modify the capability format to be list instead of set for more

efficient transmission

kong/clustering/rpc/callbacks.lua

@@ -3,16 +3,20 @@ local _MT = { __index = _M, }
 
 
 local utils = require("kong.clustering.rpc.utils")
+local pl_tablex = require("pl.tablex")
 
 
 local pairs = pairs
 local parse_method_name = utils.parse_method_name
 local unpack = table.unpack
+local pl_tablex_keys = pl_tablex.keys
 
 
 function _M.new()
   local self = {
     callbacks = {},
+    capabilities = {}, -- updated as register() is called
+    capabilities_list = {}, -- updated as register() is called
   }
 
   return setmetatable(self, _MT)
@@ -24,23 +28,21 @@ function _M:register(method, func)
     error("duplicate registration of " .. method)
   end
 
+  local cap, func_or_err = parse_method_name(method)
+  if not cap then
+    return nil, "unable to get capabilities: " .. func_or_err
+  end
+
+  self.capabilities[cap] = true
+  self.capabilities_list = pl_tablex_keys(self.capabilities)
   self.callbacks[method] = func
 end
 
 
-function _M:get_capabilities()
-  local capabilities = {}
-
-  for m in pairs(self.callbacks) do
-    local cap, func_or_err = parse_method_name(m)
-    if not cap then
-      return nil, "unable to get capabilities: " .. func_or_err
-    end
-
-    capabilities[cap] = true
-  end
-
-  return capabilities
+-- returns a list of capabilities of this node, like:
+-- ["kong.meta.v1", "kong.debug.v1", ...]
+function _M:get_capabilities_list()
+  return self.capabilities_list
 end
 
 

kong/clustering/rpc/manager.lua

@@ -11,13 +11,15 @@ local callbacks = require("kong.clustering.rpc.callbacks")
 local queue = require("kong.clustering.rpc.queue")
 local constants = require("kong.constants")
 local table_isempty = require("table.isempty")
+local pl_tablex = require("pl.tablex")
 
 
 local ngx_var = ngx.var
 local ngx_ERR = ngx.ERR
 local ngx_log = ngx.log
 local ngx_exit = ngx.exit
 local exiting = ngx.worker.exiting
+local pl_tablex_makeset = pl_tablex.makeset
 
 
 local WS_OPTS = {
@@ -40,9 +42,9 @@ function _M.new(conf, node_id)
   }
 
   self.callbacks:register("kong.meta.v1.capability_advertisement", function(node_id, capabilities)
-    self.client_capabilities[node_id] = capabilities
+    self.client_capabilities[node_id] = { set = pl_tablex_makeset(capabilities), list = capabilities, }
 
-    return self.callbacks:get_capabilities()
+    return self.callbacks:get_capabilities_list()
   end)
 
   return setmetatable(self, _MT)
@@ -81,7 +83,7 @@ function _M:call(node_id, method, ...)
     return nil, "node is not connected, node_id: " .. node_id
   end
 
-  if not self.client_capabilities[node_id][cap] then
+  if not self.client_capabilities[node_id].set[cap] then
     return nil, "requested capability does not exist, capability: " ..
                 cap .. ", node_id: " .. node_id
   end
@@ -190,7 +192,7 @@ function _M:connect(premature, node_id, host, path, cert, key)
     assert(s:start())
 
     -- capability advertisement
-    local fut = future.new(s, "kong.meta.v1.capability_advertisement", { self.callbacks:get_capabilities(), })
+    local fut = future.new(s, "kong.meta.v1.capability_advertisement", { self.callbacks:get_capabilities_list(), })
     assert(fut:start())
 
     ok, err = fut:wait(5)
@@ -200,7 +202,8 @@ function _M:connect(premature, node_id, host, path, cert, key)
       goto err
     end
 
-    self.client_capabilities[node_id] = fut.result
+    self.client_capabilities[node_id] = { list = fut.result,
+                                          set = pl_tablex_makeset(fut.result), }
 
     self:_add_socket(s)
 
@@ -225,7 +228,13 @@ end
 
 
 function _M:get_peers()
-  return self.client_capabilities
+  local res = {}
+
+  for node_id, cap in pairs(self.client_capabilities) do
+    res[node_id] = cap.list
+  end
+
+  return res
 end