a task
  *
  * The task state must be SD_RUNNING, SD_DONE or SD_FAILED.
  * If the state is not completed yet, the returned value is an estimation of the task finish time. This value can
  * vary until the task is completed.
  *
- * \param task: a task
- * \return the start time of this task
+ * @param task: a task
+ * @return the start time of this task
  */
-double SD_task_get_finish_time(SD_task_t task)
+double SD_task_get_finish_time(const_SD_task_t task)
 {
-  if (task->surf_action)        /* should never happen as actions are destroyed right after their completion */
-    return task->surf_action->getFinishTime();
-  else
-    return task->finish_time;
+  return task->get_finish_time();
 }
 
 void SD_task_distribute_comp_amdahl(SD_task_t task, int count)
 {
-  xbt_assert(task->kind == SD_TASK_COMP_PAR_AMDAHL, "Task %s is not a SD_TASK_COMP_PAR_AMDAHL typed task."
-              "Cannot use this function.", task->name);
-  task->flops_amount = xbt_new0(double, count);
-  task->bytes_amount = xbt_new0(double, count * count);
-
-  for (int i=0; i<count; i++){
-    task->flops_amount[i] = (task->alpha + (1 - task->alpha)/count) * task->amount;
-  }
+  task->distribute_comp_amdahl(count);
 }
 
-void SD_task_build_MxN_1D_block_matrix(SD_task_t task, int src_nb, int dst_nb){
-  xbt_assert(task->kind == SD_TASK_COMM_PAR_MXN_1D_BLOCK, "Task %s is not a SD_TASK_COMM_PAR_MXN_1D_BLOCK typed task."
-              "Cannot use this function.", task->name);
-  xbt_free(task->bytes_amount);
-  task->bytes_amount = xbt_new0(double,task->allocation->size() * task->allocation->size());
-
-  for (int i=0; i<src_nb; i++) {
-    double src_start = i*task->amount/src_nb;
-    double src_end = src_start + task->amount/src_nb;
-    for (int j=0; j<dst_nb; j++) {
-      double dst_start = j*task->amount/dst_nb;
-      double dst_end = dst_start + task->amount/dst_nb;
-      XBT_VERB("(%d->%d): (%.2f, %.2f)-> (%.2f, %.2f)", i, j, src_start, src_end, dst_start, dst_end);
-      task->bytes_amount[i*(src_nb+dst_nb)+src_nb+j]=0.0;
-      if ((src_end > dst_start) && (dst_end > src_start)) { /* There is something to send */
-        task->bytes_amount[i * (src_nb + dst_nb) + src_nb + j] =
-            std::min(src_end, dst_end) - std::max(src_start, dst_start);
-        XBT_VERB("==> %.2f", task->bytes_amount[i*(src_nb+dst_nb)+src_nb+j]);
-      }
-    }
-  }
+void SD_task_build_MxN_1D_block_matrix(SD_task_t task, int src_nb, int dst_nb)
+{
+  task->build_MxN_1D_block_matrix(src_nb, dst_nb);
 }
 
 /** @brief Auto-schedules a task.
  *
- * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This allows to specify the task costs at
+ * Auto-scheduling mean that the task can be used with SD_task_schedulev(). This allows one to specify the task costs at
  * creation, and decouple them from the scheduling process where you just specify which resource should deliver the
  * mandatory power.
  *
  * To be auto-schedulable, a task must be a typed computation SD_TASK_COMP_SEQ or SD_TASK_COMP_PAR_AMDAHL.
  */
-void SD_task_schedulev(SD_task_t task, int count, const sg_host_t * list)
+void SD_task_schedulev(SD_task_t task, int count, const sg_host_t* host_list)
 {
-  xbt_assert(task->kind == SD_TASK_COMP_SEQ || task->kind == SD_TASK_COMP_PAR_AMDAHL,
-      "Task %s is not typed. Cannot automatically schedule it.", SD_task_get_name(task));
-
-  for(int i =0; i<count; i++)
-    task->allocation->push_back(list[i]);
-
-  XBT_VERB("Schedule computation task %s on %zu host(s)", task->name, task->allocation->size());
-
-  if (task->kind == SD_TASK_COMP_SEQ) {
-    if (not task->flops_amount) { /*This task has failed and is rescheduled. Reset the flops_amount*/
-      task->flops_amount = xbt_new0(double, 1);
-      task->flops_amount[0] = task->amount;
-    }
-    XBT_VERB("It costs %.f flops", task->flops_amount[0]);
-  }
-
-  if (task->kind == SD_TASK_COMP_PAR_AMDAHL) {
-    SD_task_distribute_comp_amdahl(task, count);
-    XBT_VERB("%.f flops will be distributed following Amdahl's Law", task->flops_amount[0]);
-  }
-
-  SD_task_do_schedule(task);
-
-  /* Iterate over all inputs and outputs to say where I am located (and start them if runnable) */
-  for (auto const& input : *task->inputs) {
-    int src_nb = input->allocation->size();
-    int dst_nb = count;
-    if (input->allocation->empty())
-      XBT_VERB("Sender side of '%s' not scheduled. Set receiver side to '%s''s allocation", input->name, task->name);
-
-    for (int i=0; i<count;i++)
-      input->allocation->push_back(task->allocation->at(i));
-
-    if (input->allocation->size () > task->allocation->size()) {
-      if (task->kind == SD_TASK_COMP_PAR_AMDAHL)
-        SD_task_build_MxN_1D_block_matrix(input, src_nb, dst_nb);
-
-      SD_task_do_schedule(input);
-      XBT_VERB ("Auto-Schedule Communication task '%s'. Send %.f bytes from %d hosts to %d hosts.",
-          input->name,input->amount, src_nb, dst_nb);
-    }
-  }
-
-  for (auto const& output : *task->outputs) {
-    int src_nb = count;
-    int dst_nb = output->allocation->size();
-    if (output->allocation->empty())
-      XBT_VERB("Receiver side of '%s' not scheduled. Set sender side to '%s''s allocation", output->name, task->name);
-
-    for (int i=0; i<count;i++)
-      output->allocation->insert(output->allocation->begin()+i, task->allocation->at(i));
-
-    if (output->allocation->size () > task->allocation->size()) {
-      if (task->kind == SD_TASK_COMP_PAR_AMDAHL)
-        SD_task_build_MxN_1D_block_matrix(output, src_nb, dst_nb);
-
-      SD_task_do_schedule(output);
-      XBT_VERB ("Auto-Schedule Communication task %s. Send %.f bytes from %d hosts to %d hosts.",
-                output->name, output->amount, src_nb, dst_nb);
-    }
-  }
+  std::vector<sg_host_t> list(count);
+  for (int i = 0; i < count; i++)
+    list[i] = host_list[i];
+  task->schedulev(list);
 }
 
 /** @brief autoschedule a task on a list of hosts
@@ -971,12 +1099,11 @@ void SD_task_schedulev(SD_task_t task, int count, const sg_host_t * list)
 void SD_task_schedulel(SD_task_t task, int count, ...)
 {
   va_list ap;
-  sg_host_t* list = new sg_host_t[count];
+  std::vector<sg_host_t> list(count);
   va_start(ap, count);
-  for (int i=0; i<count; i++)
+  for (int i = 0; i < count; i++)
     list[i] = va_arg(ap, sg_host_t);
 
   va_end(ap);
-  SD_task_schedulev(task, count, list);
-  delete[] list;
+  task->schedulev(list);
 }