perf(tracing): simplified the dynamic hooks code

### Summary

Should be faster, but needs to be benchmarked.

Signed-off-by: Aapo Talvensaari <[email protected]>

kong-3.6.0-0.rockspec

@@ -607,6 +607,5 @@ build = {
     ["kong.timing.hooks.socket"] = "kong/timing/hooks/socket.lua",
 
     ["kong.dynamic_hook"] = "kong/dynamic_hook/init.lua",
-    ["kong.dynamic_hook.wrap_function_gen"] = "kong/dynamic_hook/wrap_function_gen.lua",
   }
 }

kong/dynamic_hook/init.lua

@@ -1,19 +1,26 @@
-local warp_function_gen = require("kong.dynamic_hook.wrap_function_gen")
-
-local ngx               = ngx
-
-local _M                = {
+local ngx = ngx
+local type = type
+local pcall = pcall
+local ipairs = ipairs
+local select = select
+local assert = assert
+local ngx_log = ngx.log
+local ngx_WARN = ngx.WARN
+local ngx_get_phase = ngx.get_phase
+
+
+local _M = {
   TYPE = {
     BEFORE = 1,
-    AFTER  = 2,
+    AFTER = 2,
     BEFORE_MUT = 3,
-    AFTER_MUT  = 4,
+    AFTER_MUT = 4,
   },
 }
 
-local pcall             = pcall
 
-local non_function_hooks = {
+
+local NON_FUNCTION_HOOKS = {
 --[[
   [group_name] = {
     [hook_name] = <function>,
@@ -23,39 +30,95 @@ local non_function_hooks = {
 --]]
 }
 
-local always_enabled_groups = {}
-
-local wrap_functions = {
-  [0] = warp_function_gen.generate_wrap_function(0),
-  [1] = warp_function_gen.generate_wrap_function(1),
-  [2] = warp_function_gen.generate_wrap_function(2),
-  [3] = warp_function_gen.generate_wrap_function(3),
-  [4] = warp_function_gen.generate_wrap_function(4),
-  [5] = warp_function_gen.generate_wrap_function(5),
-  [6] = warp_function_gen.generate_wrap_function(6),
-  [7] = warp_function_gen.generate_wrap_function(7),
-  [8] = warp_function_gen.generate_wrap_function(8),
-  ["varargs"] = warp_function_gen.generate_wrap_function("varargs"),
-}
+
+local ALWAYS_ENABLED_GROUPS = {}
+
+
+local function should_execute_original_func(group_name)
+  if ALWAYS_ENABLED_GROUPS[group_name] then
+    return
+  end
+
+  local phase = ngx_get_phase()
+  if phase == "init" or phase == "init_worker" then
+    return true
+  end
+
+  local dynamic_hook = ngx.ctx.dynamic_hook
+  if not dynamic_hook then
+    return true
+  end
+
+  local enabled_groups = dynamic_hook.enabled_groups
+  if not enabled_groups[group_name] then
+    return true
+  end
+end
+
+
+local function execute_hook(hook, hook_type, group_name, ...)
+  if not hook then
+    return
+  end  
+  local ok, err = pcall(hook, ...)
+  if not ok then
+    ngx_log(ngx_WARN, "failed to run ", hook_type, " hook of ", group_name, ": ", err)
+  end
+end
+
+
+local function execute_hooks(hooks, hook_type, group_name, ...)
+  if not hooks then
+    return
+  end
+  for _, hook in ipairs(hooks) do
+    execute_hook(hook, hook_type, group_name, ...)
+  end
+end
+
+
+local function execute_after_hooks(handlers, group_name, ...)
+  execute_hook(handlers.after_mut, "after_mut", group_name, ...)
+  execute_hooks(handlers.afters, "after", group_name, ...)
+  return ...
+end
+
+
+local function wrap_function(group_name, original_func, handlers)
+  return function (...)
+    if should_execute_original_func(group_name) then
+      return original_func(...)
+    end
+
+    if handlers.before_mut then
+      -- before_mut is not supported for varargs functions
+      local argc = select("#", ...)
+      if argc < 9 then
+        execute_hook(handlers.before_mut, "before_mut", group_name, ...)
+      end
+    end
+
+    execute_hooks(handlers.befores, "before", group_name, ...)
+    return execute_after_hooks(handlers, group_name, original_func(...))
+  end
+end
 
 
 function _M.hook_function(group_name, parent, child_key, max_args, handlers)
   assert(type(parent) == "table", "parent must be a table")
   assert(type(child_key) == "string", "child_key must be a string")
 
