util.go

/*
 * Copyright (C) THL A29 Limited, a Tencent company. All rights reserved.
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 */

package lockfree

import (
	"errors"
	"reflect"
	"runtime"
	"unsafe"
)

const (
	activeSpin       = 4
	passiveSpin      = 2
	READY            = 0 // 模块的状态之就绪态
	RUNNING          = 1 // 模块的状态之运行态
	StartErrorFormat = "start model [%s] error"
	CloseErrorFormat = "close model [%s] error"
)

var (
	ncpu        = runtime.NumCPU()
	spin        = 0
	ClosedError = errors.New("the queue has been closed")
)

func init() {
	if ncpu > 1 {
		spin = activeSpin
	}
}

//go:linkname procyield runtime.procyield
func procyield(cycles uint32)

//go:linkname osyield runtime.osyield
func osyield()

// byteArrayPointerWithUint8 创建uint8切片，返回其对应实际内容（Data）的指针
func byteArrayPointerWithUint8(capacity int) unsafe.Pointer {
	bytes := make([]uint8, capacity)
	rs := (*reflect.SliceHeader)(unsafe.Pointer(&bytes))
	return unsafe.Pointer(rs.Data)
}

// byteArrayPointer 创建uint32切片，返回其对应实际内容（Data）的指针
func byteArrayPointerWithUint32(capacity int) unsafe.Pointer {
	bytes := make([]uint32, capacity)
	rs := (*reflect.SliceHeader)(unsafe.Pointer(&bytes))
	return unsafe.Pointer(rs.Data)
}

// byteArrayPointer 创建int64切片，返回其对应实际内容（Data）的指针
func byteArrayPointerWithInt64(capacity int) unsafe.Pointer {
	bytes := make([]int64, capacity)
	rs := (*reflect.SliceHeader)(unsafe.Pointer(&bytes))
	return unsafe.Pointer(rs.Data)
}

// minSuitableCap 最小的合适的数量
func minSuitableCap(v int) int {
	if v <= 0 {
		return 2
	}
	v--
	v |= v >> 1
	v |= v >> 2
	v |= v >> 4
	v |= v >> 8
	v |= v >> 16
	v++
	return v
}