private void EscalateCopying(ConcurrentArray <TKey, TValue> array, ConcurrentArray <TKey, TValue> .AddInfo addInfo)
{
// This method is called when the old array is full
// It will help copying all remaining items from the old to the new array
var growArrayProcess = array.ReadGrowArrayProcessVolatile();
if (growArrayProcess == null)
{
// If the grow array process is not created yet (although the old array is already full), then create it now
var newSize = _growArrayStrategy.GetNextCapacity(array.Count, array.Capacity, addInfo.ReprobingCount);
if (newSize == null)
{
throw new InvalidOperationException($"The {nameof(IGrowArrayStrategy)} \"{_growArrayStrategy}\" does not provide a new size although the internal array of the dictionary is full.");
}
growArrayProcess = TryEstablishNewGrowArrayProcess(array, newSize.Value).GrowArrayProcess;
}
// Copy all remaining element from the old to the new array
growArrayProcess.CopyToTheBitterEnd();
}
private HelpCopyingInfo HelpCopying(ConcurrentArray <TKey, TValue> array, ConcurrentArray <TKey, TValue> .AddInfo addInfo)
{
// Try to get an existing grow-array-process
var growArrayProcess = array.ReadGrowArrayProcessVolatile();
// If there is none, then try to create it
if (growArrayProcess == null)
{
var newSize = _growArrayStrategy.GetNextCapacity(array.Count, array.Capacity, addInfo.ReprobingCount);
// If no new size was proposed by the grow-array-strategy, then we do not need to create a grow-array-process
if (newSize == null)
{
return(HelpCopyingInfo.CreateNoCopyingNeededInfo());
}
// Try to establish a new grow-array-process. This is a race condition because
// other threads might be doing the same, thus we might get a process object
// that was created by another thread.
var establishResult = TryEstablishNewGrowArrayProcess(array, newSize.Value);
growArrayProcess = establishResult.GrowArrayProcess;
// If we indeed established the process object, then the initial creation of the new target array
// must be performed.
if (establishResult.WasGrowArrayProcessInitializedByThisThread)
{
growArrayProcess.HelpCopying();
if (growArrayProcess.IsCopyingFinished == false)
{
_backgroundCopyTaskFactory.StartBackgroundCopyTask(growArrayProcess.CopyToTheBitterEnd);
#if CONCURRENT_LOGGING
Log($"Created background copy task for array {growArrayProcess.NewArray}.");
#endif
}
return(HelpCopyingInfo.CreateGrowArrayProcessInitializedInfo());
}
}
TryHelpExistingCopyProcess:
// Try to copy the entry to the new array (that was previously added to the old array).
// This might be necessary if the concurrent copy algorithm is already past this entry.
var copyInfo = growArrayProcess.CopyEntryThatWasJustAdded(addInfo.TargetEntry);
// When the new array is already full, then return the value indicating that the entry
// should be added to the newest array again.
if (copyInfo.OperationResult == AddResult.ArrayFull)
{
return(HelpCopyingInfo.CreateNewArrayFullInfo(growArrayProcess.NewArray));
}
// If the copying did succeed but the grow array process already finished copying, then
// check if the new array is not outdated yet.
if (copyInfo.OperationResult == AddResult.AddSuccessful && growArrayProcess.IsCopyingFinished)
{
var newestArray = Volatile.Read(ref _currentArray);
// If the newest array is the one that was established by the grow array process, then check
// if this new array already has another grow array process associated with it, and help
// copying there.
if (newestArray == growArrayProcess.NewArray)
{
var newGrowArrayProcess = newestArray.ReadGrowArrayProcessVolatile();
if (newGrowArrayProcess != null)
{
#if CONCURRENT_LOGGING
Log($"New grow array process found for array {newGrowArrayProcess.SpinGetNewArray().Id}, help copying there.");
#endif
growArrayProcess = newGrowArrayProcess;
goto TryHelpExistingCopyProcess;
}
}
// If the newest array is neither the new array of the current grow array process nor the inital
// array that we started with, then we probably were preempted for some time, and several new
// arrays were established since then.
if (newestArray != array)
{
return(HelpCopyingInfo.CreateNewArrayOutdatedInfo(newestArray));
}
}
// Try to help copying the rest of the items over to the new array
growArrayProcess.HelpCopying();
return(HelpCopyingInfo.CreateHelpedCopyingInfo());
}
