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/**

   @file This file contains the functions and definitions for the core

   module.

   The file contains all fuinctions and data structures for the core

   module of the FSF.

 */

//fsf_core.h

//=================================================================

//       FFFFFFIII   RRRRR      SSTTTTTTT

//      FF         IIR   RR    SS

//     FF           IR        SS

//    FFFFFF         RRRR    SSSSST

//   FF       FI       RRR  SS

//  FF         II     RRR  SS

// FF           IIIIIR    RS

//

// Basic FSF(FIRST Scheduling Framework) contract management

//================================================================

#include <time.h>

#include <pthread.h>

#include <sys/types.h>

#include <stdbool.h>  

#include "fsf_configuration_parameters.h"

#include "fsf_opaque_types.h"

#include "fsf_basic_types.h"

#ifndef _FSF_CORE_H_

#define _FSF_CORE_H_

//////////////////////////////////////////////////////////////////////

//           INITIALIZATION SERVICES 

//////////////////////////////////////////////////////////////////////

/**

    \ingroup coremodule

    \defgroup core_init Initialization and utilities

    @{

*/

/**

   We cannot call any fsf functions before fsf_init. After calling

   fsf_init, the main will be executing in the background. Then, it

   can do the negotiations, create the threads and, if needed,

   activate them via some user-specified synchronization mechanism. It

   may also create a contract for itself. The second time this

   function is called it fails.

   @retval 0 if the system is initialized

   @retval FSF_ERR_SYSTEM_ALREADY_INITIALIZED if the function has already

           been called before

   @retval others It may also return any of the errors that may be

         returned by the underlying operating system primitives

         required to perform the FSF system start up

*/

int fsf_init();

/**

   This function converts an error code to an error message that is

   stored in the buffer starting at the location pointed to by

   message. The size of this buffer is specified by the size

   argument. If the error message is longer than size-1, it is

   truncated to that length. Regardless of whether the message is

   truncated or not, a final zero character that marks the end of the

   string is stored in the buffer.  The function fails if the error

   code passed does not correspond to any of the fsf error codes.

   @retval FSF_ERR_BAD_ARGUMENT  error is not a valid value

*/

int fsf_strerror (int error, char *message, size_t size);

/* @} */

/////////////////////////////////////////////////////////////

//                       CONTRACT PARAMETERS

/////////////////////////////////////////////////////////////

/**

   \ingroup coremodule

   \defgroup core_contract Contract Creation and Initialization.

   These functions are used to create and initialize a contract, and

   set its parameters.

 */

/*@{*/

/**

    Contract parameters type; it is an opaque type (i.e. the internal

    structure of this data type is implementation dependent). The user

    can access and modify the parameters of a contract only with the

    proper functions, and should never access the data directly.

*/

typedef FSF_CONTRACT_PARAMETERS_T_OPAQUE fsf_contract_parameters_t;

/**

    The operation receives a pointer to a contract parameters object

    and initializes it, setting it to the default values.

    The default values are:

    - budget min and max are set to 0;

    - period min and max are set to 0;

    - the workload is unbounded (FSF_INDETERMINATE);

    - the server deadline is equal to the period;

    - the budget and deadline overrun are not notified;

    - the granularity is set to "continuous";

    - the quality and importance are set to the default values;

    - the scheduling policy is FSF_NONE.

    @param     contract the pointer to the contract variable.

    @retval   FSF_ERR_BAD_ARGUMENT   contract is NULL

*/

int fsf_initialize_contract (fsf_contract_parameters_t *contract);

//  budget_min                => {0,0};

//  period_max                => {0,0};

//  budget_max                => {0,0};

//  period_min                => {0,0};

//  workload                  => DEFAULT_WORKLOAD;

//  d_equals_t                => DEFAULT_D_EQUALS_T; (false or true)

//  deadline                  => DEFAULT_DEADLINE;

//  budget_overrun_sig_notify => 0;  (signal number)

//  budget_overrun_sig_value  => {0, NULL};

//  deadline_miss_sig_notify  => 0;  (signal number)

//  deadline_miss_sig_value   => {0, NULL};

//

//  granularity               => DEFAULT_GRANULARITY;

//  utilization_set;          => size = 0

//  quality                   => DEFAULT_QUALITY;    (range 0..100)

//  importance                => DEFAULT_IMPORTANCE; (range 1..5)

//

//  preemption_level          => 0; (range 1..2**32-1)

//  critical_sections;        => size = 0

//  sched_policy              => DEFAULT_SCHED_POLICY

//                              (FSF_NONE)

/**

   The operation updates the specified contract parameters object by

   setting its budget, period, and workload to the specified input

   parameters. (Note: the workload is a basic parameter because

   bounded tasks are triggered by the scheduler (see the

   fsf_schedule_timed_job() operation), while indeterminate tasks are

   not; therefore, their programming model is quite different).

