Struct GcStore

pub struct GcStore {
    pub allocation_index: GcHeapAllocationIndex,
    pub gc_heap: Box<dyn GcHeap>,
    pub host_data_table: ExternRefHostDataTable,
}

GC-related data that is one-to-one with a wasmtime::Store.

Contains everything we need to do collections, invoke barriers, etc…

In general, exposes a very similar interface to GcHeap, but fills in some of the context arguments for callers (such as the ExternRefHostDataTable) since they are all stored together inside GcStore.

Fields

allocation_index: GcHeapAllocationIndex

This GC heap’s allocation index (primarily used for integrating with the pooling allocator).

gc_heap: Box<dyn GcHeap>

The actual GC heap.

host_data_table: ExternRefHostDataTable

The externref host data table for this GC heap.

Implementations

impl GcStore

pub fn new( allocation_index: GcHeapAllocationIndex, gc_heap: Box<dyn GcHeap>, ) -> Self

Create a new GcStore.

pub fn gc(&mut self, roots: GcRootsIter<'_>)

Perform garbage collection within this heap.

pub fn clone_gc_ref(&mut self, gc_ref: &VMGcRef) -> VMGcRef

Clone a GC reference, calling GC write barriers as necessary.

pub fn write_gc_ref( &mut self, destination: &mut Option<VMGcRef>, source: Option<&VMGcRef>, )

Write the source GC reference into the destination slot, performing write barriers as necessary.

pub fn drop_gc_ref(&mut self, gc_ref: VMGcRef)

Drop the given GC reference, performing drop barriers as necessary.

pub fn expose_gc_ref_to_wasm(&mut self, gc_ref: VMGcRef)

Hook to call whenever a GC reference is about to be exposed to Wasm.

pub fn alloc_externref( &mut self, value: Box<dyn Any + Send + Sync>, ) -> Result<Result<VMExternRef, Box<dyn Any + Send + Sync>>>

Allocate a new externref.

Returns:

• Ok(Ok(_)): Successfully allocated the externref.

• Ok(Err(value)): Failed to allocate the externref, but doing a GC and then trying again may succeed. Returns the given value as the error payload.

• Err(_): Unrecoverable allocation failure.

pub fn externref_host_data( &self, externref: &VMExternRef, ) -> &(dyn Any + Send + Sync)

Get a shared borrow of the given externref’s host data.

Passing invalid VMExternRefs (eg garbage values or externrefs associated with a different heap is memory safe but will lead to general incorrectness such as panics and wrong results.

pub fn externref_host_data_mut( &mut self, externref: &VMExternRef, ) -> &mut (dyn Any + Send + Sync)

Get a mutable borrow of the given externref’s host data.

Passing invalid VMExternRefs (eg garbage values or externrefs associated with a different heap is memory safe but will lead to general incorrectness such as panics and wrong results.