protobuf-go VS bumpalo

Protocol Buffers: https://developers.google.com/protocol-buffers

ProtocolBuffers’ OneOf message addresses the case of having a message with many fields where at most one field will be set at the same time.

That's definitely the bigger thing. I think something like Protocol Buffers (Protobuf) is what you're looking for there. Output the data and consume it by something that can handle the analysis.

These protocols prevent an O(N x M) explosion of code that have to solve for many cases. For example, since JSON is an almost ubiquitous format for wire transfer (although other things do exist like protobufs), if I had N data formats that I want to serialize, I only need to write N serializers/deserializers (SerDes). If there was no such narrow waist and there were M alternatives to JSON in wide usage, I would have to write N x M SerDes for wire encoding my data.

So, I thought this at one point, too. But it turns out that methods is a type alias to an unnamed type, so there's no package level privacy issues: https://github.com/protocolbuffers/protobuf-go/blob/v1.26.0/...

Long story short, heap allocation is painfully slow. Any sort of malloc will always be slower than a custom pool or a bump allocator, because it has a lot more context to deal with.

Rust makes it especially hard to use custom allocators, see bumpalo for example [0]. To be fair, progress is being made in this area [1].

Theoretically one can use a "handle table" as a replacement for pools, you can find relevant discussion at [2].

[0] https://github.com/fitzgen/bumpalo

There are ways to accomplish this as well. Different allocator libraries exist for this kind of scenario, namely bumpallo which allocates a larger block of memory from the kernel, and allocates quickly thereafter. That would amortize the cost of memory allocations in the way I think you're after?

Meaning, storing a lot of things in the same block of allocated memory? Vec is a thing, you know. There's also a bump allocator library.

There are data structures like slotmap, and relatively low-level crates like bumpalo. This is not to say that either fits your use case, just that you definitely have access to the necessary parts to fit what you describe.

Sometimes you can put everything in a bump allocator, then when you're done, free the entire bump allocator in one go. https://docs.rs/bumpalo/

This is useful with crates like bumpalo which give you bump-allocation arenas whose lifetimes are tied to the objects they allocate.

TSC doesn't need to "stick around", right? Just a run-once and the program is over?

In those cases, https://github.com/fitzgen/bumpalo works amazingly as an arena. You can pretty much forget about reference counting and have direct references everywhere in your graph. The disadvantage is that it's hard to modify your tree without leaving memory around.

We use it extensively in http://github.com/dioxusLabs/dioxus and don't need to worry about Rc anywhere in the graph/diffing code.

Probably bumpalo, but then its Box will have a lifetime parameter - bumpalo::boxed::Box<'a, dyn MyTrait>

Strictly speaking, Rust doesn't need this as a built-in language feature, because its design allows it to be implemented as a third-party library: https://docs.rs/bumpalo

The biggest problem is that there's some awkwardness around RAII; I'm not sure whether that could have been avoided with a different approach.

Of course, ideally you'd want it to be compatible with the standard-library APIs that allocate. This is implemented, but is not yet at the point where they're sure they won't want to make backwards-incompatible changes to it, so you can only use it on nightly. https://doc.rust-lang.org/stable/std/alloc/trait.Allocator.h...

Or are you suggesting that the choice of allocator should be dynamically scoped, so that allocations that occur while the bump allocator is alive automatically use it even if they're in code that doesn't know about it? I think it's not possible for that to be memory-safe; all allocations using the bump allocator need to know about its lifetime, so that they can be sure not to outlive it, which would cause use-after-free bugs. I'm assuming that Odin just makes the programmer responsible for this, and if they get it wrong then memory corruption might occur; for a memory-safe language like Rust, that's not acceptable.