/**
* Removes and returns first element, or Default if empty.
*/
private T UnlinkFirst()
{
Node <T> f = First;
if (f == null)
{
return(Default);
}
Node <T> n = f.Next;
T item = f.Item;
f.Item = Default;
f.Next = f; // help GC
First = n;
if (n == null)
{
Last = null;
}
else
{
n.Prev = null;
}
--Count;
NotFull.SignalCondition();
return(item);
}
/// <summary>
/// Get & remove element from head of Q.
/// </summary>
/// <returns>Returns head element, or Default if queue is empty.</returns>
/// throws ThreadInterruptedException.
public T Pop()
{
T v = Default;
AccessLock.WaitOne();
try {
if (Head != Tail)
{
v = ContainerList[Head++];
Head %= MaxCapacity;
if (Count > 0)
{
--Count;
}
NotFull.SignalCondition();
}
} finally {
AccessLock.ReleaseMutex();
}
return(v);
}
/**
* Links node as first element, or returns false if full.
*/
private bool LinkFirst(T v)
{
// assert lock.isHeldByCurrentThread();
if (Count >= MaxCapacity)
{
return(false);
}
Node <T> f = First;
Node <T> x = new Node <T>(v, null, f);
First = x;
if (Last == null)
{
Last = x;
}
else
{
f.Prev = x;
}
++Count;
NotEmpty.SignalCondition();
return(true);
}
/// <summary>
/// Add v to tail of Q.
/// </summary>
/// <param name="v"></param>
/// <returns>Returns v, or Default if queue is full.</returns>
/// throws ThreadInterruptedException.
public T Push(T v)
{
AccessLock.WaitOne();
try {
if (((Tail + 1) % MaxCapacity) == Head)
{
v = Default;
}
else
{
ContainerList[Tail++] = v;
Tail %= MaxCapacity;
if (Count < MaxCapacity)
{
++Count;
}
NotEmpty.SignalCondition();
}
} finally {
AccessLock.ReleaseMutex();
}
return(v);
}
/// <summary>
/// Release token to free list.
/// </summary>
/// <param name="idx"></param>
/// throws ThreadInterruptedException.
public void Release(int idx)
{
AccessLock.WaitOne();
try {
if (idx < MaxCapacity)
{
ContainerList[idx] = FreeIndex;
FreeIndex = idx;
if (Count > 0)
{
--Count;
}
NotFull.SignalCondition();
}
} finally {
AccessLock.ReleaseMutex();
}
}
/// <summary>
/// Fetch a free token from list.
/// </summary>
/// <returns>Returns token, or Default if none free.</returns>
/// throws ThreadInterruptedException.
public int Allocate()
{
int idx = Default;
AccessLock.WaitOne();
try {
idx = FreeIndex;
if (idx != Default)
{
FreeIndex = ContainerList[idx];
if (Count < MaxCapacity)
{
++Count;
}
NotEmpty.SignalCondition();
}
} finally {
AccessLock.ReleaseMutex();
}
return(idx);
}
