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//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
//================================================================
/**
\defgroup core Core module
This module includes the basic functions and services that are
provided by any FSF implementation. This module includes basic type
definitions, and functions to
- create a contract and initialize it
- set/get the basci parameters of a contract
- negotiate a service contract, obtaining a server id
- create and bind threads to servers
- create/destroy a synchronization object
- manage bounded workloads
*/
/*@{*/
/**
\file fsf_core.h
This file contains the types, definitions and function prototypes
for the core module of the First Scheduling Framework.
*/
#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_
/////////////////////////////////////////////////////////////////
// BASIC TYPES AND CONSTANTS in fsf_basic_types.h
/////////////////////////////////////////////////////////////////
//typedef enum {FSF_BOUNDED, FSF_INDETERMINATE}
// fsf_workload_t;
//// Constants for assigning default values
//
//#define FSF_DEFAULT_WORKLOAD FSF_INDETERMINATE
//#define FSF_DEFAULT_D_EQUALS_T false
//#define FSF_DEFAULT_DEADLINE {0,0} //struct timespec
//
//
//// Constants for omitting the assignment of values
//// to specific arguments in calls to
//// initialization functions
//
//#define FSF_NULL_DEADLINE (struct timespec *)NULL
//#define FSF_NULL_SIGNAL 0
//
//
//// Error codes
//#define FSF_ERR_TOO_MANY_TASKS 2003001
//#define FSF_ERR_BAD_ARGUMENT 2003002
//#define FSF_ERR_INVALID_SYNCH_OBJ_HANDLE 2003003
//#define FSF_ERR_NO_RENEGOTIATION_REQUESTED 2003004
//#define FSF_ERR_CONTRACT_REJECTED 2003005
//#define FSF_ERR_NOT_SCHEDULED_CALLING_THREAD 2003006
//#define FSF_ERR_UNBOUND_THREAD 2003007
//#define FSF_ERR_UNKNOWN_APPSCHEDULED_THREAD 2003008
//#define FSF_ERR_NOT_CONTRACTED_SERVER 2003009
//#define FSF_ERR_NOT_SCHEDULED_THREAD 2003010
//#define FSF_ERR_TOO_MANY_SERVICE_JOBS 2003011
//#define FSF_ERR_TOO_MANY_SYNCH_OBJS 2003012
//#define FSF_ERR_TOO_MANY_SERVERS_IN_SYNCH_OBJ 2003013
//#define FSF_ERR_TOO_MANY_EVENTS_IN_SYNCH_OBJ 2003014
//#define FSF_ERR_INTERNAL_ERROR 2003015
//#define FSF_ERR_TOO_MANY_SERVERS 2003016
//#define FSF_ERR_INVALID_SCHEDULER_REPLY 2003017
//#define FSF_ERR_TOO_MANY_PENDING_REPLENISHMENTS 2003018
//#define FSF_WRN_MODULE_NOT_SUPPORTED 2004001
//#define FSF_ERR_SYSTEM_ALREADY_INITIALIZED 2004002
//
/**
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.
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : error is not a valid value
]
*/
int fsf_strerror (int error, char *message, size_t size);
/////////////////////////////////////////////////////////////
// CONTRACT PARAMETERS
/////////////////////////////////////////////////////////////
/**
\defgroup 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
(PEPPE: implementation dependent??)
- the scheduling policy is FSF_NONE
@param contract the pointer to the contract variable.
@returns (PEPPE: should not return anything! change to void??)
[ERR@RETURNED:
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,
FSF_INDETERMINATE or FSF_OVERHEAD)
@returns 0 if the operation is succesful
@returns FSF_ERR_BAD_ARGUMENT if some of the arguments is not in
the expected range
[ERR@RETURNED:
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, FSF_BOUNDED, or FSF_OVERHEAD)
]
*/
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
@returns (PEPPE: this should return nothing!)
[ERR@RETURNED:
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.
(PEPPE: should be return with error otherwise?)
@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
@returns 0 if the operation is succesful
@returns FSF_BAD_ARGUMENT if some argument is out of range or not
admissible.
[ERR@RETURNED:
FSF_ERR_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 contract´s 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.
