We’ve seen how NativeArray works, but what if we want more kinds of native collections? Unity 2018.1 only has that one, but you can make your own! Today’s article shows exactly how to do that.
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There are many permutations of loops we can write, but what do they compile to? We should know the consequences of using an array versus a
Length, and other factors. So today’s article dives into the C++ code that IL2CPP outputs when we write these various types of loops to examine the differences. We’ll even go further and look at the ARM assembly that the C++ compiles to and really find out how much overhead our choices are costing us.
Every time I see
for (var i = 0; i < array.Length; ++i) I wonder if accessing that
Length property is slow. Should I cache it? It’s comforting to know that
for (int i = 0, len = array.Length; i < len; ++i) is only dealing with local variables except on the first loop. Local variables must be faster, right? Likewise, I wonder the same thing about
List<T>.Count. I finally got around to running a test to see if caching these length properties makes any performance difference. The answers might surprise you!
We’re nearing the end of the series to build a no-garbage replacement for
System.Linq. Today we tackle functions that work on already-sorted ranges and functions that work on ranges that are in heap order. These include common set operations like “union” and “intersection”. Read on to see how to use them and for the updated library that you can use to eliminate your garbage creation!
Back from a brief break, we pick up this week by finishing up the “modifying sequence operations” with some gems like
RandomShuffle and go through the “partitions” category with functions like
IsPartitioned. These are all solid algorithms with a lot of potential uses, so read on to see how to use them with iterators and for the source code that implements them!
Last week’s article introduced the concept of iterators as an alternative to the GC-heavy
IEnumerable. Today’s article expands the iterator library to include a bunch of more functions to make it useful. Think of these like the extension functions in
IndexOf, etc. These have all been tailored to iterators and none of them will create any garbage whatsoever.
In C#, just about everything is an
IEnumerable. Since LINQ syntax,
foreach loops, and the
System.Linq namespace are all designed to work with
IEnumerable, you’ve got lots of tools to use. Unfortunately, the core of
IEnumerable is the
GetEnumerator function which usually creates garbage and eventually causes memory fragmentation and GC framerate spikes. Do we simply stop using all of these nice tools? Normally the answer is “yes”, but today’s article shows you another way.