QActive Class Reference

Active object class (based on the QHsm implementation strategy) More...

#include "qp.h"

Inheritance diagram for QActive:

Public Member Functions
void	QActive_setAttr (QActive *const me, uint32_t attr1, void const *attr2)

Static Public Member Functions
void	QActive_psInit (QSubscrList *const subscrSto, enum_t const maxSignal)
	Publish event to all subscribers of a given signal e->sig

Public Attributes
QAsm	super

Protected Member Functions
void	QActive_ctor (QActive *const me, QStateHandler const initial)
	QActive constructor (abstract base class)
void	QActive_stop (QActive *const me)
	Stops execution of an active object and removes it from the framework's supervision.
void	QActive_subscribe (QActive const *const me, enum_t const sig)
	Subscribes for delivery of signal sig to the active object.
void	QActive_unsubscribe (QActive const *const me, enum_t const sig)
	Unsubscribes from the delivery of signal sig to the active object.
void	QActive_unsubscribeAll (QActive const *const me)
	Unsubscribes from the delivery of all signals to the active object.
bool	QActive_defer (QActive const *const me, struct QEQueue *const eq, QEvt const *const e)
	Defer an event to a given separate event queue.
bool	QActive_recall (QActive *const me, struct QEQueue *const eq)
	Recall a deferred event from a given event queue.
uint_fast16_t	QActive_flushDeferred (QActive const *const me, struct QEQueue *const eq, uint_fast16_t const num)
	Flush the specified number of events from the deferred queue eq
Protected Member Functions inherited from QAsm
void	QAsm_ctor (QAsm *const me)
	Constructor of the QAsm base class.
QState	QHsm_top (QHsm const *const me, QEvt const *const e)

Protected Attributes
uint8_t	prio
	QF-priority [1..QF_MAX_ACTIVE] of this AO.
uint8_t	pthre
	Preemption-threshold [1..QF_MAX_ACTIVE] of this AO.
QACTIVE_THREAD_TYPE	thread
	Port-dependent representation of the thread of the active object.
QACTIVE_OS_OBJ_TYPE	osObject
	Port-dependent per-thread object.
QACTIVE_EQUEUE_TYPE	eQueue
	Port-dependent event-queue type (often QEQueue)
uint8_t	prio_dis
uint8_t	pthre_dis
Protected Attributes inherited from QAsm
struct QAsmVtable const *	vptr
	Virtual pointer inherited by all QAsm subclasses (see also Object Orientation)
union QAsmAttr	state
	Current state (pointer to the current state-handler function)
union QAsmAttr	temp
	Temporary storage for target/act-table etc.

Private Member Functions
void	QActive_start_ (QActive *const me, QPrioSpec const prioSpec, QEvt const **const qSto, uint_fast16_t const qLen, void *const stkSto, uint_fast16_t const stkSize, void const *const par)
	Starts execution of an active object and registers the object with the framework.
void	QActive_register_ (QActive *const me)
	Register this active object to be managed by the framework.
void	QActive_unregister_ (QActive *const me)
	Un-register the active object from the framework.
bool	QActive_post_ (QActive *const me, QEvt const *const e, uint_fast16_t const margin, void const *const sender)
	Posts an event e directly to the event queue of the active object using the First-In-First-Out (FIFO) policy.
void	QActive_postLIFO_ (QActive *const me, QEvt const *const e)
	Posts an event e directly to the event queue of the active object using the Last-In-First-Out (LIFO) policy.
QEvt const *	QActive_get_ (QActive *const me)
	Get an event from the event queue of an active object.
void	QActive_evtLoop_ (QActive *const me)
	Event loop thread routine for executing an active object act (defined some in QP ports)

Static Private Member Functions
void	QActive_publish_ (QEvt const *const e, void const *const sender, uint_fast8_t const qsId)
	Publish event to all subscribers of a given signal e->sig

