Here is a list of all files with brief descriptions:

AggregateException.cs
AotInterlocked.cs
SpicyPixel.Threading/AssemblyInfo.cs
SpicyPixel.Threading.Unity/AssemblyInfo.cs
System.Threading/AssemblyInfo.cs
AtomicBoolean.cs
BlockingCollection.cs
CancellationToken.cs
CancellationTokenRegistration.cs
CancellationTokenSource.cs
CollectionDebuggerView.cs
ConcurrentBag.cs
ConcurrentBehaviour.cs
ConcurrentDictionary.cs
ConcurrentExclusiveSchedulerPair.cs
ConcurrentOrderedList.cs
ConcurrentQueue.cs
ConcurrentStack.cs
ConfiguredTaskAwaitable.cs
ConfiguredTaskAwaitable_T.cs
CountdownEvent.cs
CyclicDeque.cs
EnumerablePartitioner.cs
EnumerablePartitionerOptions.cs
Fiber.ContinueWith.cs
Fiber.cs
Fiber.Delay.cs
Fiber.WhenAll.cs
Fiber.WhenAny.cs
FiberAbortException.cs
FiberContinuation.cs
FiberContinuationOptions.cs
FiberFactory.cs
FiberFactory.StartNew.cs
FiberInstruction.cs
FiberResult.cs
FiberScheduler.cs
FiberSchedulerSynchronizationContext.cs
FiberStatus.cs
FiberTaskExtensions.cs
FiberTaskScheduler.cs
Funcs.cs
IConcurrentDeque.cs
ICriticalNotifyCompletion.cs
IFiberScheduler.cs
INotifyCompletion.cs
IProducerConsumerCollection.cs
IProgress.cs
IStructuralComparable.cs
IStructuralEquatable.cs
ListPartitioner.cs
ManualResetEventSlim.cs
MonoTODOAttribute.cs
ObjectInstruction.cs
OperationCanceledException.cs
OrderablePartitioner.cs
Parallel.cs
ParallelLoopResult.cs
ParallelLoopState.cs
ParallelOptions.cs
Partitioner.cs
PopResult.cs
SharedConcurrentBehaviour.cs
SimpleConcurrentBag.cs
SpinLock.cs
SpinWait.cs
SplitOrderedList.cs
StopInstruction.cs
SynchronizationContextScheduler.cs
SystemCoroutine.cs
SystemFiberScheduler.cs
Task.cs
Task_T.cs
TaskActionInvoker.cs
TaskAwaiter.cs
TaskAwaiter_T.cs
TaskCanceledException.cs
TaskCompletionQueue.cs
TaskCompletionSource.cs
TaskConstants.cs
TaskConstants_T.cs
TaskContinuation.cs
TaskContinuationOptions.cs
TaskCreationOptions.cs
TaskDebuggerView.cs
TaskExceptionSlot.cs
TaskExtensionsImpl.cs
TaskFactory.cs
TaskFactory_T.cs
TaskScheduler.cs
TaskSchedulerException.cs
TaskStatus.cs
TpScheduler.cs
Tuple.cs
Tuples.cs
UnityCoroutine.cs
UnityFiberExtensions.cs
UnityFiberFactory.cs
UnityFiberInstruction.cs
UnityFiberScheduler.cs
UnitySynchronizationContext.cs
UnityTaskExtensions.cs
UnityTaskFactory.cs
UnityTaskScheduler.cs
UnobservedTaskExceptionEventArgs.cs
UserRangePartitioner.cs
Watch.cs
YieldableTask.cs
YieldAwaitable.cs
YieldForSeconds.cs
YieldToAnyFiber.cs
YieldToFiber.cs
YieldUntilComplete.cs