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Merge "Rewrite C++ Notifier to use HAL multi-notifier support."

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This commit is contained in:
Brad Miller (WPI)
2016-01-02 06:28:40 -08:00
committed by Gerrit Code Review
parent 8bbc1d43bb b0de0b7386
commit de4708cbdb
3 changed files with 109 additions and 198 deletions
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213
wpilibc/Athena/src/Notifier.cpp
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@@ -11,12 +11,6 @@
#include "WPIErrors.h"
#include "HAL/HAL.hpp"
Notifier *Notifier::timerQueueHead = nullptr;
priority_recursive_mutex Notifier::queueMutex;
priority_mutex Notifier::halMutex;
void *Notifier::m_notifier = nullptr;
std::atomic<int> Notifier::refcount{0};
/**
* Create a Notifier for timer event notification.
* @param handler The handler is called at the notification time which is set
@@ -27,41 +21,18 @@ Notifier::Notifier(TimerEventHandler handler, void *param) {
wpi_setWPIErrorWithContext(NullParameter, "handler must not be nullptr");
m_handler = handler;
m_param = param;
// do the first time intialization of static variables
if (refcount.fetch_add(1) == 0) {
int32_t status = 0;
{
std::lock_guard<priority_mutex> sync(halMutex);
if (!m_notifier)
m_notifier = initializeNotifier(ProcessQueue, nullptr, &status);
}
wpi_setErrorWithContext(status, getHALErrorMessage(status));
}
int32_t status = 0;
m_notifier = initializeNotifier(&Notifier::Notify, this, &status);
wpi_setErrorWithContext(status, getHALErrorMessage(status));
}
/**
* Free the resources for a timer event.
* All resources will be freed and the timer event will be removed from the
* queue if necessary.
*/
Notifier::~Notifier() {
{
std::lock_guard<priority_recursive_mutex> sync(queueMutex);
DeleteFromQueue();
}
// Delete the static variables when the last one is going away
if (refcount.fetch_sub(1) == 1) {
int32_t status = 0;
{
std::lock_guard<priority_mutex> sync(halMutex);
if (m_notifier) {
cleanNotifier(m_notifier, &status);
m_notifier = nullptr;
}
}
wpi_setErrorWithContext(status, getHALErrorMessage(status));
}
int32_t status = 0;
cleanNotifier(m_notifier, &status);
wpi_setErrorWithContext(status, getHALErrorMessage(status));
// Acquire the mutex; this makes certain that the handler is
// not being executed by the interrupt manager.
@@ -69,149 +40,35 @@ Notifier::~Notifier() {
}
/**
* Update the alarm hardware to reflect the current first element in the queue.
* Compute the time the next alarm should occur based on the current time and
* the
* period for the first element in the timer queue.
* WARNING: this method does not do synchronization! It must be called from
* somewhere
* that is taking care of synchronizing access to the queue.
* Update the HAL alarm time.
*/
void Notifier::UpdateAlarm() {
if (timerQueueHead != nullptr) {
int32_t status = 0;
// This locking is necessary in order to avoid two things:
// 1) Race condition issues with calling cleanNotifer() and
// updateNotifierAlarm() at the same time.
// 2) Avoid deadlock by making it so that this won't block waiting
// for the mutex to unlock.
// Checking refcount as well is unnecessary, but will not hurt.
if (halMutex.try_lock() && refcount != 0) {
if (m_notifier)
updateNotifierAlarm(m_notifier,
(uint32_t)(timerQueueHead->m_expirationTime * 1e6),
&status);
halMutex.unlock();
}
wpi_setStaticErrorWithContext(timerQueueHead, status,
getHALErrorMessage(status));
}
int32_t status = 0;
updateNotifierAlarm(m_notifier, (uint32_t)(m_expirationTime * 1e6), &status);
wpi_setErrorWithContext(status, getHALErrorMessage(status));
}
/**
* ProcessQueue is called whenever there is a timer interrupt.
* We need to wake up and process the current top item in the timer queue as
* long
* as its scheduled time is after the current time. Then the item is removed or
* rescheduled (repetitive events) in the queue.
* Notify is called by the HAL layer. We simply need to pass it through to
* the user handler.
