Trait wasmtime_runtime::InstanceAllocator

pub unsafe trait InstanceAllocator {
    // Required methods
    fn allocate_index(
        &self,
        req: &InstanceAllocationRequest<'_>,
    ) -> Result<usize>;
    fn deallocate_index(&self, index: usize);
    fn allocate_memories(
        &self,
        index: usize,
        req: &mut InstanceAllocationRequest<'_>,
        mems: &mut PrimaryMap<DefinedMemoryIndex, Memory>,
    ) -> Result<()>;
    fn deallocate_memories(
        &self,
        index: usize,
        mems: &mut PrimaryMap<DefinedMemoryIndex, Memory>,
    );
    fn allocate_tables(
        &self,
        index: usize,
        req: &mut InstanceAllocationRequest<'_>,
        tables: &mut PrimaryMap<DefinedTableIndex, Table>,
    ) -> Result<()>;
    fn deallocate_tables(
        &self,
        index: usize,
        tables: &mut PrimaryMap<DefinedTableIndex, Table>,
    );
    fn purge_module(&self, module: CompiledModuleId);

    // Provided methods
    fn validate(
        &self,
        module: &Module,
        offsets: &VMOffsets<HostPtr>,
    ) -> Result<()> { ... }
    fn allocate(
        &self,
        req: InstanceAllocationRequest<'_>,
    ) -> Result<InstanceHandle> { ... }
    fn deallocate(&self, handle: &mut InstanceHandle) { ... }
}

Represents a runtime instance allocator.

Safety

This trait is unsafe as it requires knowledge of Wasmtime’s runtime internals to implement correctly.

Required Methods

fn allocate_index(&self, req: &InstanceAllocationRequest<'_>) -> Result<usize>

Optionally allocates an allocator-defined index for the req provided.

The return value here, if successful, is passed to the various methods below for memory/table allocation/deallocation.

fn deallocate_index(&self, index: usize)

Deallocates indices allocated by allocate_index.

fn allocate_memories( &self, index: usize, req: &mut InstanceAllocationRequest<'_>, mems: &mut PrimaryMap<DefinedMemoryIndex, Memory>, ) -> Result<()>

Attempts to allocate all defined linear memories for a module.

Pushes all memories for req onto the mems storage provided which is already appropriately allocated to contain all memories.

Note that this is allowed to fail. Failure can additionally happen after some memories have already been successfully allocated. All memories pushed onto mem are guaranteed to one day make their way to deallocate_memories.

fn deallocate_memories( &self, index: usize, mems: &mut PrimaryMap<DefinedMemoryIndex, Memory>, )

Deallocates all memories provided, optionally reclaiming resources for the pooling allocator for example.

fn allocate_tables( &self, index: usize, req: &mut InstanceAllocationRequest<'_>, tables: &mut PrimaryMap<DefinedTableIndex, Table>, ) -> Result<()>

Same as allocate_memories, but for tables.

fn deallocate_tables( &self, index: usize, tables: &mut PrimaryMap<DefinedTableIndex, Table>, )

Same as deallocate_memories, but for tables.

fn purge_module(&self, module: CompiledModuleId)

Purges all lingering resources related to module from within this allocator.

Primarily present for the pooling allocator to remove mappings of this module from slots in linear memory.

Provided Methods

fn validate(&self, module: &Module, offsets: &VMOffsets<HostPtr>) -> Result<()>

Validates that a module is supported by the allocator.

fn allocate(&self, req: InstanceAllocationRequest<'_>) -> Result<InstanceHandle>

Allocates a fresh InstanceHandle for the req given.

This will allocate memories and tables internally from this allocator and weave that altogether into a final and complete InstanceHandle ready to be registered with a store.

Note that the returned instance must still have .initialize(..) called on it to complete the instantiation process.

fn deallocate(&self, handle: &mut InstanceHandle)

Deallocates the provided instance.

This will null-out the pointer within handle and otherwise reclaim resources such as tables, memories, and the instance memory itself.

Implementors

impl InstanceAllocator for OnDemandInstanceAllocator

impl InstanceAllocator for PoolingInstanceAllocator