Struct cpu_affinity::LogicalCores

pub struct LogicalCores(_);

Logical cores to use for process and thread affinity, abstracting away platform, library and Operating System differences.

Provides the following definitions:-

• Constant LogicalCores::IsSettingProcessAffinitySupported: Boolean that is true if the current platform contains a way to attempt to set process affinity.

• Constant LogicalCores::IsSettingThreadAffinitySupported: Boolean that is true if the current platform contains a way to attempt to set thread affinity. Note that this is true for Fuschia and Empscripten, but that setting thread affinity always fails as unsupported as of 3rd December 2018.

• Method set_current_process_affinity(&self) -> io::Result<()>: Tries to set the current process' affinity; may fail (eg may not be supported in particular revisions of an OS, particularly so on Fuschia and Emscripten).

• Method set_process_affinity(&self, process_identifier) -> io::Result<()>: As above, but for a particular process. Usually fails with permission denied if not root.

• Method set_current_thread_affinity(&self) -> io::Result<()>: Tries to set the thread process' affinity; may fail (eg may not be supported in particular revisions of an OS, particularly so on Fuschia and Emscripten).

• Method set_thread_affinity(&self, thread_identifier) -> io::Result<()>: As above, but for a thread process. Usually fails with permission denied if not root.

If support for a platform has not been explicitly added to this library then it will not fail on that platform but it will not change any process or thread affinities, either.

At this time, there is no support for Solaris. If you're interested in adding support, see https://stackoverflow.com/questions/14085515/obtain-lwp-id-from-a-pthread-t-on-solaris-to-use-with-processor-bind.

DragonFlyBSD and FreeBSD currently (as of 3rd December 2018) support 256 cores.

Windows is a bit squiffy with more than 64 cores.

Create using one of the From implementations.

Sadly, actually getting a list of the cores the current process can use is quite tricky; a little more Linux specific information can be obtained using the dpdk-unix crate's HyperThread struct and the libnuma-sys crate's static field numa_all_cpus_ptr, which is derived from the parsing of the line starting Cpus_allowed: in /proc/self/status and capping it with the maximum CPUs in the system. Yuck!

Methods

impl LogicalCores

pub const IsSettingProcessAffinitySupported: bool

Is setting process affinity is supported?

Note that on emscripten and fuschia an error (ENOSYS) by the platform will always be returned as of the 3rd December 2018.

The following do not support setting process affinity:-

• iOS
• Mac OS
• OpenBSD
• BitRig

pub const IsSettingThreadAffinitySupported: bool

Is setting thread affinity is supported?

Note that on emscripten and fuschia an error (ENOSYS) by the platform will always be returned as of the 3rd December 2018.

The following do not support setting thread affinity:-

• Android
• iOS
• Mac OS
• OpenBSD
• BitRig

pub fn set_current_process_affinity(&self) -> Result<()>

Sets the current process' logical core affinity.

This is not efficiently implemented (it uses a loop).

Failure occurs if a CPU in the set does not exist, is offline or in some other way is unavailable to the process_identifier (EINVAL).

pub fn set_process_affinity(     &self,     process_identifier: ProcessIdentifier ) -> Result<()>

Sets the process' logical core affinity.

This is not efficiently implemented (it uses a loop).

Failure occurs if:-

• Permission is denied to change the process affinity for process_identifier (EPERM) (for example, the process isn't a child of this process);
• A CPU in the set does not exist, is offline or in some other way is unavailable to the process_identifier (EINVAL);
• process_identifier does not exist (ESRCH)
• Operating system is not yet implemented (ENOSYS) - typical of Emscripten and Fuschia.

pub fn set_current_thread_affinity(&self) -> Result<()>

Sets the thread's logical core affinity.

Threads are never resident on just on core, and hence a lot of thread local opimizations (eg with clever non-blocking alogorithms) are useless.

pub fn set_thread_affinity(     &self,     thread_identifier: ThreadIdentifier ) -> Result<()>

Sets the thread's logical core affinity.

This is only used as a hint on iOS and MacOS; it is near useless.