   @param contract          the pointer to the contract object

   @param [in] budget_min   the minimum budget for the contract

   @param [in] period_max   the maximum period for the contract

   @param [in] workload     the kind of workload (can be FSF_BOUNDED or

                            FSF_INDETERMINATE)

   @retval 0 if the operation is succesful

   @retval FSF_ERR_BAD_ARGUMENT if any of the pointers is NULL

       or if only one of the timespec values is 0, and also if the workload

       is not a proper value (FSF_INDETERMINATE or FSF_BOUNDED)

*/

int

fsf_set_contract_basic_parameters

  (fsf_contract_parameters_t *contract,

   const struct timespec     *budget_min,

   const struct timespec     *period_max,

   fsf_workload_t            workload);

/**

   This operation obtains from the specified contract parameters

   object its budget, period, and workload, and copies them to the

   places pointed to by the corresponding input parameters.

   @param [in] contract   the pointer to the contract object

   @param[out] budget_min pointer to the variable that will contain

   the minimum budget

   @param[out] period_max pointer to the variable that will contain the

   max_period

   @param[out] workload pointer to the variable that will contain the

   workload type

   @retval  FSF_ERR_BAD_ARGUMENT :  if contract is NULL

*/

int

fsf_get_contract_basic_parameters

  (const fsf_contract_parameters_t *contract,

   struct timespec  *budget_min,

   struct timespec  *period_max,

   fsf_workload_t   *workload);

/**

   The operation updates the specified contract parameters

   object, specifying the additional parameters requirements of

   a contract.

   @param  contract The pointer to the contract object

   @param [in] d_equals_t It is a boolean value, set to true (1) if the

                 we want to specify a deadline different from the period

                 for the contract.

   @param [in] deadline If the previous parameter is set to true,

                 this parameter should be set to NULL_DEADLINE. Otherwise,

                 it contains the desired deadline value.

   @param [in] budget_overrun_sig_notify contains the number of posix signal

                 that must be raised if the budget of the server is overrun.

                 If the value of this parameter is NULL_SIGNAL, no signal will

                 be raised.

   @param [in] budget_overrun_sig_value contains the value that will be

                 passed to the signal "catcher" when the signal is raised.

                 This parameters is not used if the budget_overrun_sig_notify

                 parameters is set to NULL_SIGNAL.

   @param [in] deadline_miss_sig_notify contains the number of posix

                 signal that must be raised if the deadline of the server

                 is missed. If the value of this parameter is NULL_SIGNAL,

                 no signal is raised.

   @param [in] deadline_miss_sig_value contains the value that will be

                 passed to the signal "catcher" when the signal is raised.

                 This parameters is not used if the budget_overrun_sig_notify

                 parameters is set to NULL_SIGNAL

   @retval 0    if the operation is succesful

   @retval FSF_BAD_ARGUMENT if contract is NULL or  

       (d_equals_t is true and  deadline is not FSF_NULL_DEADLINE) or

       (budget_overrun_sig_notify is not a valid signal)  or

       (deadline_miss_sig_notify is not a valid signal)  or

       (d_equals_t is false but (deadline is FSF_NULL_DEADLINE or its value

                                 is grater than the contracts maximum period))

   @see sigexplanation

*/

int

fsf_set_contract_timing_requirements

  (fsf_contract_parameters_t *contract,

   bool                   d_equals_t,

   const struct timespec *deadline,

   int                    budget_overrun_sig_notify,

   union sigval           budget_overrun_sig_value,

   int                    deadline_miss_sig_notify,

   union sigval           deadline_miss_sig_value);

/**

   The operation obtains the corresponding input parameters from the

   specified contract parameters object. If d_equals_t is true, the

   deadline will not be updated.

