perf: avoid #path

src/resty/trie.lua

@@ -185,7 +185,7 @@ function TrieNode:traverse(path, ctx)
   local node = self
   local prefix
   local prefix_n
-  local path_n
+  local path_n = #path
   local idx
 
 
@@ -194,14 +194,15 @@ function TrieNode:traverse(path, ctx)
 
     -- 到这里的 node 节点都是 static
     if node.type == TYPES.PARAM then
-      local i = find(path, "/", 1, true) or #path + 1 -- todo 写一个 while 来实现
+      local i = find(path, "/", 1, true) or path_n + 1 -- todo 写一个 while 来实现
       i = i - 1
       if binding_params then
         -- todo 参数绑定
       end
-      if i < #path then -- 还没到终点
+      if i < path_n then -- 还没到终点
         if node.children_n > 0 then
           path = str_sub(path, i + 1)
+          path_n = path_n - i
           local first_char = str_sub(path, 1, 1)
           idx = node.indexs[first_char]
           if idx then
@@ -224,17 +225,17 @@ function TrieNode:traverse(path, ctx)
 
     prefix = node.path
     prefix_n = node.path_n
-    path_n = #path -- path_n 有没有可能可以通过游标去减，而不是每次都 #path?
 
     if path_n > prefix_n then
       if starts_with(path, prefix, path_n, prefix_n) then
         path = str_sub(path, prefix_n + 1)
+        path_n = path_n - prefix_n
 
         idx = node.indexs["*"]
         if idx then
           -- 如果子节点中有 catchall 类型，说明 child 节点是能匹配的
           matched_n = matched_n + 1
-          matched_values[matched_n] = node.children[idx].value -- todo 既然这里已经选中了，为什么不做参数绑定呢？
+          matched_values[matched_n] = node.children[idx].value
           if binding_params then
             param_n = param_n + 1
             ctx.matched[param_n] = path
@@ -270,16 +271,17 @@ function TrieNode:traverse(path, ctx)
         idx = node.indexs[":"]
         if idx then
           node = node.children[idx]
-          local i = find(path, "/", 1, true) or #path + 1 -- todo 写一个 while 来实现
+          local i = find(path, "/", 1, false) or path_n + 1 -- 为啥写 while 性能比 find 还慢?
           i = i - 1
           if binding_params then
             local param_value = str_sub(path, 1, i)
             param_n = param_n + 1
             ctx.matched[param_n] = param_value
           end
-          if i < #path then -- 还没到终点
+          if i < path_n then -- 还没到终点
             if node.children_n > 0 then
               path = str_sub(path, i + 1)
+              path_n = path_n - i
               first_char = str_sub(path, 1, 1)
               idx = node.indexs[first_char]
               if idx then
@@ -322,6 +324,7 @@ function TrieNode:traverse(path, ctx)
     if branchs_n > 0 then
       node = branchs[branchs_n]
       path = paths[branchs_n]
+      path_n = #path
       branchs[branchs_n] = nil
       paths[branchs_n] = nil
       branchs_n = branchs_n - 1