Increment error metric on resty_counter errors

dist.ini

@@ -7,5 +7,5 @@ license = mit
 lib_dir = .
 doc_dir = .
 main_module = prometheus.lua
-exclude_files = prometheus_test.lua, integration, prometheus_resty_counter.update.sh
+exclude_files = prometheus_test.lua, integration
 repo_link = https://github.com/knyar/nginx-lua-prometheus

prometheus.lua

@@ -742,7 +742,7 @@ function Prometheus:init_worker(sync_interval)
   end
   self.sync_interval = sync_interval or DEFAULT_SYNC_INTERVAL
   local counter_instance, err = resty_counter_lib.new(
-      self.dict_name, self.sync_interval)
+      self.dict_name, self.sync_interval, self.error_metric_name)
   if err then
     error(err, 2)
   end

prometheus_resty_counter.lua

@@ -37,6 +37,7 @@ local function sync(_, self)
     _, err, forcible = self.dict:incr(k, v, 0)
     if forcible then
       ngx.log(ngx.ERR, "increasing counter in shdict: lru eviction: key=", k)
+      ok = false
     end
     if err then
       ngx.log(ngx.ERR, "error increasing counter in shdict key: ", k, ", err: ", err)
@@ -45,10 +46,14 @@ local function sync(_, self)
   end
 
   clear_tab(self.increments)
+  if ok == false then
+    self.dict:incr(self.error_metric_name, 1, 0)
+  end
+
   return ok
 end
 
-function _M.new(shdict_name, sync_interval)
+function _M.new(shdict_name, sync_interval, error_metric_name)
   id = ngx.worker.id()
 
   if not ngx_shared[shdict_name] then
@@ -62,6 +67,7 @@ function _M.new(shdict_name, sync_interval)
   local self = setmetatable({
     dict = ngx_shared[shdict_name],
     increments = increments[shdict_name],
+    error_metric_name = error_metric_name,
   }, mt)
 
   if sync_interval then

prometheus_test.lua

@@ -170,7 +170,7 @@ function TestPrometheus.testErrorUnknownDict()
   luaunit.assertEquals(pok, false)
   luaunit.assertStrContains(perr, "does not seem to exist")
 end
-function TestPrometheus:testErrorNoMemory()
+function TestPrometheus:testErrorNoMemoryGauge()
   local gauge3 = self.p:gauge("willnotfitk")
   self.counter1:inc(5)
   gauge3:inc(111)
@@ -181,6 +181,17 @@ function TestPrometheus:testErrorNoMemory()
   luaunit.assertEquals(self.dict:get("willnotfitk"), 111)
   luaunit.assertEquals(#ngx.logs, 1)
 end
+function TestPrometheus:testErrorNoMemoryCounter()
+  local counter = self.p:counter("willnotfitk")
+  self.counter1:inc(5)
+  counter:inc(11)
+
+  self.p._counter:sync()
+  luaunit.assertEquals(self.dict:get("metric1"), 5)
+  luaunit.assertEquals(self.dict:get("nginx_metric_errors_total"), 1)
+  luaunit.assertEquals(self.dict:get("willnotfitk"), 11)
+  luaunit.assertEquals(#ngx.logs, 1)
+end
 function TestPrometheus:testErrorInvalidMetricName()
   self.p:histogram("name with a space", "Histogram")
   self.p:gauge("nonprintable\004characters", "Gauge")