fix: properly compute socket usage

This partially reverts commit 4b49887.

The change was not properly implementing previous behaviour in presence
of multiple sockets reporting to the same set of attributes. Instead of
summing their usage it was reporting only the latest one.

lib/supavisor/monitoring/telem.ex

@@ -25,15 +25,15 @@ defmodule Supavisor.Monitoring.Telem do
 
   @spec network_usage(:client | :db, Supavisor.sock(), Supavisor.id(), map()) ::
           {:ok | :error, map()}
-  def network_usage(type, {mod, socket}, id, _stats) do
+  def network_usage(type, {mod, socket}, id, stats) do
     network_usage_disable do
       mod = if mod == :ssl, do: :ssl, else: :inet
 
       case mod.getstat(socket, [:recv_oct, :send_oct]) do
         {:ok, [{:recv_oct, recv_oct}, {:send_oct, send_oct}]} ->
           stats = %{
-            send_oct: send_oct,
-            recv_oct: recv_oct
+            send_oct: send_oct - stats.send_oct,
+            recv_oct: recv_oct - stats.recv_oct
           }
 
           {{ptype, tenant}, user, mode, db_name, search_path} = id
@@ -51,11 +51,11 @@ defmodule Supavisor.Monitoring.Telem do
             }
           )
 
-          {:ok, %{}}
+          {:ok, stats}
 
         {:error, reason} ->
           Logger.error("Failed to get socket stats: #{inspect(reason)}")
-          {:error, %{}}
+          {:error, stats}
       end
     end
   end

lib/supavisor/monitoring/tenant.ex

@@ -81,25 +81,19 @@ defmodule Supavisor.PromEx.Plugins.Tenant do
             peep_bucket_calculator: Buckets
           ]
         ),
-        last_value(
+        sum(
           [:supavisor, :client, :network, :recv],
           event_name: [:supavisor, :client, :network, :stat],
           measurement: :recv_oct,
           description: "The total number of bytes received by clients.",
-          tags: @tags,
-          reporter_options: [
-            prometheus_type: :sum
-          ]
+          tags: @tags
         ),
-        last_value(
+        sum(
           [:supavisor, :client, :network, :send],
           event_name: [:supavisor, :client, :network, :stat],
           measurement: :send_oct,
           description: "The total number of bytes sent by clients.",
-          tags: @tags,
-          reporter_options: [
-            prometheus_type: :sum
-          ]
+          tags: @tags
         ),
         counter(
           [:supavisor, :client, :queries, :count],