feat(cache): add redis cache with lookup, persist and deactivate feature

cache/redis.go

@@ -0,0 +1,99 @@
+package cache
+
+import (
+    "log"
+    "net/http"
+    "os"
+    "sync"
+
+    "github.com/adhocore/urlsh/model"
+    "github.com/gomodule/redigo/redis"
+)
+
+var once sync.Once
+var conn redis.Conn
+var prefix = "url:"
+
+func connect() redis.Conn {
+    cacheHost := os.Getenv("APP_CACHE_HOST")
+    if cacheHost == "" {
+        return  nil
+    }
+
+    c, err := redis.Dial("tcp", cacheHost)
+    if err != nil {
+        log.Printf("%v", err)
+        return nil
+    }
+
+    return c
+}
+
+func Connection() redis.Conn {
+    once.Do(func() {
+        conn = connect()
+    })
+
+    return conn
+}
+
+func LookupURL(shortCode string) (model.URL, int) {
+    var urlModel model.URL
+    if nil == Connection() {
+        return urlModel, 0
+    }
+
+    line, err := conn.Do("GET", urlKey(model.URL{ShortCode: shortCode}))
+    if err != nil || line == nil {
+        return urlModel, 0
+    }
+
+    data := string(line.([]uint8))
+
+    // 0 = Inactive, 1 = Active
+    if data[0:1] == "0" {
+        return urlModel, http.StatusGone
+    }
+
+    urlModel.OriginURL = data[1:]
+    urlModel.ShortCode = shortCode
+
+    return urlModel, http.StatusFound
+}
+
+func DeactivateUrl(urlModel model.URL) {
+    cacheModel, status := LookupURL(urlModel.ShortCode)
+    if status == 0 {
+        return
+    }
+
+    urlModel.OriginURL = cacheModel.OriginURL
+    SavePopularUrl(urlModel, true)
+}
+
+func SavePopularUrl(urlModel model.URL, force bool) {
+    if nil == Connection() || (!force && hasUrl(urlModel)) {
+        return
+    }
+
+    _, _ = conn.Do("SET", urlKey(urlModel), urlValue(urlModel))
+}
+
+func hasUrl(urlModel model.URL) bool {
+    exist, err := conn.Do("EXISTS", urlKey(urlModel))
+
+    return err == nil && exist.(int64) > 0
+}
+
+func urlKey(urlModel model.URL) string {
+    return prefix + urlModel.ShortCode
+}
+
+func urlValue(urlModel model.URL) string {
+    active := "0"
+    if urlModel.IsActive() {
+        active = "1"
+    }
+
+    return active + urlModel.OriginURL
+}