Merge pull request #267 from iancoolidge/devel-cpuset

Import 'cpuset' from kubernetes repository in kubernetes/utils

cpuset/OWNERS

@@ -0,0 +1,8 @@
+# See the OWNERS docs at https://go.k8s.io/owners
+
+approvers:
+  - dchen1107
+  - derekwaynecarr
+  - ffromani
+  - klueska
+  - SergeyKanzhelev

cpuset/cpuset.go

@@ -0,0 +1,256 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package cpuset represents a collection of CPUs in a 'set' data structure.
+//
+// It can be used to represent core IDs, hyper thread siblings, CPU nodes, or processor IDs.
+//
+// The only special thing about this package is that
+// methods are provided to convert back and forth from Linux 'list' syntax.
+// See http://man7.org/linux/man-pages/man7/cpuset.7.html#FORMATS for details.
+//
+// Future work can migrate this to use a 'set' library, and relax the dubious 'immutable' property.
+//
+// This package was originally developed in the 'kubernetes' repository.
+package cpuset
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+// CPUSet is a thread-safe, immutable set-like data structure for CPU IDs.
+type CPUSet struct {
+	elems map[int]struct{}
+}
+
+// New returns a new CPUSet containing the supplied elements.
+func New(cpus ...int) CPUSet {
+	s := CPUSet{
+		elems: map[int]struct{}{},
+	}
+	for _, c := range cpus {
+		s.add(c)
+	}
+	return s
+}
+
+// add adds the supplied elements to the CPUSet.
+// It is intended for internal use only, since it mutates the CPUSet.
+func (s CPUSet) add(elems ...int) {
+	for _, elem := range elems {
+		s.elems[elem] = struct{}{}
+	}
+}
+
+// Size returns the number of elements in this set.
+func (s CPUSet) Size() int {
+	return len(s.elems)
+}
+
+// IsEmpty returns true if there are zero elements in this set.
+func (s CPUSet) IsEmpty() bool {
+	return s.Size() == 0
+}
+
+// Contains returns true if the supplied element is present in this set.
+func (s CPUSet) Contains(cpu int) bool {
+	_, found := s.elems[cpu]
+	return found
+}
+
+// Equals returns true if the supplied set contains exactly the same elements
+// as this set (s IsSubsetOf s2 and s2 IsSubsetOf s).
+func (s CPUSet) Equals(s2 CPUSet) bool {
+	return reflect.DeepEqual(s.elems, s2.elems)
+}
+
+// filter returns a new CPU set that contains all of the elements from this
+// set that match the supplied predicate, without mutating the source set.
+func (s CPUSet) filter(predicate func(int) bool) CPUSet {
+	r := New()
+	for cpu := range s.elems {
+		if predicate(cpu) {
+			r.add(cpu)
+		}
+	}
+	return r
+}
+
+// IsSubsetOf returns true if the supplied set contains all the elements
+func (s CPUSet) IsSubsetOf(s2 CPUSet) bool {
+	result := true
+	for cpu := range s.elems {
+		if !s2.Contains(cpu) {
+			result = false
+			break
+		}
+	}
+	return result
+}
+
+// Union returns a new CPU set that contains all of the elements from this
+// set and all of the elements from the supplied sets, without mutating
+// either source set.
+func (s CPUSet) Union(s2 ...CPUSet) CPUSet {
+	r := New()
+	for cpu := range s.elems {
+		r.add(cpu)
+	}
+	for _, cs := range s2 {
+		for cpu := range cs.elems {
+			r.add(cpu)
+		}
+	}
+	return r
+}
+
+// Intersection returns a new CPU set that contains all of the elements
+// that are present in both this set and the supplied set, without mutating
+// either source set.
+func (s CPUSet) Intersection(s2 CPUSet) CPUSet {