Threads are never resident on just on core, and hence a lot of thread local opimizations (eg with clever non-blocking alogorithms) are useless.

• Permission is denied to change the process affinity for process_identifier (EPERM) (for example, the process isn't a child of this process);
• A CPU in the set does not exist, is offline or in some other way is unavailable to the process_identifier (EINVAL);
• process_identifier does not exist (ESRCH)
• Operating system is not yet implemented (ENOSYS) - typical of Emscripten and Fuschia.
• ERANGE - on FreeBSD, the cpu set was far too large.
• EDEADLK - on FreeBSD, the cpu set could not be honoured.

Methods from Deref<Target = HashSet<LogicalCoreIdentifier>>

pub fn hasher(&self) -> &S

Returns a reference to the set's BuildHasher.

Examples

use std::collections::HashSet;
use std::collections::hash_map::RandomState;

let hasher = RandomState::new();
let set: HashSet<i32> = HashSet::with_hasher(hasher);
let hasher: &RandomState = set.hasher();

pub fn capacity(&self) -> usize

Returns the number of elements the set can hold without reallocating.

Examples

use std::collections::HashSet;
let set: HashSet<i32> = HashSet::with_capacity(100);
assert!(set.capacity() >= 100);

pub fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more elements to be inserted in the HashSet. The collection may reserve more space to avoid frequent reallocations.

Panics

Panics if the new allocation size overflows usize.

Examples

use std::collections::HashSet;
let mut set: HashSet<i32> = HashSet::new();
set.reserve(10);
assert!(set.capacity() >= 10);

pub fn shrink_to_fit(&mut self)

Shrinks the capacity of the set as much as possible. It will drop down as much as possible while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.

Examples

use std::collections::HashSet;

let mut set = HashSet::with_capacity(100);
set.insert(1);
set.insert(2);
assert!(set.capacity() >= 100);
set.shrink_to_fit();
assert!(set.capacity() >= 2);

pub fn shrink_to(&mut self, min_capacity: usize)

🔬 This is a nightly-only experimental API. (shrink_to)

new API

Shrinks the capacity of the set with a lower limit. It will drop down no lower than the supplied limit while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.

Panics if the current capacity is smaller than the supplied minimum capacity.

Examples

#![feature(shrink_to)]
use std::collections::HashSet;

let mut set = HashSet::with_capacity(100);
set.insert(1);
set.insert(2);
assert!(set.capacity() >= 100);
set.shrink_to(10);
assert!(set.capacity() >= 10);
set.shrink_to(0);
assert!(set.capacity() >= 2);

pub fn iter(&self) -> Iter<T>

An iterator visiting all elements in arbitrary order. The iterator element type is &'a T.

Examples

use std::collections::HashSet;
let mut set = HashSet::new();
set.insert("a");
set.insert("b");

// Will print in an arbitrary order.
for x in set.iter() {
    println!("{}", x);
}

pub fn difference(&'a self, other: &'a HashSet<T, S>) -> Difference<'a, T, S>

Visits the values representing the difference, i.e., the values that are in self but not in other.

Examples

use std::collections::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();

// Can be seen as `a - b`.
for x in a.difference(&b) {
    println!("{}", x); // Print 1
}

let diff: HashSet<_> = a.difference(&b).collect();
assert_eq!(diff, [1].iter().collect());

// Note that difference is not symmetric,
// and `b - a` means something else:
let diff: HashSet<_> = b.difference(&a).collect();
assert_eq!(diff, [4].iter().collect());

pub fn symmetric_difference(     &'a self,     other: &'a HashSet<T, S> ) -> SymmetricDifference<'a, T, S>

Visits the values representing the symmetric difference, i.e., the values that are in self or in other but not in both.

Examples

use std::collections::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();

// Print 1, 4 in arbitrary order.
for x in a.symmetric_difference(&b) {
    println!("{}", x);
}

let diff1: HashSet<_> = a.symmetric_difference(&b).collect();
let diff2: HashSet<_> = b.symmetric_difference(&a).collect();

assert_eq!(diff1, diff2);
assert_eq!(diff1, [1, 4].iter().collect());

pub fn intersection(     &'a self,     other: &'a HashSet<T, S> ) -> Intersection<'a, T, S>

Visits the values representing the intersection, i.e., the values that are both in self and other.

