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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,137 @@ | ||
| package weightpool | ||
|
|
||
| import ( | ||
| "sync" | ||
|
|
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| "github.com/ServiceComb/go-chassis/core/common" | ||
| "github.com/ServiceComb/go-chassis/core/config/model" | ||
| ) | ||
|
|
||
| var weightPool *SafePool | ||
| var once sync.Once | ||
|
|
||
| func init() { once.Do(func() { weightPool = &SafePool{pool: map[string]*Pool{}} }) } | ||
|
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| // GetPool returns singleton of weightPool | ||
| func GetPool() *SafePool { return weightPool } | ||
|
|
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| // SafePool is a cache for pool of all destination | ||
| type SafePool struct { | ||
| sync.RWMutex | ||
| pool map[string]*Pool | ||
| } | ||
|
|
||
| // Get returns specific pool for key | ||
| func (s *SafePool) Get(key string) (*Pool, bool) { | ||
| s.RLock() | ||
| value, ok := s.pool[key] | ||
| s.RUnlock() | ||
| return value, ok | ||
| } | ||
|
|
||
| // Set can set pool to safe cache | ||
| func (s *SafePool) Set(key string, value *Pool) { | ||
| s.Lock() | ||
| s.pool[key] = value | ||
| s.Unlock() | ||
| } | ||
|
|
||
| // Reset can delete pool for specific key | ||
| func (s *SafePool) Reset(key string) { | ||
| s.Lock() | ||
| delete(s.pool, key) | ||
| s.Unlock() | ||
| } | ||
|
|
||
| /* Weighted Round-Robin Scheduling | ||
| http://zh.linuxvirtualserver.org/node/37 | ||
| while (true) { | ||
| i = (i + 1) mod n; | ||
| if (i == 0) { | ||
| cw = cw - gcd(S); | ||
| if (cw <= 0) { | ||
| cw = max(S); | ||
| if (cw == 0) | ||
| return NULL; | ||
| } | ||
| } | ||
| if (W(Si) >= cw) | ||
| return Si; | ||
| }*/ | ||
|
|
||
| // Pool defines sets of weighted tags | ||
| type Pool struct { | ||
| tags []model.RouteTag | ||
|
|
||
| gcd int | ||
| max int | ||
| i int | ||
| cw int | ||
| num int | ||
| } | ||
|
|
||
| // NewPool returns pool for provided tags | ||
| func NewPool(routeTags ...*model.RouteTag) *Pool { | ||
| var total int | ||
| p := &Pool{tags: make([]model.RouteTag, len(routeTags))} | ||
| for i, t := range routeTags { | ||
| if t.Weight > 0 { | ||
| total += t.Weight | ||
| p.refreshGCD(t) | ||
| } | ||
| p.tags[i] = *t | ||
| } | ||
|
|
||
| if total < 100 { | ||
| latestT := model.RouteTag{ | ||
| Weight: 100 - total, | ||
| Tags: map[string]string{ | ||
| common.BuildinTagVersion: common.LatestVersion, | ||
| }, | ||
| } | ||
| p.refreshGCD(&latestT) | ||
| p.tags = append(p.tags, latestT) | ||
| } | ||
|
|
||
| p.num = len(p.tags) | ||
| return p | ||
| } | ||
|
|
||
| // PickOne returns tag according to its weight | ||
| func (p *Pool) PickOne() *model.RouteTag { | ||
| if p.num == 0 || p.max == 0 { | ||
| return nil | ||
| } | ||
| if p.num == 1 { | ||
| return &p.tags[0] | ||
| } | ||
|
|
||
| for { | ||
| p.i = (p.i + 1) % p.num | ||
| if p.i == 0 { | ||
| p.cw = p.cw - p.gcd | ||
| if p.cw <= 0 { | ||
| p.cw = p.max | ||
| } | ||
| } | ||
|
|
||
| if p.tags[p.i].Weight >= p.cw { | ||
| return &p.tags[p.i] | ||
| } | ||
| } | ||
| } | ||
|
|
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| func (p *Pool) refreshGCD(t *model.RouteTag) { | ||
| p.gcd = gcd(p.gcd, t.Weight) | ||
| if p.max < t.Weight { | ||
| p.max = t.Weight | ||
| } | ||
| } | ||
|
|
||
| func gcd(a, b int) int { | ||
| if b == 0 { | ||
| return a | ||
| } | ||
| return gcd(b, a%b) | ||
| } |