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filter.go
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filter.go
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package blacklist
import (
"math/rand"
"sync"
"time"
"github.com/micro/go-micro/registry"
)
type node struct {
age time.Time
id string
service string
count int
}
type blacklist struct {
ttl int
exit chan bool
sync.RWMutex
bl map[string]node
}
var (
// number of times we see an error before blacklisting
count = 3
// the ttl to blacklist for
ttl = 30
)
func init() {
rand.Seed(time.Now().Unix())
}
func (r *blacklist) purge() {
now := time.Now()
r.Lock()
for k, v := range r.bl {
if d := v.age.Sub(now); d.Seconds() < 0 {
delete(r.bl, k)
}
}
r.Unlock()
}
func (r *blacklist) run() {
t := time.NewTicker(time.Duration(r.ttl) * time.Second)
for {
select {
case <-r.exit:
t.Stop()
return
case <-t.C:
r.purge()
}
}
}
func (r *blacklist) Filter(services []*registry.Service) ([]*registry.Service, error) {
var viableServices []*registry.Service
r.RLock()
for _, service := range services {
var viableNodes []*registry.Node
for _, node := range service.Nodes {
n, ok := r.bl[node.Id]
if !ok {
// blacklist miss so add it
viableNodes = append(viableNodes, node)
continue
}
// got some blacklist info
// skip the node if it exceeds count
if n.count >= count {
continue
}
// doesn't exceed count, still viable
viableNodes = append(viableNodes, node)
}
if len(viableNodes) == 0 {
continue
}
viableService := new(registry.Service)
*viableService = *service
viableService.Nodes = viableNodes
viableServices = append(viableServices, viableService)
}
r.RUnlock()
return viableServices, nil
}
func (r *blacklist) Mark(service string, nod *registry.Node, err error) {
r.Lock()
defer r.Unlock()
// reset when error is nil
// basically closing the circuit
if err == nil {
delete(r.bl, nod.Id)
return
}
n, ok := r.bl[nod.Id]
if !ok {
n = node{
id: nod.Id,
service: service,
}
}
// mark it
n.count++
// set age to ttl seconds in future
n.age = time.Now().Add(time.Duration(r.ttl) * time.Second)
// save
r.bl[nod.Id] = n
}
func (r *blacklist) Reset(service string) {
r.Lock()
defer r.Unlock()
for k, v := range r.bl {
// delete every node that matches the service
if v.service == service {
delete(r.bl, k)
}
}
}
func (r *blacklist) Close() error {
select {
case <-r.exit:
return nil
default:
close(r.exit)
}
return nil
}
func newBlacklist() *blacklist {
bl := &blacklist{
ttl: ttl,
bl: make(map[string]node),
exit: make(chan bool),
}
go bl.run()
return bl
}