internal override WaitNode TryTakePrologue(StParker pk, int key, out T di, ref WaitNode hint)
{
var localQueue = Current;
if (TryTake(out di, localQueue))
{
if (pk.TryLock())
{
pk.UnparkSelf(key);
}
else
{
localQueue.TryAdd(di);
}
return(null);
}
var wn = new WaitNode(pk, key);
waitQueue.Enqueue(wn);
if (!pk.IsLocked && TryTake(out di, localQueue))
{
if (pk.TryLock())
{
waitQueue.Unlink(wn, hint);
pk.UnparkSelf(key);
return(null);
}
localQueue.TryAdd(di);
}
return(wn);
}
internal WaitBlock(WaitType t, int r, int k)
{
parker = new StParker();
waitType = t;
request = r;
waitKey = k;
}
//
// Exchanges a data item, activating the specified cancellers.
//
public bool Exchange(T myData, out T yourData, StCancelArgs cargs)
{
if (TryExchange(myData, out yourData))
{
return(true);
}
var pk = new StParker();
var wn = new WaitNode(pk, myData);
if (TryExchange(wn, myData, out yourData))
{
return(true);
}
int ws = pk.Park(spinCount, cargs);
if (ws == StParkStatus.Success)
{
yourData = wn.Channel;
return(true);
}
CancelExchange(wn);
StCancelArgs.ThrowIfException(ws);
return(false);
}
//
// Executes the prologue of the TryTake operation.
//
internal override WaitNode TryTakePrologue(StParker pk, int key, out T di, ref WaitNode hint) {
WaitNode wn = base.TryTakePrologue(pk, key, out di, ref hint);
if (wn == null) {
FreeSlot();
}
return wn;
}
internal WaitBlock(StParker pk, WaitType t, int r, int k)
{
parker = pk;
waitType = t;
request = r;
waitKey = k;
}
public static int Sleep(StCancelArgs cargs)
{
int ws = new StParker().Park(0, cargs);
StCancelArgs.ThrowIfException(ws);
return(ws);
}
//
// Tries to take a data item from the queue, activating the
// specified cancellers.
//
public bool TryTake(out T di, StCancelArgs cargs)
{
if (TryTake(out di))
{
return(true);
}
if (cargs.Timeout == 0)
{
return(false);
}
StParker pk = new StParker();
WaitNode wn, hint = null;
if ((wn = TryTakePrologue(pk, StParkStatus.Success, out di, ref hint)) == null)
{
return(true);
}
int ws = pk.Park(cargs);
if (ws == StParkStatus.Success)
{
TakeEpilogue();
di = wn.channel;
return(true);
}
//
// The take was cancelled; so, cancel the take attempt and
// report the failure appropriately.
//
CancelTakeAttempt(wn, hint);
StCancelArgs.ThrowIfException(ws);
return(false);
}
internal WaitBlock WaitWithParker(StParker pk, WaitType type, int key, ref int sc)
{
WaitBlock wb = null;
do
{
WaitBlock s;
if ((s = state) == SET)
{
return(null);
}
if (wb == null)
{
wb = new WaitBlock(pk, type, 0, key);
}
wb.next = s;
if (Interlocked.CompareExchange(ref state, wb, s) == s)
{
sc = s == null ? spinCount : 0;
return(wb);
}
} while (true);
}
/*++
*
* Generic API
*
* --*/
//
// Tries to add a data item to the queue, activating the specified
// cancellers.
//
public bool TryAdd(T di, StCancelArgs cargs)
{
if (TryAdd(di))
{
return(true);
}
if (cargs.Timeout == 0)
{
return(false);
}
WaitNode hint = null;
WaitNode wn;
StParker pk = new StParker();
if ((wn = TryAddPrologue(pk, StParkStatus.Success, di, ref hint)) == null)
{
return(true);
}
int ws = pk.Park(cargs);
if (ws == StParkStatus.Success)
{
return(true);
}
//
// The add operation was cancelled; so, cancel the add attempt
// and report the failure appropriately.
