Span<T> and ArraySegment<T> provide optimized ways to perform operations on contiguous memory regions. Both data structures are used to reference a contiguous region of memory allocated in .NET memory space.
Span provides a safe way to access and modify memory regions. The use of Span safely brings down the overhead of value transfers between function calls, by avoiding intermediate allocations. With Span the memory allocation is typically on the stack, and therefore less expensive. The main advantage of Span over ArraySegment is the fact that it can be used with both stack-allocated and heap-allocated data.
ArraySegment, on the other hand, is a similar structure that acts as a pointer to a subset of an existing array. Array is both a pointer and a metadata holder while ArraySegment can be considered only as a pointer but with extra length information. If you make changes to the ArraySegment the original array will be affected. This might not always be desirable.
It is important that the actual performance benefits of Span and ArraySegment depend on the specific use cases for which they are being employed.
While Span and ArraySegment are quite useful, they are not a panacea for all programming problems. When using unsafe memory, the lifetime of the underlying memory block may not be known, and this can lead to hard-to-debug problems in large applications. Additionally, Span and ArraySegment should only be used in scenarios where they can be verified as safe. Incorrect use of these data structures can cause performance issues or memory problems.
In summary, both Span and ArraySegment are useful when working with contiguous memory, however the main difference is that Span is a safer and lower-overhead solution for stack and heap-allocated memory access, while ArraySegment provides an equivalent functionality to Span but is limited to accessing sections of pre-existing arrays. They should be used with care and only in appropriate scenarios.
gistlibby LogSnag