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if contract is NULL
]
*/
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
//////////////////////////////////////////////////////////////////
/**
\defgroup synch Synchronization objects
*/
/*@{*/
/**
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] pointer to the variable that will contain the handle to the
newly created synchronization object
@returns 0 if the operation is succesful
@returns FSF_ERR_TOO_MANY_SYNCH_OBJS if the number of synchronization
objects in the system has already exceeded the maximum
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if synch_handle is 0
FSF_ERR_TOO_MANY_SYNCH_OBJS : if the number of synchronization
objects in the system has already exceeded the maximum
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
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 thread waiting on
the synchronization object, it is awaken. If more than one thread
is waiting, just one of them is awaken. However, which one is
awaken is implementation dependent. If no thread is waiting on the
synchronization object, the notification is queued.
[JULIO: all the ocurrrences of the word "thread" should be changed
by "server" in the paragraph above
]
@param [in] synch_handle the handle of the synchronization object to
notify.
@returns 0 if the operation is completed succesfully
@returns FSF_ERR_INVALID_SYNCH_OBJ_HANDLE is the handle is not valid
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if synch_handle is 0
FSF_ERR_INVALID_SYNCH_OBJ_HANDLE if the handle is not valid
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
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
]
@sa 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
@returns 0 if the operation is succesful
@returns FSF_ERR_INVALID_SYNCH_OBJ_HANDLE is the handle is not valid
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if synch_handle is 0
FSF_ERR_INVALID_SYNCH_OBJ_HANDLE if the handle is not valid
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
]
@sa fsf_create_synch_obj
*/
int
fsf_destroy_synch_obj
(fsf_synch_obj_handle_t synch_handle);
// 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.
////////////////////////////////////////////////////
// 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. (PEPPE: I have a question, what
happens to the budget? if I do not get it wrong, the replenishment
time is set to abs_time and the bandwidth of the server up to time
abs_time can be reassigned. Is it true? what is the exact
relationship between this abs_time and the server period? What if
the user specifies an abs_time less than the end of the current
server period??)
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_overrun 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.
@returns 0 if the operation is succesful
@returns FSF_ERR_TIME_SPEC_IN_THE_PAST if the absolute time specification
is in the past.
[ERR@RETURNED:
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
FSF_ERR_INTERNAL_ERROR : erroneous binding or malfunction of the FSF
main scheduler
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not scheduled
under the FSF
FSF_ERR_UNBOUND_THREAD : if the calling thread does not have a valid
server bound to it
FSF_ERR_BAD_ARGUMENT : if abs_time is NULL
FSF_ERR_SERVER_WORKLOAD_NOT_COMPATIBLE: if the kind of 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.
[ERR@RETURNED:
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
FSF_ERR_INTERNAL_ERROR : erroneous binding or malfunction of the FSF
main scheduler
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not scheduled
under the FSF
FSF_ERR_UNBOUND_THREAD : if the calling thread does not have a valid
server bound to it
FSF_ERR_BAD_ARGUMENT : if the synch_handle given is not valid
FSF_ERR_SERVER_WORKLOAD_NOT_COMPATIBLE: if the kind of workload of the server
is not FSF_BOUNDED
]
*/
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
[ERR@RETURNED:
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
FSF_ERR_INTERNAL_ERROR : erroneous binding or malfunction of the FSF
main scheduler
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not scheduled
under the FSF
FSF_ERR_UNBOUND_THREAD : if the calling thread does not have a valid
server bound to it
FSF_ERR_BAD_ARGUMENT : if the synch_handle given is not valid or the
abs_timeout argument is NULL or its value is in the past
FSF_ERR_SERVER_WORKLOAD_NOT_COMPATIBLE: if the kind of workload of the server
is not FSF_BOUNDED
]
*/
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
///////////////////////////////////////////////////////////////////
/**
\defgroup 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 (Note: the current implementation only supports one thread
per server; this limitation will be removed in the next phase of
the project)
*/
/*@{*/
/**
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.
[ERR@RETURNED:
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
FSF_ERR_INTERNAL_ERROR : erroneous binding or malfunction of the FSF
main scheduler
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not scheduled
under the FSF
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 policy and priority,
according to the preemption level given in the contract and the
fsf_priority_map() function defined by the user. If the contract is
rejected, the thread is not created and the corresponding 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)
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if the contract or server arguments are NULL
FSF_ERR_CONTRACT_REJECTED : if the contract is rejected.