//
CancelAddAttempt(wn, hint);
StCancelArgs.ThrowIfException(ws);
return(false);
}
internal override WaitBlock _WaitAnyPrologue(StParker pk, int key,
ref WaitBlock hint, ref int sc)
{
WaitBlock wb = null;
do
{
if (_TryAcquire())
{
return(null);
}
if (wb == null)
{
wb = new WaitBlock(pk, WaitType.WaitAny, ACQUIRE, key);
}
WaitBlock pred;
if (EnqueueWaiter(wb, out pred))
{
sc = ((hint = pred) == head) ? spinCount : 0;
return(wb);
}
} while (true);
}
//
// Registers the specified parker with the alerter.
//
internal bool RegisterParker(StParker pk)
{
do
{
StParker s;
//
// If the alerter is already set, return false.
//
if ((s = state) == ALERTED)
{
return(false);
}
//
// Try to insert the parker in the alert list.
//
pk.pnext = s;
if (Interlocked.CompareExchange <StParker>(ref state, pk, s) == s)
{
return(true);
}
} while (true);
}
//
// Waits until the synchronizer allows the acquire, activating
// the specified cancellers.
//
public bool WaitOne(StCancelArgs cargs)
{
if (_TryAcquire())
{
return(true);
}
if (cargs.Timeout == 0)
{
return(false);
}
var pk = new StParker();
WaitBlock hint = null;
int sc = 0;
WaitBlock wb;
if ((wb = _WaitAnyPrologue(pk, StParkStatus.Success, ref hint, ref sc)) == null)
{
return(true);
}
int ws = pk.Park(sc, cargs);
if (ws == StParkStatus.Success)
{
_WaitEpilogue();
return(true);
}
_CancelAcquire(wb, hint);
StCancelArgs.ThrowIfException(ws);
return(false);
}
internal override WaitBlock _WaitAllPrologue(StParker pk, ref WaitBlock hint,
ref int sc)
{
WaitBlock wb = null;
if (_AllowsAcquire)
{
return(null);
}
if (wb == null)
{
wb = new WaitBlock(pk, WaitType.WaitAll, ACQUIRE, StParkStatus.StateChange);
}
WaitBlock pred;
if (EnqueueWaiter(wb, out pred))
{
sc = ((hint = pred) == head) ? spinCount : 0;
return(wb);
}
return(null);
}
//
// Executes the prologue of the TryAdd operation.
//
internal override WaitNode TryAddPrologue(StParker pk, int key, T di, ref WaitNode ignored)
{
if (pk.TryLock())
{
pk.UnparkSelf(key);
}
AddWorker(di);
return(null);
}
//
// Constructor: registers a take with a blocking queue.
//
internal StRegisteredTake(StBlockingQueue <T> queue, StTakeCallback <T> callback,
object cbState, int timeout, bool executeOnce)
{
//
// Validate the arguments.
//
if (timeout == 0)
{
throw new ArgumentOutOfRangeException("\"timeout\" can not be zero");
}
if (callback == null)
{
throw new ArgumentOutOfRangeException("\"callback\" must be specified");
}
//
// Initialize the registered take fields.
//
this.queue = queue;
cbparker = new CbParker(UnparkCallback);
if ((this.timeout = timeout) != Timeout.Infinite)
{
toTimer = new RawTimer(cbparker);
}
this.executeOnce = executeOnce;
this.callback = callback;
this.cbState = cbState;
//
// Execute the TryTakePrologue prologue on the queue.
//
waitNode = queue.TryTakePrologue(cbparker, StParkStatus.Success, out dataItem,
ref hint);
//
// Set the state to active and enable the unpark callback.
//
state = ACTIVE;
int ws;
if ((ws = cbparker.EnableCallback(timeout, toTimer)) != StParkStatus.Pending)
{
//
// The take operation was already accomplished. To prevent
// uncontrolled reentrancy, the unpark callback is executed inline.
//
UnparkCallback(ws);
}
}
//
// Executes the prologue of the Waitable.WaitAny method.
