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package main
import (
"bufio"
"fmt"
"os"
)
var CPU_PATH = "/sys/fs/cgroup/cpuset.cpus.effective"
type CpuContext struct {
cpuAllocator *CpuAllocatorT
cpus []int
}
func (c *CpuContext) Release() {
c.cpuAllocator.cpus = append(c.cpuAllocator.cpus, c.cpus...)
c.cpus = c.cpus[:0] // empty the list
}
type CpuAllocatorT struct {
cpus []int
}
var cpuAllocator *CpuAllocatorT = nil
func (c *CpuAllocatorT) Allocate(nCpus int) (*CpuContext, error) {
var cpuCtx CpuContext
if len(c.cpus) < nCpus {
return nil, fmt.Errorf("could not allocate %d CPUs; available: %d", nCpus, len(c.cpus))
}
cpuCtx.cpus = c.cpus[0:nCpus]
cpuCtx.cpuAllocator = c
c.cpus = c.cpus[nCpus:]
return &cpuCtx, nil
}
func (c *CpuAllocatorT) readCpus(fname string) error {
var first, last int
file, err := os.Open(CPU_PATH)
if err != nil {
return err
}
defer file.Close()
sc := bufio.NewScanner(file)
sc.Scan()
line := sc.Text()
_, err = fmt.Sscanf(line, "%d-%d", &first, &last)
if err != nil {
return err
}
for i := first; i <= last; i++ {
c.cpus = append(c.cpus, i)
}
return nil
}
func CpuAllocator() (*CpuAllocatorT, error) {
if cpuAllocator == nil {
cpuAllocator = new(CpuAllocatorT)
err := cpuAllocator.readCpus(CPU_PATH)
if err != nil {
return nil, err
}
}
return cpuAllocator, nil
}
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