private CalculationProcessInfo CreateCalculationProcessInfo(TParameters parameters)
{
CalculationProcessInfo calculationProcessInfo = new CalculationProcessInfo();
processingCalculations.Add(parameters, calculationProcessInfo);
return(calculationProcessInfo);
}
private bool TryAcquireCalculationWait(
TParameters parameters,
out CalculationProcessInfo calculationProcessInfo)
{
bool result;
try
{
}
// Finally block will not be interrupted by thread aborting
finally
{
result = processingCalculations.TryGetValue(parameters, out calculationProcessInfo);
if (result)
{
checked
{
calculationProcessInfo.WaitCount++;
}
}
}
return(result);
}
private void ReleaseCalculationWait(
TParameters parameters,
CalculationProcessInfo calculationProcessInfo)
{
calculationProcessInfo.WaitCount--;
if (calculationProcessInfo.Done && (calculationProcessInfo.WaitCount == 0))
{
processingCalculations.Remove(parameters);
calculationProcessInfo.Dispose();
}
}
private void CompleteCalculationProcessInfo(
TParameters parameters,
CalculationProcessInfo calculationProcessInfo)
{
calculationProcessInfo.Done = true;
if (calculationProcessInfo.WaitCount > 0)
{
calculationProcessInfo.Event.Set();
}
else
{
processingCalculations.Remove(parameters);
calculationProcessInfo.Dispose();
}
}
/// <summary>
/// Returns cached result, or calculates a new one, or waits until the calculation is complete.
/// Thread-safe.
/// </summary>
/// <param name="parameters">Calculation parameters</param>
/// <returns>Calculation result</returns>
public TResult GetResult(TParameters parameters)
{
if (parameters == null)
{
throw new ArgumentNullException("parameters");
}
TResult result;
while (true)
{
CalculationProcessInfo calculationProcessInfo = null;
bool shouldWait = false;
try
{
lock (syncRoot)
{
if (cachedResults.TryGetValue(parameters, out result))
{
return(result);
}
shouldWait = TryAcquireCalculationWait(parameters, out calculationProcessInfo);
if (!shouldWait)
{
calculationProcessInfo = CreateCalculationProcessInfo(parameters);
}
}
if (shouldWait)
{
calculationProcessInfo.Event.WaitOne();
}
else
{
result = calculation(parameters);
lock (syncRoot)
cachedResults.Add(parameters, result);
return(result);
}
}
finally
{
lock (syncRoot)
{
if (shouldWait)
{
ReleaseCalculationWait(parameters, calculationProcessInfo);
}
else if (calculationProcessInfo != null)
{
CompleteCalculationProcessInfo(parameters, calculationProcessInfo);
}
}
}
}
}
