Dont incur the cost of checking the cwd of a process on every tabbar update unless actually needed

kitty/tab_bar.py

@@ -5,8 +5,9 @@ import os
 from functools import lru_cache, partial, wraps
 from string import Formatter as StringFormatter
 from typing import (
-    Any, Callable, Dict, List, NamedTuple, Optional, Sequence, Tuple, Union
+    Any, Callable, Dict, List, NamedTuple, Optional, Sequence, Tuple, Union, TYPE_CHECKING
 )
+from weakref import ReferenceType
 
 from .borders import Border, BorderColor
 from .config import build_ansi_color_table
@@ -21,11 +22,15 @@ from .typing import EdgeLiteral, PowerlineStyle
 from .utils import color_as_int, log_error, sgr_sanitizer_pat
 
 
+if TYPE_CHECKING:
+    from .tabs import Tab
+
+
 class TabBarData(NamedTuple):
     title: str
     is_active: bool
     needs_attention: bool
-    cwd: str
+    tab_ref: ReferenceType['Tab']
     num_windows: int
     num_window_groups: int
     layout_name: str
@@ -173,14 +178,28 @@ def template_has_field(template: str, field: str) -> bool:
     return False
 
 
+class TabCWD:
+
+    def __init__(self, tab_ref: ReferenceType['Tab']):
+        self.tab_ref = tab_ref
+        self.saved_val: Optional[str] = None
+
+    def __str__(self) -> str:
+        if self.saved_val is None:
+            tab = self.tab_ref()
+            self.saved_val = (tab.get_cwd_of_active_window() or '') if tab else ''
+        return self.saved_val
+
+
 def draw_title(draw_data: DrawData, screen: Screen, tab: TabBarData, index: int) -> None:
+    tcwd = TabCWD(tab.tab_ref)
     data = {
         'index': index,
         'layout_name': tab.layout_name,
         'num_windows': tab.num_windows,
         'num_window_groups': tab.num_window_groups,
         'title': tab.title,
-        'cwd': tab.cwd,
+        'cwd': tcwd,
     }
     ColorFormatter.draw_data = draw_data
     ColorFormatter.tab_data = tab
@@ -190,7 +209,7 @@ def draw_title(draw_data: DrawData, screen: Screen, tab: TabBarData, index: int)
         'num_windows': tab.num_windows,
         'num_window_groups': tab.num_window_groups,
         'title': tab.title,
-        'cwd': tab.cwd,
+        'cwd': tcwd,
         'fmt': Formatter,
         'sup': SupSub(data),
         'sub': SupSub(data, True),

kitty/tabs.py

@@ -230,10 +230,9 @@ class Tab:  # {{{
                 ans += 1
         return ans
 
-    @property
+    def get_cwd_of_active_window(self, oldest: bool = False) -> Optional[str]:
-    def get_cwd(self) -> str:
         w = self.active_window
-        return w.cwd_of_child if w and w.cwd_of_child else self.cwd
+        return w.get_cwd_of_child(oldest) if w else None
 
     def set_title(self, title: str) -> None:
         self.name = title or ''
@@ -1083,14 +1082,13 @@ class TabManager:  # {{{
             title = (t.name or t.title or appname).strip()
             needs_attention = False
             has_activity_since_last_focus = False
-            cwd = os.path.abspath(t.get_cwd)
             for w in t:
                 if w.needs_attention:
                     needs_attention = True
                 if w.has_activity_since_last_focus:
                     has_activity_since_last_focus = True
             ans.append(TabBarData(
-                title, t is at, needs_attention, cwd,
+                title, t is at, needs_attention, weakref.ref(t),
                 len(t), t.num_window_groups, t.current_layout.name or '',
                 has_activity_since_last_focus, t.active_fg, t.active_bg,
                 t.inactive_fg, t.inactive_bg