improved query cache

cache.go

@@ -7,20 +7,26 @@ import (
 	"sync"
 )
 
+// DefaultCacheSize is the default cache size
+const DefaultCacheSize = 100
+
 // QueryCache can be used to cache queries
 type QueryCache struct {
 	// protects m
 	sync.RWMutex
 
-	m   map[string]Query
-	max int
+	m    map[string]*Query
+	size int
 }
 
 // NewQueryCache returns a new QueryCache
-func NewQueryCache(max int) *QueryCache {
+func NewQueryCache(size int) *QueryCache {
+	if size <= 0 {
+		size = DefaultCacheSize
+	}
 	return &QueryCache{
-		m:   make(map[string]Query),
-		max: max,
+		m:    make(map[string]*Query),
+		size: size,
 	}
 }
 
@@ -37,10 +43,10 @@ func (qc *QueryCache) NewQuery(s string) (q *Query, err error) {
 	}
 	qc.Lock()
 	defer qc.Unlock()
-	if len(qc.m) == qc.max {
+	if len(qc.m) == qc.size {
 		qc.clean()
 	}
-	qc.m[s] = *q
+	qc.m[s] = q
 	return
 }
 
@@ -49,7 +55,7 @@ func (qc *QueryCache) Lookup(s string) *Query {
 	qc.RLock()
 	defer qc.RUnlock()
 	if q, ok := qc.m[s]; ok {
-		return &q
+		return q
 	}
 	return nil
 }