Computes CPU states every 5 seconds in the system interface

attic/scripts/lua/plugins/cpu_states_monitor/manifest.lua

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+--
+-- (C) 2019-20 - ntop.org
+--
+
+return {
+  title = "CPU States Monitor",
+  description = "Monitors the various states of the CPU (e.g., user, system and iowait)",
+  author = "ntop",
+  dependencies = {},
+}

attic/scripts/lua/plugins/cpu_states_monitor/user_scripts/system/cpu_states_monitor.lua

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+--
+-- (C) 2019-20 - ntop.org
+--
+
+local ts_utils = require("ts_utils_core")
+local user_scripts = require("user_scripts")
+local ts_utils = require("ts_utils_core")
+local alerts_api = require("alerts_api")
+local json = require "dkjson"
+
+local STATES_KEY = "ntopng.cache.cpu_states_monitor.last"
+
+local script = {
+  -- Script category
+  category = user_scripts.script_categories.system,
+
+  -- This module is enabled by default
+  default_enabled = not ntop.isWindows(),
+
+  -- No default configuration is provided
+  default_value = {},
+
+  -- See below
+  hooks = {},
+
+  gui = {
+    i18n_title = "system_stats.cpu_states_monitor",
+    i18n_description = "system_stats.cpu_states_monitor_description",
+  },
+}
+
+-- ##############################################
+
+-- Computes the CPU states in percentage
+function script.hooks.min(params)
+   if not ntop.isWindows() then
+      local f = io.open("/proc/stat", "r")
+      local res
+
+      if f then
+         -- The first line of the file contains cpu jiffies
+         -- See http://man7.org/linux/man-pages/man5/proc.5.html for the meaning of each column
+         local cpu = f:read("*line")
+
+         if not isEmptyString(cpu) then
+            -- Parse the cpu string using an sscanf-like pattern
+            local user, nice, system, idle, iowait, irq, softirq, steal, guest, guest_nice = cpu:match("cpu%s+(%d+)%s+(%d+)%s+(%d+)%s+(%d+)%s+(%d+)%s+(%d+)%s+(%d+)%s+(%d+)%s+(%d+)%s+(%d+)")
+            local states = {user = user, nice = nice, system = system, idle = idle, iowait = iowait, softirq = softirq, steal = steal, guest = guest, guest_nice = guest_nice}
+
+            -- Compute the deltas with reference to the previous values
+            local delta_total = 0
+            local delta_states = {}
+            for state, state_total in pairs(states) do
+               local delta = alerts_api.interface_delta_val(script.key..state, params.granularity, state_total or 0)
+               delta_states[state] = delta
+               delta_total = delta_total + delta
+            end
+
+            -- Compute the deltas in percent
+	    if delta_total > 0 then
+	       local delta_total_pct = 0
+	       local delta_states_pct = {}
+	       for state, state_delta in pairs(delta_states) do
+		  local delta_pct = state_delta / delta_total * 100
+		  delta_states_pct[state] = delta_pct
+		  delta_total_pct = delta_total_pct + delta_pct
+	       end
+
+	       local res = {delta_states_pct = delta_states_pct}
+	       ntop.setCache(STATES_KEY, json.encode(res), 120 --[[ keep it for at most 2 minutes --]])
+
+	       -- tprint(cpu)
+	       -- tprint(states)
+	       -- tprint(delta_states)
+	       -- tprint(delta_states_pct)
+	       -- tprint(delta_total_pct)
+	    end
+            -- Cache the cpu value so it can be re-read during next call
+         end
+
+         f:close()
+      end
+   end
+end
+
+-- ##############################################
+
+return(script)