linux-support 0.0.25

Comprehensive Linux support for namespaces, cgroups, processes, scheduling, parsing /proc, parsing /sys, signals, hyper threads, CPUS, NUMA nodes, unusual file descriptors, PCI devices and much, much more
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// This file is part of linux-support. It is subject to the license terms in the COPYRIGHT file found in the top-level directory of this distribution and at https://raw.githubusercontent.com/lemonrock/linux-support/master/COPYRIGHT. No part of linux-support, including this file, may be copied, modified, propagated, or distributed except according to the terms contained in the COPYRIGHT file.
// Copyright © 2020 The developers of linux-support. See the COPYRIGHT file in the top-level directory of this distribution and at https://raw.githubusercontent.com/lemonrock/linux-support/master/COPYRIGHT.


/// Nice settings for the current process.
///
/// Defaults to aggresive promotion of the current process.
#[derive(Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
#[derive(Deserialize, Serialize)]
#[serde(default, deny_unknown_fields)]
pub struct ProcessNiceConfiguration
{
	/// If autogroups are enabled, should we take as close to 100% of all CPU cycles in the autogroup?
	pub share_of_cpu_cycles_in_autogroup: Option<Nice>,

	/// Downgrade all other processes for the current user to this value.
	pub all_other_processes_for_current_user: Option<Nice>,

	/// Downgrade all other processes in the process group to this value.
	pub all_other_processes_in_process_group: Option<Nice>,

	/// Current process non-real-time priority (nice value).
	pub current_process_priority: Option<Nice>,
}

impl Default for ProcessNiceConfiguration
{
	#[inline(always)]
	fn default() -> Self
	{
		Self
		{
			share_of_cpu_cycles_in_autogroup: Some(Nice::Negative_20),
			all_other_processes_for_current_user: Some(Nice::Positive_19),
			all_other_processes_in_process_group: Some(Nice::Positive_19),
			current_process_priority: Some(Nice::Negative_20),
		}
	}
}

impl ProcessNiceConfiguration
{
	/// Configures.
	#[inline(always)]
	pub fn configure(&self, proc_path: &ProcPath) -> Result<(), ProcessNiceConfigurationError>
	{
		#[inline(always)]
		fn set_nice_value<Error>(nice_value: Option<Nice>, function: impl FnOnce(Nice) -> Result<(), Error>, error: impl FnOnce(Error) -> ProcessNiceConfigurationError) -> Result<(), ProcessNiceConfigurationError>
		{
			if let Some(nice_value) = nice_value
			{
				function(nice_value).map_err(|cause| error(cause))
			}
			else
			{
				Ok(())
			}
		}

		use self::ProcessNiceConfigurationError::*;

		set_nice_value(self.share_of_cpu_cycles_in_autogroup, |nice| Self::set_autogroup_for_current_process_if_desired(nice, proc_path), CouldNotSetCurrentProcessAutogroupPriorityNice)?;
		set_nice_value(self.all_other_processes_for_current_user, |nice| nice.set_real_user_priority(UserIdentifier::default()), |_: ()| CouldNotSetCurrentUserPriorityNice)?;
		set_nice_value(self.all_other_processes_in_process_group, |nice| nice.set_process_group_priority(ProcessGroupIdentifierChoice::Current), |_: ()| CouldNotSetCurrentProcessGroupPriorityNice)?;
		set_nice_value(self.current_process_priority, |nice| nice.set_process_priority(ProcessIdentifierChoice::Current), |_: ()| CouldNotSetCurrentProcessPriorityNice)?;

		Ok(())
	}

	/// Set the autogroup for the current process.
	#[inline(always)]
	fn set_autogroup_for_current_process_if_desired(share_of_cpu_cycles_in_autogroup: Nice, proc_path: &ProcPath) -> Result<(), io::Error>
	{
		if Self::is_autogroup_active(proc_path)?
		{
			share_of_cpu_cycles_in_autogroup.set_autogroup_for_current_process(proc_path)
		}
		else
		{
			Ok(())
		}
	}
	#[inline(always)]
	fn is_autogroup_active(proc_path: &ProcPath) -> Result<bool, io::Error>
	{
		Self::sched_autogroup_enabled_file_path(proc_path).read_zero_or_one_bool()
	}

	#[inline(always)]
	fn sched_autogroup_enabled_file_path(proc_path: &ProcPath) -> PathBuf
	{
		proc_path.sys_kernel_file_path("sched_autogroup_enabled")
	}
}