[sandbox] sandbox cache

Loading policy multiple times returns the same instance.

gateway/src/apicast/policy_loader.lua

@@ -131,11 +131,17 @@ function _M:load_path(name, version, paths)
   return nil, nil, failures
 end
 
+local package_cache = setmetatable({}, {
+  __index = function(t, k) local n = { }; t[k] = n; return n end
+})
+
 function _M:call(name, version, dir)
   local v = version or 'builtin'
   local load_path, policy_config_schema, invalid_paths = self:load_path(name, v, dir)
 
-  local loader = sandbox.new(load_path and { load_path } or invalid_paths)
+  local cache = package_cache[table.concat({name, v, dir}, '-')]
+  local loader = sandbox.new(load_path and { load_path } or invalid_paths,
+          cache)
 
   ngx.log(ngx.DEBUG, 'loading policy: ', name, ' version: ', v)
 

gateway/src/resty/sandbox.lua

@@ -87,7 +87,7 @@ local function gen_require(package)
     -- to determine whether modname is already loaded.
     -- NOTE: this is different from the spec: use the top level package.loaded,
     --       otherwise it would try to sandbox load already loaded shared code
-    local mod = root_loaded[modname]
+    local mod = root_loaded[modname] or package.loaded[modname]
 
     --  If it is, then require returns the value stored at package.loaded[modname].
     if mod then return mod end
@@ -211,10 +211,10 @@ local mt = {
 
 local empty_t = {}
 
-function _M.new(load_paths)
+function _M.new(load_paths, cache)
   -- need to create global variable package that mimics the native one
   local package = {
-    loaded = {},
+    loaded = cache or {},
     preload = preload,
     searchers = {}, -- http://www.lua.org/manual/5.2/manual.html#pdf-package.searchers
     searchpath = searchpath,

spec/policy_loader_spec.lua

@@ -38,7 +38,7 @@ describe('APIcast Policy Loader', function()
       assert.are_not.same(test, test2)
 
       assert.are.same(test.dependency, test2.dependency)
-      assert.are_not.equal(test.dependency, test2.dependency)
+      assert.are.equal(test.dependency, test2.dependency)
     end)
 
     it('loads two versions of the same policy', function()