*/
void Notifier::ProcessQueue(uint32_t currentTimeInt, void *params) {
Notifier *current;
while (true) // keep processing past events until no more
{
{
std::lock_guard<priority_recursive_mutex> sync(queueMutex);
double currentTime = currentTimeInt * 1.0e-6;
current = timerQueueHead;
if (current == nullptr || current->m_expirationTime > currentTime) {
break; // no more timer events to process
}
// need to process this entry
timerQueueHead = current->m_nextEvent;
if (current->m_periodic) {
// if periodic, requeue the event
// compute when to put into queue
current->InsertInQueue(true);
} else {
// not periodic; removed from queue
current->m_queued = false;
}
// Take handler mutex while holding queue mutex to make sure
// the handler will execute to completion in case we are being deleted.
current->m_handlerMutex.lock();
}
void Notifier::Notify(uint32_t currentTimeInt, void *param) {
Notifier* notifier = static_cast<Notifier*>(param);
current->m_handler(current->m_param); // call the event handler
current->m_handlerMutex.unlock();
notifier->m_processMutex.lock();
if (notifier->m_periodic) {
notifier->m_expirationTime += notifier->m_period;
notifier->UpdateAlarm();
}
// reschedule the first item in the queue
std::lock_guard<priority_recursive_mutex> sync(queueMutex);
UpdateAlarm();
}
/**
* Insert this Notifier into the timer queue in right place.
* WARNING: this method does not do synchronization! It must be called from
* somewhere
* that is taking care of synchronizing access to the queue.
* @param reschedule If false, the scheduled alarm is based on the current time
* and UpdateAlarm
* method is called which will enable the alarm if necessary.
* If true, update the time by adding the period (no drift) when rescheduled
* periodic from ProcessQueue.
* This ensures that the public methods only update the queue after finishing
* inserting.
*/
void Notifier::InsertInQueue(bool reschedule) {
if (reschedule) {
m_expirationTime += m_period;
} else {
m_expirationTime = GetClock() + m_period;
}
if (m_expirationTime > Timer::kRolloverTime) {
m_expirationTime -= Timer::kRolloverTime;
}
if (timerQueueHead == nullptr ||
timerQueueHead->m_expirationTime >= this->m_expirationTime) {
// the queue is empty or greater than the new entry
// the new entry becomes the first element
this->m_nextEvent = timerQueueHead;
timerQueueHead = this;
if (!reschedule) {
// since the first element changed, update alarm, unless we already plan
// to
UpdateAlarm();
}
} else {
for (Notifier **npp = &(timerQueueHead->m_nextEvent);;
npp = &(*npp)->m_nextEvent) {
Notifier *n = *npp;
if (n == nullptr || n->m_expirationTime > this->m_expirationTime) {
*npp = this;
this->m_nextEvent = n;
break;
}
}
}
m_queued = true;
}
auto handler = notifier->m_handler;
auto hparam = notifier->m_param;
/**
* Delete this Notifier from the timer queue.
* WARNING: this method does not do synchronization! It must be called from
* somewhere
* that is taking care of synchronizing access to the queue.
* Remove this Notifier from the timer queue and adjust the next interrupt time
* to reflect
* the current top of the queue.
*/
void Notifier::DeleteFromQueue() {
if (m_queued) {
m_queued = false;
wpi_assert(timerQueueHead != nullptr);
if (timerQueueHead == this) {
// remove the first item in the list - update the alarm
timerQueueHead = this->m_nextEvent;
UpdateAlarm();
} else {
for (Notifier *n = timerQueueHead; n != nullptr; n = n->m_nextEvent) {
if (n->m_nextEvent == this) {
// this element is the next element from *n from the queue
n->m_nextEvent = this->m_nextEvent; // point around this one
}
}
}
}
notifier->m_handlerMutex.lock();
notifier->m_processMutex.unlock();
if (handler) handler(hparam);
notifier->m_handlerMutex.unlock();
}
/**
@@ -220,11 +77,11 @@ void Notifier::DeleteFromQueue() {
* @param delay Seconds to wait before the handler is called.
*/
void Notifier::StartSingle(double delay) {
std::lock_guard<priority_recursive_mutex> sync(queueMutex);
std::lock_guard<priority_mutex> sync(m_processMutex);
m_periodic = false;
m_period = delay;
DeleteFromQueue();
InsertInQueue(false);
m_expirationTime = GetClock() + m_period;
UpdateAlarm();
}
/**
@@ -236,11 +93,11 @@ void Notifier::StartSingle(double delay) {
* the call to this method.
*/
void Notifier::StartPeriodic(double period) {
std::lock_guard<priority_recursive_mutex> sync(queueMutex);
std::lock_guard<priority_mutex> sync(m_processMutex);
m_periodic = true;
m_period = period;
DeleteFromQueue();
InsertInQueue(false);
m_expirationTime = GetClock() + m_period;
UpdateAlarm();
}
/**
@@ -253,10 +110,10 @@ void Notifier::StartPeriodic(double period) {
* block until the handler call is complete.
*/
void Notifier::Stop() {
{
std::lock_guard<priority_recursive_mutex> sync(queueMutex);
DeleteFromQueue();
}
int32_t status = 0;
stopNotifierAlarm(m_notifier, &status);
wpi_setErrorWithContext(status, getHALErrorMessage(status));
// Wait for a currently executing handler to complete before returning from
// Stop()
std::lock_guard<priority_mutex> sync(m_handlerMutex);