Add caching results of API calls

app.go

@@ -5,6 +5,7 @@ import (
 	"crypto/sha1"
 	"errors"
 	"fmt"
+	"log"
 	"net/http"
 	"net/url"
 	"sort"
@@ -14,6 +15,7 @@ import (
 
 	"golang.org/x/net/context"
 
+	"github.com/Luzifer/badge-gen/cache"
 	"github.com/Luzifer/rconfig"
 	"github.com/gorilla/mux"
 	"github.com/tdewolff/minify"
@@ -29,9 +31,11 @@ var (
 	cfg = struct {
 		Port   int64  `env:"PORT"`
 		Listen string `flag:"listen" default:":3000" description:"Port/IP to listen on"`
+		Cache  string `flag:"cache" default:"mem://" description:"Where to cache query results from thirdparty APIs"`
 	}{}
 	serviceHandlers = map[string]serviceHandler{}
 	version         = "dev"
+	cacheStore      cache.Cache
 )
 
 type serviceHandlerDocumentation struct {
@@ -72,6 +76,12 @@ func main() {
 		cfg.Listen = fmt.Sprintf(":%d", cfg.Port)
 	}
 
+	var err error
+	cacheStore, err = cache.GetCacheByURI(cfg.Cache)
+	if err != nil {
+		log.Fatalf("Unable to open cache: %s", err)
+	}
+
 	r := mux.NewRouter()
 	r.HandleFunc("/v1/badge", generateBadge).Methods("GET")
 	r.HandleFunc("/{service}/{parameters:.*}", generateServiceBadge).Methods("GET")

cache/cache.go

@@ -0,0 +1,33 @@
+package cache
+
+import (
+	"errors"
+	"net/url"
+	"time"
+)
+
+type KeyNotFoundError struct{}
+
+func (k KeyNotFoundError) Error() string {
+	return "Requested key was not found in database"
+}
+
+type Cache interface {
+	Get(namespace, key string) (value string, err error)
+	Set(namespace, key, value string, ttl time.Duration) (err error)
+	Delete(namespace, key string) (err error)
+}
+
+func GetCacheByURI(uri string) (Cache, error) {
+	url, err := url.Parse(uri)
+	if err != nil {
+		return nil, err
+	}
+
+	switch url.Scheme {
+	case "mem":
+		return NewInMemCache(), nil
+	default:
+		return nil, errors.New("Invalid cache scheme: " + url.Scheme)
+	}
+}

cache/inMemCache.go

@@ -0,0 +1,53 @@
+package cache
+
+import (
+	"sync"
+	"time"
+)
+
+type inMemCacheEntry struct {
+	Value   string
+	Expires time.Time
+}
+
+type InMemCache struct {
+	cache map[string]inMemCacheEntry
+	lock  sync.RWMutex
+}
+
+func NewInMemCache() *InMemCache {
+	return &InMemCache{
+		cache: map[string]inMemCacheEntry{},
+	}
+}
+
+func (i InMemCache) Get(namespace, key string) (value string, err error) {
+	i.lock.RLock()
+	defer i.lock.RUnlock()
+
+	e, ok := i.cache[namespace+"::"+key]
+	if !ok || e.Expires.Before(time.Now()) {
+		return "", KeyNotFoundError{}
+	}
+	return e.Value, nil
+}
+
+func (i InMemCache) Set(namespace, key, value string, ttl time.Duration) (err error) {
+	i.lock.Lock()
+	defer i.lock.Unlock()
+
+	i.cache[namespace+"::"+key] = inMemCacheEntry{
+		Value:   value,
+		Expires: time.Now().Add(ttl),
+	}
+
+	return nil
+}
+
+func (i InMemCache) Delete(namespace, key string) (err error) {
+	i.lock.Lock()
+	defer i.lock.Unlock()
+
+	delete(i.cache, namespace+"::"+key)
+	return nil
+}

service_github.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"net/http"
 	"strings"
+	"time"
 
 	"golang.org/x/net/context"
 	"golang.org/x/net/context/ctxhttp"
@@ -45,6 +46,9 @@ func (g githubServiceHandler) Handle(ctx context.Context, params []string) (titl
 func (g githubServiceHandler) handleLicense(ctx context.Context, params []string) (title, text, color string, err error) {
 	path := strings.Join([]string{"repos", params[0], params[1], "license"}, "/")
 
+	text, err = cacheStore.Get("github_license", path)
+
+	if err != nil {
 		req, _ := http.NewRequest("GET", "https://api.github.com/"+path, nil)
 		req.Header.Set("Accept", "application/vnd.github.drax-preview+json")
 
@@ -64,8 +68,11 @@ func (g githubServiceHandler) handleLicense(ctx context.Context, params []string
 			return
 		}
 
-	title = "license"
 		text = r.License.Name
+		cacheStore.Set("github_license", path, text, 10*time.Minute)
+	}
+
+	title = "license"
 	color = "007ec6"
 
 	if text == "" {

service_travis.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"net/http"
 	"strings"
+	"time"
 
 	"golang.org/x/net/context"
 	"golang.org/x/net/context/ctxhttp"
@@ -36,6 +37,10 @@ func (t travisServiceHandler) Handle(ctx context.Context, params []string) (titl
 
 	path := strings.Join([]string{"repos", params[0], params[1], "branches", params[2]}, "/")
 
+	var state string
+	state, err = cacheStore.Get("travis", path)
+
+	if err != nil {
 		var resp *http.Response
 		resp, err = ctxhttp.Get(ctx, http.DefaultClient, "https://api.travis-ci.org/"+path)
 		if err != nil {
@@ -53,9 +58,12 @@ func (t travisServiceHandler) Handle(ctx context.Context, params []string) (titl
 		if err = json.NewDecoder(resp.Body).Decode(&r); err != nil {
 			return
 		}
+		state = r.Branch.State
+		cacheStore.Set("travis", path, state, 5*time.Minute)
+	}
 
 	title = "travis"
-	text = r.Branch.State
+	text = state
 	if text == "" {
 		text = "unknown"
 	}