   @retval FSF_ERR_BAD_ARGUMENT if contract is NULL

   @see fsf_set_contract_timing_requirements

*/

int

fsf_get_contract_timing_requirements

  (const fsf_contract_parameters_t *contract,

   bool                    *d_equals_t,

   struct timespec         *deadline,

   int                     *budget_overrun_sig_notify,

   union sigval            *budget_overrun_sig_value,

   int                     *deadline_miss_sig_notify,

   union sigval            *deadline_miss_sig_value);

/*@}*/

//////////////////////////////////////////////////////////////////

//                 SYNCHRONIZATION OBJECTS

//////////////////////////////////////////////////////////////////

/**

   \ingroup coremodule

   \defgroup core_synch  Synchronization objects

   These objects are used to synchronize threads belonging to bounded

   workload servers.

   In the future we may add a broadcast operation that would signal a

   group of synchronization objects. We have not included a broadcast

   service in this version because it can be easily created by the

   user by signalling individual synchronization objects inside a

   loop.

   Notice that for synchronization objects there is no naming service

   like in shared objects because tasks that use synchronization are

   not developed independently, as they are closely coupled.

*/

/*@{*/

/**

   An abstract synchronization object is defined by the application.

   This object can be used by an application to wait for an event to

   arrive by invoking the fsf_schedule_triggered_job() operation.  It

   can also be used to signal the event either causing a waiting

   server to wake up, or the event to be queued if no server is

   waiting for it.

*/

typedef FSF_SYNCH_OBJ_HANDLE_T_OPAQUE fsf_synch_obj_handle_t;

/**

   This operation creates and initializes a synchronization object

   variable managed by the scheduler, and returns a handle to it in

   the variable pointed to by synch_handle.

   @param[out] synch_handle pointer to the variable that will contain

                the handle to the newly created synchronization object

   @retval  0 if the operation is succesful

   @retval  FSF_ERR_BAD_ARGUMENT   if synch_handle is 0

   @retval  FSF_ERR_TOO_MANY_SYNCH_OBJS  if the number of synchronization

             objects in the system has already exceeded the maximum

   @retval FSF_ERR_NOT_SCHEDULED_CALLING_THREAD  if the calling thread is not

            scheduled under the FSF

   @retval  FSF_ERR_INVALID_SCHEDULER_REPLY  the scheduler is wrong

             or not running

*/

int

fsf_create_synch_obj

    (fsf_synch_obj_handle_t *synch_handle);

/**

   This function sends a notification to the synchronization object

   specified as parameter. If there is at least one server waiting on

   the synchronization object, the corresponding thread is unblocked,

   and the server rules for budget recharging apply.

   If more than one server is waiting, just one of them is woken.

   However, which one is woken is implementation dependent.

   If no thread is waiting on the synchronization object, the

   notification is queued.

   @param [in] synch_handle the handle of the synchronization object to

                  notify.

   @retval 0 if the operation is completed succesfully

   @retval FSF_ERR_BAD_ARGUMENT   if synch_handle is 0

   @retval FSF_ERR_INVALID_SYNCH_OBJ_HANDLE if the handle is not valid

   @retval FSF_ERR_NOT_SCHEDULED_CALLING_THREAD  if the calling thread

              is not scheduled under the FSF

   @retval FSF_ERR_INVALID_SCHEDULER_REPLY  the scheduler is wrong or

              not running

   @retval FSF_ERR_TOO_MANY_EVENTS_IN_SYNCH_OBJ  if the number of

              events stored in the synchronization object reaches the

              maximum defined in the configuration parameter header file

   @see fsf_schedule_triggered_job, fsf_timed_schedule_triggered_job

*/

int

fsf_signal_synch_obj

    (fsf_synch_obj_handle_t synch_handle);

/**

   This operation destroys the synchronization object (created by a

   previous call to fsf_create_synch_obj) that is referenced by the

   synch_handle variable. After calling this operation, the

   synch_handle variable can not be used until it is initialized again

   by a call to fsf_create_synch_obj.

   @param synch_handle the handle to the synchronization object

             to be destroyed

   @retval 0 if the operation is succesful

   @retval FSF_ERR_INVALID_SYNCH_OBJ_HANDLE is the handle is not valid

   @retval FSF_ERR_BAD_ARGUMENT   if synch_handle is 0

   @retval FSF_ERR_INVALID_SYNCH_OBJ_HANDLE if the handle is not valid

   @retval FSF_ERR_NOT_SCHEDULED_CALLING_THREAD if the calling thread is not

       scheduled under the FSF

   @retval FSF_ERR_INVALID_SCHEDULER_REPLY  the scheduler is wrong or

       not running

   @see fsf_create_synch_obj

*/

int

fsf_destroy_synch_obj

    (fsf_synch_obj_handle_t synch_handle);

////////////////////////////////////////////////////

//           SCHEDULING BOUNDED WORKLOADS

////////////////////////////////////////////////////

/**

   This operation is invoked by threads associated with bounded

   workload servers to indicate that a job has been completed (and

   that the scheduler may reassign the unused capacity of the current

   job to other servers). It is also invoked when the first job of

   such threads has to be scheduled.