Examples

use std::collections::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();

// Print 2, 3 in arbitrary order.
for x in a.intersection(&b) {
    println!("{}", x);
}

let intersection: HashSet<_> = a.intersection(&b).collect();
assert_eq!(intersection, [2, 3].iter().collect());

pub fn union(&'a self, other: &'a HashSet<T, S>) -> Union<'a, T, S>

Visits the values representing the union, i.e., all the values in self or other, without duplicates.

Examples

use std::collections::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();

// Print 1, 2, 3, 4 in arbitrary order.
for x in a.union(&b) {
    println!("{}", x);
}

let union: HashSet<_> = a.union(&b).collect();
assert_eq!(union, [1, 2, 3, 4].iter().collect());

pub fn len(&self) -> usize

Returns the number of elements in the set.

Examples

use std::collections::HashSet;

let mut v = HashSet::new();
assert_eq!(v.len(), 0);
v.insert(1);
assert_eq!(v.len(), 1);

pub fn is_empty(&self) -> bool

Returns true if the set contains no elements.

Examples

use std::collections::HashSet;

let mut v = HashSet::new();
assert!(v.is_empty());
v.insert(1);
assert!(!v.is_empty());

pub fn drain(&mut self) -> Drain<T>

Clears the set, returning all elements in an iterator.

Examples

use std::collections::HashSet;

let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert!(!set.is_empty());

// print 1, 2, 3 in an arbitrary order
for i in set.drain() {
    println!("{}", i);
}

assert!(set.is_empty());

pub fn clear(&mut self)

Clears the set, removing all values.

Examples

use std::collections::HashSet;

let mut v = HashSet::new();
v.insert(1);
v.clear();
assert!(v.is_empty());

pub fn contains<Q>(&self, value: &Q) -> bool where     Q: Hash + Eq + ?Sized,     T: Borrow<Q>,

Returns true if the set contains a value.

The value may be any borrowed form of the set's value type, but Hash and Eq on the borrowed form must match those for the value type.

Examples

use std::collections::HashSet;

let set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.contains(&1), true);
assert_eq!(set.contains(&4), false);

pub fn get<Q>(&self, value: &Q) -> Option<&T> where     Q: Hash + Eq + ?Sized,     T: Borrow<Q>,

Returns a reference to the value in the set, if any, that is equal to the given value.

The value may be any borrowed form of the set's value type, but Hash and Eq on the borrowed form must match those for the value type.

Examples

use std::collections::HashSet;

let set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.get(&2), Some(&2));
assert_eq!(set.get(&4), None);

pub fn is_disjoint(&self, other: &HashSet<T, S>) -> bool

Returns true if self has no elements in common with other. This is equivalent to checking for an empty intersection.

Examples

use std::collections::HashSet;

let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let mut b = HashSet::new();

assert_eq!(a.is_disjoint(&b), true);
b.insert(4);
assert_eq!(a.is_disjoint(&b), true);
b.insert(1);
assert_eq!(a.is_disjoint(&b), false);

pub fn is_subset(&self, other: &HashSet<T, S>) -> bool

Returns true if the set is a subset of another, i.e., other contains at least all the values in self.

Examples

use std::collections::HashSet;

let sup: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let mut set = HashSet::new();

assert_eq!(set.is_subset(&sup), true);
set.insert(2);
assert_eq!(set.is_subset(&sup), true);
set.insert(4);
assert_eq!(set.is_subset(&sup), false);

pub fn is_superset(&self, other: &HashSet<T, S>) -> bool

Returns true if the set is a superset of another, i.e., self contains at least all the values in other.

Examples

use std::collections::HashSet;

let sub: HashSet<_> = [1, 2].iter().cloned().collect();
let mut set = HashSet::new();

assert_eq!(set.is_superset(&sub), false);

set.insert(0);
set.insert(1);
assert_eq!(set.is_superset(&sub), false);

set.insert(2);
assert_eq!(set.is_superset(&sub), true);

pub fn insert(&mut self, value: T) -> bool

Adds a value to the set.

