Broom

An ergonomic tracing garbage collector that supports mark 'n sweep garbage collection.

Features

• Ergonomic API
• Mark and sweep heap cleaning
• Easy (and safe) mutation of heap values, despite cycles
• Zero-cost access to heap objects through handles

Example

```rust use broom::prelude::*;

// The type you want the heap to contain pub enum Object { Num(f64), List(Vec>), }

// Tell the garbage collector how to explore a graph of this object impl Trace for Object { unsafe fn trace(&self, tracer: &mut Tracer) { match self { Object::Num(_) => {}, Object::List(objects) => objects.trace(tracer), } } }

// Create a new heap let mut heap = Heap::default();

// Temporary objects are cheaper than rooted objects, but don't survive heap cleans let a = heap.inserttemp(Object::Num(42.0)); let b = heap.inserttemp(Object::Num(1337.0));

// Turn the numbers into a rooted list let c = heap.insert(Object::List(vec![a, b]));

// Change one of the numbers - this is safe, even if the object is self-referential! heap.mutate(a, |a| *a = Object::Num(256.0));

// Create another number object let d = heap.insert_temp(Object::Num(0.0));

// Clean up unused heap objects heap.clean();

// a, b and c are all kept alive because c is rooted and a and b are its children assert!(heap.contains(a)); assert!(heap.contains(b)); assert!(heap.contains(c));

// Because d was temporary and unused, it did not survive the heap clean assert!(!heap.contains(d)); ```

Who this crate is for

• People writing dynamically-typed languages in Rust that want a simple, reliable garbage collector
• People that want to have complex graph data structures with mutation and cycles but who don't want memory leaks

Who this crate is not for

• People that want garbage collection when writing ordinary Rust code

TODO

There are a few things I want to do with broom if I get the time:

• Smarter cleanup strategies than mark 'n sweep
• Partial cleans to prevent garbage collection lag spikes

If you're interested in working on any of these things, feel free to open a pull request!

License

Broom is licensed under either of:

• Apache License 2.0, (http://www.apache.org/licenses/LICENSE-2.0)

• MIT license (http://opensource.org/licenses/MIT)