   As an effect, the system will make the current server's budget zero

   for the remainder of the server's period, and will not replenish

   the budget until the specified absolute time.  At that time, all

   pending budget replenishments (if any) are made effective. Once the

   server has a positive budget and the scheduler schedules the

   calling thread again, the call returns and at that time, except for

   those parameters equal to NULL pointers, the system reports the

   current period and budget for the current job, whether the deadline

   of the previous job was missed or not, and whether the budget of

   the previous job was overrun or not.

   In a system with hierarchical scheduling, since this call makes the

   budget zero, the other threads in the same server are not run. As

   mentioned abobe, only when the call finishes the budget may be

   replenished.

   @param [in] abs_time     absolute time at which the budget will be

                            replenished

   @param [out] next_budget upon return of this function, the variable

                            pointed by this function will be equal to

                            the current server budget. If this parameter is

                            set to NULL, no action is taken.

   @param [out] next_period upon return of this function, the variable

                            pointed by this function will be equal to

                            the current server period. If this parameter is

                            set to NULL, no action is taken.

   @param [out] was_deadline_missed upon return of this function, the

                            variable pointed by this function will be

                            equal to true if the previous server deadline

                            was missed, to false otherwise. If this

                            parameter is set to NULL, no action is

                            taken.

   @param [out] was_budget_overran upon return of this function, the

                            variable pointed by this function will be

                            equal to true if the previous server budget was

                            overrun, to false otherwise. If this

                            parameter is set to NULL, no action is

                            taken.

   @retval 0 if the operation is succesful

   @retval FSF_ERR_INVALID_SCHEDULER_REPLY  the scheduler is wrong or

              not running

   @retval FSF_ERR_INTERNAL_ERROR  erroneous binding or malfunction of the FSF

       main scheduler

   @retval FSF_ERR_NOT_SCHEDULED_CALLING_THREAD if the calling thread is

       not scheduled under the FSF

   @retval FSF_ERR_UNBOUND if the calling thread does not have a valid

       server bound to it

   @retval FSF_ERR_BAD_ARGUMENT   if the workload of the server is not

       FSF_BOUNDED

   @sa fsf_schedule_triggered_job, fsf_timed_schedule_triggered_job

*/

int

fsf_schedule_timed_job

  (const struct timespec *abs_time,

   struct timespec       *next_budget,

   struct timespec       *next_period,

   bool                  *was_deadline_missed,

   bool                  *was_budget_overran);

/**

   This operation is invoked by threads associated with bounded

   workload servers to indicate that a job has been completed (and

   that the scheduler may reassign the unused capacity of the current

   job to other servers). It is also invoked when the first job of

   such threads has to be scheduled. If the specified synchronization

   object has events queued, one of them is dequeued; otherwise the

   server will wait upon the specified synchronization object, the

   server's budget will be made zero for the remainder of the server's

   period, and the implementation will not replenish the budget until

   the specified synchronization object is signalled.

   At that time, all pending budget replenishments (if any) are made

   effective. Once the server has a positive budget and the scheduler

   schedules the calling thread again, the call returns and at that

   time, except for those parameters equal to NULL pointers, the

   system reports the current period and budget for the current job,

   whether the deadline of the previous job was missed or not, and

   whether the budget of the previous job was overrun or not.

   In a system with hierarchical scheduling, since this call makes the

   budget zero, the other threads in the same server are not run. As

   mentioned above, only when the call finishes the budget may be

   replenished.

   @param [in]  synch_handle   handle of the synchronization object

   @param [out] next_budget    upon return of this function, the variable

                               pointed by this function will be equal

                               to the current server budget. If this

                               parameter is set to NULL, no action is

                               taken.

   @param [out] next_period    upon return of this function, the variable

                               pointed by this function will be equal to

                               the current server period. If this parameter is

                               set to NULL, no action is taken.

