Add Keys function

Keys() method added for listing stored keys in database. Usage added in README and pkg/main.go.

Signed-off-by: Gökhan Özeloğlu <gozeloglu@gmail.com>

README.md

@@ -104,7 +104,12 @@ func main() {
 		log.Fatalf(err.Error())
 	}
 	fmt.Printf("key name changed: %v1\n", ok)
-
+
+	keys := db.Keys()
+	for _, k := range keys {
+		fmt.Println(k)
+	}
+
 	err = db.Close() // Call while closing the database.
 	if err != nil {
 		log.Fatalf(err.Error())

example/pkg/main.go

@@ -51,6 +51,11 @@ func main() {
 	}
 	fmt.Printf("key name changed: %v1\n", ok)
 
+	keys := db.Keys()
+	for _, k := range keys {
+		fmt.Println(k)
+	}
+
 	err = db.Close()
 	if err != nil {
 		log.Fatalf(err.Error())

keys.go

@@ -0,0 +1,14 @@
+package kvs
+
+// Keys list the stored keys in a slice. If db is empty, empty slice is returned.
+func (k *Kvs) Keys() []string {
+	k.mu.Lock()
+	defer k.mu.Unlock()
+	var keys []string
+
+	for key := range k.kv {
+		keys = append(keys, key)
+	}
+
+	return keys
+}

keys_test.go

@@ -0,0 +1,69 @@
+package kvs
+
+import (
+	"os"
+	"testing"
+	"time"
+)
+
+func TestKvs_Keys(t *testing.T) {
+	db, err := open(t.Name(), "", 2*time.Minute)
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+	t.Logf("db created.")
+
+	pairs := []string{"foo", "1", "bar", "2", "fizz", "3", "buzz", "4"}
+	for i := 0; i < len(pairs); i += 2 {
+		db.Set(pairs[i], pairs[i+1])
+	}
+	t.Logf("key-value pairs are set.")
+
+	keys := db.Keys()
+	if len(keys) != len(pairs)/2 {
+		t.Errorf("Fetched keys are wrong. pairs len is %d, "+
+			"fetched len is %d.", len(pairs)/2, len(keys))
+	}
+	for _, k := range keys {
+		t.Logf(k)
+	}
+
+	err = db.Close()
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+	t.Logf("db closed.")
+
+	err = os.RemoveAll(db.dir)
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+	t.Logf("temp db removed.")
+}
+
+func TestKvs_EmptyKeys(t *testing.T) {
+	db, err := open(t.Name(), "", 2*time.Minute)
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+	t.Logf("db created.")
+
+	keys := db.Keys()
+	if len(keys) != 0 {
+		t.Errorf("Fetched keys are wrong. pairs len is %d, "+
+			"fetched len is %d.", 0, len(keys))
+	}
+	t.Logf("Empty slice: %d", len(keys))
+
+	err = db.Close()
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+	t.Logf("db closed.")
+
+	err = os.RemoveAll(db.dir)
+	if err != nil {
+		t.Fatalf(err.Error())
+	}
+	t.Logf("temp db removed.")
+}