gracefully handle lemonbar crashesHEADmaster

1 files changed, 31 insertions, 7 deletions

diff --git a/panel.py b/panel.py
index 8885d4f..854d57d 100755
--- a/panel.py
+++ b/panel.py
@@ -551,10 +551,7 @@ class Panel:
             if mod := self.mod_by_id.get(int(mod_id)):
                 mod.process_cmd(cmd)
 
-    def run(self):
-        for mod in self.mods:
-            mod.run()
-
+    def spawn_panel(self):
         self.panel = subprocess.Popen(
             ('/home/david/dev/lemonbar-xft/lemonbar',
                 '-f', 'Monospace:size=10:dpi=96',
@@ -567,12 +564,31 @@ class Panel:
             stdout=subprocess.PIPE,
             text=True)
 
+        # closed pipe terminates thread via EOF when panel dies
         threading.Thread(
             target=self.process_cmds,
             args=(self.panel.stdout,),
             daemon=True
         ).start()
 
+    def respawn_panel(self):
+        # silence _io.TextIOWrapper exceptions
+        for pipe in (self.panel.stdin, self.panel.stdout):
+            try:
+                pipe.close()
+            except BrokenPipeError:
+                pass
+
+        self.panel.kill()
+        self.panel.wait()
+        self.spawn_panel()
+
+    def run(self):
+        for mod in self.mods:
+            mod.run()
+
+        self.spawn_panel()
+
         while True:
             self.e_repaint.wait()
             self.e_repaint.clear()
@@ -585,9 +601,17 @@ class Panel:
                     if self.e_flush.is_set():
                         break
             self.e_flush.clear()
-            print(
-                ''.join([s for m in self.mods if (s := m.to_paint())]),
-                file=self.panel.stdin, flush=True)
+            out = ''.join([s for m in self.mods if (s := m.to_paint())])
+
+            # sometimes lemonbar crashes with X error BadIDChoice, resulting in
+            # BrokenPipeError on print. when this happens, we spawn a new panel
+            # process and trigger a repaint.
+            try:
+                print(out, file=self.panel.stdin, flush=True)
+            except BrokenPipeError:
+                self.respawn_panel()
+                self.e_repaint.set()
+                self.e_flush.set()
 
 Panel(
     ModHLWMTags(spacing=0),