-  if type(max_args) == "string" then
-    assert(max_args == "varargs", "max_args must be a number or \"varargs\"")
+  if max_args == "varargs" then
     assert(handlers.before_mut == nil, "before_mut is not supported for varargs functions")
-
   else
-    assert(type(max_args) == "number", "max_args must be a number or \"varargs\"")
-    assert(max_args >= 0 and max_args <= 8, "max_args must be >= 0")
+    assert(type(max_args) == "number", 'max_args must be a number or "varargs"')
+    assert(max_args >= 0 and max_args <= 8, 'max_args must be >= 0 and <= 8, or "varargs"')
   end
 
   local old_func = parent[child_key]
   assert(type(old_func) == "function", "parent[" .. child_key .. "] must be a function")
 
-  parent[child_key] = wrap_functions[max_args](always_enabled_groups, group_name, old_func, handlers)
+  parent[child_key] = wrap_function(group_name, old_func, handlers)
 end
 
 
@@ -64,18 +127,18 @@ function _M.hook(group_name, hook_name, handler)
   assert(type(hook_name) == "string", "hook_name must be a string")
   assert(type(handler) == "function", "handler must be a function")
 
-  local hooks = non_function_hooks[group_name]
+  local hooks = NON_FUNCTION_HOOKS[group_name]
   if not hooks then
     hooks = {}
-    non_function_hooks[group_name] = hooks
+    NON_FUNCTION_HOOKS[group_name] = hooks
   end
 
   hooks[hook_name] = handler
 end
 
 
 function _M.is_group_enabled(group_name)
-  if always_enabled_groups[group_name] then
+  if ALWAYS_ENABLED_GROUPS[group_name] then
     return true
   end
 
@@ -93,12 +156,12 @@ function _M.is_group_enabled(group_name)
 end
 
 
-function _M.run_hooks(ctx, group_name, hook_name, ...)
+function _M.run_hooks(_, group_name, hook_name, ...)
   if not _M.is_group_enabled(group_name) then
     return
   end
 
-  local hooks = non_function_hooks[group_name]
+  local hooks = NON_FUNCTION_HOOKS[group_name]
   if not hooks then
     return
   end
@@ -110,28 +173,27 @@ function _M.run_hooks(ctx, group_name, hook_name, ...)
 
   local ok, err = pcall(handler, ...)
   if not ok then
-    ngx.log(ngx.WARN,
-            string.format("failed to run dynamic hook %s.%s: %s",
-                          group_name, hook_name, err))
+    ngx_log(ngx_WARN, "failed to run dynamic hook ", group_name, ".", hook_name, ": ", err)
   end
 end
 
 
-function _M.enable_on_this_request(group_name)
-  local info = ngx.ctx.dynamic_hook
-  if not info then
-    info = {
-      enabled_groups = {},
+function _M.enable_on_this_request(group_name, ngx_ctx)
+  ngx_ctx = ngx_ctx or ngx.ctx
+  if ngx_ctx.dynamic_hook then
+    ngx_ctx.dynamic_hook.enabled_groups[group_name] = true
+  else
+    ngx_ctx.dynamic_hook = {
+      enabled_groups = {
+        [group_name] = true
+      },
     }
-    ngx.ctx.dynamic_hook = info
   end
-
-  info.enabled_groups[group_name] = true
 end
 
 
 function _M.always_enable(group_name)
-  always_enabled_groups[group_name] = true
+  ALWAYS_ENABLED_GROUPS[group_name] = true
 end