// class constructor //
public MutexHandler(bool case1, Mutual_Exclusion_Form form)
{
// if true, then use case 1 operation //
// Ricart & Agrawalas mutual exclusion algorithm, one person on bridge at a time. Everyone eventually allowed to cross (via queue) //
parentForm = form;
populateHandles(case1); // Create handles data structure, needed for all operational cases //
this.setInitialData(); // Sets inital thread data in the shared memory //
// Common init code between case 1 and case 2 //
parentForm.rInsert(Color.Red);
parentForm.rInsert(Color.Red);
parentForm.lInsert(Color.Blue);
parentForm.lInsert(Color.Blue);
// Specific case code execution //
if (case1)
{
// FOR CASE 1 -> EXECUTE MUTUAL EXCLUSION ALGORITHM //
Richart_Agrawala(form);
}
// if false, design protocol 2 states that bridge crossings allowed directionally in sync, but no job indefinately prevented from crossing
else
{
// FOR CASE 2 -> EXECUTE MUTUAL EXCLUSION ALGORITHM //
Multi_Bridge(form);
}
}
void Richart_Thread(int number)
{
if (endIt)
{
return;
}
// function code goes here for a thread //
int myThreadNr = number;
while (true) // infinitely execute unil terminated //
{
Thread.Sleep(parentForm.getSliderValue()); // sleeps for ms value indicated on slider (100ms - 500ms range) //
if (sharedMemoryLock.WaitOne())
{
if (!sharedMemory[myThreadNr].request)
{
// Have critical section to shared memory, set shared memory for bridge lock, then release Mutex and give other threads opportunity to respond //
sharedMemory[myThreadNr].request = true;
sharedMemory[myThreadNr].timeStamp = DateTime.Now;
sharedMemoryLock.ReleaseMutex();
}
else
{
sharedMemoryLock.ReleaseMutex();
}
}
// only needed if entering the bridge //
bool result = false;
string direction = string.Empty;
// ^^ only needed if entering the bridge //
if (sharedMemoryLock.WaitOne())
{
result = enterBridge(myThreadNr);
if (result)
{
sharedMemory[myThreadNr].CS = true;
sharedMemory[myThreadNr].request = false;
direction = sharedMemory[myThreadNr].direction;
}
sharedMemoryLock.ReleaseMutex();
}
// go onto the bridge if true //
if (result)
{
switch (direction)
{
case "L":
Color col = parentForm.rShift();
parentForm.iMiddle(col);
Thread.Sleep(parentForm.getSliderValue());
Color colT = parentForm.rMiddle();
parentForm.lInsert(colT);
if (sharedMemoryLock.WaitOne())
{
sharedMemory[myThreadNr].CS = false;
sharedMemory[myThreadNr].direction = "R";
sharedMemoryLock.ReleaseMutex();
}
break;
case "R":
Color col2 = parentForm.lShift();
parentForm.iMiddle(col2);
Thread.Sleep(parentForm.getSliderValue());
Color colT2 = parentForm.rMiddle();
parentForm.rInsert(colT2);
if (sharedMemoryLock.WaitOne())
{
sharedMemory[myThreadNr].CS = false;
sharedMemory[myThreadNr].direction = "L";
sharedMemoryLock.ReleaseMutex();
}
break;
}
}
}
}