Private Attributes
QActive *	QActive_registry_ [QF_MAX_ACTIVE+1U]
	Static (one per-class) array of registered active objects.
QSubscrList *	QActive_subscrList_
	Static (one per-class) pointer to all subscriber AOs for a given event signal.
enum_t	QActive_maxPubSignal_
	Static (one per-class) maximum published signal (the size of the subscrList_ array)

Detailed Description

Active object class (based on the QHsm implementation strategy)

Details

Active Objects (a.k.a., Actors) are autonomous software objects, each possessing an event queue, execution context, and an internal state machine. All interactions with an Active Object occur by asynchronous posting of events, which are processed one at a time (to completion) in the execution context of the Active Object. As long as there is no sharing of data or resources among Active Objects (or any other concurrent entities), there are no concurrency hazards.

The QActive class represents an Active Object that uses the QHsm-style implementation strategy for state machines. This strategy is tailored to manual coding, but it is also supported by the QM modeling tool.

Note

QActive is not intended to be instantiated directly, but rather serves as the abstract base class for derivation of active objects in the applications.

See also

• QMActive

Backward Traceability

• SAS_QP_QActive

Usage

The following example illustrates how to derive an active object from QActive.

typedef struct {
    QActive super;    // inherit QActive
 
    QTimeEvt timeEvt; // to timeout the blinking
} Blinky;
. . .
 
void Blinky_ctor(Blinky * const me) {
    // constructor of the superclass <---
    QActive_ctor(&me->super, Q_STATE_CAST(&Blinky_initial));
 
    // constructor(s) of the members
    QTimeEvt_ctorX(&me->timeEvt, &me->super, TIMEOUT_SIG, 0U);
}

Definition at line 804 of file qp.h.

Member Function Documentation

QActive_ctor()

void QActive_ctor ( QActive *const me, QStateHandler const initial )

protected

QActive constructor (abstract base class)

Parameters

[in,out]	me	current instance pointer (see Object Orientation)
[in]	initial	pointer to the top-most initial state-handler function in the derived active object

QActive_setAttr()

void QActive_setAttr	(	QActive *const	me,
		uint32_t	attr1,
		void const *	attr2 )

Generic setting of additional attributes (defined in some QP ports)

QActive_start_()

void QActive_start_ ( QActive *const me, QPrioSpec const prioSpec, QEvt const **const qSto, uint_fast16_t const qLen, void *const stkSto, uint_fast16_t const stkSize, void const *const par )

private

Starts execution of an active object and registers the object with the framework.

Details

Starts execution of the AO and registers the AO with the framework.

Parameters

[in,out]	me	current instance pointer (see Object Orientation)
[in]	prioSpec	priority specification for the AO (See QPrioSpec)
[in]	qSto	pointer to the storage for the ring buffer of the event queue
[in]	qLen	length of the event queue [# QEvt* pointers]
[in]	stkSto	pointer to the stack storage (might be NULL)
[in]	stkSize	stack size [bytes]
[in]	par	pointer to an extra parameter (might be NULL)

Backward Traceability

• DVR_QP_MC4_R08_13

Usage

The following example shows starting an AO when a per-task stack is needed:

#include "qpc.h"
 
int main() {
    QF_init();  // initialize the framework and the underlying RT kernel
    BSP_init(); // initialize the Board Support Package
    . . .
    // instantiate and start the active objects...
    Blinky_ctor();
    static QEvt const *l_blinkyQSto[10]; // Event queue storage for Blinky
    QACTIVE_START(AO_Blinky,      // AO pointer to start
                  1U,             // unique QP priority of the AO
                  l_blinkyQSto,   // storage for the AO's queue
                  Q_DIM(l_blinkyQSto), // length of the queue [entries]
                  (void *)0,      // stack storage (not used in QK)
                  0U,             // stack size [bytes] (not used in QK)
                  (void *)0);     // initialization parameter (or 0)
    . . .
    return QF_run(); // run the QF application
}

Definition at line 440 of file qk.c.

QActive_stop()

void QActive_stop ( QActive *const me )

protected

Stops execution of an active object and removes it from the framework's supervision.

