75acec0aea
Fixes #15136 Currently `UnsafeCallback` class' `ref()` and `unref()` methods rely on the `event_loop_middleware` implementation in core. If even a single `UnsafeCallback` is ref'ed, then the FFI event loop middleware will always return `true` to signify that there may still be more work for the event loop to do. The middleware handling in core does not wait a moment to check again, but will instead synchronously directly re-poll the event loop and middlewares for more work. This becomes a live-loop. This PR introduces a `Future` implementation for the `CallbackInfo` struct that acts as the intermediary data storage between an `UnsafeCallback` and the `libffi` C callback. Ref'ing a callback now means calling an async op that binds to the `CallbackInfo` Future and only resolves once the callback is unref'ed. The `libffi` C callback will call the waker of this Future when it fires to make sure that the main thread wakes up to receive the callback. |
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| .. | ||
| 00_ffi.js | ||
| Cargo.toml | ||
| fast_call.rs | ||
| lib.rs | ||
| README.md | ||
deno_ffi
This crate implements dynamic library ffi.
Performance
Deno FFI calls have extremely low overhead (~1ns on M1 16GB RAM) and perform on par with native code. Deno leverages V8 fast api calls and JIT compiled bindings to achieve these high speeds.
Deno.dlopen generates an optimized and a fallback path. Optimized paths are
triggered when V8 decides to optimize the function, hence call through the Fast
API. Fallback paths handle types like function callbacks and implement proper
error handling for unexpected types, that is not supported in Fast calls.
Optimized calls enter a JIT compiled function "trampoline" that translates Fast
API values directly for symbol calls. JIT compilation itself is super fast,
thanks to tinycc. Currently, the optimized path is only supported on Linux and
MacOS.
To run benchmarks:
target/release/deno bench --allow-ffi --allow-read --unstable ./test_ffi/tests/bench.js