This adopts the new function store, replacing the C++ version.
It also reimplements builtin_function in Rust, as these was too coupled to
the function store to handle in a separate commit.
Prior to this change, we had a silly wrapper type EventDescription which wrapped
EventType, which actually described the event.
Remove this wrapper and rename EventType to EventDescription (since it describes
more than just the type of event).
This ports some signal setup and handling bits to Rust.
The signal handling machinery requires walking over the list of known signals;
that's not supported by the Signal type. Rather than duplicate the list of
signals yet again, switch back to a table, as we had in C++.
This also adds two further pieces which were neglected by the Signal struct:
1. Localize signal descriptions
2. Support for integers as the signal name
A JobId is not supposed to convert to other types.
Since this type is defined as NonZeroU32 (which cannot be -1), we need to
add some conversion functions to match the C++ behavior.
Overall, it would have been better to keep using the C++ type.
This allows us to use the scoped push in more scenarios by appeasing the
borrow checker.
Use it in a couple of places instead of ScopeGuard. Hopefully this is makes
porting easier.
Everything but signal handlers has been changed to use `Signal` instead of
`c_int` or `i32` signal values.
Event handlers are using `usize` to match C++, at least for now.
Just address two clippy lints that are fallout from changing the signal type.
There's no longer any need to convert these (which gets rid of an unwrap).
This was added to support signals; however we are unlikely to use this
for anything else. Remove it; just use a u64 to report signals that have
been set.
This optimizes over both the rust rewrite and the original C++ code. The rust
rewrite saw `std::bitset` replaced with `[bool; 65]` which could result in a
lot of memory copy bandwidth each time we checked for and received no signals.
The original C++ code would iterate over all signal slots to see if any were
set. The code now returns a single u64 and only checks slots that are known to
have signals via an intelligent `Iterator` impl.