   @param [out] was_deadline_missed upon return of this function, the

                            variable pointed by this function will be

                            equal to true if the previous server deadline

                            was missed, to false otherwise. If this

                            parameter is set to NULL, no action is

                            taken.

   @param [out] was_budget_overran upon return of this function, the

                            variable pointed by this function will be

                            equal to true if the previous server budget was

                            overrun, to false otherwise. If this

                            parameter is set to NULL, no action is

                            taken.

   @retval 0 if the operation is succesful

   @retval  FSF_ERR_INVALID_SYNCH_OBJ_HANDLE if the handle is not valid

   @retval  FSF_ERR_INVALID_SCHEDULER_REPLY  the scheduler is wrong or not

            running

   @retval  FSF_ERR_INTERNAL_ERROR  erroneous binding or malfunction of

            the FSF main scheduler

   @retval  FSF_ERR_NOT_SCHEDULED_CALLING_THREAD if the calling thread

            is not scheduled under the FSF

   @retval  FSF_ERR_UNBOUND if the calling thread does not have

            a valid server bound to it

   @retval  FSF_ERR_BAD_ARGUMENT if the workload of the server is not

            FSF_BOUNDED or the synch_handle given is not valid

   @sa fsf_schedule_triggered_job, fsf_schedule_timed_job

*/

int

fsf_schedule_triggered_job

  (fsf_synch_obj_handle_t  synch_handle,

   struct timespec         *next_budget,

   struct timespec         *next_period,

   bool                    *was_deadline_missed,

   bool                    *was_budget_overran);

/**

   This call is the same as fsf_schedule_triggered_job, but with an

   absolute timeout. The timed_out argument, indicates whether the

   function returned because of a timeout or not

   @retval FSF_ERR_INVALID_SCHEDULER_REPLY the scheduler is wrong or

       not running

   @retval FSF_ERR_INTERNAL_ERROR  erroneous binding or malfunction

       of the FSF main scheduler

   @retval FSF_ERR_NOT_SCHEDULED_CALLING_THREAD if the calling thread is

       not scheduled under the FSF

   @retval FSF_ERR_UNBOUND  if the calling thread does not have a valid

       server bound to it

   @retval FSF_ERR_BAD_ARGUMENT   if the workload of the server is not

       FSF_BOUNDED, the synch_handle given is not valid or the abs_timeout

       argument is NULL or its value is in the past

   @see fsf_schedule_triggered_job

*/

int

fsf_timed_schedule_triggered_job

  (fsf_synch_obj_handle_t  synch_handle,

   const struct timespec   *abs_timeout,

   bool                    *timed_out,

   struct timespec         *next_budget,

   struct timespec         *next_period,

   bool                    *was_deadline_missed,

   bool                    *was_budget_overran);

/*@}*/

///////////////////////////////////////////////////////////////////

//                 CONTRACT NEGOCIATION OPERATIONS

///////////////////////////////////////////////////////////////////

/**

   \ingroup coremodule

   \defgroup core_negotiate Negotiate contract functions

   The following functions are used to create servers for a contract

   parameters specification and also to assign one or more threads to

   a server.

*/

/*@{*/

/**

    Server Id type, that identifies a server created to manage a given

    contract

*/

typedef int      fsf_server_id_t;             // => 0

/**

    The type references a function that may become a thread's

    code

*/

typedef void * (*fsf_thread_code_t) (void *);

/**

   The operation negotiates a contract for a new server. If the

   on-line admission test is enabled it determines whether the

   contract can be admitted or not based on the current contracts

   established in the system. Then it creates the server and

   recalculates all necessary parameters for the contracts already

   present in the system.

   This is a potentially blocking operation; it returns when the

   system has either rejected the contract, or admitted it and made it

   effective. It returns zero and places the server identification

   number in the location pointed to by the server input parameter if

   accepted, or an error if rejected.  No thread is bound to the newly

   created server, which will be idle until a thread is bound to

   it. This operation can only be executed by threads that are already

   bound to an active server and therefore are being scheduled by the

   fsf scheduler.