Parameters

[in,out]

me

current instance pointer (see Object Orientation)

Attention

QActive_stop() must be called only from the AO that is about to stop its execution. By that time, any pointers or references to the AO are considered invalid (dangling) and it becomes illegal for the rest of the application to post events to the AO.

Definition at line 241 of file qutest.c.

QActive_register_()

void QActive_register_ ( QActive *const me )

private

Register this active object to be managed by the framework.

Details

This function adds a given active object to the active objects managed by the QF framework. It should not be called by the application directly, only through the function QActive::start().

Parameters

[in,out]

me

current instance pointer (see Object Orientation)

Precondition qf_qact:100

• the "QF-priority" of the AO must be in range (must be set before calling QActive_register_())
• the "QF-priority" must not be already in use (unique priority)
• the "QF-priority" must not exceed the "preemption-threshold"

Postcondition qf_qact:190

• the preceding pre-thre must not exceed the preemption-threshold
• the preemption-threshold must not exceed the next preemption-threshold

Definition at line 98 of file qf_qact.c.

QActive_unregister_()

void QActive_unregister_ ( QActive *const me )

private

Un-register the active object from the framework.

Details

This function un-registers a given active object from the active objects managed by the QF framework. It should not be called by the QP ports.

Parameters

[in]

me

pointer to the active object to remove from the framework.

Precondition qf_qact:200

• the priority of the active object must not be zero and cannot exceed the maximum QF_MAX_ACTIVE
• the priority of the AO must be already registered.

Note

The active object that is removed from the framework can no longer participate in any event exchange.

Definition at line 150 of file qf_qact.c.

QActive_post_()

bool QActive_post_ ( QActive *const me, QEvt const *const e, uint_fast16_t const margin, void const *const sender )

private

Posts an event e directly to the event queue of the active object using the First-In-First-Out (FIFO) policy.

Details

Direct event posting is the simplest asynchronous communication method available in QF. Should be called only through the macro QACTIVE_POST().

Parameters

[in,out]	me	current instance pointer (see Object Orientation)
[in]	e	pointer to the event to be posted
[in]	margin	number of required free slots in the queue after posting the event or QF_NO_MARGIN.
[in]	sender	pointer to a sender object (used in QS only)

Returns

'true' (success) if the posting succeeded (with the provided margin) and 'false' (failure) when the posting fails.

Precondition qf_actq:102

• the event pointer must be valid
• check internal event integrity (QP FuSa Subsystem)

  Postcondition qf_actq:110

• the event must be posted if (margin == QF_NO_MARGIN)

Attention

For margin == QF_NO_MARGIN, this function will assert internally if the event posting fails. In that case, it is unnecessary to check the return value from this function.

Note

This function should be called only through the macro QACTIVE_POST(). The reason is that the last parameter (sender) is needed only for software tracing, and typically is only defined when software tracing is enabled. When software tracing is disabled, the macro QACTIVE_POST() does not use the sender parameter, so it might not be defined.

Remarks

This function might be implemented differently in various QP/C ports. The provided implementation assumes that the QEQueue class is used for the QActive event queue.

Backward Traceability

• DVP_QS_MC4_R15_05

Usage

extern QActive * const AO_Table;
 
QState Philo_hungry(Philo * const me, QEvt const * const e) {
    QState status;
    switch (e->sig) {
        case Q_ENTRY_SIG: {
            TableEvt *pe = Q_NEW(TableEvt, HUNGRY_SIG); // dynamic alloc
            pe->philNum = me->num;
            QACTIVE_POST(AO_Table, &pe->super, me); // <===
            status = Q_HANDLED();
            break;
        }
        . . .
        default: {
            status = Q_SUPER(&QHsm_top);
            break;
        }
    }
    return status;
}

QActive_postLIFO_()

void QActive_postLIFO_ ( QActive *const me, QEvt const *const e )

private

Posts an event e directly to the event queue of the active object using the Last-In-First-Out (LIFO) policy.

Details

The LIFO policy should be used only for self-posting and with caution because it alters order of events in the queue.

