Trait oxidd_core::util::GCContainer

pub trait GCContainer<M: Manager> {
    // Required methods
    fn pre_gc(&self, manager: &M);
    unsafe fn post_gc(&self, manager: &M);
}

A container that may hold “weak” references to nodes and needs to be informed about operations potentially removing nodes

The main motivation behind this trait is the following observation: When using reference counting to implement garbage collection of dead nodes, cloning and dropping edges when inserting entries into the apply cache may cause many CPU cache misses. To circumvent this performance issue, the apply cache may store Borrowed<M::Edge>s (e.g., using the unsafe Borrowed::into_inner()). Now the apply cache implementation has to guarantee that every edge returned by the get() method still points to a valid node. To that end, the cache may, e.g., clear itself when Self::pre_gc() is called and reject any insertion of new entries until Self::post_gc().

Required Methods

fn pre_gc(&self, manager: &M)

Prepare for garbage collection

The implementing container data structure may rely on that this method is called before the Manager performs garbage collection or any other operation that possibly removes nodes from the manager. (If this is required for SAFETY, however, creation of a GCContainer instance must be marked unsafe).

This method may lock (parts of) self. Unlocking is then done in Self::post_gc().

unsafe fn post_gc(&self, manager: &M)

Post-process a garbage collection

Safety

Each call to this method must be paired with a distinct preceding Self::pre_gc() call. All operations potentially removing nodes must happen between Self::pre_gc() and the call to this method.

Implementors