void *runPA() {
produce('A');
signalSemaphore(&siA);
signalSemaphore(&siii);
while (1) {
produce('A');
signalSemaphore(&siii);
}
}
void *runPB() {
waitSemaphore(&siii);
produce('B');
signalSemaphore(&siB);
signalSemaphore(&siiC);
while (1) {
waitSemaphore(&siiB);
waitSemaphore(&siii);
produce('B');
signalSemaphore(&siiC);
}
}
void *runC() {
while (1) {
waitSemaphore(&sC);
putchar(buf[ri++]);
ri %= BUF_SIZE;
signalSemaphore(&sP);
}
}
void produce(char ch) {
pthread_mutex_lock(&mutexP);
waitSemaphore(&sP);
buf[wi++] = ch;
wi %= BUF_SIZE;
signalSemaphore(&sC);
pthread_mutex_unlock(&mutexP);
}
// Signal a specified semaphore after the specified milliseconds duration (the argument).
// NOTE: NOT ABSOLUTE VALUE!
// If the specified time has already passed, then the TimingSemaphore is signalled immediately.
Oop* __fastcall Interpreter::primitiveSignalAtTick(CompiledMethod&, unsigned argumentCount)
{
Oop tickPointer = stackTop();
SMALLINTEGER nDelay;
if (ObjectMemoryIsIntegerObject(tickPointer))
nDelay = ObjectMemoryIntegerValueOf(tickPointer);
else
{
OTE* oteArg = reinterpret_cast<OTE*>(tickPointer);
return primitiveFailureWith(PrimitiveFailureNonInteger, oteArg); // ticks must be SmallInteger
}
// To avoid any race conditions against the global timerID value (it is quite
// common for the timer to fire, for example, before the timeSetEvent() call
// has actually returned in the duration is very short because the timer thread
// is operating at a very high priority), we use an interlocked operation
UINT outstandingID = InterlockedExchange(reinterpret_cast<SHAREDLONG*>(&timerID), 0);
// If outstanding timer now fires, it will do nothing. We'll end up killing something which is already
// dead of course, but that should be OK
if (outstandingID)
{
#ifdef OAD
TRACESTREAM << "Killing existing timer with id " << outstandingID << endl;
#endif
UINT kill = ::timeKillEvent(outstandingID);
if (kill != TIMERR_NOERROR)
trace("Failed to kill timer %u (%d,%d)!\n\r", outstandingID, kill, GetLastError());
}
if (nDelay > 0)
{
// Temporarily handle old image code that passes timer semaphore as an argument
if (argumentCount > 1 && (POTE)Pointers.TimingSemaphore == Pointers.Nil)
{
ObjectMemory::ProtectConstSpace(PAGE_READWRITE);
_Pointers.TimingSemaphore = (SemaphoreOTE*)stackValue(1);
ObjectMemory::ProtectConstSpace(PAGE_READONLY);
}
// Clamp the requested delay to the maximum if it is too large. This simplifies the Delay code in the image a little.
if (nDelay > SMALLINTEGER(wTimerMax))
{
nDelay = wTimerMax;
}
// Set the timerID to a non-zero value just in case the timer fires before timeSetEvent() returns.
// This allows the TimerProc to recognise the timer as valid (it doesn't really care about the
// timerID anyway, just that we're interested in it).
// N.B. We shouldn't need an interlocked operation here because, assuming no bugs in the Win32 MM
// timers, we've killed any outstanding timer, and the timer thread should be dormant
timerID = UINT(-1); // -1 is not used as a timer ID.
UINT newTimerID = ::timeSetEvent(nDelay, 0, TimeProc, 0, TIME_ONESHOT);
if (newTimerID && newTimerID != UINT(-1))
{
// Unless timer has already fired, record the timer id so can cancel if necessary
_InterlockedCompareExchange(reinterpret_cast<SHAREDLONG*>(&timerID), newTimerID, -1);
pop(argumentCount); // No ref. counting required
}
else
{
// System refused to set timer for some reason
DWORD error = GetLastError();
trace("Oh no, failed to set a timer for %d mS (%d)!\n\r", nDelay, error);
return primitiveFailureWithInt(PrimitiveFailureSystemError, error);
}
}
else if (nDelay == 0)
{
#ifdef _DEBUG
TRACESTREAM << "Requested delay " << dec << nDelay << " passed, signalling immediately" << endl;
#endif
// The request time has already passed, or does not fall within the
// available timer resolution (i.e. it will happen too soon), so signal
// it immediately
// We must adjust stack before signalling, as may change Process (and therefore stack!)
pop(argumentCount);
// N.B. Signalling may detect a process switch, but does not actually perform it
signalSemaphore(Pointers.TimingSemaphore);
}
// else requested delay was negative - we allow this to clear down the existing timer
#ifdef _DEBUG
if (newProcessWaiting())
{
ASSERT(m_oteNewProcess->m_oteClass == Pointers.ClassProcess);
ProcessOTE* activeProcess = scheduler()->m_activeProcess;
TRACESTREAM << "signalAtTick: Caused process switch to " << m_oteNewProcess
<< endl << "\t\tfrom " << activeProcess << endl
<< "\tasync signals " << m_qAsyncSignals.isEmpty() << ')' << endl;
}
#endif
// Delay could already have fired
CheckProcessSwitch();
return primitiveSuccess(0);
}