+	return s.filter(func(cpu int) bool { return s2.Contains(cpu) })
+}
+
+// Difference returns a new CPU set that contains all of the elements that
+// are present in this set and not the supplied set, without mutating either
+// source set.
+func (s CPUSet) Difference(s2 CPUSet) CPUSet {
+	return s.filter(func(cpu int) bool { return !s2.Contains(cpu) })
+}
+
+// List returns a slice of integers that contains all elements from
+// this set. The list is sorted.
+func (s CPUSet) List() []int {
+	result := s.UnsortedList()
+	sort.Ints(result)
+	return result
+}
+
+// UnsortedList returns a slice of integers that contains all elements from
+// this set.
+func (s CPUSet) UnsortedList() []int {
+	result := make([]int, 0, len(s.elems))
+	for cpu := range s.elems {
+		result = append(result, cpu)
+	}
+	return result
+}
+
+// String returns a new string representation of the elements in this CPU set
+// in canonical linux CPU list format.
+//
+// See: http://man7.org/linux/man-pages/man7/cpuset.7.html#FORMATS
+func (s CPUSet) String() string {
+	if s.IsEmpty() {
+		return ""
+	}
+
+	elems := s.List()
+
+	type rng struct {
+		start int
+		end   int
+	}
+
+	ranges := []rng{{elems[0], elems[0]}}
+
+	for i := 1; i < len(elems); i++ {
+		lastRange := &ranges[len(ranges)-1]
+		// if this element is adjacent to the high end of the last range
+		if elems[i] == lastRange.end+1 {
+			// then extend the last range to include this element
+			lastRange.end = elems[i]
+			continue
+		}
+		// otherwise, start a new range beginning with this element
+		ranges = append(ranges, rng{elems[i], elems[i]})
+	}
+
+	// construct string from ranges
+	var result bytes.Buffer
+	for _, r := range ranges {
+		if r.start == r.end {
+			result.WriteString(strconv.Itoa(r.start))
+		} else {
+			result.WriteString(fmt.Sprintf("%d-%d", r.start, r.end))
+		}
+		result.WriteString(",")
+	}
+	return strings.TrimRight(result.String(), ",")
+}
+
+// Parse CPUSet constructs a new CPU set from a Linux CPU list formatted string.
+//
+// See: http://man7.org/linux/man-pages/man7/cpuset.7.html#FORMATS
+func Parse(s string) (CPUSet, error) {
+	// Handle empty string.
+	if s == "" {
+		return New(), nil
+	}
+
+	result := New()
+
+	// Split CPU list string:
+	// "0-5,34,46-48" => ["0-5", "34", "46-48"]
+	ranges := strings.Split(s, ",")
+
+	for _, r := range ranges {
+		boundaries := strings.SplitN(r, "-", 2)
+		if len(boundaries) == 1 {
+			// Handle ranges that consist of only one element like "34".
+			elem, err := strconv.Atoi(boundaries[0])
+			if err != nil {
+				return New(), err
+			}
+			result.add(elem)
+		} else if len(boundaries) == 2 {
+			// Handle multi-element ranges like "0-5".
+			start, err := strconv.Atoi(boundaries[0])
+			if err != nil {
+				return New(), err
+			}
+			end, err := strconv.Atoi(boundaries[1])
+			if err != nil {
+				return New(), err
+			}
+			if start > end {
+				return New(), fmt.Errorf("invalid range %q (%d > %d)", r, start, end)
+			}
+			// start == end is acceptable (1-1 -> 1)
+
+			// Add all elements to the result.
+			// e.g. "0-5", "46-48" => [0, 1, 2, 3, 4, 5, 46, 47, 48].
+			for e := start; e <= end; e++ {
+				result.add(e)
+			}
+		}
+	}
+	return result, nil
+}
+
+// Clone returns a copy of this CPU set.
+func (s CPUSet) Clone() CPUSet {
+	r := New()
+	for elem := range s.elems {
+		r.add(elem)
+	}
+	return r
+}