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fixed event clear while flow control is running deadlock

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This commit is contained in:
Jeff Hill
2001-08-27 20:38:46 +00:00
parent 560e9d5bf2
commit 8d4adef787
1 changed files with 64 additions and 51 deletions
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115
src/db/dbEvent.c
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@@ -91,6 +91,7 @@
#include "memDebugLib.h"
static struct event_block canceledEvent;
/* local function declarations */
@@ -420,6 +421,27 @@ int db_event_disable(struct event_block *pevent)
}
}
/*
* event_remove()
* event queue lock _must_ be applied
*/
LOCAL void event_remove ( struct event_que *ev_que,
unsigned short index, struct event_block *placeHolder )
{
struct event_block *pEvent = ev_que->evque[index];
ev_que->evque[index] = placeHolder;
if ( pEvent->npend == 1u ) {
pEvent->pLastLog = NULL;
}
else {
assert ( pEvent->npend > 1u );
assert ( ev_que->nDuplicates >= 1u );
ev_que->nDuplicates--;
}
pEvent->npend--;
}
/*
* DB_CANCEL_EVENT()
@@ -433,6 +455,7 @@ int db_event_disable(struct event_block *pevent)
*/
int db_cancel_event(struct event_block *pevent)
{
unsigned getix;
struct dbCommon *precord;
int status;
@@ -452,18 +475,40 @@ int db_cancel_event(struct event_block *pevent)
* its call back changes
*/
LOCKEVQUE(pevent->ev_que)
pevent->user_sub = NULL;
while (pevent->npend || pevent->callBackInProgress) {
UNLOCKEVQUE(pevent->ev_que)
/*
* purge this event from the queue
*
* Its better to take this approach rather than waiting
* for the event thread to finish removing this event
* from the queue because the event thread will not
* process if we are in flow control mode. Since blocking
* here will block CA's TCP input queue then a dead lock
* would be possible.
*/
for ( getix = pevent->ev_que->getix;
pevent->ev_que->evque[getix] != EVENTQEMPTY;
getix = RNGINC ( getix ) ) {
if ( pevent->ev_que->evque[getix] == pevent ) {
event_remove ( pevent->ev_que, getix, &canceledEvent );
}
}
assert ( pevent->npend == 0u );
while ( pevent->callBackInProgress ) {
UNLOCKEVQUE ( pevent->ev_que )
semTake(pevent->ev_que->evUser->pflush_sem, sysClkRateGet());
LOCKEVQUE(pevent->ev_que)
}
UNLOCKEVQUE(pevent->ev_que)
LOCKEVQUE ( pevent->ev_que )
}
/*
* Decrement event que quota
*/
pevent->ev_que->quota -= EVENTENTRIES;
pevent->ev_que->quota -= EVENTENTRIES;
UNLOCKEVQUE(pevent->ev_que)
return OK;
}
@@ -916,20 +961,16 @@ int init_func_arg
*/
LOCAL int event_read (struct event_que *ev_que)
{
struct event_block *event;
unsigned int nextgetix;
db_field_log *pfl;
void (*user_sub) (void *user_arg, struct dbAddr *paddr,
int eventsRemaining, db_field_log *pfl);
int status;
/*
* evUser ring buffer must be locked for the multiple
* threads writing/reading it
*/
LOCKEVQUE(ev_que)
LOCKEVQUE(ev_que)
/*
* if in flow control mode drain duplicates and then
@@ -944,17 +985,16 @@ LOCAL int event_read (struct event_que *ev_que)
/*
* Fetch fast register copy
*/
for( event=ev_que->evque[ev_que->getix];
(event) != EVENTQEMPTY;
ev_que->getix = nextgetix, event = ev_que->evque[nextgetix]){
while ( ev_que->evque[ev_que->getix] != EVENTQEMPTY ) {
db_field_log fl = ev_que->valque[ev_que->getix];
struct event_block *event = ev_que->evque[ev_que->getix];
/*
* So I can tell em if more are comming
*/
nextgetix = RNGINC(ev_que->getix);
if ( event == &canceledEvent ) {
ev_que->evque[ev_que->getix] = EVENTQEMPTY;
ev_que->getix = RNGINC ( ev_que->getix );
continue;
}
/*
* Simple type values queued up for reliable interprocess
@@ -968,31 +1008,8 @@ LOCAL int event_read (struct event_que *ev_que)
pfl = NULL;
}
ev_que->evque[ev_que->getix] = EVENTQEMPTY;
/*
* remove event from the queue
*/
if (event->npend==1u) {
event->pLastLog = NULL;
}
else {
assert (event->npend>1u);
assert (ev_que->nDuplicates>=1u);
ev_que->nDuplicates--;
}
/*
* this provides a way to test to see if an event is in use
* despite the fact that the event queue does not point to this event
*/
event->callBackInProgress = TRUE;
/*
* it is essential that the npend count is not lowered
* before the callBackInProgress flag is set
*/
event->npend--;
event_remove ( ev_que, ev_que->getix, EVENTQEMPTY );
ev_que->getix = RNGINC ( ev_que->getix );
/*
* create a local copy of the call back parameters while
@@ -1011,18 +1028,14 @@ LOCAL int event_read (struct event_que *ev_que)
* for the event queue lock (which this thread now has).
*/
if (user_sub != NULL) {
event->callBackInProgress = TRUE;
UNLOCKEVQUE(ev_que)
(*user_sub) (event->user_arg, event->paddr,
ev_que->evque[nextgetix]?TRUE:FALSE, pfl);
ev_que->evque[ev_que->getix]?TRUE:FALSE, pfl);
LOCKEVQUE(ev_que)
event->callBackInProgress = FALSE;
}
/*
* this provides a way to test to see if an event is in use
* despite the fact that the event queue does not point to this event
*/
event->callBackInProgress = FALSE;
/*
* check to see if this event has been canceled each
* time that the callBackInProgress flag is set to false