Trait Store

pub unsafe trait Store {
    // Required methods
    fn vmruntime_limits(&self) -> *mut VMRuntimeLimits;
    fn epoch_ptr(&self) -> *const AtomicU64;
    fn maybe_gc_store(&mut self) -> Option<&mut GcStore>;
    fn memory_growing(
        &mut self,
        current: usize,
        desired: usize,
        maximum: Option<usize>,
    ) -> Result<bool, Error>;
    fn memory_grow_failed(&mut self, error: Error) -> Result<()>;
    fn table_growing(
        &mut self,
        current: u32,
        desired: u32,
        maximum: Option<u32>,
    ) -> Result<bool, Error>;
    fn table_grow_failed(&mut self, error: Error) -> Result<()>;
    fn out_of_gas(&mut self) -> Result<(), Error>;
    fn new_epoch(&mut self) -> Result<u64, Error>;
    fn gc(&mut self, root: Option<VMGcRef>) -> Result<Option<VMGcRef>>;

    // Provided method
    fn gc_store(&mut self) -> &mut GcStore { ... }
}

Dynamic runtime functionality needed by this crate throughout the execution of a wasm instance.

This trait is used to store a raw pointer trait object within each VMContext. This raw pointer trait object points back to the wasmtime::Store internally but is type-erased so this wasmtime_runtime crate doesn’t need the entire wasmtime crate to build.

Note that this is an extra-unsafe trait because no heed is paid to the lifetime of this store or the Send/Sync-ness of this store. All of that must be respected by embedders (e.g. the wasmtime::Store structure). The theory is that wasmtime::Store handles all this correctly.

Required Methods

fn vmruntime_limits(&self) -> *mut VMRuntimeLimits

Returns the raw pointer in memory where this store’s shared VMRuntimeLimits structure is located.

Used to configure VMContext initialization and store the right pointer in the VMContext.

fn epoch_ptr(&self) -> *const AtomicU64

Returns a pointer to the global epoch counter.

Used to configure the VMContext on initialization.

fn maybe_gc_store(&mut self) -> Option<&mut GcStore>

Get this store’s GC heap, if it has been allocated.

fn memory_growing( &mut self, current: usize, desired: usize, maximum: Option<usize>, ) -> Result<bool, Error>

Callback invoked to allow the store’s resource limiter to reject a memory grow operation.

fn memory_grow_failed(&mut self, error: Error) -> Result<()>

Callback invoked to notify the store’s resource limiter that a memory grow operation has failed.

Note that this is not invoked if memory_growing returns an error.

fn table_growing( &mut self, current: u32, desired: u32, maximum: Option<u32>, ) -> Result<bool, Error>

Callback invoked to allow the store’s resource limiter to reject a table grow operation.

fn table_grow_failed(&mut self, error: Error) -> Result<()>

Callback invoked to notify the store’s resource limiter that a table grow operation has failed.

Note that this is not invoked if table_growing returns an error.

fn out_of_gas(&mut self) -> Result<(), Error>

Callback invoked whenever fuel runs out by a wasm instance. If an error is returned that’s raised as a trap. Otherwise wasm execution will continue as normal.

fn new_epoch(&mut self) -> Result<u64, Error>

Callback invoked whenever an instance observes a new epoch number. Cannot fail; cooperative epoch-based yielding is completely semantically transparent. Returns the new deadline.

fn gc(&mut self, root: Option<VMGcRef>) -> Result<Option<VMGcRef>>

Callback invoked whenever an instance needs to trigger a GC.

Optionally given a GC reference that is rooted for the collection, and then whose updated GC reference is returned.

Cooperative, async-yielding (if configured) is completely transparent.

If the async GC was cancelled, returns an error. This should be raised as a trap to clean up Wasm execution.

Provided Methods

fn gc_store(&mut self) -> &mut GcStore

Get this store’s GC heap.

Implementors