   @param [in] contract pointer to the contract

   @param [out] server server id

   @retval 0 if the call is succesful

   @retval FSF_ERR_INVALID_SCHEDULER_REPLY  the scheduler is wrong or not

                                            running

   @retval FSF_ERR_INTERNAL_ERROR  erroneous binding or malfunction of the FSF

                                   main scheduler

   @retval FSF_ERR_NOT_SCHEDULED_CALLING_THREAD  

                                   if the calling thread is not scheduled

                                   under the FSF

   @retval FSF_ERR_BAD_ARGUMENT    if the contract or server arguments

                                   are NULL

*/

int

fsf_negotiate_contract

  (const fsf_contract_parameters_t *contract,

   fsf_server_id_t      *server);

/**

   This operation negotiates a contract for a new server, creates a

   thread and binds it to the server. If the contract is accepted, the

   operation creates a thread with the arguments thread, attr,

   thread_code and arg as they are defined for the pthread_create()

   POSIX function call, and attaches it to the fsf scheduler. Then, it

   binds the created thread to the new server. It returns zero and

   puts the server identification number in the location pointed to by

   the server input parameter.

   The attr parameter is overwritten as necessary to introduce the

   adequate scheduling attributes, according to the information given

   in the contract.

   The server is created with the FSF_NONE scheduling policy, which

   means no hierarchical scheduling, and only one thread per server,

   except for the case of background tasks (see below)

   If the contract is rejected, the thread is not created and the

   corresponding error is returned.

   @param [in] contract pointer to the contract

   @param [out] server server id

   @param [out] thread thread id

   @param [in] attr threads attributes

   @param [in] thread_code  pointer to the function that implements

               the thread

   @param [in] arg  arguments for the thread

   @retval  FSF_ERR_BAD_ARGUMENT  if the contract or server arguments are NULL

   @retval  FSF_ERR_CONTRACT_REJECTED  if the contract is rejected

   @retval  others it may also return all the errors that may be returned

            by the pthread_create()POSIX function call

*/

int

fsf_negotiate_contract_for_new_thread

  (const fsf_contract_parameters_t *contract,

   fsf_server_id_t      *server,

   pthread_t            *thread,

   pthread_attr_t       *attr,

   fsf_thread_code_t     thread_code,

   void                 *arg);

/**

   This operation negotiates a contract for a new server, and binds

   the calling thread to it. If the contract is accepted it returns

   zero and copies the server identification number in the location

   pointed to by the server input parameter.  If it is rejected, an

   error is returned.

   The server is created with the FSF_NONE scheduling policy, which

   means no hierarchical scheduling, and only one thread per server,

   except for the case of background tasks (see below)

   Implementation dependent issue: In order to allow the usage of

   application defined schedulers, the calling thread must not have

   the SCHED_APP scheduling policy and at the same time be attached to

   an application scheduler different than the fsf scheduler; in such

   case, an error is returned. After a successful call the calling

   thread will have the SCHED_APP scheduling policy and will be

   attached to the fsf scheduler.

   @param [in] contract pointer to the contract

   @param [out] server id

   @retval 0 if the contract negotation is succesful

   @retval  FSF_ERR_UNKNOWN_APPSCHEDULED_THREAD  if the thread is attached to

       an application defined scheduler different than the fsf scheduler

   @retval FSF_ERR_BAD_ARGUMENT  if the contract or server arguments

       are NULL

   @retval FSF_ERR_CONTRACT_REJECTED  if the contract is rejected.

*/

int

fsf_negotiate_contract_for_myself

  (const fsf_contract_parameters_t *contract,

   fsf_server_id_t      *server);

/**

   This operation associates a thread with a server, which means that

   it starts consuming the server's budget and is executed according

   to the contract established for that server. If the thread is

   already bound to another server, and error is returned.

   It fails if the server's policy is different than FSF_NONE, or if

   there is already a thread bound to this server

   Implementation dependent issue: In order to allow the usage of

   application defined schedulers, the given thread must not have the

   scheduling policy SCHED_APP and at the same time be attached to an

   application scheduler different than the fsf scheduler.

   @param [in] server id

   @param [in] thread id

   @retval FSF_ERR_INTERNAL_ERROR  erroneous binding or malfunction

       of the FSF main scheduler

   @retval FSF_ERR_UNKNOWN_APPSCHEDULED_THREAD if the thread is attached to

       an application defined scheduler different than the fsf scheduler

   @retval FSF_ERR_BAD_ARGUMENT if the server value does not complain with the

       expected format or valid range or the given thread does not exist

   @retval FSF_ERR_NOT_CONTRACTED_SERVER if the referenced server

       is not valid

   @retval FSF_ERR_ALREADY_BOUND if the thread is already bound to

       another server.

