+/** \ingroup TRACE_user_variables
+ * \brief Set the value of a variable of a host at a given timestamp.
+ *
+ * Same as #TRACE_host_variable_set, but let user specify
+ * the time used to trace it. Users can specify a time that
+ * is not the simulated clock time as defined by the core
+ * simulator. This allows a fine-grain control of time
+ * definition, but should be used with caution since the trace
+ * can be inconsistent if resource utilization traces are also traced.
+ *
+ * \param time The timestamp to be used to tag this change of value.
+ * \param host The name of the host to be considered.
+ * \param variable The name of the variable to be considered.
+ * \param value The new value of the variable.
+ *
+ * \see TRACE_host_variable_declare, TRACE_host_variable_add_with_time, TRACE_host_variable_sub_with_time
+ */
+void TRACE_host_variable_set_with_time (double time, const char *host, const char *variable, double value)
+{
+ instr_user_variable(time, host, variable, "HOST", value, INSTR_US_SET, NULL, user_host_variables);
+}
+
+/** \ingroup TRACE_user_variables
+ * \brief Add a value to a variable of a host at a given timestamp.
+ *
+ * Same as #TRACE_host_variable_add, but let user specify
+ * the time used to trace it. Users can specify a time that
+ * is not the simulated clock time as defined by the core
+ * simulator. This allows a fine-grain control of time
+ * definition, but should be used with caution since the trace
+ * can be inconsistent if resource utilization traces are also traced.
+ *
+ * \param time The timestamp to be used to tag this change of value.
+ * \param host The name of the host to be considered.
+ * \param variable The name of the variable to be considered.
+ * \param value The value to be added to the variable.
+ *
+ * \see TRACE_host_variable_declare, TRACE_host_variable_set_with_time, TRACE_host_variable_sub_with_time
+ */
+void TRACE_host_variable_add_with_time (double time, const char *host, const char *variable, double value)
+{
+ instr_user_variable(time, host, variable, "HOST", value, INSTR_US_ADD, NULL, user_host_variables);
+}
+
+/** \ingroup TRACE_user_variables
+ * \brief Subtract a value from a variable of a host at a given timestamp.
+ *
+ * Same as #TRACE_host_variable_sub, but let user specify
+ * the time used to trace it. Users can specify a time that
+ * is not the simulated clock time as defined by the core
+ * simulator. This allows a fine-grain control of time
+ * definition, but should be used with caution since the trace
+ * can be inconsistent if resource utilization traces are also traced.
+ *
+ * \param time The timestamp to be used to tag this change of value.
+ * \param host The name of the host to be considered.
+ * \param variable The name of the variable to be considered.
+ * \param value The value to be subtracted from the variable.
+ *
+ * \see TRACE_host_variable_declare, TRACE_host_variable_set_with_time, TRACE_host_variable_add_with_time
+ */
+void TRACE_host_variable_sub_with_time (double time, const char *host, const char *variable, double value)
+{
+ instr_user_variable(time, host, variable, "HOST", value, INSTR_US_SUB, NULL, user_host_variables);
+}
+
+/** \ingroup TRACE_user_variables
+ * \brief Get declared user host variables
+ *
+ * This function should be used to get host variables that were already
+ * declared with #TRACE_host_variable_declare or with #TRACE_host_variable_declare_with_color.
+ *
+ * \return A dynar with the declared host variables, must be freed with xbt_dynar_free.
+ */
+xbt_dynar_t TRACE_get_host_variables (void)
+{
+ return instr_dict_to_dynar (user_host_variables);
+}
+
+/* for link variables */
+/** \ingroup TRACE_user_variables
+ * \brief Declare a new user variable associated to links.
+ *
+ * Declare a user variable that will be associated to links.
+ * A user link variable can be used, for example, to trace
+ * user variables such as the number of messages being
+ * transferred through network links. The color
+ * associated to this new variable will be random.
+ *
+ * \param variable The name of the new variable to be declared.
+ *
+ * \see TRACE_link_variable_declare_with_color
+ */
+void TRACE_link_variable_declare (const char *variable)
+{
+ instr_user_variable (0, NULL, variable, "LINK", 0, INSTR_US_DECLARE, NULL, user_link_variables);
+}
+
+/** \ingroup TRACE_user_variables
+ * \brief Declare a new user variable associated to links with a color.
+ *
+ * Same as #TRACE_link_variable_declare, but associated a color
+ * to the newly created user link variable. The color needs to be
+ * a string with three numbers separated by spaces in the range [0,1].
+ * A light-gray color can be specified using "0.7 0.7 0.7" as color.
+ *
+ * \param variable The name of the new variable to be declared.
+ * \param color The color for the new variable.
+ *
+ */
+void TRACE_link_variable_declare_with_color (const char *variable, const char *color)
+{
+ instr_user_variable (0, NULL, variable, "LINK", 0, INSTR_US_DECLARE, color, user_link_variables);
+}
+
+/** \ingroup TRACE_user_variables
+ * \brief Set the value of a variable of a link.
+ *
+ * \param link The name of the link to be considered.
+ * \param variable The name of the variable to be considered.
+ * \param value The new value of the variable.
