This PR makes pointer read methods of `Deno.UnsafePointerView` Fast API
compliant, with the exception of `getCString` which cannot be made fast
with current V8 Fast API.
Welcome to better optimised op calls! Currently opSync is called with parameters of every type and count. This most definitely makes the call megamorphic. Additionally, it seems that spread params leads to V8 not being able to optimise the calls quite as well (apparently Fast Calls cannot be used with spread params).
Monomorphising op calls should lead to some improved performance. Now that unwrapping of sync ops results is done on Rust side, this is pretty simple:
```
opSync("op_foo", param1, param2);
// -> turns to
ops.op_foo(param1, param2);
```
This means sync op calls are now just directly calling the native binding function. When V8 Fast API Calls are enabled, this will enable those to be called on the optimised path.
Monomorphising async ops likely requires using callbacks and is left as an exercise to the reader.
This commit adds support for unstable FFI
callbacks. A callback is registered using
the `Deno.UnsafeCallback` API.
The backing memory for the callback can
be disposed of using `Deno.UnsafeCallback#close`.
It is not safe to pass the callback after calling
close.
Callbacks from other than the isolate thread
are not supported.
Co-authored-by: Divy Srivastava <dj.srivastava23@gmail.com>
Co-authored-by: Bert Belder <bertbelder@gmail.com>
