refactor(dns): implement mlcache:get callback

kong/globalpatches.lua

@@ -252,10 +252,10 @@ return function(options)
       -- See https://github.com/openresty/resty-cli/pull/12
       -- for a definitive solution of using shms in CLI
       local SharedDict = {}
-      local function set(data, key, value, expire_at)
+      local function set(data, key, value, expire_at, flags)
         data[key] = {
           value = value,
-          info = {expire_at = expire_at}
+          info = {expire_at = expire_at, flags=flags}
         }
       end
       function SharedDict:new()
@@ -268,20 +268,34 @@ return function(options)
         return 0
       end
       function SharedDict:get(key)
-        return self.data[key] and self.data[key].value, nil
+        local v = self.data[key]
+        if v and not v.info.expired then
+          return v.value, v.info.flags
+        end
+
+        return nil
       end
-      SharedDict.get_stale = SharedDict.get
-      function SharedDict:set(key, value, exptime)
+      function SharedDict:get_stale(key)
+        local v = self.data[key]
+        if v then
+          return v.value, v.info.flags, v.info.expired
+        end
+        return nil
+      end
+      function SharedDict:set(key, value, exptime, flags)
         local expire_at = nil
 
         if exptime then
           ngx.timer.at(exptime, function()
-            self.data[key] = nil
+            local v = self.data[key]
+            if v then
+              v.info.expired = true
+            end
           end)
           expire_at = ngx.now() + exptime
         end
 
-        set(self.data, key, value, expire_at)
+        set(self.data, key, value, expire_at, flags)
         return true, nil, false
       end
       SharedDict.safe_set = SharedDict.set
@@ -369,11 +383,10 @@ return function(options)
             return 0
           else
             local remaining = expire_at - ngx.now()
-            if remaining < 0 then
+            if remaining == 0 then
               return nil, "not found"
-            else
-              return remaining
             end
+            return remaining
           end
         end
       end