+ *
+ * \see TRACE_link_variable_declare, TRACE_link_variable_add, TRACE_link_variable_sub
+ */
+void TRACE_link_variable_set (const char *link, const char *variable, double value)
+{
+ TRACE_link_variable_set_with_time (MSG_get_clock(), link, variable, value);
+}
+
+/** \ingroup TRACE_user_variables
+ * \brief Add a value to a variable of a link.
+ *
+ * \param link The name of the link to be considered.
+ * \param variable The name of the variable to be considered.
+ * \param value The value to be added to the variable.
+ *
+ * \see TRACE_link_variable_declare, TRACE_link_variable_set, TRACE_link_variable_sub
+ */
+void TRACE_link_variable_add (const char *link, const char *variable, double value)
+{
+ TRACE_link_variable_add_with_time (MSG_get_clock(), link, variable, value);
+}
+
+/** \ingroup TRACE_user_variables
+ * \brief Subtract a value from a variable of a link.
+ *
+ * \param link The name of the link to be considered.
+ * \param variable The name of the variable to be considered.
+ * \param value The value to be subtracted from the variable.
+ *
+ * \see TRACE_link_variable_declare, TRACE_link_variable_set, TRACE_link_variable_add
+ */
+void TRACE_link_variable_sub (const char *link, const char *variable, double value)
+{
+ TRACE_link_variable_sub_with_time (MSG_get_clock(), link, variable, value);
+}
+
+/** \ingroup TRACE_user_variables
+ * \brief Set the value of a variable of a link at a given timestamp.
+ *
+ * Same as #TRACE_link_variable_set, but let user specify
+ * the time used to trace it. Users can specify a time that
+ * is not the simulated clock time as defined by the core
+ * simulator. This allows a fine-grain control of time
+ * definition, but should be used with caution since the trace
+ * can be inconsistent if resource utilization traces are also traced.
+ *
+ * \param time The timestamp to be used to tag this change of value.
+ * \param link The name of the link to be considered.
+ * \param variable The name of the variable to be considered.
+ * \param value The new value of the variable.
+ *
+ * \see TRACE_link_variable_declare, TRACE_link_variable_add_with_time, TRACE_link_variable_sub_with_time
+ */
+void TRACE_link_variable_set_with_time (double time, const char *link, const char *variable, double value)
+{
+ instr_user_variable (time, link, variable, "LINK", value, INSTR_US_SET, NULL, user_link_variables);
+}
+
+/** \ingroup TRACE_user_variables
+ * \brief Add a value to a variable of a link at a given timestamp.
+ *
+ * Same as #TRACE_link_variable_add, but let user specify
+ * the time used to trace it. Users can specify a time that
+ * is not the simulated clock time as defined by the core
+ * simulator. This allows a fine-grain control of time
+ * definition, but should be used with caution since the trace
+ * can be inconsistent if resource utilization traces are also traced.
+ *
+ * \param time The timestamp to be used to tag this change of value.
+ * \param link The name of the link to be considered.
+ * \param variable The name of the variable to be considered.
+ * \param value The value to be added to the variable.
+ *
+ * \see TRACE_link_variable_declare, TRACE_link_variable_set_with_time, TRACE_link_variable_sub_with_time
+ */
+void TRACE_link_variable_add_with_time (double time, const char *link, const char *variable, double value)
+{
+ instr_user_variable (time, link, variable, "LINK", value, INSTR_US_ADD, NULL, user_link_variables);
+}
+
+/** \ingroup TRACE_user_variables
+ * \brief Subtract a value from a variable of a link at a given timestamp.
+ *
+ * Same as #TRACE_link_variable_sub, but let user specify
+ * the time used to trace it. Users can specify a time that
+ * is not the simulated clock time as defined by the core
+ * simulator. This allows a fine-grain control of time
+ * definition, but should be used with caution since the trace
+ * can be inconsistent if resource utilization traces are also traced.
+ *
+ * \param time The timestamp to be used to tag this change of value.
+ * \param link The name of the link to be considered.
+ * \param variable The name of the variable to be considered.
+ * \param value The value to be subtracted from the variable.
+ *
+ * \see TRACE_link_variable_declare, TRACE_link_variable_set_with_time, TRACE_link_variable_add_with_time
+ */
+void TRACE_link_variable_sub_with_time (double time, const char *link, const char *variable, double value)
+{
+ instr_user_variable (time, link, variable, "LINK", value, INSTR_US_SUB, NULL, user_link_variables);
+}
+
+/* for link variables, but with src and dst used for get_route */
+/** \ingroup TRACE_user_variables
+ * \brief Set the value of the variable present in the links connecting source and destination.
+ *
+ * Same as #TRACE_link_variable_set, but instead of providing the
+ * name of link to be considered, provide the source and destination
+ * hosts. All links that are part of the route between source and
+ * destination will have the variable set to the provided value.
+ *
+ * \param src The name of the source host for get route.
+ * \param dst The name of the destination host for get route.
+ * \param variable The name of the variable to be considered.
+ * \param value The new value of the variable.
+ *
+ * \see TRACE_link_variable_declare, TRACE_link_srcdst_variable_add, TRACE_link_srcdst_variable_sub
+ */
+void TRACE_link_srcdst_variable_set (const char *src, const char *dst, const char *variable, double value)