//
internal override WaitBlock _WaitAnyPrologue(StParker pk, int key,
ref WaitBlock ignored, ref int sc)
{
if (TryEnterWriteInternal())
{
return(null);
}
var wb = new WaitBlock(pk, WaitType.WaitAny, ENTER_WRITE, key);
sc = EnqueueEnterWrite(wb);
return(wb);
}
internal override WaitBlock _WaitAnyPrologue(StParker pk, int key,
ref WaitBlock ignored, ref int sc)
{
if (TryAcquireInternal(1))
{
return(null);
}
var wb = new WaitBlock(pk, WaitType.WaitAny, 1, key);
sc = EnqueueAcquire(wb, 1);
return(wb);
}
//
// Executes the prologue of the Waitable.WaitAll method.
//
internal override WaitBlock _WaitAllPrologue(StParker pk,
ref WaitBlock ignored, ref int sc)
{
if (_AllowsAcquire)
{
return(null);
}
var wb = new WaitBlock(pk, WaitType.WaitAll, ENTER_WRITE, StParkStatus.StateChange);
sc = EnqueueEnterWrite(wb);
return(wb);
}
private bool SlowTryInit(int spinCount)
{
StParker s;
do
{
if ((s = state) == FREE &&
Interlocked.CompareExchange(ref state, BUSY, FREE) == FREE)
{
return(true);
}
if (s == AVAILABLE)
{
return(false);
}
if (spinCount-- <= 0)
{
break;
}
Platform.SpinWait(1);
} while (true);
//
// The initialization is taking place. So, create a locked parker
// and insert it in the wait queue, if the lock remains busy.
//
var pk = new StParker(0);
do
{
if ((s = state) == FREE &&
Interlocked.CompareExchange(ref state, BUSY, FREE) == FREE)
{
return(true);
}
if (s == AVAILABLE)
{
return(false);
}
pk.pnext = s;
if (Interlocked.CompareExchange(ref state, pk, s) == s)
{
break;
}
} while (true);
return(pk.Park() == STATUS_INIT);
}
//
// Deregisters the specified parker from the alerter.
//
internal void DeregisterParker(StParker pk)
{
//
// Very often there is only a parker inserted in the alerter
// list. So, consider first this case.
//
if (pk.pnext == null &&
Interlocked.CompareExchange <StParker>(ref state, null, pk) == pk)
{
return;
}
SlowDeregisterParker(pk);
}
//
// Deregisters the specified parker when it isn't the only
// parker in the alerter list.
//
private void SlowDeregisterParker(StParker pk)
{
//
// Absorb the locked parkers at top of the stack.
//
StParker p;
do
{
if ((p = state) == null || p == ALERTED)
{
return;
}
if (p.IsLocked)
{
Interlocked.CompareExchange <StParker>(ref state, p.pnext, p);
}
else
{
break;
}
} while (true);
//
// Compute a entry ahead the parker that we want to unlink,
// and try to unsplice it.
//
StParker past;
if ((past = pk.pnext) != null && past.IsLocked)
{
past = past.pnext;
}
while (p != null && p != past)
{
StParker n = p.pnext;
if (n != null && n.IsLocked)
{
p.CasNext(n, n.pnext);
}
else
{
p = n;
}
}
}
//
// Exits the lock.
//
public void Exit()
{
//
// Since that atomic operations on references are more
// expensive than on integers, we optimize the release when
// the spin lock's wait queue is empty. However, when the queue
// seems empty before the lock is released, but it's seen
// non-empty after the lock is released, our algorithm resorts
// to two atomic instructions.
//
if (top == null)
{
Interlocked.Exchange(ref state, FREE);
if (top == null)
{
return;
}
}
else
{
state = FREE;
}
//
// Unpark all waiting threads.
//
// NOTE: Since that the spin lock's queue is implemented with
// a stack, we build another stack in order to unpark the
// waiting thread according to its arrival order.
//
StParker p = Interlocked.Exchange <StParker>(ref top, null);
StParker ws = null, n;
while (p != null)
{
n = p.pnext;
p.pnext = ws;
ws = p;
p = n;
}
while (ws != null)
{
n = ws.pnext;
ws.Unpark(StParkStatus.Success);
ws = n;
}
}
//
// Constructors.
//
public StTimer(bool notificationTimer)
{
if (notificationTimer)
{
tmrEvent = new StNotificationEvent();
}
else
{
tmrEvent = new StSynchronizationEvent();
}
state = INACTIVE;
cbparker = new CbParker(TimerCallback);
timer = new RawTimer(cbparker);
}
//
// Tries to unregister the callback. This method is thread-safe.
