EventQueue Class Reference

#include <event_queue.h>

Collaboration diagram for EventQueue:

Public Member Functions
	EventQueue (efidur_t lateDelay=0)
bool	insertTask (scheduling_s *scheduling, efitick_t timeX, action_s const &action)
void	remove (scheduling_s *scheduling)
int	executeAll (efitick_t now)
bool	executeOne (efitick_t now)
expected< efitick_t >	getNextEventTime (efitick_t nowUs) const
void	clear ()
int	size () const
scheduling_s *	getElementAtIndexForUnitText (int index)
scheduling_s *	getHead ()
scheduling_s *	getFreeScheduling ()
void	tryReturnScheduling (scheduling_s *sched)

Private Member Functions
void	assertListIsSorted () const

Private Attributes
scheduling_s *	m_head = nullptr
const efidur_t	m_lateDelay
scheduling_s *	m_freelist = nullptr
scheduling_s	m_pool [64]

Detailed Description

Execution sorted linked list

Definition at line 19 of file event_queue.h.

Constructor & Destructor Documentation

EventQueue()

EventQueue::EventQueue ( efidur_t  lateDelay = 0 )

explicit

Definition at line 29 of file event_queue.cpp.

    : m_lateDelay(lateDelay)
{
    for (size_t i = 0; i < efi::size(m_pool); i++) {
        tryReturnScheduling(&m_pool[i]);
    }
 
#if EFI_PROD_CODE
    getTunerStudioOutputChannels()->schedulingUsedCount = 0;
#endif
}

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Member Function Documentation

assertListIsSorted()

void EventQueue::assertListIsSorted ( ) const

private

Definition at line 302 of file event_queue.cpp.

                                          {
#if EFI_UNIT_TEST || EFI_SIMULATOR
    int counter = 0;
    scheduling_s *current = m_head;
    while (current != NULL && current->nextScheduling_s != NULL) {
        efiAssertVoid(ObdCode::CUSTOM_ERR_6623, current->getMomentNt() <= current->nextScheduling_s->getMomentNt(), "list order");
        current = current->nextScheduling_s;
        if (counter++ > 1'000'000'000)
            criticalError("EventQueue: looks like a loop?!");
    }
#endif // EFI_UNIT_TEST || EFI_SIMULATOR
}

Referenced by executeAll(), executeOne(), insertTask(), and remove().

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clear()

void EventQueue::clear

(

)

Definition at line 334 of file event_queue.cpp.

                       {
    // Flush the queue, resetting all scheduling_s as though we'd executed them
    while(m_head) {
        auto x = m_head;
        // link next element to head
        m_head = x->nextScheduling_s;
 
        // Reset this element
        x->setMomentNt(0);
        x->nextScheduling_s = nullptr;
        x->action = {};
    }
 
    m_head = nullptr;
}

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executeAll()

int EventQueue::executeAll

(

efitick_t

now

)

Invoke all pending actions prior to specified timestamp

Returns

number of executed actions

Definition at line 207 of file event_queue.cpp.

                                        {
    ScopePerf perf(PE::EventQueueExecuteAll);
 
    int executionCounter = 0;
 
    assertListIsSorted();
 
    bool didExecute;
    do {
        didExecute = executeOne(now);
        executionCounter += didExecute ? 1 : 0;
    } while (didExecute);
 
    return executionCounter;
}

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executeOne()

bool EventQueue::executeOne

(

efitick_t

now

)

Definition at line 223 of file event_queue.cpp.

                                         {
    // Read the head every time - a previously executed event could
    // have inserted something new at the head
    scheduling_s* current = m_head;
 
    // Queue is empty - bail
    if (!current) {
        return false;
    }
 
    // If the next event is far in the future, we'll reschedule
    // and execute it next time.
    // We do this when the next event is close enough that the overhead of
    // resetting the timer and scheduling an new interrupt is greater than just
    // waiting for the time to arrive.  On current CPUs, this is reasonable to set
    // around 10 microseconds.
    if (current->getMomentNt() > now + m_lateDelay) {
        return false;
    }
 
#if EFI_UNIT_TEST
//  efitick_t spinDuration = current->getMomentNt() - getTimeNowNt();
//  if (spinDuration > 0) {
//      throw std::runtime_error("Time Spin in unit test");
//  }
#endif
 
    // near future - spin wait for the event to happen and avoid the
    // overhead of rescheduling the timer.
    // yes, that's a busy wait but that's what we need here
    while (current->getMomentNt() > getTimeNowNt()) {
#if EFI_UNIT_TEST
  // todo: remove this hack see https://github.com/rusefi/rusefi/issues/6457
extern bool unitTestBusyWaitHack;
    if (unitTestBusyWaitHack) {
        break;
      }
#endif
        UNIT_TEST_BUSY_WAIT_CALLBACK();
    }
 
