public void WorkAndSetTcs(Func <CancellationToken, Task <IReadOnlyList <HierarchicalSymbol> > > asyncWork)
{
CancellationTokenSource currentCts;
TaskCompletionSource <IReadOnlyList <HierarchicalSymbol> > currentTcs;
lock (_syncObj) {
switch (state)
{
case WorkQueueState.Working:
CancelExistingWork();
RenewTcs();
break;
case WorkQueueState.WaitingForWork:
break;
case WorkQueueState.FinishedWork:
RenewTcs();
break;
default:
throw new InvalidOperationException();
}
state = WorkQueueState.Working;
currentCts = _fileCts;
currentTcs = _fileTcs;
}
DoWork(currentCts, asyncWork).SetCompletionResultTo(currentTcs);
}
private async Task <IReadOnlyList <HierarchicalSymbol> > DoWork(CancellationTokenSource tcs, Func <CancellationToken, Task <IReadOnlyList <HierarchicalSymbol> > > asyncWork)
{
var token = tcs.Token;
try {
return(await asyncWork(token));
} finally {
lock (_syncObj) {
tcs.Dispose();
if (!token.IsCancellationRequested)
{
state = WorkQueueState.FinishedWork;
}
}
}
}
public void MarkAsPending()
{
lock (_syncObj) {
switch (state)
{
case WorkQueueState.WaitingForWork:
break;
case WorkQueueState.Working:
CancelExistingWork();
RenewTcs();
break;
case WorkQueueState.FinishedWork:
RenewTcs();
break;
default:
throw new InvalidOperationException();
}
state = WorkQueueState.WaitingForWork;
}
}
public void Dispose()
{
lock (_syncObj) {
switch (state)
{
case WorkQueueState.Working:
CancelExistingWork();
break;
case WorkQueueState.WaitingForWork:
CancelExistingWork();
// Manually cancel tcs, in case any task is awaiting
_fileTcs.TrySetCanceled();
break;
case WorkQueueState.FinishedWork:
break;
default:
throw new InvalidOperationException();
}
state = WorkQueueState.FinishedWork;
}
}
