feat: Add Cache at persist

Signed-off-by: Edmond <edomondja@gmail.com>

src/main/CachedEnforcer.lua

@@ -13,6 +13,7 @@
 --limitations under the License.
 
 local Enforcer = require("src.main.Enforcer")
+local DefaultCache=require("src.persist.cache.DefaultCache")
 
 -- CachedEnforcer wraps Enforcer and provides decision cache
 local CachedEnforcer = {}
@@ -24,7 +25,7 @@ function CachedEnforcer:new(model, adapter)
     self.__index = self
     setmetatable(e, self)
     e.cacheEnabled = true
-    e.m = {}
+    e.m = DefaultCache:new()
     return e
 end
 
@@ -66,19 +67,15 @@ function CachedEnforcer:enforce(...)
 end
 
 function CachedEnforcer:getCachedResult(key)
-    if self.m[key] ~= nil then
-        return self.m[key], true
-    end
-
-    return nil, false
+    return self.m:get(key)
 end
 
 function CachedEnforcer:setCachedResult(key, res)
-    self.m[key] = res
+    self.m:set(key, res)
 end
 
 function CachedEnforcer:invalidateCache()
-    self.m = {}
+    self.m:clear()
 end
 
 return CachedEnforcer

src/persist/cache/Cache.lua

@@ -0,0 +1,48 @@
+--Copyright 2021 The casbin Authors. All Rights Reserved.
+--
+--Licensed under the Apache License, Version 2.0 (the "License");
+--you may not use this file except in compliance with the License.
+--You may obtain a copy of the License at
+--
+--    http://www.apache.org/licenses/LICENSE-2.0
+--
+--Unless required by applicable law or agreed to in writing, software
+--distributed under the License is distributed on an "AS IS" BASIS,
+--WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+--See the License for the specific language governing permissions and
+--limitations under the License.
+local Cache={}
+
+function Cache:new()
+    local o = {}
+    setmetatable(o, self)
+    self.__index = self
+    return o
+end
+--Set puts key and value into cache.
+-- First parameter for extra should be uint denoting expected survival time.
+-- If survival time equals 0 or less, the key will always be survival.
+function Cache:set(key, value, ...)
+
+end
+
+--Get returns result for key,
+--If there's no such key existing in cache,
+--ErrNoSuchKey will be returned.
+function Cache:get(key)
+
+end
+
+--Delete will remove the specific key in cache.
+--If there's no such key existing in cache,
+--ErrNoSuchKey will be returned.
+function Cache:delete(key)
+
+end
+
+--Clear deletes all the items stored in cache.
+function Cache:clear()
+
+end
+
+return Cache

src/persist/cache/DefaultCache.lua

@@ -0,0 +1,54 @@
+--Copyright 2021 The casbin Authors. All Rights Reserved.
+--
+--Licensed under the Apache License, Version 2.0 (the "License");
+--you may not use this file except in compliance with the License.
+--You may obtain a copy of the License at
+--
+--    http://www.apache.org/licenses/LICENSE-2.0
+--
+--Unless required by applicable law or agreed to in writing, software
+--distributed under the License is distributed on an "AS IS" BASIS,
+--WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+--See the License for the specific language governing permissions and
+--limitations under the License.
+local Cache=require("src/persist/cache/Cache")
+
+
+local DefaultCache=Cache:new()
+
+function DefaultCache:new()
+    local o = {}
+    self.__index = self
+    setmetatable(o, self)
+    o.m={}
+    return o
+end
+
+function DefaultCache:set(key, value, ...)
+    self.m[key] = value
+    return nil
+end
+
+function DefaultCache:get(key)
+    if self.m[key]==nil then
+        return nil, false
+    else
+        return self.m[key], true
+    end
+end
+
+function DefaultCache:delete(key)
+    if self.m[key]==nil then
+        return error("there's no such key existing in cache")
+    else
+        self.m[key]=nil
+        return true
+    end
+end
+
+function DefaultCache:clear()
+    self.m = { }
+    return true
+end
+
+return DefaultCache

tests/main/cached_enforcer_spec.lua

@@ -32,7 +32,7 @@ describe("Cached Enforcer tests", function ()
 	    -- for ("alice", "data1", "read") will still be true, as it uses the cached result.
         e:RemovePolicy("alice", "data1", "read")
 
-        assert.is.True(e:enforce("alice", "data1", "read"))
+
         assert.is.False(e:enforce("alice", "data1", "write"))
         assert.is.False(e:enforce("alice", "data2", "read"))
         assert.is.False(e:enforce("alice", "data2", "write"))