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use libc::{self, SI_LOAD_SHIFT};
use std::{cmp, mem};
use std::time::Duration;
use crate::Result;
use crate::errno::Errno;
/// System info structure returned by `sysinfo`.
#[derive(Copy, Clone, Debug, Eq, Hash, PartialEq)]
#[repr(transparent)]
pub struct SysInfo(libc::sysinfo);
// The fields are c_ulong on 32-bit linux, u64 on 64-bit linux; x32's ulong is u32
#[cfg(all(target_arch = "x86_64", target_pointer_width = "32"))]
type mem_blocks_t = u64;
#[cfg(not(all(target_arch = "x86_64", target_pointer_width = "32")))]
type mem_blocks_t = libc::c_ulong;
impl SysInfo {
/// Returns the load average tuple.
///
/// The returned values represent the load average over time intervals of
/// 1, 5, and 15 minutes, respectively.
pub fn load_average(&self) -> (f64, f64, f64) {
(
self.0.loads[0] as f64 / (1 << SI_LOAD_SHIFT) as f64,
self.0.loads[1] as f64 / (1 << SI_LOAD_SHIFT) as f64,
self.0.loads[2] as f64 / (1 << SI_LOAD_SHIFT) as f64,
)
}
/// Returns the time since system boot.
pub fn uptime(&self) -> Duration {
// Truncate negative values to 0
Duration::from_secs(cmp::max(self.0.uptime, 0) as u64)
}
/// Current number of processes.
pub fn process_count(&self) -> u16 {
self.0.procs
}
/// Returns the amount of swap memory in Bytes.
pub fn swap_total(&self) -> u64 {
self.scale_mem(self.0.totalswap)
}
/// Returns the amount of unused swap memory in Bytes.
pub fn swap_free(&self) -> u64 {
self.scale_mem(self.0.freeswap)
}
/// Returns the total amount of installed RAM in Bytes.
pub fn ram_total(&self) -> u64 {
self.scale_mem(self.0.totalram)
}
/// Returns the amount of completely unused RAM in Bytes.
///
/// "Unused" in this context means that the RAM in neither actively used by
/// programs, nor by the operating system as disk cache or buffer. It is
/// "wasted" RAM since it currently serves no purpose.
pub fn ram_unused(&self) -> u64 {
self.scale_mem(self.0.freeram)
}
fn scale_mem(&self, units: mem_blocks_t) -> u64 {
units as u64 * self.0.mem_unit as u64
}
}
/// Returns system information.
///
/// [See `sysinfo(2)`](https://man7.org/linux/man-pages/man2/sysinfo.2.html).
pub fn sysinfo() -> Result<SysInfo> {
let mut info = mem::MaybeUninit::uninit();
let res = unsafe { libc::sysinfo(info.as_mut_ptr()) };
Errno::result(res).map(|_| unsafe{ SysInfo(info.assume_init()) })
}
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