Add caching

.gitignore

@@ -1,2 +1,3 @@
 .vscode
 /assets/
+.cache/

cache.go

@@ -0,0 +1,76 @@
+package manifest
+
+import (
+	"encoding/gob"
+	"fmt"
+	"os"
+
+	"github.com/patrickmn/go-cache"
+)
+
+var (
+	versionCache *cache.Cache
+)
+
+func init() {
+	gob.Register(&Version{})
+
+	finfo, _ := os.Stat(".cache/versions")
+	if finfo == nil {
+		versionCache = cache.New(cache.NoExpiration, cache.NoExpiration)
+		return
+	}
+	f, err := os.Open(".cache/versions")
+	if err != nil {
+		fmt.Printf("Failed to open cache file: %+v\n", err.(*os.PathError))
+		return
+	}
+	defer f.Close()
+
+	items := make(map[string]cache.Item)
+	err = gob.NewDecoder(f).Decode(&items)
+	if err != nil {
+		fmt.Printf("Failed to decode cache file: %+v\n", err.(*os.PathError))
+		return
+	}
+	versionCache = cache.NewFrom(cache.NoExpiration, cache.NoExpiration, items)
+	fmt.Printf("Loaded cache from .cache/versions (%d items)\n", versionCache.ItemCount())
+}
+
+// SaveCache saves the cache to the .cache folder
+func SaveCache() {
+	versionCache.DeleteExpired()
+	finfo, _ := os.Stat(".cache")
+	var err error
+	if finfo == nil {
+		err = os.Mkdir(".cache", 0755)
+		if err != nil {
+			fmt.Printf("Failed to create cache directory: %+v\n", err.(*os.PathError))
+			return
+		}
+	}
+
+	finfo, _ = os.Stat(".cache/versions")
+	var f *os.File
+	if finfo == nil {
+		f, err = os.Create(".cache/versions")
+		if err != nil {
+			fmt.Printf("Failed to create cache file: %+v\n", err.(*os.PathError))
+			return
+		}
+	} else {
+		f, err = os.OpenFile(".cache/versions", os.O_TRUNC|os.O_WRONLY, 0644)
+		if err != nil {
+			fmt.Printf("Failed to create cache file: %+v\n", err.(*os.PathError))
+			return
+		}
+	}
+	defer f.Close()
+
+	err = gob.NewEncoder(f).Encode(versionCache.Items())
+	if err != nil {
+		fmt.Printf("Failed to save cache: %+v\n", err)
+		return
+	}
+	fmt.Printf("Saved cache to .cache/versions (%d items)\n", versionCache.ItemCount())
+}

examples/with_cache/main.go

@@ -0,0 +1,23 @@
+package main
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/Kesuaheli/go-manifest"
+)
+
+func main() {
+	// make sure the cache will be saved as files on exit
+	defer manifest.SaveCache()
+
+	for range make([]int, 5) {
+		now := time.Now()
+		_, err := manifest.GetVersion("1.7.10")
+		if err != nil {
+			panic(err)
+		}
+		fmt.Printf("Got version in %s\n", time.Since(now))
+		time.Sleep(2 * time.Second)
+	}
+}

go.mod

@@ -1,3 +1,5 @@
 module github.com/Kesuaheli/go-manifest
 
 go 1.23.1
+
+require github.com/patrickmn/go-cache v2.1.0+incompatible

go.sum

@@ -0,0 +1,2 @@
+github.com/patrickmn/go-cache v2.1.0+incompatible h1:HRMgzkcYKYpi3C8ajMPV8OFXaaRUnok+kx1WdO15EQc=
+github.com/patrickmn/go-cache v2.1.0+incompatible/go.mod h1:3Qf8kWWT7OJRJbdiICTKqZju1ZixQ/KpMGzzAfe6+WQ=

go_manifest.go

@@ -42,6 +42,10 @@ func GetManifest() (manifest *Manifest, err error) {
 //
 // v can be any version id like "1.7.10" or "24w10a" or even "a1.0.4".
 func GetVersion(v string) (version *Version, err error) {
+	if cachedVersion, ok := versionCache.Get(v); ok {
+		return cachedVersion.(*Version), nil
+	}
+
 	manifest, err := GetManifest()
 	if err != nil {
 		return &Version{}, fmt.Errorf("get version: %w", err)
@@ -61,6 +65,8 @@ func GetVersion(v string) (version *Version, err error) {
 	if err != nil {
 		err = fmt.Errorf("get version: failed to decode body: %w", err)
 	}
+
+	versionCache.SetDefault(v, version)
 	return version, err
 }