//
public bool Unregister()
{
StParker p = parker;
if (p == null)
{
return(false);
}
parker = null;
if (p.TryCancel())
{
p.Unpark(StParkStatus.WaitCancelled);
return(true);
}
return(false);
}
//
// Executes the prologue of the TryAdd operation.
//
internal override WaitNode TryAddPrologue(StParker pk, int key, T di, ref WaitNode hint) {
if (TryReserveSlot()) {
if (pk.TryLock()) {
AddWorker(di);
pk.UnparkSelf(key);
} else {
FreeSlot();
}
return null;
}
//
// ...
//
WaitNode wn;
hint = waitQueue.Enqueue(wn = new WaitNode(pk, key, di));
//
// As a slot could have been free after the check done
// above, but before we insert the wait block in the wait queue,
// we must retry to reserve a free slot.
//
if (TryReserveSlot()) {
if (pk.TryLock()) {
AddWorker(di);
pk.UnparkSelf(key);
} else {
waitQueue.Unlink(wn, hint);
FreeSlot();
}
return null;
}
return wn;
}
static TimerList()
{
//
// Create the objects.
//
_lock = new SpinLock(TIMER_LIST_LOCK_SPINS);
timerListHead = new RawTimer(null);
limitTimer = new RawTimer(null);
parker = new StParker(1);
//
// Initialize the limit timer as unlinked.
//
limitTimer.next = limitTimer;
//
// Initialize the timer list as empty.
//
timerListHead.next = timerListHead.prev = timerListHead;
//
// Set the start base time e set the *delay* sentinel.
//
baseTime = Environment.TickCount;
timerListHead.delay = Int32.MaxValue;
//
// Create and start the timer thread.
//
new Thread(TimerThread).Start();
}
//
// Frees the lock and selects a candidate owner from the queue
// of waiting threads.
//
public void Exit()
{
WaitBlock wb = head;
bool unpark = false;
StParker pk = null;
while ((wb = wb.next) != null && wb.request != CANDIDATE)
{
pk = wb.parker;
if (pk.TryLock())
{
wb.request = CANDIDATE;
unpark = true;
break;
}
}
state = FREE;
if (unpark)
{
pk.Unpark(StParkStatus.Success);
}
}
//
// Constructors.
//
public SpinLock(int sc)
{
state = FREE;
top = null;
spinCount = Platform.IsMultiProcessor ? sc : 0;
}
//
// Slow path to acquire the spin lock.
//
private void SlowEnter()
{
StParker pk = null;
do
{
//
// First, try to acquire the spin lock, spinning for the
// specified number of cycles, if the wait queue is empty.
//
int sc = spinCount;
do
{
if (state == FREE &&
Interlocked.CompareExchange(ref state, BUSY, FREE) == FREE)
{
return;
}
if (top != null || sc-- <= 0)
{
break;
}
Platform.SpinWait(1);
} while (true);
//
// The spin lock is busy. So, create, or reset, a parker and
// insert it in the wait queue.
//
if (pk == null)
{
pk = new StParker(0);
}
else
{
pk.Reset(0);
}
do
{
StParker t;
pk.pnext = (t = top);
if (Interlocked.CompareExchange <StParker>(ref top, pk, t) == t)
{
break;
}
} while (true);
//
// Since that the lock can become free after the parker is
// inserted in the wait queue, we must retry to acquire the spinlock
// if it seems free.
//
// NOTE: We don't remove the parker from the wait queue, because
// it will be surely removed next time the lock is release.
//
if (state == FREE &&
Interlocked.CompareExchange(ref state, BUSY, FREE) == FREE)
{
return;
}
//
// Park the current thread and, after release, retry the
// spin lock acquire.
//
pk.Park();
} while (true);
}
internal override WaitBlock _WaitAllPrologue(StParker pk, ref WaitBlock hint, ref int sc)
{
return(waitEvent.WaitWithParker(pk, WaitType.WaitAll, StParkStatus.StateChange, ref sc));
}
