stuffs

grain-pool.go

@@ -0,0 +1,89 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"time"
+)
+
+type GrainPool interface {
+	GetOrSpawn(id string) (Grain, error)
+	Get(id string) (Grain, error)
+}
+
+type Ttl struct {
+	Expires time.Time
+	Item    Grain
+}
+
+type GrainLocalPool struct {
+	grains   map[string]Grain
+	expiry   []Ttl
+	Ttl      time.Duration
+	PoolSize int
+}
+
+func NewGrainLocalPool(size int, ttl time.Duration) *GrainLocalPool {
+	ret := &GrainLocalPool{
+		grains:   make(map[string]Grain),
+		expiry:   make([]Ttl, 0),
+		Ttl:      ttl,
+		PoolSize: size,
+	}
+	cartPurge := time.NewTicker(time.Minute)
+	go func() {
+		<-cartPurge.C
+		ret.Purge()
+	}()
+	return ret
+}
+
+func (p *GrainLocalPool) Purge() {
+	lastChangeTime := time.Now().Add(-p.Ttl)
+	keepChanged := lastChangeTime.Unix()
+	for i := 0; i < len(p.expiry); i++ {
+		item := p.expiry[i]
+		if item.Expires.Before(time.Now()) {
+			if item.Item.GetLastChange() > keepChanged {
+				log.Printf("Changed item %s expired, keeping", item.Item.GetId())
+				p.expiry = append(p.expiry[:i], p.expiry[i+1:]...)
+				p.expiry = append(p.expiry, item)
+			} else {
+				log.Printf("Item %s expired", item.Item.GetId())
+				delete(p.grains, item.Item.GetId())
+				p.expiry = append(p.expiry[:i], p.expiry[i+1:]...)
+			}
+		} else {
+			break
+		}
+	}
+}
+
+func (p *GrainLocalPool) GetGrains() map[string]Grain {
+	return p.grains
+}
+
+func (p *GrainLocalPool) GetOrSpawn(id string, generator func(id string) Grain) (Grain, error) {
+	grain, ok := p.grains[id]
+	if !ok {
+		if len(p.grains) >= p.PoolSize {
+			if p.expiry[0].Expires.Before(time.Now()) {
+				delete(p.grains, p.expiry[0].Item.GetId())
+				p.expiry = p.expiry[1:]
+			} else {
+				return nil, fmt.Errorf("pool is full")
+			}
+		}
+		grain = generator(id)
+		p.grains[id] = grain
+	}
+	return grain, nil
+}
+
+func (p *GrainLocalPool) Get(id string) (Grain, error) {
+	grain, ok := p.grains[id]
+	if !ok {
+		return nil, fmt.Errorf("grain not found")
+	}
+	return grain, nil
+}