Struct StoreContext

pub(crate) struct StoreContext {
    id: StoreId,
    borrow_count: u32,
    entry: UnsafeCell<StoreContextEntry>,
}

Fields

id: StoreId

borrow_count: u32

entry: UnsafeCell<StoreContextEntry>

Implementations

impl StoreContext

fn is_active(id: StoreId) -> bool

fn is_suspended(id: StoreId) -> bool

fn install(id: StoreId, entry: StoreContextEntry)

pub(crate) fn is_empty() -> bool

Returns true if there are no active store context entries.

pub(crate) fn install_async( guard: LocalRwLockWriteGuard<Box<StoreInner>>, ) -> ForcedStoreInstallGuard

The write guard ensures this is the only reference to the store, so installation can never fail.

pub(crate) unsafe fn ensure_installed( store_ptr: *mut StoreInner, ) -> StoreInstallGuard

Install the store context as sync if it is not already installed.

Safety

The pointer must be dereferenceable and remain valid until the store context is uninstalled.

pub(crate) unsafe fn pause(id: StoreId) -> StorePtrPauseGuard

“Pause” one borrow of the store context.

Safety

Code must ensure it does not use the StorePtrWrapper or StoreAsyncGuardWrapper that it owns, or any StoreRef/StoreMut derived from them, while the store context is paused.

The safe, correct use-case for this method is to pause the store context while executing WASM code, which cannot use the store context directly. This allows an async context to uninstall the store context when suspending if it’s called from a sync imported function. The imported function will have borrowed the store context in its trampoline, which will prevent the async context from uninstalling the store. However, since the imported function passes a mutable borrow of its store into Function::call, it will expect the store to change before the call returns.

pub(crate) unsafe fn get_current(id: StoreId) -> StorePtrWrapper

Safety: This method lets you borrow multiple mutable references to the currently active store context. The caller must ensure that:

• there is only one mutable reference alive, or
• all but one mutable reference are inaccessible and passed into a function that lost the reference (e.g. into WASM code)

The intended, valid use-case for this method is from within imported function trampolines.

pub(crate) unsafe fn get_current_transient(id: StoreId) -> *mut StoreInner

Safety: In addition to the safety requirements of Self::get_current, the pointer returned from this function will become invalid if the store context is changed in any way (via installing or uninstalling a store context). The caller must ensure that the store context remains unchanged as long as the pointer is being accessed.

pub(crate) unsafe fn try_get_current(id: StoreId) -> Option<StorePtrWrapper>

Safety: See Self::get_current.

pub(crate) unsafe fn try_get_current_async( id: StoreId, ) -> GetStoreAsyncGuardResult

Safety: See Self::get_current.