pygui: implemented cpu usage monitor to status bar

daemon/core/gui/graph/graph.py

@@ -590,8 +590,7 @@ class CanvasGraph(tk.Canvas):
         )
         logging.debug("ratio: %s", self.ratio)
         logging.debug("offset: %s", self.offset)
-        zoom_label = f"{self.ratio * 100:.0f}%"
-        self.app.statusbar.zoom.config(text=zoom_label)
+        self.app.statusbar.set_zoom(self.ratio)
         if self.wallpaper:
             self.redraw_wallpaper()
 

daemon/core/gui/statusbar.py

@@ -1,7 +1,10 @@
 """
 status bar
 """
+import sched
 import tkinter as tk
+from pathlib import Path
+from threading import Thread
 from tkinter import ttk
 from typing import TYPE_CHECKING, List, Optional
 
@@ -13,6 +16,41 @@ if TYPE_CHECKING:
     from core.gui.app import Application
 
 
+class CpuUsage:
+    def __init__(self, statusbar: "StatusBar") -> None:
+        self.scheduler: sched.scheduler = sched.scheduler()
+        self.running: bool = False
+        self.thread: Optional[Thread] = None
+        self.prev_idle: int = 0
+        self.prev_total: int = 0
+        self.stat_file: Path = Path("/proc/stat")
+        self.statusbar: "StatusBar" = statusbar
+
+    def start(self) -> None:
+        self.running = True
+        self.thread = Thread(target=self._start, daemon=True)
+        self.thread.start()
+
+    def _start(self):
+        self.scheduler.enter(0, 0, self.run)
+        self.scheduler.run()
+
+    def run(self) -> None:
+        lines = self.stat_file.read_text().splitlines()[0]
+        values = [int(x) for x in lines.split()[1:]]
+        idle = sum(values[3:5])
+        non_idle = sum(values[:3] + values[5:8])
+        total = idle + non_idle
+        total_diff = total - self.prev_total
+        idle_diff = idle - self.prev_idle
+        cpu_percent = (total_diff - idle_diff) / total_diff
+        self.statusbar.after(0, self.statusbar.set_cpu, cpu_percent)
+        self.prev_idle = idle
+        self.prev_total = total
+        if self.running:
+            self.scheduler.enter(3, 0, self.run)
+
+
 class StatusBar(ttk.Frame):
     def __init__(self, master: tk.Widget, app: "Application") -> None:
         super().__init__(master)
@@ -20,12 +58,14 @@ class StatusBar(ttk.Frame):
         self.status: Optional[ttk.Label] = None
         self.statusvar: tk.StringVar = tk.StringVar()
         self.zoom: Optional[ttk.Label] = None
-        self.cpu_usage: Optional[ttk.Label] = None
+        self.cpu_label: Optional[ttk.Label] = None
         self.alerts_button: Optional[ttk.Button] = None
         self.alert_style = Styles.no_alert
         self.running: bool = False
         self.core_alarms: List[ExceptionEvent] = []
         self.draw()
+        self.cpu_usage: CpuUsage = CpuUsage(self)
+        self.cpu_usage.start()
 
     def draw(self) -> None:
         self.columnconfigure(0, weight=7)
@@ -46,25 +86,27 @@ class StatusBar(ttk.Frame):
         )
         self.status.grid(row=0, column=0, sticky="ew")
 
-        self.zoom = ttk.Label(
-            self,
-            text="%s" % (int(self.app.canvas.ratio * 100)) + "%",
-            anchor=tk.CENTER,
-            borderwidth=1,
-            relief=tk.RIDGE,
-        )
+        self.zoom = ttk.Label(self, anchor=tk.CENTER, borderwidth=1, relief=tk.RIDGE)
         self.zoom.grid(row=0, column=1, sticky="ew")
+        self.set_zoom(self.app.canvas.ratio)
 
-        self.cpu_usage = ttk.Label(
-            self, text="CPU TBD", anchor=tk.CENTER, borderwidth=1, relief=tk.RIDGE
+        self.cpu_label = ttk.Label(
+            self, anchor=tk.CENTER, borderwidth=1, relief=tk.RIDGE
         )
-        self.cpu_usage.grid(row=0, column=2, sticky="ew")
+        self.cpu_label.grid(row=0, column=2, sticky="ew")
+        self.set_cpu(0.0)
 
         self.alerts_button = ttk.Button(
             self, text="Alerts", command=self.click_alerts, style=self.alert_style
         )
         self.alerts_button.grid(row=0, column=3, sticky="ew")
 
+    def set_cpu(self, usage: float) -> None:
+        self.cpu_label.config(text=f"CPU {usage * 100:.2f}%")
+
+    def set_zoom(self, zoom: float) -> None:
+        self.zoom.config(text=f"ZOOM {zoom * 100:.0f}%")
+
     def add_alert(self, event: ExceptionEvent) -> None:
         self.core_alarms.append(event)
         level = event.exception_event.level