epics/pcas
0
0
Fork 0
Code Issues Pull Requests Projects Wiki Activity

This was defensive coding against deadlock occurring when they hold a lock

Browse Source 
in the expire callback that they also hold when starting the timer.  I dont know
how to protect them against a situation where they hold a lock in the expire
callback and also hold it when canceling the timer, but at least that is a less
common situation.
This commit is contained in:
Jeff Hill
2002-08-16 00:07:09 +00:00
parent 936053422b
commit aa54a26c8b
2 changed files with 64 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
src/libCom/timer/timerQueue.cpp
View File

@@ -43,7 +43,7 @@ double timerQueue::process ( const epicsTime & currentTime )
if ( this->pExpireTmr ) {
// if some other thread is processing the queue
// (or if this is a recursive call)
timer *pTmr = this->timerList.first ();
timer * pTmr = this->timerList.first ();
if ( pTmr ) {
double delay = pTmr->exp - currentTime;
if ( delay < 0.0 ) {
@@ -100,14 +100,17 @@ double timerQueue::process ( const epicsTime & currentTime )
expStat = pTmpNotify->expire ( currentTime );
}
this->pExpireTmr->curState = timer::stateLimbo;
//
// only restart if they didnt cancel() the timer
// while the call back was running
//
if ( this->cancelPending ) {
this->pExpireTmr->curState = timer::stateLimbo;
this->pExpireTmr->pNotify = 0;
// 1) if another thread is canceling cancel() waits for this
// 1) if another thread is canceling then cancel() waits for
// the event below
// 2) if this thread is canceling in the timer callback then
// dont touch timer or notify here because the cancel might
// have occurred because they destroyed the timer in the
@@ -115,15 +118,19 @@ double timerQueue::process ( const epicsTime & currentTime )
this->cancelPending = false;
this->cancelBlockingEvent.signal ();
}
else if ( this->pExpireTmr->pNotify ) {
// pNotify was cleared above so if it is valid now we know that
// someone has started the timer from another thread and that
// predominates over the restart parameters from expire.
this->pExpireTmr->privateStart (
*this->pExpireTmr->pNotify, this->pExpireTmr->exp );
}
else {
// restart as nec
if ( expStat.restart() ) {
this->pExpireTmr->privateStart (
*pTmpNotify, currentTime + expStat.expirationDelay() );
}
else {
this->pExpireTmr->curState = timer::stateLimbo;
}
}
this->pExpireTmr = 0;