Parameters

[in,out]	me	current instance pointer (see Object Orientation)
[in]	e	pointer to the event to be posted

Precondition qf_actq:200

• for the QXK kernel, postLIFO_() cannot be called from an extended thread

  Precondition qf_actq:201

• the queue must be able to accept the event (cannot overflow)

Backward Traceability

• DVP_QS_MC4_R15_05

Note

This function might be implemented differently in various QP/C ports. The provided implementation assumes that the QEQueue class is used for the QActive event queue.

See also

• QActive_post_()

Definition at line 228 of file qf_actq.c.

QActive_get_()

QEvt const * QActive_get_ ( QActive *const me )

private

Get an event from the event queue of an active object.

Details

This function is only for internal use inside the QP Framework and QP Application should not call this function (there is never a need for it). The behavior of this function depends on the kernel used in the QF port. For built-in kernels (QV or QK) the function can be called only when the queue is not empty, so it doesn't block. For a blocking kernel/OS the function can block and wait for delivery of an event.

Parameters

[in,out]

me

current instance pointer (see Object Orientation)

Returns

A pointer to the received event. The returned pointer is guaranteed to be valid (can't be NULL).

Note

This function might be implemented differently in various QP/C ports. The provided implementation assumes that the QEQueue class is used for the QActive event queue.

Definition at line 322 of file qf_actq.c.

QActive_psInit()

void QActive_psInit ( QSubscrList *const subscrSto, enum_t const maxSignal )

static

Publish event to all subscribers of a given signal e->sig

Details

This function posts (using the FIFO policy) the event e to all active objects that have subscribed to the signal e->sig, which is called multicasting. The multicasting performed in this function is very efficient based on reference-counting inside the published event ("zero-copy" event multicasting). This function is designed to be callable from any part of the system, including ISRs, device drivers, and active objects.

Note

To avoid any unexpected re-ordering of events posted into AO queues, the event multicasting is performed with scheduler locked. However, the scheduler is locked only up to the priority level of the highest-priority subscriber, so any AOs of even higher priority, which did not subscribe to this event are not affected.

QActive_publish_()

void QActive_publish_ ( QEvt const *const e, void const *const sender, uint_fast8_t const qsId )

staticprivate

Publish event to all subscribers of a given signal e->sig

Details

This function posts (using the FIFO policy) the event e to all active objects that have subscribed to the signal e->sig, which is called multicasting. The multicasting performed in this function is very efficient based on reference-counting inside the published event ("zero-copy" event multicasting). This function is designed to be callable from any part of the system, including ISRs, device drivers, and active objects.

Precondition qf_ps:200

• the published signal must be within the configured range

  Precondition qf_ps:202

• check the integrity of the subscriber set (QP FuSa Subsystem)

Note

To avoid any unexpected re-ordering of events posted into AO queues, the event multicasting is performed with scheduler locked. However, the scheduler is locked only up to the priority level of the highest-priority subscriber, so any AOs of even higher priority, which did not subscribe to this event are not affected.

Attention

This operation is typically used via macro QACTIVE_PUBLISH(). This is because the last parameter qsId might be defined/provided only in the Spy build configuration (see Q_SPY). The macro ignores the qsId parameter outside the Spy configuration, so the same code builds correctly in all configurations.

Usage

QState Philo_eating(Philo * const me, QEvt const * const e) {
    QState status_;
    switch (e->sig) {
        . . .
        case Q_EXIT_SIG: {
            TableEvt const *pe = Q_NEW(TableEvt, DONE_SIG, me->id);
            QACTIVE_PUBLISH(&me->super, pe, me); // <===
            status_ = Q_RET_HANDLED;
            break;
        }
        . . .
    }
    return status_;
}

Definition at line 95 of file qf_ps.c.

QActive_subscribe()

void QActive_subscribe ( QActive const *const me, enum_t const sig )

protected

Subscribes for delivery of signal sig to the active object.

