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.


/// Settings for a RETA table.
#[derive(Default, Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[derive(Deserialize, Serialize)]
#[serde(default, deny_unknown_fields)]
pub struct HashFunctionConfiguration
{
	/// Hash function in use.
	pub(crate) function: Option<HashFunctionName>,
	
	/// Hash indirection table (RETA).
	///
	/// Uses the value produced by the hash `function` with the `key` as an index into this table to find a `QueueIdentifier`.
	pub(crate) indirection_table: Option<IndirectionTable>,

	/// Seed used by the hash `function`.
	///
	/// Called a 'key' in Receive Side Scaling (RSS) literature, but this is confusing; the key is actually the set of fields in the incoming data packet that are hashed.
	pub(crate) seed: Option<HashFunctionSeed>,
}

impl HashFunctionConfiguration
{
	pub(crate) const Unsupported: Self = Self
	{
		function: None,
		indirection_table: None,
		seed: None,
	};
	
	#[inline(always)]
	pub(crate) fn indirection_table_length_u32(&self) -> Result<Option<NonZeroU32>, IndirectionTableLengthError>
	{
		use self::IndirectionTableLengthError::*;
		
		match self.indirection_table
		{
			None => Ok(None),
			
			Some(ref indirection_table) =>
			{
				let len: usize = indirection_table.len();
				let x = len.try_into().map_err(IndirectionTableIsTooLongForU32)?;
				Ok(Some(NonZeroU32::new(x).ok_or(IndirectionTableLengthIsZero)?))
			}
		}
	}
	
	#[inline(always)]
	pub(crate) fn new_seed_matching_in_length(&self, hash_function_seed: &HashFunctionSeed) -> Option<HashFunctionSeed>
	{
		self.seed.as_ref().map(|existing_seed|
		{
			let must_be_seed_length = existing_seed.len();
			let mut hash_function_seed = hash_function_seed.clone();
			hash_function_seed.resize(must_be_seed_length);
			hash_function_seed
		})
	}
}