fix(prometheus): reduce expensive gsub call, and table.insert NYI

Kong · Jun 2, 2023 · d062459 · d062459
1 parent d5d49e2
commit d062459
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Showing 2 changed files with 16 additions and 7 deletions.
diff --git a/kong/plugins/prometheus/exporter.lua b/kong/plugins/prometheus/exporter.lua
@@ -6,6 +6,8 @@ local concat = table.concat
 local ngx_timer_pending_count = ngx.timer.pending_count
 local ngx_timer_running_count = ngx.timer.running_count
 local balancer = require("kong.runloop.balancer")
+local yield = require("kong.tools.utils").yield
+
 local get_all_upstreams = balancer.get_all_upstreams
 if not balancer.get_all_upstreams then -- API changed since after Kong 2.5
   get_all_upstreams = require("kong.runloop.balancer.upstreams").get_all_upstreams
@@ -457,6 +459,7 @@ local function metric_data(write_fn)
     -- upstream targets accessible?
     local upstreams_dict = get_all_upstreams()
     for key, upstream_id in pairs(upstreams_dict) do
+      yield()
       local _, upstream_name = key:match("^([^:]*):(.-)$")
       upstream_name = upstream_name and upstream_name or key
       -- based on logic from kong.db.dao.targets

diff --git a/kong/plugins/prometheus/prometheus.lua b/kong/plugins/prometheus/prometheus.lua
@@ -69,6 +69,7 @@ local tonumber = tonumber
 local st_format = string.format
 local table_sort = table.sort
 local tb_clear = require("table.clear")
+local tb_new = require("table.new")
 local yield = require("kong.tools.utils").yield
 
 
@@ -176,24 +177,29 @@ local function full_metric_name(name, label_names, label_values)
   if not label_names then
     return name
   end
-  local label_parts = {}
+  local label_parts = tb_new(#label_names, 0)
+  local label_value
   for idx, key in ipairs(label_names) do
-    local label_value
     if type(label_values[idx]) == "string" then
       local valid, pos = validate_utf8_string(label_values[idx])
       if not valid then
         label_value = string.sub(label_values[idx], 1, pos - 1)
-                        :gsub("\\", "\\\\")
-                        :gsub('"', '\\"')
       else
         label_value = label_values[idx]
-                        :gsub("\\", "\\\\")
-                        :gsub('"', '\\"')
       end
     else
       label_value = tostring(label_values[idx])
     end
-    table.insert(label_parts, key .. '="' .. label_value .. '"')
+
+    if string.find(label_value, "\\") then
+      label_value = ngx.re.gsub(label_value, "\\", "\\\\", "j")
+    end
+
+    if string.find(label_value, '"') then
+      label_value = ngx.re.gsub(label_value, '"', '\\"', "j")
+    end
+
+    label_parts[idx] = table.concat({key, '="', label_value, '"'})
   end
   return name .. "{" .. table.concat(label_parts, ",") .. "}"
 end