otter-nif 0.3.1

Write Erlang NIFs in Rust. Direct mapping of the NIF C ABI with compile-time lifetime safety and no hidden magic.
Documentation 
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//! BEAM system information and thread introspection.

use std::ffi::c_int;

/// BEAM system information, filled by [`system_info`] (`ErlNifSysInfo`).
/// Re-exported from `enif_ffi`.
pub use enif_ffi::SysInfo;

/// The type of thread the current code is running on.
#[derive(Clone, Copy, PartialEq, Eq, Debug)]
pub enum ThreadType {
    /// A normal BEAM scheduler thread.
    Scheduler,
    /// A dirty CPU scheduler thread.
    DirtyCpu,
    /// A dirty I/O scheduler thread.
    DirtyIo,
    /// A non-scheduler thread (e.g. created by the user).
    NonScheduler,
    /// Unknown thread type (returned -1 from the BEAM).
    Unknown(c_int),
}

/// Return the type of the current thread.
///
/// Wraps `enif_thread_type`.
pub fn thread_type() -> ThreadType {
    match unsafe { enif_ffi::thread_type() } {
        enif_ffi::THR_UNDEFINED           => ThreadType::NonScheduler,
        enif_ffi::THR_NORMAL_SCHEDULER    => ThreadType::Scheduler,
        enif_ffi::THR_DIRTY_CPU_SCHEDULER => ThreadType::DirtyCpu,
        enif_ffi::THR_DIRTY_IO_SCHEDULER  => ThreadType::DirtyIo,
        other                             => ThreadType::Unknown(other),
    }
}

/// Fill a [`SysInfo`] struct with BEAM system information (`enif_system_info`).
///
/// Pass a `&mut SysInfo` to be populated; otter forwards `size_of::<SysInfo>()`
/// as the struct-size argument the C API requires for version negotiation.
pub fn system_info(info: &mut SysInfo) {
    unsafe { enif_ffi::system_info(info, std::mem::size_of::<SysInfo>()) };
}