    // step the head forward, unlink this element, clear scheduled flag
    m_head = current->nextScheduling_s;
    current->nextScheduling_s = nullptr;
 
    // Grab the action but clear it in the event so we can reschedule from the action's execution
    auto const action{ std::move(current->action) };
 
    tryReturnScheduling(current);
    current = nullptr;
 
#if EFI_DETAILED_LOGGING
    printf("QUEUE: execute current=%d param=%d\r\n", reinterpret_cast<uintptr_t>(current), action.getArgumentRaw());
#endif
 
    // Execute the current element
    {
        ScopePerf perf2(PE::EventQueueExecuteCallback);
#if EFI_DETAILED_LOGGING && EFI_UNIT_TEST_VERBOSE_ACTION
        std::cout << "EventQueue::executeOne: " << action.getCallbackName() << "(" << reinterpret_cast<uintptr_t>(action.getCallback()) << ") with raw arg = " << action.getArgumentRaw() << std::endl;
#endif
        action.execute();
 
#if EFI_UNIT_TEST
        // std::cout << "Executed at " << now << std::endl;
#endif
    }
 
    assertListIsSorted();
    return true;
}

Referenced by executeAll(), and SingleTimerExecutor::executeAllPendingActions().

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getElementAtIndexForUnitText()

scheduling_s * EventQueue::getElementAtIndexForUnitText

(

int

index

)

Definition at line 320 of file event_queue.cpp.

                                                                {
    scheduling_s * current;
 
    LL_FOREACH2(m_head, current, nextScheduling_s)
    {
        if (index == 0) {
            return current;
        }
        index--;
    }
 
    return NULL;
}

getFreeScheduling()

scheduling_s * EventQueue::getFreeScheduling

(

)

Definition at line 41 of file event_queue.cpp.

                                            {
    auto retVal = m_freelist;
 
    if (retVal) {
        m_freelist = retVal->nextScheduling_s;
        retVal->nextScheduling_s = nullptr;
 
#if EFI_PROD_CODE
        getTunerStudioOutputChannels()->schedulingUsedCount++;
#endif
    }
 
    return retVal;
}

Referenced by insertTask().

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getHead()

scheduling_s * EventQueue::getHead

(

)

Definition at line 315 of file event_queue.cpp.

                                   {
    return m_head;
}

getNextEventTime()

expected< efitick_t > EventQueue::getNextEventTime

(

efitick_t

nowNt

)

const

On this layer it does not matter which units are used - us, ms ot nt.

This method is always invoked under a lock

Returns

Get the timestamp of the soonest pending action, skipping all the actions in the past

We are here if action timestamp is in the past. We should rarely be here since this 'getNextEventTime()' is always invoked by 'scheduleTimerCallback' which is always invoked right after 'executeAllPendingActions' - but still, for events which are really close to each other we would end up here.

looks like we end up here after 'writeconfig' (which freezes the firmware) - we are late for the next scheduled event

Definition at line 178 of file event_queue.cpp.

                                                                      {
    if (m_head) {
        if (m_head->getMomentNt() <= nowNt) {
            /**
             * We are here if action timestamp is in the past. We should rarely be here since this 'getNextEventTime()' is
             * always invoked by 'scheduleTimerCallback' which is always invoked right after 'executeAllPendingActions' - but still,
             * for events which are really close to each other we would end up here.
             *
             * looks like we end up here after 'writeconfig' (which freezes the firmware) - we are late
             * for the next scheduled event
             */
            return nowNt + m_lateDelay;
        } else {
            return m_head->getMomentNt();
        }
    }
 
    return unexpected;
}

Referenced by SingleTimerExecutor::scheduleTimerCallback().

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insertTask()

bool EventQueue::insertTask	(	scheduling_s *	scheduling,
		efitick_t	timeNt,
		action_s const &	action
	)

O(size) - linear search in sorted linked list

Returns

true if inserted into the head of the list

Definition at line 71 of file event_queue.cpp.