FSF_ERR_SERVER_WORKLOAD_NOT_COMPATIBLE: if the kind of workload
in the contract is FSF_OVERHEAD
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.
[ERR@RETURNED:
FSF_ERR_UNKNOWN_APPSCHEDULED_THREAD : if the thread is attached to
an application defined scheduler different than the fsf scheduler
FSF_ERR_BAD_ARGUMENT : if the contract or server arguments are NULL
FSF_ERR_CONTRACT_REJECTED : if the contract is rejected.
FSF_ERR_SERVER_WORKLOAD_NOT_COMPATIBLE: if the kind of workload
in the contract is FSF_OVERHEAD
]
*/
int
fsf_negotiate_contract_for_myself
(const fsf_contract_parameters_t *contract,
fsf_server_id_t *server);
/**
fsf_bind_thread_to_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, it is
effectively unbound from it and bound to the specified one.
It fails if the server's policy is different than FSF_NONE, or if
there is already a thread bound to this server
[JULIO: it should not fail if the thread is bound to other thread
in this case the server shall be unbind and bind to the given one
]
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.
[ERR@RETURNED:
FSF_ERR_INTERNAL_ERROR : erroneous binding or malfunction of the FSF
main scheduler
FSF_ERR_UNKNOWN_APPSCHEDULED_THREAD : if the thread is attached to
an application defined scheduler different than the fsf scheduler
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
FSF_ERR_NOT_CONTRACTED_SERVER : if the referenced server is not valid
FSF_ERR_SERVER_WORKLOAD_NOT_COMPATIBLE: if the kind of workload
of the server is FSF_OVERHEAD
]
*/
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.
[ERR@RETURNED:
FSF_ERR_INTERNAL_ERROR : erroneous binding or malfunction of the FSF
main scheduler
FSF_ERR_BAD_ARGUMENT : if the given thread does not exist
FSF_ERR_NOT_SCHEDULED_THREAD : if the given thread is not scheduled
under the FSF
FSF_ERR_UNKNOWN_APPSCHEDULED_THREAD : if the thread is attached to
an application defined scheduler different than the fsf scheduler
FSF_ERR_UNBOUND_THREAD : 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.
[ERR@RETURNED:
FSF_ERR_NOT_SCHEDULED_THREAD : if the given thread is not scheduled
under the FSF
FSF_ERR_UNBOUND_THREAD : if the given thread does not have a valid
server bound to it
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.
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if the contract argument is NULL or the value
of the server argument is not in range
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
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.
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if the value of server is not in range
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
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.
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if the new_contract argument is NULL or the
value of the server argument is not in range
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
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, as soon as it is practical; meanwhile the
system operation will continue normally. When the renegotiation is
made, 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.
[ERR@RETURNED:
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
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
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.
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if the renegotiation_status argument is
NULL or the value of the server argument is not in range
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
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);
/*@}*/
////////////////////////////////////////////////////
// OBTAINING INFORMATION FROM THE SCHEDULER
////////////////////////////////////////////////////
/**
Returns true if the system is
configured with the on-line admission test enabled, or false
otherwise.
*/
bool
fsf_is_admission_test_enabled();
/**
This function stores the current execution time spent by the
threads bound to the specified server in the variable pointed to by
cpu_time.
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if the value of the server argument is not in range or
cpu_time is NULL
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
FSF_ERR_NOT_CONTRACTED_SERVER : if the server of the calling thread
has been cancelled or it is not valid
]
*/
int
fsf_get_cpu_time
(fsf_server_id_t server,
struct timespec *cpu_time);
/**
This function stores in the variable pointed to by budget the
remaining execution-time budget associated with the specified
server
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if the value of the server argument is not in range or
budget is NULL
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
FSF_ERR_NOT_CONTRACTED_SERVER : if the server of the calling thread
has been cancelled or it is not valid
]
*/
int
fsf_get_remaining_budget
(fsf_server_id_t server,
struct timespec *budget);
/**
This function stores in the variables
pointed to by budget and period, the execution-time budget and the
period respectively associated with the specified server. If any of
these pointers is NULL, the corresponding information is not stored.
