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microbit: BUGFIX safe deletion of listeners

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also correction to minor bu in MicroBitFiber that could conceivably send more
notifications that it should...
This commit is contained in:
Joe Finney 2015-10-29 00:08:33 +00:00
parent 1eeaeca2c6
commit 0fa8296048
4 changed files with 66 additions and 26 deletions
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2
inc/MicroBitListener.h
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@ -14,6 +14,8 @@
#define MESSAGE_BUS_LISTENER_DROP_IF_BUSY 0x0020
#define MESSAGE_BUS_LISTENER_NONBLOCKING 0x0040
#define MESSAGE_BUS_LISTENER_URGENT 0x0080
#define MESSAGE_BUS_LISTENER_DELETING 0x8000
#define MESSAGE_BUS_LISTENER_IMMEDIATE (MESSAGE_BUS_LISTENER_NONBLOCKING | MESSAGE_BUS_LISTENER_URGENT)

6
inc/MicroBitMessageBus.h
View file

@ -222,6 +222,12 @@ class MicroBitMessageBus : public MicroBitComponent
int add(MicroBitListener *newListener);
int remove(MicroBitListener *newListener);
/**
* Cleanup any MicroBitListeners marked for deletion from the list.
* @return The number of listeners removed from the list.
*/
int deleteMarkedListeners();
MicroBitListener *listeners; // Chain of active listeners.
MicroBitEventQueueItem *evt_queue_head; // Head of queued events to be processed.
MicroBitEventQueueItem *evt_queue_tail; // Tail of queued events to be processed.

16
source/MicroBitFiber.cpp
View file

@ -221,15 +221,19 @@ void scheduler_event(MicroBitEvent evt)
uint16_t value = (f->context & 0xFFFF0000) >> 16;
// Special case for the NOTIFY_ONE channel...
if ((notifyOneComplete == 0) && (id == MICROBIT_ID_NOTIFY && evt.source == MICROBIT_ID_NOTIFY_ONE) && (value == MICROBIT_EVT_ANY || value == evt.value))
if ((evt.source == MICROBIT_ID_NOTIFY_ONE && id == MICROBIT_ID_NOTIFY) && (value == MICROBIT_EVT_ANY || value == evt.value))
{
// Wakey wakey!
dequeue_fiber(f);
queue_fiber(f,&runQueue);
notifyOneComplete = 1;
if (!notifyOneComplete)
{
// Wakey wakey!
dequeue_fiber(f);
queue_fiber(f,&runQueue);
notifyOneComplete = 1;
}
}
if ((id == MICROBIT_ID_ANY || id == evt.source) && (value == MICROBIT_EVT_ANY || value == evt.value))
// Normal case.
else if ((id == MICROBIT_ID_ANY || id == evt.source) && (value == MICROBIT_EVT_ANY || value == evt.value))
{
// Wakey wakey!
dequeue_fiber(f);

68
source/MicroBitMessageBus.cpp
View file

@ -142,6 +142,45 @@ MicroBitEventQueueItem* MicroBitMessageBus::dequeueEvent()
return item;
}
/**
* Cleanup any MicroBitListeners marked for deletion from the list.
* @return The number of listeners removed from the list.
*/
int MicroBitMessageBus::deleteMarkedListeners()
{
MicroBitListener *l, *p;
int removed = 0;
l = listeners;
p = NULL;
// Walk this list of event handlers. Delete any that match the given listener.
while (l != NULL)
{
if (l->flags & MESSAGE_BUS_LISTENER_DELETING)
{
if (p == NULL)
listeners = l->next;
else
p->next = l->next;
// delete the listener.
MicroBitListener *t = l;
l = l->next;
delete t;
removed++;
continue;
}
p = l;
l = l->next;
}
return removed;
}
/**
* Periodic callback from MicroBit.
* Process at least one event from the event queue, if it is not empty.
@ -149,6 +188,9 @@ MicroBitEventQueueItem* MicroBitMessageBus::dequeueEvent()
*/
void MicroBitMessageBus::idleTick()
{
// Clear out any listeners marked for deletion
this->deleteMarkedListeners();
MicroBitEventQueueItem *item = this->dequeueEvent();
// Whilst there are events to process and we have no useful other work to do, pull them off the queue and process them.
@ -225,7 +267,7 @@ int MicroBitMessageBus::process(MicroBitEvent &evt, uint32_t mask)
{
if((l->id == evt.source || l->id == MICROBIT_ID_ANY) && (l->value == evt.value || l->value == MICROBIT_EVT_ANY))
{
if(l->flags & mask)
if(l->flags & mask && !(l->flags & MESSAGE_BUS_LISTENER_DELETING))
{
l->evt = evt;
@ -377,7 +419,7 @@ int MicroBitMessageBus::add(MicroBitListener *newListener)
{
methodCallback = (newListener->flags & MESSAGE_BUS_LISTENER_METHOD) && (l->flags & MESSAGE_BUS_LISTENER_METHOD);
if (l->id == newListener->id && l->value == newListener->value && (methodCallback ? *l->cb_method == *newListener->cb_method : l->cb == newListener->cb))
if (l->id == newListener->id && l->value == newListener->value && (methodCallback ? *l->cb_method == *newListener->cb_method : l->cb == newListener->cb) && !(l->flags & MESSAGE_BUS_LISTENER_DELETING))
return 0;
l = l->next;
@ -437,7 +479,7 @@ int MicroBitMessageBus::add(MicroBitListener *newListener)
*/
int MicroBitMessageBus::remove(MicroBitListener *listener)
{
MicroBitListener *l, *p;
MicroBitListener *l;
int removed = 0;
//handler can't be NULL!
@ -445,7 +487,6 @@ int MicroBitMessageBus::remove(MicroBitListener *listener)
return 0;
l = listeners;
p = NULL;
// Walk this list of event handlers. Delete any that match the given listener.
while (l != NULL)
@ -453,29 +494,16 @@ int MicroBitMessageBus::remove(MicroBitListener *listener)
if ((listener->flags & MESSAGE_BUS_LISTENER_METHOD) == (l->flags & MESSAGE_BUS_LISTENER_METHOD))
{
if(((listener->flags & MESSAGE_BUS_LISTENER_METHOD) && (*l->cb_method == *listener->cb_method)) ||
((!(listener->flags & MESSAGE_BUS_LISTENER_METHOD) && l->cb == listener->cb)))
((!(listener->flags & MESSAGE_BUS_LISTENER_METHOD) && l->cb == listener->cb)))
{
if ((listener->id == MICROBIT_ID_ANY || listener->id == l->id) && (listener->value == MICROBIT_EVT_ANY || listener->value == l->value))
{
// Found a match. Remove from the list.
if (p == NULL)
listeners = l->next;
else
p->next = l->next;
// delete the listener.
MicroBitListener *t = l;
l = l->next;
delete t;
removed++;
continue;
// Found a match. mark this to be removed from the list.
l->flags |= MESSAGE_BUS_LISTENER_DELETING;
}
}
}
p = l;
l = l->next;
}