/// <summary>
/// Waits for any of the work items in the specified array to complete, cancel, or timeout
/// </summary>
/// <param name="waitableResults">Array of work item result objects</param>
/// <param name="millisecondsTimeout">The number of milliseconds to wait, or Timeout.Infinite (-1) to wait indefinitely.</param>
/// <param name="exitContext">
/// true to exit the synchronization domain for the context before the wait (if in a synchronized context), and reacquire it; otherwise, false.
/// </param>
/// <param name="cancelWaitHandle">A cancel wait handle to interrupt the wait if needed</param>
/// <returns>
/// The array index of the work item result that satisfied the wait, or WaitTimeout if no work item result satisfied the wait and a time interval equivalent to millisecondsTimeout has passed or the work item has been canceled.
/// </returns>
internal static int WaitAny(
IWaitableResult[] waitableResults,
int millisecondsTimeout,
bool exitContext,
WaitHandle cancelWaitHandle)
{
WaitHandle[] waitHandles;
if (null != cancelWaitHandle)
{
waitHandles = new WaitHandle[waitableResults.Length + 1];
GetWaitHandles(waitableResults, waitHandles);
waitHandles[waitableResults.Length] = cancelWaitHandle;
}
else
{
waitHandles = new WaitHandle[waitableResults.Length];
GetWaitHandles(waitableResults, waitHandles);
}
int result = CTPEventWaitHandle.WaitAny(waitHandles, millisecondsTimeout, exitContext);
// Treat cancel as timeout
if (null != cancelWaitHandle)
{
if (result == waitableResults.Length)
{
result = CTPEventWaitHandle.WaitTimeout;
}
}
ReleaseWaitHandles(waitableResults);
return(result);
}
/// <summary>
/// Get the result of the work item.
/// If the work item didn't run yet then the caller waits for the result, timeout, or cancel.
/// In case of error the e argument is filled with the exception
/// </summary>
/// <returns>The result of the work item</returns>
private object GetResult(
int millisecondsTimeout,
bool exitContext,
WaitHandle cancelWaitHandle,
out Exception e)
{
e = null;
// Check for cancel
if (WorkItemState.Canceled == GetWorkItemState())
{
throw new WorkItemCancelException("Work item canceled");
}
// Check for completion
if (IsCompleted)
{
e = _exception;
return(_result);
}
// If no cancelWaitHandle is provided
if (null == cancelWaitHandle)
{
WaitHandle wh = GetWaitHandle();
bool timeout = !CTPEventWaitHandle.WaitOne(wh, millisecondsTimeout, exitContext);
ReleaseWaitHandle();
if (timeout)
{
throw new WorkItemTimeoutException("Work item timeout");
}
}
else
{
WaitHandle wh = GetWaitHandle();
int result = CTPEventWaitHandle.WaitAny(new WaitHandle[] { wh, cancelWaitHandle });
ReleaseWaitHandle();
switch (result)
{
case 0:
// The work item signaled
// Note that the signal could be also as a result of canceling the
// work item (not the get result)
break;
case 1:
case CTPEventWaitHandle.WaitTimeout:
throw new WorkItemTimeoutException("Work item timeout");
default:
Debug.Assert(false);
break;
}
}
// Check for cancel
if (WorkItemState.Canceled == GetWorkItemState())
{
throw new WorkItemCancelException("Work item canceled");
}
Debug.Assert(IsCompleted);
e = _exception;
// Return the result
return(_result);
}
/// <summary>
/// Waits for a work item or exits on timeout or cancel
/// </summary>
/// <param name="millisecondsTimeout">Timeout in milliseconds</param>
/// <param name="cancelEvent">Cancel wait handle</param>
/// <returns>Returns true if the resource was granted</returns>
public WorkItem DequeueWorkItem(
int millisecondsTimeout,
WaitHandle cancelEvent)
{
// This method cause the caller to wait for a work item.
// If there is at least one waiting work item then the
// method returns immidiately with it.
//
// If there are no waiting work items then the caller
// is queued between other waiters for a work item to arrive.
//
// If a work item didn't come within millisecondsTimeout or
// the user canceled the wait by signaling the cancelEvent
// then the method returns null to indicate that the caller
// didn't get a work item.
WaiterEntry waiterEntry;
WorkItem workItem = null;
lock (this)
{
ValidateNotDisposed();
// If there are waiting work items then take one and return.
if (_workItems.Count > 0)
{
workItem = _workItems.Dequeue() as WorkItem;
return(workItem);
}
// No waiting work items ...