                                                                                              {
    ScopePerf perf(PE::EventQueueInsertTask);
 
    if (!scheduling) {
        scheduling = getFreeScheduling();
 
        // If still null, the free list is empty and all schedulings in the pool have been expended.
        if (!scheduling) {
            // TODO: should we warn or error here?
// todo: look into why units tests fail here
#if EFI_PROD_CODE
      criticalError("No slots in scheduling pool");
#endif
            return false;
        }
    }
 
    assertListIsSorted();
    efiAssert(ObdCode::CUSTOM_ERR_ASSERT, action.getCallback() != NULL, "NULL callback", false);
 
// please note that simulator does not use this code at all - simulator uses signal_executor_sleep
 
    if (scheduling->action) {
#if EFI_UNIT_TEST
        if (verboseMode) {
            printf("Already scheduled was %d\r\n", (int)scheduling->getMomentNt());
            printf("Already scheduled now %d\r\n", (int)timeNt);
        }
#endif /* EFI_UNIT_TEST */
        return false;
    }
 
    scheduling->setMomentNt(timeNt);
    scheduling->action = action;
 
    if (!m_head || timeNt < m_head->getMomentNt()) {
        // here we insert into head of the linked list
        LL_PREPEND2(m_head, scheduling, nextScheduling_s);
        assertListIsSorted();
        return true;
    } else {
        // here we know we are not in the head of the list, let's find the position - linear search
        scheduling_s *insertPosition = m_head;
        while (insertPosition->nextScheduling_s != NULL && insertPosition->nextScheduling_s->getMomentNt() < timeNt) {
            insertPosition = insertPosition->nextScheduling_s;
        }
 
        scheduling->nextScheduling_s = insertPosition->nextScheduling_s;
        insertPosition->nextScheduling_s = scheduling;
        assertListIsSorted();
        return false;
    }
}

Referenced by SingleTimerExecutor::schedule().

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remove()

void EventQueue::remove

(

scheduling_s *

scheduling

)

Definition at line 125 of file event_queue.cpp.

                                                {
    assertListIsSorted();
 
    // Special case: event isn't scheduled, so don't cancel it
    if (!scheduling->action) {
        return;
    }
 
    // Special case: empty list, nothing to do
    if (!m_head) {
        return;
    }
 
    // Special case: is the item to remove at the head?
    if (scheduling == m_head) {
        m_head = m_head->nextScheduling_s;
        scheduling->nextScheduling_s = nullptr;
        scheduling->action = {};
    } else {
        auto prev = m_head; // keep track of the element before the one to remove, so we can link around it
        auto current = prev->nextScheduling_s;
 
        // Find our element
        while (current && current != scheduling) {
            prev = current;
            current = current->nextScheduling_s;
        }
 
        // Walked off the end, this is an error since this *should* have been scheduled
        if (!current) {
            firmwareError(ObdCode::OBD_PCM_Processor_Fault, "EventQueue::remove didn't find element");
            return;
        }
 
        efiAssertVoid(ObdCode::OBD_PCM_Processor_Fault, current == scheduling, "current not equal to scheduling");
 
        // Link around the removed item
        prev->nextScheduling_s = current->nextScheduling_s;
 
        // Clean the item to remove
        current->nextScheduling_s = nullptr;
        current->action = {};
    }
 
    assertListIsSorted();
}

Referenced by SingleTimerExecutor::cancel().

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size()

int EventQueue::size

(

)

const

Definition at line 295 of file event_queue.cpp.

                           {
    scheduling_s *tmp;
    int result;
    LL_COUNT2(m_head, tmp, result, nextScheduling_s);
    return result;
}

tryReturnScheduling()

void EventQueue::tryReturnScheduling

(

scheduling_s *

sched

)

Definition at line 56 of file event_queue.cpp.

                                                        {
    // Only return this scheduling to the free list if it's from the correct pool
    if (sched >= &m_pool[0] && sched <= &m_pool[efi::size(m_pool) - 1]) {
        sched->nextScheduling_s = m_freelist;
        m_freelist = sched;
 
#if EFI_PROD_CODE
        getTunerStudioOutputChannels()->schedulingUsedCount--;
#endif
    }
}

Referenced by EventQueue(), and executeOne().

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Field Documentation

m_freelist

scheduling_s* EventQueue::m_freelist = nullptr

private

Definition at line 51 of file event_queue.h.

Referenced by getFreeScheduling(), and tryReturnScheduling().

m_head

scheduling_s* EventQueue::m_head = nullptr

private

this list is sorted

Definition at line 48 of file event_queue.h.

Referenced by assertListIsSorted(), clear(), executeOne(), getElementAtIndexForUnitText(), getHead(), getNextEventTime(), insertTask(), remove(), and size().

m_lateDelay

const efidur_t EventQueue::m_lateDelay

private

Definition at line 49 of file event_queue.h.

Referenced by executeOne(), and getNextEventTime().

m_pool

scheduling_s EventQueue::m_pool[64]

private

Definition at line 52 of file event_queue.h.

Referenced by EventQueue(), and tryReturnScheduling().

---

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

• controllers/system/timer/event_queue.h
• controllers/system/timer/event_queue.cpp