[wip] prototype of running __gc metamethod on policies

gateway/src/apicast/configuration_loader.lua

@@ -219,6 +219,8 @@ function lazy.rewrite(configuration, host)
     ngx.log(ngx.WARN, 'failed to acquire lock to lazy load: ', host, ' error: ', err)
   end
 
+  collectgarbage()
+
   return configuration
 end
 

gateway/src/apicast/policy.lua

@@ -19,7 +19,7 @@ local PHASES = {
 local setmetatable = setmetatable
 local ipairs = ipairs
 local format = string.format
-
+local empty = table.new(0,0 )
 local noop = function() end
 
 local function __tostring(policy)
@@ -30,6 +30,29 @@ local function __eq(policy, other)
     return policy._NAME == other._NAME and policy._VERSION == other._VERSION
 end
 
+local inspect = require('inspect')
+
+local function __gc(proxy)
+    local policy = getmetatable(proxy).__index -- proxy always points to the policy
+    local mt = getmetatable(policy) or empty-- in case someone changed the policy metatable
+
+    local gc = mt.__gc or noop
+
+    return gc(policy)
+end
+
+local function metatable(policy)
+    local proxy = newproxy(true)
+    local mt = getmetatable(proxy)
+
+    mt.__index = policy
+    mt.__tostring = __tostring
+    mt.__gc = __gc
+policy.proxy = proxy
+
+    return mt
+end
+
 --- Initialize new policy
 -- Returns a new policy that you can extend however you want.
 -- @tparam string name Name of the new policy.
@@ -40,7 +63,8 @@ function _M.new(name, version)
         _NAME = name,
         _VERSION = version or '0.0',
     }
-    local mt = { __index = policy, __tostring = __tostring, policy = policy }
+
+    local mt = metatable(policy)
 
     function policy.new()
         return setmetatable({}, mt)

gateway/src/apicast/policy/echo/echo.lua

@@ -10,6 +10,11 @@ local new = _M.new
 
 function _M.new(configuration)
   local policy = new(configuration)
+  local mt = getmetatable(policy)
+
+  function mt.__gc(policy)
+    ngx.log(ngx.STDERR, 'running __gc of echo policy')
+  end
 
   if configuration then
     policy.status = tonumber(configuration.status)