nsqdlookupd: Add cache for nsqlookupd find producers

Godeps

@@ -11,3 +11,4 @@ github.com/julienschmidt/httprouter     6aacfd5ab513e34f7e64ea9627ab9670371b34e7
 github.com/judwhite/go-svc/svc          63c12402f579f0bdf022653c821a1aa5d7544f01
 k8s.io/apimachinery/pkg/util/cache      05b5762916b3dbc115737640b04ce9f7c003c793
 github.com/vmihailenco/msgpack          88d11f2b24498888c4eccac691122a0f38880f9a
+github.com/patrickmn/go-cache           46f407853014144407b6c2ec7ccc76bf67958d93

nsqlookupd/registration_db.go

@@ -5,11 +5,15 @@ import (
 	"sync"
 	"sync/atomic"
 	"time"
+
+	"github.com/patrickmn/go-cache"
 )
 
 type RegistrationDB struct {
 	sync.RWMutex
 	registrationMap map[Registration]ProducerMap
+
+	cachedFindProducersResults *cache.Cache
 }
 
 type MetaDB struct {
@@ -59,7 +63,8 @@ func (p *Producer) IsTombstoned(lifetime time.Duration) bool {
 
 func NewRegistrationDB() *RegistrationDB {
 	return &RegistrationDB{
-		registrationMap: make(map[Registration]ProducerMap),
+		registrationMap:            make(map[Registration]ProducerMap),
+		cachedFindProducersResults: cache.New(1*time.Minute, 5*time.Minute),
 	}
 }
 
@@ -181,8 +186,16 @@ func (r *RegistrationDB) FindRegistrations(category string, key string, subkey s
 func (r *RegistrationDB) FindProducers(category string, key string, subkey string) Producers {
 	r.RLock()
 	defer r.RUnlock()
+
+	cachedKey := fmt.Sprintf("%s:%s:%s", category, key, subkey)
+
+	if val, found := r.cachedFindProducersResults.Get(cachedKey); found {
+		return val.(Producers)
+	}
+
 	if !r.needFilter(key, subkey) {
 		k := Registration{category, key, subkey}
+		r.cachedFindProducersResults.Set(cachedKey, ProducerMap2Slice(r.registrationMap[k]), cache.DefaultExpiration)
 		return ProducerMap2Slice(r.registrationMap[k])
 	}
 
@@ -200,6 +213,9 @@ func (r *RegistrationDB) FindProducers(category string, key string, subkey strin
 			}
 		}
 	}
+
+	r.cachedFindProducersResults.Set(cachedKey, retProducers, cache.DefaultExpiration)
+
 	return retProducers
 }