If the set did not have this value present, true is returned.

If the set did have this value present, false is returned.

Examples

use std::collections::HashSet;

let mut set = HashSet::new();

assert_eq!(set.insert(2), true);
assert_eq!(set.insert(2), false);
assert_eq!(set.len(), 1);

pub fn replace(&mut self, value: T) -> Option<T>

Adds a value to the set, replacing the existing value, if any, that is equal to the given one. Returns the replaced value.

Examples

use std::collections::HashSet;

let mut set = HashSet::new();
set.insert(Vec::<i32>::new());

assert_eq!(set.get(&[][..]).unwrap().capacity(), 0);
set.replace(Vec::with_capacity(10));
assert_eq!(set.get(&[][..]).unwrap().capacity(), 10);

pub fn remove<Q>(&mut self, value: &Q) -> bool where     Q: Hash + Eq + ?Sized,     T: Borrow<Q>,

Removes a value from the set. Returns true if the value was present in the set.

The value may be any borrowed form of the set's value type, but Hash and Eq on the borrowed form must match those for the value type.

Examples

use std::collections::HashSet;

let mut set = HashSet::new();

set.insert(2);
assert_eq!(set.remove(&2), true);
assert_eq!(set.remove(&2), false);

pub fn take<Q>(&mut self, value: &Q) -> Option<T> where     Q: Hash + Eq + ?Sized,     T: Borrow<Q>,

Removes and returns the value in the set, if any, that is equal to the given one.

The value may be any borrowed form of the set's value type, but Hash and Eq on the borrowed form must match those for the value type.

Examples

use std::collections::HashSet;

let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.take(&2), Some(2));
assert_eq!(set.take(&2), None);

pub fn retain<F>(&mut self, f: F) where     F: FnMut(&T) -> bool,

Retains only the elements specified by the predicate.

In other words, remove all elements e such that f(&e) returns false.

Examples

use std::collections::HashSet;

let xs = [1,2,3,4,5,6];
let mut set: HashSet<i32> = xs.iter().cloned().collect();
set.retain(|&k| k % 2 == 0);
assert_eq!(set.len(), 3);

Trait Implementations

impl From<u16> for LogicalCores

fn from(core_index: LogicalCoreIdentifier) -> Self

From a core index.

impl From<HashSet<u16, RandomState>> for LogicalCores

fn from(logical_cores: HashSet<LogicalCoreIdentifier>) -> Self

Performs the conversion.

impl Eq for LogicalCores

impl Into<HashSet<u16, RandomState>> for LogicalCores

fn into(self) -> HashSet<LogicalCoreIdentifier>

Performs the conversion.

impl AsMut<HashSet<u16, RandomState>> for LogicalCores

fn as_mut(&mut self) -> &mut HashSet<LogicalCoreIdentifier>

Performs the conversion.

impl PartialEq<LogicalCores> for LogicalCores

fn eq(&self, other: &LogicalCores) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &LogicalCores) -> bool

This method tests for !=.

impl AsRef<HashSet<u16, RandomState>> for LogicalCores

fn as_ref(&self) -> &HashSet<LogicalCoreIdentifier>

Performs the conversion.

impl Clone for LogicalCores

fn clone(&self) -> LogicalCores

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for LogicalCores

fn fmt(&self, f: &mut Formatter) -> Result

Formats the value using the given formatter.

impl DerefMut for LogicalCores

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl Deref for LogicalCores

type Target = HashSet<LogicalCoreIdentifier>

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl Borrow<HashSet<u16, RandomState>> for LogicalCores

fn borrow(&self) -> &HashSet<LogicalCoreIdentifier>

Immutably borrows from an owned value.

impl BorrowMut<HashSet<u16, RandomState>> for LogicalCores

fn borrow_mut(&mut self) -> &mut HashSet<LogicalCoreIdentifier>

Mutably borrows from an owned value.