Details

This function is part of the Publish-Subscribe event delivery mechanism available in QF. Subscribing to an event means that the framework will start posting all published events with a given signal sig to the event queue of the active object.

Parameters

[in,out]	me	current instance pointer (see Object Orientation)
[in]	sig	event signal to subscribe

Precondition qf_ps:300

• signal must be in range of subscribe signals
• subscriber AO priority must be in range
• the AO must be registered (started)

  Precondition qf_ps:302

• check the integrity of the subscriber set (QP FuSa Subsystem)

Usage

The following example shows how the Table active object subscribes to three signals in the initial transition:

QState Table_initial(Table * const me, QEvt const * const e) {
    Q_UNUSED_PAR(e);
 
    // subscribe to event signals...
    QActive_subscribe(&me->super, (enum_t)HUNGRY_SIG);
    QActive_subscribe(&me->super, (enum_t)DONE_SIG);
    QActive_subscribe(&me->super, (enum_t)TERMINATE_SIG);
 
    for (uint8_t n = 0U; n < N; ++n) {
        me->fork[n] = FREE;
        me->isHungry[n] = false;
    }
    return Q_TRAN(&Table_serving);
}

Definition at line 204 of file qf_ps.c.

QActive_unsubscribe()

void QActive_unsubscribe ( QActive const *const me, enum_t const sig )

protected

Unsubscribes from the delivery of signal sig to the active object.

Details

This function is part of the Publish-Subscribe event delivery mechanism available in QF. Unsubscribing from an event means that the framework will stop posting published events with a given signal sig to the event queue of the active object.

Parameters

[in,out]	me	current instance pointer (see Object Orientation)
[in]	sig	event signal to unsubscribe

Precondition qf_ps:400

• signal must be in range of subscribe signals
• subscriber AO priority must be in range
• the AO must be registered (started)

  Precondition qf_ps:402

• check the integrity of the subscriber set (QP FuSa Subsystem)

Note

Due to the latency of event queues, an active object should NOT assume that a given signal sig will never be dispatched to the state machine of the active object after un-subscribing from that signal. The event might be already in the queue, or just about to be posted and the un-subscribe operation will not flush such events.

Un-subscribing from a signal that has never been subscribed in the first place is considered an error and QF will raise an assertion.

Definition at line 243 of file qf_ps.c.

QActive_unsubscribeAll()

void QActive_unsubscribeAll ( QActive const *const me )

protected

Unsubscribes from the delivery of all signals to the active object.

Details

This function is part of the Publish-Subscribe event delivery mechanism available in QF. Un-subscribing from all events means that the framework will stop posting any published events to the event queue of the active object.

Parameters

[in,out]

me

current instance pointer (see Object Orientation)

Precondition qf_ps:500

• subscriber AO priority must be in range
• the AO must be registered (started)

Note

Due to the latency of event queues, an active object should NOT assume that no events will ever be dispatched to the state machine of the active object after un-subscribing from all events. The events might be already in the queue, or just about to be posted and the un-subscribe operation will not flush such events. Also, the alternative event-delivery mechanisms, such as direct event posting or time events, can be still delivered to the event queue of the active object.

Definition at line 282 of file qf_ps.c.

QActive_defer()

bool QActive_defer ( QActive const *const me, struct QEQueue *const eq, QEvt const *const e )

protected

Defer an event to a given separate event queue.

Details

This function is part of the event deferral support. An active object uses this function to defer an event e to the QF-supported native event queue eq. QF correctly accounts for another outstanding reference to the event and will not recycle the event at the end of the RTC step. Later, the active object might recall one event at a time from the event queue.

Remarks

An active object can use multiple event queues to defer events of different kinds.

Parameters

[in,out]	me	current instance pointer (see Object Orientation)
[in]	eq	pointer to a "raw" thread-safe queue to recall an event from.
[in]	e	pointer to the event to be deferred

Returns

'true' (success) when the event could be deferred and 'false' (failure) if event deferral failed due to overflowing the queue.

