UnsafeCollections

As this fork diverged too much from the original, it became its own repository.

This project contains various collections that perform no managed memory allocation. It alleviates GC (Garbage Collector) pressure useful for usecases such as Unity.

Project is targeted as a .Net 2.0 Standard library. Usable in Unity via dll.

Usage

The NativeCollections (under UnsafeCollections/Collections/Native/) are usable just like the matching collections in C# would. The API matches as much as possible with the C# API of the same collection. All of the NativeCollection objects are safe to pass as value.

You must instantiate the collections with any non-default constructor. After you are done using it, you again must call the Dispose function. The matching UnsafeCollection objects work similarly, but instead you must call Allocate and Free respectively.

Currently Implemented

• Array
• List
• LinkedList
• Stack
• Queue
• Bit Set
• Ring Buffer
• Min Heap
• Max Heap
• Dictionary
• HashSet
• SortedDictionary
• SortedSet
• Concurrent SPSC Lockfree Queue
• Concurrent MPSC Lockfree Queue
• Concurrent MPMC Queue (Lockfree with fixed size)

Build

Use Preprocessor directive UNITY to build the project using the Unity memory allocators instead of the .Net ones.

The library is usable in both .Net and Unity.

Performance

Comparison is made for List between .Net List, UnsafeList and NativeList. This is done not only to show the difference between this and the .Net implementation, but also between the Native and Unsafe implementations.

List

Adding x items to a list, followed by a clear:

Method	Mean	Error	StdDev	Gen 0	Gen 1	Gen 2	Allocated
ListAdd	196.98 ns	0.253 ns	0.236 ns	-	-	-	-
NativeListAdd	76.38 ns	0.496 ns	0.464 ns	-	-	-	-
UnsafeListAdd	58.59 ns	0.293 ns	0.274 ns	-	-	-	-

Adding x items to a list where the list has to resize (followed by a clear):

Method	Mean	Error	StdDev	Gen 0	Gen 1	Gen 2	Allocated
ListAdd	399.7 ns	4.60 ns	4.30 ns	-	-	-	-
NativeListAdd	161.2 ns	0.13 ns	0.12 ns	-	-	-	-
UnsafeListAdd	124.9 ns	0.30 ns	0.28 ns	-	-	-	-

Grabbing the index of a "random" item in the list

Method	Mean	Error	StdDev	Gen 0	Gen 1	Gen 2	Allocated
ListIndexOf	28.76 ns	0.206 ns	0.193 ns	-	-	-	-
NativeListIndexOf	23.69 ns	0.038 ns	0.036 ns	-	-	-	-
UnsafeListIndexOf	23.94 ns	0.190 ns	0.178 ns	-	-	-	-

Because the difference in performance between Unsafe and Native is minor, only a comparison between .Net and Native will be made from this point onwards. Do note that the timings for the Unsafe collections are usually slightly lower.

Queue

Enqueue > Peek > Dequeue operations

Method	Mean	Error	StdDev
QueueAddPeekRemove	444.3 ns	0.37 ns	0.35 ns
NativeQueueAddPeekRemove	194.4 ns	1.47 ns	1.23 ns
SPSCQueueAddPeekRemove	219.2 ns	0.19 ns	0.17 ns

Sorted Set

SortedSet Add in reverse order (worst case)

Method	Mean	Error	StdDev
SortedSetAdd	1.118 μs	0.0042 μs	0.0040 μs
NativeSortedSetAdd	1.964 μs	0.0104 μs	0.0098 μs

Dictionary

Dictionary Add followed by Remove

Method	Mean	Error	StdDev
DictionaryAdd	580.0 ns	0.82 ns	0.73 ns
NativeDictionaryAdd	461.8 ns	2.82 ns	2.64 ns