# CleanupFn

<!-- DO NOT EDIT: this page is autogenerated from the type comments -->

```ts
type CleanupFn = (() => void) | (() => Promise<void>);
```

Defined in: [packages/db/src/types.ts:430](https://github.com/TanStack/db/blob/main/packages/db/src/types.ts#L430)

Ends one sync run and releases its adapter-owned resources.

Collection cleanup waits for a returned promise before publishing the
`cleaned-up` status or admitting a replacement sync run.
TypeScript permits Promise-returning functions where `() => void` is
expected, so the Promise branch must be explicit here to preserve and await
it. Keeping the callable types separate also preserves contextual-void
callbacks that return an incidental value.