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fix pdb monitor locking

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Guard PV*Monitor::complete to prevent
concurrent access from dbEvent callback,
and PVA server calling release().
This commit is contained in:
Michael Davidsaver
2018-02-06 18:05:11 -08:00
parent 1635e75c86
commit b6b6ac3305
3 changed files with 185 additions and 195 deletions
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146
common/pvahelper.h
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@ -76,6 +76,7 @@ struct BaseMonitor : public epics::pvAccess::Monitor
epicsMutex& lock; // not held during any callback
typedef epicsGuard<epicsMutex> guard_t;
typedef epicsGuardRelease<epicsMutex> unguard_t;
private:
const requester_t::weak_pointer requester;
@ -106,121 +107,136 @@ public:
//! Must call before first post(). Sets .complete and calls monitorConnect()
//! @note that value will never by accessed except by post() and requestUpdate()
void connect(const epics::pvData::PVStructurePtr& value)
void connect(guard_t& guard, const epics::pvData::PVStructurePtr& value)
{
guard.assertIdenticalMutex(lock);
epics::pvData::StructureConstPtr dtype(value->getStructure());
epics::pvData::PVDataCreatePtr create(epics::pvData::getPVDataCreate());
BaseMonitor::shared_pointer self(shared_from_this());
requester_t::shared_pointer req(requester.lock());
{
guard_t G(lock);
assert(!complete); // can't call twice
complete = value;
empty.resize(nbuffers);
for(size_t i=0; i<empty.size(); i++) {
empty[i].reset(new epics::pvAccess::MonitorElement(create->createPVStructure(dtype)));
}
assert(!complete); // can't call twice
complete = value;
empty.resize(nbuffers);
for(size_t i=0; i<empty.size(); i++) {
empty[i].reset(new epics::pvAccess::MonitorElement(create->createPVStructure(dtype)));
}
epics::pvData::Status sts;
if(req)
if(req) {
unguard_t U(guard);
epics::pvData::Status sts;
req->monitorConnect(sts, self, dtype);
}
}
struct no_overflow {};
//! post update if queue not full, if full return false w/o overflow
bool post(const epics::pvData::BitSet& updated, no_overflow)
bool post(guard_t& guard, const epics::pvData::BitSet& updated, no_overflow)
{
guard.assertIdenticalMutex(lock);
requester_t::shared_pointer req;
{
guard_t G(lock);
if(!complete || !running) return false;
changed |= updated;
if(!complete || !running) return false;
if(empty.empty()) return false;
changed |= updated;
if(p_postone())
req = requester.lock();
inoverflow = false;
if(empty.empty()) return false;
if(p_postone())
req = requester.lock();
inoverflow = false;
if(req) {
unguard_t U(guard);
req->monitorEvent(shared_from_this());
}
if(req) req->monitorEvent(shared_from_this());
return true;
}
//! post update of pending changes. eg. call from requestUpdate()
bool post()
bool post(guard_t& guard)
{
guard.assertIdenticalMutex(lock);
bool oflow;
requester_t::shared_pointer req;
{
guard_t G(lock);
if(!complete || !running) return false;
if(empty.empty()) {
oflow = inoverflow = true;
if(!complete || !running) return false;
} else {
if(empty.empty()) {
oflow = inoverflow = true;
if(p_postone())
req = requester.lock();
oflow = inoverflow = false;
}
} else {
if(p_postone())
req = requester.lock();
oflow = inoverflow = false;
}
if(req) {
unguard_t U(guard);
req->monitorEvent(shared_from_this());
}
if(req) req->monitorEvent(shared_from_this());
return !oflow;
}
//! post update with changed and overflowed masks (eg. when updates were lost in some upstream queue)
bool post(const epics::pvData::BitSet& updated, const epics::pvData::BitSet& overflowed)
bool post(guard_t& guard,
const epics::pvData::BitSet& updated,
const epics::pvData::BitSet& overflowed)
{
guard.assertIdenticalMutex(lock);
bool oflow;
requester_t::shared_pointer req;
{
guard_t G(lock);
if(!complete || !running) return false;
if(empty.empty()) {
oflow = inoverflow = true;
overflow |= overflowed;
overflow.or_and(updated, changed);
changed |= updated;
if(!complete || !running) return false;
} else {
if(empty.empty()) {
oflow = inoverflow = true;
overflow |= overflowed;
overflow.or_and(updated, changed);
changed |= updated;
changed |= updated;
if(p_postone())
req = requester.lock();
oflow = inoverflow = false;
}
} else {
changed |= updated;
if(p_postone())
req = requester.lock();
oflow = inoverflow = false;
}
if(req) {
unguard_t U(guard);
req->monitorEvent(shared_from_this());
}
if(req) req->monitorEvent(shared_from_this());
return !oflow;
}
//! post update with changed
bool post(const epics::pvData::BitSet& updated) {
bool post(guard_t& guard, const epics::pvData::BitSet& updated) {
bool oflow;
requester_t::shared_pointer req;
{
guard_t G(lock);
if(!complete || !running) return false;
if(empty.empty()) {
oflow = inoverflow = true;
overflow.or_and(updated, changed);
changed |= updated;
if(!complete || !running) return false;
} else {
if(empty.empty()) {
oflow = inoverflow = true;
overflow.or_and(updated, changed);
changed |= updated;
changed |= updated;
if(p_postone())
req = requester.lock();
oflow = inoverflow = false;
}
} else {
changed |= updated;
if(p_postone())
req = requester.lock();
oflow = inoverflow = false;
}
if(req) {
unguard_t U(guard);
req->monitorEvent(shared_from_this());
}
if(req) req->monitorEvent(shared_from_this());
return !oflow;
}
@ -252,7 +268,7 @@ public:
virtual void onStop() {}
//! called when within release() when the opportunity exists to end the overflow condition
//! May do nothing, or lock and call post()
virtual void requestUpdate() {guard_t G(lock); post();}
virtual void requestUpdate() {guard_t G(lock); post(G);}
virtual void destroy()
{