QActive_recall()

bool QActive_recall ( QActive *const me, struct QEQueue *const eq )

protected

Recall a deferred event from a given event queue.

Details

This function is part of the event deferral support. An active object uses this function to recall a deferred event from a given QF event queue. Recalling an event means that it is removed from the deferred event queue eq and posted (LIFO) to the event queue of the active object.

Parameters

[in,out]	me	current instance pointer (see Object Orientation)
[in]	eq	pointer to a "raw" thread-safe queue to recall an event from.

Returns

'true' if an event has been recalled and 'false' if not.

Note

An active object can use multiple event queues to defer events of different kinds.

Definition at line 92 of file qf_defer.c.

QActive_flushDeferred()

uint_fast16_t QActive_flushDeferred ( QActive const *const me, struct QEQueue *const eq, uint_fast16_t const num )

protected

Flush the specified number of events from the deferred queue eq

Details

This function is part of the event deferral support. An active object can use this function to flush a given QF event queue. The function makes sure that the events are not leaked.

Parameters

[in,out]	me	current instance pointer (see Object Orientation)
[in]	eq	pointer to a "raw" thread-safe queue to flush.
[in]	num	number of events to flush (note can be a big number, like 0xFFFFU to flush all events)

Returns

the number of events actually flushed from the queue.

Definition at line 153 of file qf_defer.c.

QActive_evtLoop_()

void QActive_evtLoop_ ( QActive *const me )

private

Event loop thread routine for executing an active object act (defined some in QP ports)

Member Data Documentation

super

QAsm QActive::super

Definition at line 806 of file qp.h.

prio

uint8_t prio

protected

QF-priority [1..QF_MAX_ACTIVE] of this AO.

See also

• QPrioSpec

Definition at line 809 of file qp.h.

pthre

uint8_t pthre

protected

Preemption-threshold [1..QF_MAX_ACTIVE] of this AO.

See also

• QPrioSpec

Definition at line 812 of file qp.h.

thread

QACTIVE_THREAD_TYPE thread

protected

Port-dependent representation of the thread of the active object.

Details

This data might be used in various ways, depending on the QF port. In some ports me->thread is used store the thread handle. In other ports me->thread can be a pointer to the Thread-Local-Storage (TLS).

Definition at line 816 of file qp.h.

osObject

QACTIVE_OS_OBJ_TYPE osObject

protected

Port-dependent per-thread object.

Details

This data might be used in various ways, depending on the QF port. In some ports me->osObject is used to block the calling thread when the native QF queue is empty. In other QF ports the OS-dependent object might be used differently.

Definition at line 821 of file qp.h.

eQueue

QACTIVE_EQUEUE_TYPE eQueue

protected

Port-dependent event-queue type (often QEQueue)

Details

The type of the queue depends on the underlying operating system or a kernel. Many kernels support "message queues" that can be adapted to deliver QF events to the active object. Alternatively, QF provides a native event queue implementation that can be used as well.

Note

The native QF event queue is configured by defining the macro QACTIVE_EQUEUE_TYPE as QEQueue.

Definition at line 826 of file qp.h.

prio_dis

uint8_t prio_dis

protected

Definition at line 831 of file qp.h.

pthre_dis

uint8_t pthre_dis

protected

Definition at line 836 of file qp.h.

QActive_registry_

QActive * QActive_registry_

private

Static (one per-class) array of registered active objects.

Definition at line 843 of file qp.h.

QActive_subscrList_

QSubscrList* QActive_subscrList_

private

Static (one per-class) pointer to all subscriber AOs for a given event signal.

Definition at line 846 of file qp.h.

QActive_maxPubSignal_

enum_t QActive_maxPubSignal_

private

Static (one per-class) maximum published signal (the size of the subscrList_ array)

Definition at line 849 of file qp.h.

---

The documentation for this class was generated from the following files:

• qp.h
• qf_act.c
• qf_actq.c
• qf_defer.c
• qf_ps.c
• qf_qact.c
• qk.c
• qutest.c
• qv.c
• qxk.c
• qp.dox