/
util.go
46 lines (40 loc) · 926 Bytes
/
util.go
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package xsync
import (
"runtime"
_ "unsafe"
)
// test-only assert()-like flag
var assertionsEnabled = false
const (
// cacheLineSize is used in paddings to prevent false sharing;
// 64B are used instead of 128B as a compromise between
// memory footprint and performance; 128B usage may give ~30%
// improvement on NUMA machines.
cacheLineSize = 64
)
// nextPowOf2 computes the next highest power of 2 of 32-bit v.
// Source: https://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
func nextPowOf2(v uint32) uint32 {
if v == 0 {
return 1
}
v--
v |= v >> 1
v |= v >> 2
v |= v >> 4
v |= v >> 8
v |= v >> 16
v++
return v
}
func parallelism() uint32 {
maxProcs := uint32(runtime.GOMAXPROCS(0))
numCores := uint32(runtime.NumCPU())
if maxProcs < numCores {
return maxProcs
}
return numCores
}
//go:noescape
//go:linkname runtime_fastrand runtime.fastrand
func runtime_fastrand() uint32