*/

int

fsf_bind_thread_to_server

  (fsf_server_id_t server,

   pthread_t       thread);

/**

   This operation unbinds a thread from a server.  Since threads with

   no server associated are not allow to execute, they remain in a

   dormant state until they are either eliminated or bound again.

   If the thread is inside a critical section the effects of this call

   are deferred until the critical section is ended

   Implementation dependent issue: in the implementation with an

   application scheduler, the thread is still attached to the fsf

   scheduler, but suspended.

   @param [in] thread thread id

   @retval 0 if the operation is succesful

   @retval FSF_ERR_INTERNAL_ERROR  erroneous binding or malfunction of the FSF

       main scheduler

   @retval FSF_ERR_BAD_ARGUMENT  if the given thread does not exist

   @retval FSF_ERR_NOT_SCHEDULED_THREAD  if the given thread is not scheduled

       under the FSF

   @retval FSF_ERR_UNKNOWN_APPSCHEDULED_THREAD if the thread is attached to

       an application defined scheduler different than the fsf scheduler

   @retval FSF_ERR_NOT_BOUND if the given thread does not have a valid

       server bound to it

*/

int

fsf_unbind_thread_from_server (pthread_t thread);

/**

   This operation stores the Id of the server associated with the

   specified thread in the variable pointed to by server. It returns

   an error if the thread does not exist, it is not under the control

   of the scheduling framework, or is not bound.

   @param [in] thread thread id

   @param [out] server server

   @retval 0 if the operation is succesful

   @return FSF_ERR_NOT_SCHEDULED_THREAD if the given thread is not scheduled

       under the FSF

   @return FSF_ERR_UNBOUND if the given thread does not have a valid

       server bound to it

   @return FSF_ERR_BAD_ARGUMENT if the given thread does not exist or the

       server argument is NULL

*/

int

fsf_get_server

  (pthread_t       thread,

   fsf_server_id_t *server);

/**

   This operation stores the contract parameters currently associated

   with the specified server in the variable pointed to by

   contract. It returns an error if the server id is incorrect.

   @param [in] server server id

   @param [out] contract pointer to the contract structure

   @retval 0 if the operation is succesful

   @retval FSF_ERR_BAD_ARGUMENT  if the contract argument is

         NULL or the value of the server argument is not in range

   @retval FSF_ERR_NOT_SCHEDULED_CALLING_THREAD if the calling thread is not

       scheduled under the FSF

   @retval FSF_ERR_INVALID_SCHEDULER_REPLY  the scheduler is wrong or

       not running

   @retval FSF_ERR_NOT_CONTRACTED_SERVER if the server of the calling thread

       has been cancelled or it is not valid

*/

int

fsf_get_contract

   (fsf_server_id_t server,

    fsf_contract_parameters_t *contract);

/**

   The operation eliminates the specified server

   and recalculates all necessary parameters for the contracts

   remaining in the system. This is a potentially blocking operation;

   it returns when the system has made the changes effective.

   @param [in] server server id

   @retval 0 if the operation is succesful

   @retval FSF_ERR_BAD_ARGUMENT   if the value of server is not in range

   @retval FSF_ERR_NOT_SCHEDULED_CALLING_THREAD  if the calling thread is not

           scheduled under the FSF

   @retval FSF_ERR_INVALID_SCHEDULER_REPLY  the scheduler is wrong or not

           running

   @retval FSF_ERR_NOT_CONTRACTED_SERVER  if the server of the calling thread

           has been cancelled or it is not valid

*/

int

fsf_cancel_contract (fsf_server_id_t server);

/**

   The operation renegotiates a contract for an existing server. If

   the on-line admission test is enabled it determines whether the

   contract can be admitted or not based on the current contracts

   established in the system. If it cannot be admitted, the old

   contract remains in effect and an error is returned. If it can be

   admitted, it recalculates all necessary parameters for the

   contracts already present in the system anr returns zero. This is a

   potentially blocking operation; it returns when the system has

   either rejected the new contract, or admitted it and made it

   effective.

