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leastloaded.go
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/
leastloaded.go
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package leastloaded
import (
"math/rand"
"sync"
"sync/atomic"
"time"
"github.com/abulo/ratel/v3/client/grpc/balancer/p2c/basep2c"
"google.golang.org/grpc/balancer"
)
type leastLoadedNode struct {
item any
inflight int64
}
type leastLoaded struct {
items []*leastLoadedNode
mu sync.Mutex
rand *rand.Rand
}
// New ...
func New() basep2c.P2c {
return &leastLoaded{
items: make([]*leastLoadedNode, 0),
rand: rand.New(rand.NewSource(time.Now().Unix())),
}
}
// Add ...
func (p *leastLoaded) Add(item any) {
p.items = append(p.items, &leastLoadedNode{item: item})
}
// Next ...
func (p *leastLoaded) Next() (any, func(balancer.DoneInfo)) {
var sc, backsc *leastLoadedNode
switch len(p.items) {
case 0:
return nil, func(balancer.DoneInfo) {}
case 1:
sc = p.items[0]
default:
// rand needs lock
p.mu.Lock()
a := p.rand.Intn(len(p.items))
b := p.rand.Intn(len(p.items) - 1)
p.mu.Unlock()
if b >= a {
b = b + 1
}
sc, backsc = p.items[a], p.items[b]
// choose the least loaded item based on inflight
if sc.inflight > backsc.inflight {
sc, _ = backsc, sc
}
}
atomic.AddInt64(&sc.inflight, 1)
return sc.item, func(balancer.DoneInfo) {
atomic.AddInt64(&sc.inflight, -1)
}
}