3 files changed, 37 insertions, 8 deletions
diff --git a/skate/schema.go b/skate/schema.go
index baead09..dea3509 100644
--- a/skate/schema.go
+++ b/skate/schema.go
@@ -5,6 +5,7 @@ import (
 	"regexp"
 	"strconv"
 	"strings"
+	"sync"
 
 	"git.archive.org/martin/cgraph/skate/isbn"
 	"git.archive.org/martin/cgraph/skate/set"
@@ -14,6 +15,16 @@ var (
 	isbn10Regex = regexp.MustCompile(`[O0-9xX -]{10,18}`)
 	isbn13Regex = regexp.MustCompile(`9[O0-9xX -]{12,20}`)
 
+	rune16pool = sync.Pool{
+		New: func() interface{} {
+			return make([]rune, 0, 16)
+		},
+	}
+	setPool = sync.Pool{
+		New: func() interface{} {
+			return set.New()
+		},
+	}
 )
 
 // RefToRelease converts a ref to a release. Set a extra.skate.status flag to
@@ -66,27 +77,36 @@ func parseIsbn(s string) []string {
 	var (
 		candidates10 = isbn10Regex.FindAllString(s, -1)
 		candidates13 = isbn13Regex.FindAllString(s, -1)
-		valid        = set.New()
+		u            []rune
+		z            string
 	)
+	valid := setPool.Get().(*set.Set)
+	valid.Clear()
+	defer setPool.Put(valid)
 	for _, v := range append(candidates10, candidates13...) {
-		var u []rune
+		u = rune16pool.Get().([]rune)
+		u = u[:0]
 		for _, c := range v {
+			if c == 'O' {
+				c = '0'
+			}
 			if c >= '0' && c <= '9' || c == 'x' || c == 'X' {
 				u = append(u, c)
 			}
 		}
-		s := string(u)
-		if !isbn.Validate(s) {
+		z = string(u)
+		rune16pool.Put(u)
+		if !isbn.Validate(z) {
 			continue
 		}
-		if len(s) < 12 {
-			w, err := isbn.To13(s)
+		if len(z) < 12 {
+			w, err := isbn.To13(z)
 			if err != nil {
 				continue
 			}
 			valid.Add(w)
 		} else {
-			valid.Add(s)
+			valid.Add(z)
 		}
 	}
 	return valid.Slice()
diff --git a/skate/set/set.go b/skate/set/set.go
index a198094..6bad47e 100644
--- a/skate/set/set.go
+++ b/skate/set/set.go
@@ -5,9 +5,15 @@ import (
 	"strings"
 )
 
-// Set implements basic string set operations.
+// Set implements basic string set operations, not thread-safe.
 type Set map[string]struct{}
 
+func (s *Set) Clear() {
+	for k := range *s {
+		delete(*s, k)
+	}
+}
+
 // Add adds an element.
 func (s *Set) Add(v string) *Set {
 	(*s)[v] = struct{}{}
diff --git a/skate/set/set_test.go b/skate/set/set_test.go
index c319759..403b6df 100644
--- a/skate/set/set_test.go
+++ b/skate/set/set_test.go
@@ -36,4 +36,7 @@ func TestSet(t *testing.T) {
 	top.Add("2")
 	top.Add("3")
 	is.Equal(r.TopK(2), &top)
+
+	r.Clear()
+	is.Equal(r.Len(), 0)
 }