   @param [in]  new_contract a pointer to the new contract

   @param [in]  server server id

   @retval 0 if the operation is succesful

   @retval FSF_ERR_BAD_ARGUMENT  if the new_contract argument is NULL or the  

       value of the server argument is not in range

   @retval FSF_ERR_NOT_SCHEDULED_CALLING_THREAD if the calling thread is not

       scheduled under the FSF

   @retval FSF_ERR_INVALID_SCHEDULER_REPLY the scheduler is wrong or not

       running

   @retval FSF_ERR_NOT_CONTRACTED_SERVER if the server of the calling thread

       has been cancelled or it is not valid

*/

int

fsf_renegotiate_contract

  (const fsf_contract_parameters_t *new_contract,

   fsf_server_id_t server);

/**

   The operation enqueues a renegotiate operation for an existing

   server, and returns immediately. The renegotiate operation is

   performed asynchronously and the calling thread may continue

   executing normally. Of course, wheter the operation is performed

   immediately or not depends on the relative priority of the service

   thread and the calling thread, on the scheduler used, etc.

   When the renegotiation is completed, if the on-line admission test

   is enabled it determines whether the contract can be admitted or

   not based on the current contracts established in the system. If it

   cannot be admitted, the old contract remains in effect. If it can

   be admitted, it recalculates all necessary parameters for the

   contracts already present in the system. When the operation is

   completed, notification is made to the caller, if requested, via a

   signal. The status of the operation (in progress, admitted,

   rejected) can be checked with the get_renegotiation_status

   operation.  The argument sig_notify can be NULL_SIGNAL (no

   notification), or any POSIX signal; and in this case sig_value is

   to be sent with the signal.

   @param [in] new_contract pointer to the new contract to be negotiated

   @param [in] server  server id

   @param [in] sig_notify NULL (no signal) or any POSIX signal

   @param [in] sig_value a sigval structure that contains values to be

               passed to the signal handler. Valid only if sig_notify

               is different from NULL.

   @retval 0 if the call is succesful

   @retval FSF_ERR_BAD_ARGUMENT  if the new_contract argument is NULL, the  

       value of the server argument is not in range or sig_notify is

       neither NULL nor a valid POSIX signal

   @retval FSF_ERR_NOT_SCHEDULED_CALLING_THREAD if the calling thread is not

       scheduled under the FSF

   @retval FSF_ERR_INVALID_SCHEDULER_REPLY the scheduler is wrong or not

       running

   @retval FSF_ERR_NOT_CONTRACTED_SERVER if the server of the calling thread

       has been cancelled or it is not valid

*/

int

fsf_request_contract_renegotiation

  (const fsf_contract_parameters_t *new_contract,

   fsf_server_id_t                  server,

   int                              sig_notify,

   union sigval                     sig_value);

/**

   Possible values returned by fsf_get_renegotiation_status

*/

typedef enum {FSF_IN_PROGRESS,

              FSF_REJECTED,

              FSF_ADMITTED}

    fsf_renegotiation_status_t;

/**

   The operation reports on the status of the last renegotiation

   operation enqueued for the specified server. It is callable even

   after notification of the completion of such operation, if

   requested.

   @param [in] server server id

   @param [out] renegotiation_status the status of the renegotiation;

   @retval 0 if succesful completion;

   @retval FSF_ERR_BAD_ARGUMENT  if the renegotiation_status argument is

       NULL or the value of the server argument is not in range

   @retval FSF_ERR_NOT_SCHEDULED_CALLING_THREAD if the calling thread is not

       scheduled under the FSF

   @retval FSF_ERR_INVALID_SCHEDULER_REPLY the scheduler is wrong or not

       running

   @retval FSF_ERR_NOT_CONTRACTED_SERVER if the server of the calling thread

       has been cancelled or it is not valid

*/

int

fsf_get_renegotiation_status

  (fsf_server_id_t server,

   fsf_renegotiation_status_t *renegotiation_status);

//Data types

/// List of contracts to negotiate

typedef struct {

  int  size;

  fsf_contract_parameters_t*  contracts[FSF_MAX_N_SERVERS];

} fsf_contracts_group_t;

/// List of servers to cancel

typedef  struct {

  int             size;

  fsf_server_id_t servers[FSF_MAX_N_SERVERS];

} fsf_servers_group_t;

/**

   This operation analizes the schedulability of the context that

   results from negitiating the contracts specified in the

   contracts_up list and cacelling the contracts referenced by the

   servers_down list. If the overall negotiation is successful, a new

   server will be created for each of the elements of the contracts_up

   group, the servers in servers_down will be cancelled, the list of

   new server ids will be returned in the variable pointed to by

   servers_up, and the variable pointed to by accepted will be made

   true. Otherwise, this variable will be made false, and no other

   effect will take place. The function returns the corresponding