public bool Calculate()
{
if (string.IsNullOrEmpty(InputString) || FramesCount <= 0)
{
return(false);
}
var list = new List <OSASVMObject>();
for (int i = 0; i < InputString.Length; i++)
{
// Get the object
object obj = InputString[i];
var vmObj = new OSASVMObject();
vmObj.InputObject = obj;
// Set this item index to current i value
vmObj.Index = i;
if (i == 0)
{
vmObj.Frames.Add(new OSASFrameObject(obj));
vmObj.Hit = false;
Faults++;
list.Add(vmObj);
continue;
}
// Store frames values of the previous object
//(useful in the up-coming check of existence in the next loop iteration)
vmObj.Frames = new List <OSASFrameObject>(list[i - 1].Frames);
// Check if the object exists in this copied frames
var ex = vmObj.Frames.Contains(obj);
if (ex)
{
vmObj.Hit = true;
Hits++;
vmObj.Frames.Find(a => a.Value.Equals(obj)).SecondChance = true;
}
else
{
vmObj.Hit = false;
Faults++;
if (vmObj.Frames.Count < FramesCount)
{
vmObj.Frames.Add(new OSASFrameObject(obj));
}
else
{
vmObj.Frames[ObjectToRemoveIndex(list, vmObj, i, InputString, AlgorithmType)] = new OSASFrameObject(obj);
}
}
list.Add(vmObj);
}
OutputList = list;
return(true);
}
private int ObjectToRemoveIndex(List <OSASVMObject> objects, OSASVMObject vmObj, int current, string input, VMAlgorithmType type)
{
int ObjToRemoveIndex = -1;
if (type == VMAlgorithmType.FIFO)
{
var lastFObjects = objects.Where(a => a.Index < current && !a.Hit).ToList();
var objToRemoveValue = lastFObjects[lastFObjects.Count - FramesCount].InputObject;
return(ObjToRemoveIndex = vmObj.Frames.FindIndex(a => a.Equals(objToRemoveValue)));
}
else if (type == VMAlgorithmType.LRU)
{
var lastFObjects = objects.AsEnumerable().Reverse().Distinct().ToList();
var objToRemoveValue = lastFObjects[FramesCount - 1].InputObject;
return(ObjToRemoveIndex = vmObj.Frames.FindIndex(a => a.Equals(objToRemoveValue)));
}
else if (type == VMAlgorithmType.Optimal)
{
var rightString = input.Substring(current, input.Length - current);
var rightUsed = rightString.Where(a => vmObj.Frames.Exists(b => b.Equals(a))).ToList();
if (rightUsed.Count == 0)
{
return(ObjToRemoveIndex = 0);
}
var grouped = rightUsed.GroupBy(a => a).ToList();
if (grouped.Count < vmObj.Frames.Count)
{
var notExists = vmObj.Frames.Where(a => !grouped.Exists(b => a.Equals(b.Key))).ToList();
var objToRemoveValue = notExists.FirstOrDefault();
return(ObjToRemoveIndex = vmObj.Frames.FindIndex(a => a.Equals(objToRemoveValue)));
}
grouped = grouped.OrderByDescending(a => a.Count()).ToList();
var objToRemoveValuee = grouped.LastOrDefault().Key;
return(ObjToRemoveIndex = vmObj.Frames.FindIndex(a => a.Equals(objToRemoveValuee)));
}
else if (type == VMAlgorithmType.MFU)
{
var groupedObjects = vmObj.Frames.Select(a => new
{
obj = a,
count = input.Substring(0, current).Where(b => b.Equals(a.Value)).Count()
});
var max = groupedObjects.Max(a => a.count);
// Now get the objects with this max count value
var maxCountObjects = groupedObjects.Where(a => a.count == max);
return(ObjToRemoveIndex = vmObj.Frames.FindIndex(a => a.Equals(maxCountObjects.FirstOrDefault().obj.Value)));
}
else if (type == VMAlgorithmType.SecondChance)
{
//var orderedObjects = objects.SelectMany(a => a.Frames).
// Where(e=>vmObj.Frames.Exists(f=>f.Equals(e))).
// GroupBy(b => b).
// OrderByDescending(c => c.Count());
var orderedObjects = GetValuesCounts(objects, vmObj).OrderBy(a => a.Value);
point:
foreach (var obj in orderedObjects.Reverse())
{
var frameObj = vmObj.Frames.Find(a => a.Equals(obj.Key));
if (frameObj == null)
{
continue;
}
if (frameObj.SecondChance)
{
frameObj.SecondChance = false;
continue;
}
else
{
return(ObjToRemoveIndex = vmObj.Frames.FindIndex(a => a.Equals(obj.Key)));
}
}
goto point;
}
else if (type == VMAlgorithmType.LFU)
{
var groupedObjects = vmObj.Frames.Select(a => new
{
obj = a,
count = input.Substring(0, current).Where(b => b.Equals(a.Value)).Count(),
stringIndex = input.Substring(0, current).IndexOf((char)a.Value),
});
var min = groupedObjects.Min(a => a.count);
// Now get the objects with this min count value ordered by input string index
var minCountObjects = groupedObjects.Where(a => a.count == min).OrderBy(a => a.stringIndex);
return(ObjToRemoveIndex = vmObj.Frames.FindIndex(a => a.Equals(minCountObjects.FirstOrDefault().obj.Value)));
}
return(ObjToRemoveIndex);
}
private Dictionary <object, int> GetValuesCounts(List <OSASVMObject> objects, OSASVMObject vmObj)
{
var dic = new Dictionary <object, int>();
for (var i = 0; i < vmObj.Frames.Count; i++)
{
dic.Add(vmObj.Frames[i].Value, 0);
foreach (var obj in objects.AsEnumerable().Reverse())
{
if (obj.Frames.Count > i)
{
if (obj.Frames[i].Value == vmObj.Frames[i].Value)
{
dic[vmObj.Frames[i].Value]++;
}
else
{
break;
}
}
}
}
return(dic);
}
public OSASVMObject(OSASVMObject vmObject)
{
InputObject = vmObject.InputObject;
Frames = vmObject.Frames;
Hit = vmObject.Hit;
}