// Get the waiter entry for the waiters queue
waiterEntry = GetThreadWaiterEntry();
// Put the waiter with the other waiters
PushWaiter(waiterEntry);
}
// Prepare array of wait handle for the WaitHandle.WaitAny()
WaitHandle[] waitHandles = new WaitHandle[] {
waiterEntry.WaitHandle,
cancelEvent
};
// Wait for an available resource, cancel event, or timeout.
// During the wait we are supposes to exit the synchronization
// domain. (Placing true as the third argument of the WaitAny())
// It just doesn't work, I don't know why, so I have two lock(this)
// statments instead of one.
int index = CTPEventWaitHandle.WaitAny(
waitHandles,
millisecondsTimeout,
true);
lock (this)
{
// success is true if it got a work item.
bool success = (0 == index);
// The timeout variable is used only for readability.
// (We treat cancel as timeout)
bool timeout = !success;
// On timeout update the waiterEntry that it is timed out
if (timeout)
{
// The Timeout() fails if the waiter has already been signaled
timeout = waiterEntry.Timeout();
// On timeout remove the waiter from the queue.
// Note that the complexity is O(1).
if (timeout)
{
RemoveWaiter(waiterEntry, false);
}
// Again readability
success = !timeout;
}
// On success return the work item
if (success)
{
workItem = waiterEntry.WorkItem;
if (null == workItem)
{
workItem = _workItems.Dequeue() as WorkItem;
}
}
}
// On failure return null.
return(workItem);
}
/// <summary>
/// Wait for all work items to complete
/// </summary>
/// <param name="waitableResults">Array of work item result objects</param>
/// <param name="millisecondsTimeout">The number of milliseconds to wait, or Timeout.Infinite (-1) to wait indefinitely.</param>
/// <param name="exitContext">
/// true to exit the synchronization domain for the context before the wait (if in a synchronized context), and reacquire it; otherwise, false.
/// </param>
/// <param name="cancelWaitHandle">A cancel wait handle to interrupt the wait if needed</param>
/// <returns>
/// true when every work item in waitableResults has completed; otherwise false.
/// </returns>
internal static bool WaitAll(
IWaitableResult[] waitableResults,
int millisecondsTimeout,
bool exitContext,
WaitHandle cancelWaitHandle)
{
if (0 == waitableResults.Length)
{
return(true);
}
bool success;
WaitHandle[] waitHandles = new WaitHandle[waitableResults.Length];
GetWaitHandles(waitableResults, waitHandles);
if ((null == cancelWaitHandle) && (waitHandles.Length <= 64))
{
success = CTPEventWaitHandle.WaitAll(waitHandles, millisecondsTimeout, exitContext);
}
else
{
success = true;
int millisecondsLeft = millisecondsTimeout;
Stopwatch stopwatch = Stopwatch.StartNew();
WaitHandle[] whs;
if (null != cancelWaitHandle)
{
whs = new WaitHandle[] { null, cancelWaitHandle };
}
else
{
whs = new WaitHandle[] { null };
}
bool waitInfinitely = (Timeout.Infinite == millisecondsTimeout);
// Iterate over the wait handles and wait for each one to complete.
// We cannot use WaitHandle.WaitAll directly, because the cancelWaitHandle
// won't affect it.
// Each iteration we update the time left for the timeout.
for (int i = 0; i < waitableResults.Length; ++i)
{
// WaitAny don't work with negative numbers
if (!waitInfinitely && (millisecondsLeft < 0))
{
success = false;
break;
}
whs[0] = waitHandles[i];
int result = CTPEventWaitHandle.WaitAny(whs, millisecondsLeft, exitContext);
if ((result > 0) || (CTPEventWaitHandle.WaitTimeout == result))
{
success = false;
break;
}
if (!waitInfinitely)
{
// Update the time left to wait
millisecondsLeft = millisecondsTimeout - (int)stopwatch.ElapsedMilliseconds;
}
}
}
// Release the wait handles
ReleaseWaitHandles(waitableResults);
return(success);
}
/// <summary>
/// Wait for the thread pool to be idle
/// </summary>
public override bool WaitForIdle(int millisecondsTimeout)
{
CThreadPool.ValidateWorkItemsGroupWaitForIdle(this);
return(CTPEventWaitHandle.WaitOne(_isIdleWaitHandle, millisecondsTimeout, false));
}
