environment/training-source/source-snapshot/tests/threading.rs

//! Compile-time constraints that dictate how inference is threaded.
//!
//! `blade_graphics::Context` is `Send + Sync` — it guards its queue,
//! memory manager, and XR session state behind mutexes — so an
//! `Arc<Context>` can be shared with a worker thread.
//!
//! `meganeura::Session` is **not** `Send`: it owns a
//! `blade_graphics::CommandEncoder`. The single offending field is
//! `ScratchBuffer::mapped`, a raw pointer into a persistently mapped
//! allocation — everything else is Vulkan handles, which are fine. (Rust has
//! no stable way to *assert* a negative, hence a comment not a test.)
//!
//! That is why [`dinovision::inference`] hands the worker an
//! `Arc<Context>` and has it construct the session in place. A one-line
//! `unsafe impl Send for ScratchBuffer` in blade lifts the constraint —
//! verified, and on the `command-encoder-send` branch there.

fn assert_send<T: Send>() {}
fn assert_sync<T: Sync>() {}

#[test]
fn context_can_be_shared_across_threads() {
    assert_send::<blade_graphics::Context>();
    assert_sync::<blade_graphics::Context>();
    // Buffer handles carry explicit `unsafe impl Send/Sync`, so GPU-side
    // results can be published to the render thread by handle.
    assert_send::<blade_graphics::Buffer>();
    assert_sync::<blade_graphics::Buffer>();
}