Add synchronous and asynchronous events

[szymon-zadworny]

This PR adds:

• The Event class bindings
• Synchronization methods:
  • through synchronous .wait() for Queues and Events
  • through asynchronous Futures and .await for Events
  • through barriers (which return an Event) for Queues
• memset bindings
• event dependencies
• examples showcasing synchronous and asynchronous waiting

Breaking change: queues are now in-order by default.

This PR also finalizes the Buffer safety model - safe Buffers are initialized by default and need to be waited/awaited. You can still create uninitialized Buffers through unsafe uninit methods.

Synchronous waiting:

fn main() {
    let mut queue = Queue::new();
    let mut buffer = queue.alloc_shared::<u32>(10).wait();
}

Asynchronous waiting:

#[tokio::main]
async fn main() {
    let mut queue = Queue::new();
    let mut buffer = queue.alloc_shared::<u32>(10).await;
}

Note: tokio was used as a dev dependency for the async.rs example but the actual Futures are executor-agnostic.

This PR requires the following SYCL extensions for the asynchronous execution implementation:

• sycl_ext_intel_queue_immediate_command_list
• sycl_ext_oneapi_enqueue_barrier

[Copilot]

Pull request overview

This PR introduces SYCL Event bindings and queue/event synchronization primitives in oneapi-rs, including blocking waits (.wait()), async waits (.await via IntoFuture), barriers returning events, and USM memset plus dependency wiring. It also updates the buffer safety model so “safe” allocations are zero-initialized via an enqueued operation that must be waited/awaited before use.

Changes:

• Add Event wrapper + event info queries + async EventFuture implementation.
• Add queue-side synchronization APIs (wait, barrier(_with_deps)) and USM memset(_with_deps) that return Event.
• Introduce EnqueuedBuffer/BufferFuture so safe host/shared allocations enqueue initialization and require wait/await.

Reviewed changes

Copilot reviewed 20 out of 21 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
oneapi-rs/src/usm.rs	Makes USM allocator own a cloned Queue so buffers can outlive the original queue reference.
oneapi-rs/src/queue.rs	Adds immediate queue construction, USM memset + deps, barriers + deps, and blocking queue wait; adds zero-initializing alloc APIs returning EnqueuedBuffer.
oneapi-rs/src/lib.rs	Exposes new event module publicly.
oneapi-rs/src/info/event-info.rs	Adds EventInfo trait + CommandExecutionStatus query binding.
oneapi-rs/src/info.rs	Wires info::event module and re-exports EventCommandStatus.
oneapi-rs/src/event.rs	Implements Event wrapper, cloning, blocking wait, event info, and async EventFuture/IntoFuture.
oneapi-rs/src/buffer.rs	Adds EnqueuedBuffer + BufferFuture so safe allocations are initialized asynchronously and require wait/await.
oneapi-rs/examples/async.rs	New example demonstrating async .await on an enqueued allocation.
oneapi-rs/examples/alloc.rs	Updates allocation example to use .wait() on safe initialization.
oneapi-rs/Cargo.toml	Adds bytemuck + pin-project deps and tokio as a dev-dependency for the async example.
oneapi-rs-sys/src/types-sys.rs	Adds opaque Waker wrapper and new Event/EventPtr/EventCommandStatus types for cxx bridging.
oneapi-rs-sys/src/queue.cpp	Adds in-order/immediate queue constructors; adds memset, barrier, and wait shims returning Event.
oneapi-rs-sys/src/queue-sys.rs	Extends cxx bridge for queue to include immediate queue, cloning, memset/barrier/wait, and EventPtr plumbing.
oneapi-rs-sys/src/lib.rs	Exposes new event sys module.
oneapi-rs-sys/src/event.cpp	Adds Event wait/clone/info and callback registration using host_task to wake a Rust waker.
oneapi-rs-sys/src/event-sys.rs	Adds cxx bridge for Event APIs and Rust-side wake trampoline.
oneapi-rs-sys/include/types.hpp	Adds using Event = sycl::event;.
oneapi-rs-sys/include/queue.hpp	Declares new queue shims (immediate queue, clone, memset, barrier, wait) returning/using Event.
oneapi-rs-sys/include/event.hpp	Declares event shims and EventCommandStatus API surface.
oneapi-rs-sys/build.rs	Registers new event bridge + C++ source/header in the build.
Cargo.lock	Locks new dependency graph for bytemuck, pin-project, and tokio.

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[Copilot]

Pull request overview

Copilot reviewed 20 out of 21 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

oneapi-rs-sys/src/queue.cpp:49

• e.ptr.release() relinquishes ownership of the heap-allocated sycl::event without deleting it, so this loop leaks every dependency event passed to barrier(...). There’s no need to release() here; match the memset(...) implementation and move/copy the event value instead.

std::unique_ptr<Event> barrier(std::unique_ptr<Queue> & queue, rust::Vec<EventPtr> dep_events) {
  std::vector<sycl::event> deps;
  for (auto&& e: dep_events)
    deps.push_back(std::move(*e.ptr.release()));
  return std::make_unique<Event>(queue->ext_oneapi_submit_barrier(deps));