156 lines
2.7 KiB
Go
156 lines
2.7 KiB
Go
package common
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import (
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"math/rand"
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"time"
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)
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const (
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MAX_TRY_RAND_CNT = 10
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RANDID_INVALID = -1
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)
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type BitPool struct {
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flag []uint64
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cnt int
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}
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func (bp *BitPool) Init(cnt int) {
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bp.cnt = cnt/64 + 1
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bp.flag = make([]uint64, bp.cnt, bp.cnt)
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}
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func (bp *BitPool) Mark(n int) bool {
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idx := n / 64
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off := n % 64
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if idx < 0 || idx >= bp.cnt {
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return false
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}
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bp.flag[idx] |= 1 << uint(off)
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return true
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}
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func (bp *BitPool) Unmark(n int) bool {
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idx := n / 64
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off := n % 64
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if idx < 0 || idx >= bp.cnt {
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return false
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}
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bp.flag[idx] &= ^(1 << uint(off))
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return true
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}
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func (bp *BitPool) IsMark(n int) bool {
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idx := n / 64
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off := n % 64
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if idx < 0 || idx >= bp.cnt {
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return false
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}
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return (bp.flag[idx] & (1 << uint(off))) != 0
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}
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type RandDistinctId struct {
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rand *rand.Rand
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bp BitPool
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min int
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max int
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cap int
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}
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func NewRandDistinctId(min, max int) *RandDistinctId {
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var id RandDistinctId
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id.Init(min, max)
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return &id
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}
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func (rid *RandDistinctId) Init(min, max int) {
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rid.min = min
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rid.max = max
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rid.cap = max - min
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rid.bp.Init(rid.cap)
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rid.rand = rand.New(rand.NewSource(time.Now().UnixNano()))
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}
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func (rid *RandDistinctId) Alloc(id int) bool {
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if !rid.bp.IsMark(id) {
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rid.bp.Mark(id)
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return true
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}
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return false
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}
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func (rid *RandDistinctId) Free(id int) bool {
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if rid.bp.IsMark(id) {
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rid.bp.Unmark(id)
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return true
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}
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return false
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}
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func (rid *RandDistinctId) RandOne() int {
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for i := 0; i < MAX_TRY_RAND_CNT; i++ {
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pos := rid.rand.Intn(rid.cap)
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if !rid.bp.IsMark(pos) {
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rid.bp.Mark(pos)
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return pos + rid.min
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}
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}
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//try one by one
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rpos := rid.rand.Intn(rid.cap)
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if rpos < rid.cap/2 {
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for i := rpos; i >= 0; i-- {
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if !rid.bp.IsMark(i) {
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rid.bp.Mark(i)
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return i + rid.min
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}
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}
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} else {
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for i := rpos; i < rid.cap; i++ {
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if !rid.bp.IsMark(i) {
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rid.bp.Mark(i)
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return i + rid.min
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}
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}
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}
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return RANDID_INVALID
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}
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//func memConsumed() uint64 {
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// runtime.GC() //GC，排除对象影响
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// var memStat runtime.MemStats
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// runtime.ReadMemStats(&memStat)
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// return memStat.Sys
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//}
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//func main() {
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// var idPool RandDistinctId
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// before := memConsumed()
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// idPool.Init(MIN, MAX)
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// after := memConsumed()
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//
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// idMap := make(map[int]bool)
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// for i := 0; i < 1000000; i++ {
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// id := idPool.RandId()
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// if id != -1 {
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// idMap[id] = true
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// }
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// }
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//
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// start := time.Now()
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// for i := 0; i < 10000; i++ {
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// id := idPool.RandId()
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// if id != -1 {
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// fmt.Println(i, "->", id)
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// idMap[id] = true
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// }
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//
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// }
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//
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// fmt.Println("total take:", time.Now().Sub(start), " len:", len(idMap))
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// fmt.Println(fmt.Sprintf("new %v pool consume %.3f MB", MAX-MIN, float64(after-before)/1024/1024))
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//}
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