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if the value of the server argument is not in range,
budget is NULL or period is NULL
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
FSF_ERR_NOT_CONTRACTED_SERVER : if the server of the calling thread
has been cancelled or it is not valid
]
*/
int
fsf_get_budget_and_period
(fsf_server_id_t server,
struct timespec *budget,
struct timespec *period);
/////////////////////////////////////////////////////////////////////
// SERVICE THREAD TUNING
/////////////////////////////////////////////////////////////////////
/**
This function allows the application to
change the period and budget of the service thread that makes the
negotiations. Increasing the utilization of this thread makes the
negotiations faster, but introduces additional load in the system
that may decrease the bandwidth available for the servers. For this
call, the system will make a schedulability analysis to determine if
the new situation is acceptable or not. This is reported back in the
variable pointed to by accepted. If the new service thread data is
accepted, the system will reassign budgets and periods to the
servers according to the new bandwidth available, in the same way as
it does for a regular contract negotiation.
When its budget is exhausted, the service thread may run in the
background
The service thread starts with a default budget and period that are
configurable
Implementation dependency: in the fixed priority implementtaion of
fsf, the default priority is lower than the priority of any server,
but higher than the background. According to the
implementation-dependent module the priority is adjustable by means
of a function that changes its preemption level
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if any of the pointer arguments is NULL or
the budget value is greater than the period value
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
FSF_ERR_NOT_CONTRACTED_SERVER : if the server of the calling thread
has been cancelled or it is not valid
]
*/
int
fsf_set_service_thread_data
(const struct timespec *budget,
const struct timespec *period,
bool *accepted);
/**
this function returns in the variables pointed by budget and
period, respectively, the current budget and period of the service
thread.
[ERR@RETURNED:
FSF_ERR_BAD_ARGUMENT : if any of the pointer arguments is NULL
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not
scheduled under the FSF
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
FSF_ERR_NOT_CONTRACTED_SERVER : if the server of the calling thread
has been cancelled or it is not valid
]
*/
int
fsf_get_service_thread_data
(struct timespec *budget,
struct timespec *period);
////////////////////////////////////////////////////////////////////////
// BACKGROUND MANAGEMENT
////////////////////////////////////////////////////////////////////////
//A round-robin background scheduling policy is available for those
//threads that do not have real-time requirements. Because some of
//these threads may require sharing information with other threads run
//by regular servers, special background contracts may be created for
//specifying the synchronization requirements.
//The way of specifying a background contract is by setting budget_min
//= period_max = 0. Negotiation may fail if the contract uses
//shared_objects. If the contract has no shared_objects the returned
//server id represents the background and may be used to bind more
//than one thread. If the contract has shared objects a server is
//created to keep track of them, but the associated threads are
//executed in the background, together with the other background
//threads
////////////////////////////////////////////////////////////////////////
// CHANGE OF MODE: GROUPS OF CONTRACTS
////////////////////////////////////////////////////////////////////////
//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 error
code if any of the contracts is not correct or any of the server ids
is not valid.
[JULIO: I think it would be clarifying to say that, in order to be
able to receive the returned arguments, the calling thread's server
should not be in the servers_down list.
[ERR@RETURNED:
FSF_ERR_INVALID_SCHEDULER_REPLY : the scheduler is wrong or not running
FSF_ERR_INTERNAL_ERROR : erroneous binding or malfunction of the FSF
main scheduler
FSF_ERR_NOT_SCHEDULED_CALLING_THREAD : if the calling thread is not scheduled
under the FSF
FSF_ERR_BAD_ARGUMENT : if any of the servers_up or accepted arguments
is NULL, if the contracts_up and servers_down arguments are both NULL,
or any of them has erroneous size or its elements are NULL or not in the
valid range respectively
]
*/
int
fsf_negotiate_group
(const fsf_contracts_group_t *contracts_up,
const fsf_servers_group_t *severs_down,
fsf_servers_group_t *severs_up,
bool *accepted);
//////////////////////////////////////////////////////////////////////
// INITIALIZATION SERVICES
//////////////////////////////////////////////////////////////////////
/**
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.
[ERR@RETURNED:
FSF_ERR_SYSTEM_ALREADY_INITIALIZED : if the function has already
been called before
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();
/*@}*/
#endif // _FSF_CORE_H_