Reland "Improve ui for non-interactive terminals"

This is a reland of commit 1009ebd
Reason for reland: crbug.com/428049900#comment7

Original change's description:
> Improve ui for non-interactive terminals
>
> Timer and Countdown:
> - Only show single message line
>
> Spinner:
> - Only print single title and message update lines
> - Avoid an additional sleep on the main thread
>
> Change-Id: Iba56e895638655c23918fa055ffa318d83aa7ce1
> Reviewed-on: https://chromium-review.googlesource.com/c/crossbench/+/6632506
> Commit-Queue: Camillo Bruni <[email protected]>
> Reviewed-by: Patrick Thier <[email protected]>

Change-Id: If0f9a27c4fa2b30fc474451aa5ffacaa4392e432
Bug: 428049900
Reviewed-on: https://chromium-review.googlesource.com/c/crossbench/+/6696145
Reviewed-by: Camillo Bruni <[email protected]>
Auto-Submit: Victor Vianna <[email protected]>
Commit-Queue: Camillo Bruni <[email protected]>

Author: camillobruni

crossbench/cli/ui.py

@@ -21,6 +21,7 @@
 
 colorama.init()
 
+IS_ATTY: Final[bool] = hasattr(sys.stdout, "isatty") and sys.stdout.isatty()
 COLOR_LOGGING: bool = True
 
 
@@ -91,12 +92,14 @@ def clear_indented() -> None:
 @contextlib.contextmanager
 def timer(msg: str = "Elapsed Time",
           update_interval=DEFAULT_INTERVAL_S) -> Iterator[None]:
-  start_time = dt.datetime.now()
+  if not IS_ATTY:
+    yield
+    return
 
+  start_time = dt.datetime.now()
   def print_timer():
     delta = dt.datetime.now() - start_time
     write_indented(f"{msg}: {format_duration(delta)}")
-
   with RepeatTimer(interval=update_interval, function=print_timer):
     yield
   clear_indented()
@@ -106,13 +109,16 @@ def print_timer():
 def countdown(duration: dt.timedelta,
               msg: str = "Waiting",
               update_interval=DEFAULT_INTERVAL_S) -> Iterator[None]:
-  start_time = dt.datetime.now()
+  if not IS_ATTY:
+    print(f"{msg}: {format_duration(duration)}")
+    yield
+    return
 
+  start_time = dt.datetime.now()
   def print_timer():
     delta = dt.datetime.now() - start_time
     time_left = duration - delta
     write_indented(f"{msg}: {format_duration(time_left)}")
-
   with RepeatTimer(interval=update_interval, function=print_timer):
     yield
   clear_indented()
@@ -131,5 +137,5 @@ def __exit__(self, *args, **kwargs) -> None:
     self.cancel()
 
 
-def spinner(*args, **kwargs) -> Spinner:
-  return Spinner(*args, **kwargs)
+def spinner(sleep: float = 0.5, title: str = "") -> Spinner:
+  return Spinner(IS_ATTY, sleep, title)

crossbench/helper/spinner.py

@@ -15,34 +15,35 @@
 class Spinner:
   CURSORS = "◐◓◑◒"
 
-  def __init__(self, sleep: float = 0.5, title: str = "") -> None:
+  def __init__(self, is_atty: bool, sleep: float, title: str) -> None:
     self._is_running: bool = False
+    # Only enable the spinner if the output is an interactive terminal.
+    self._is_atty: bool = is_atty
     self._sleep_time_seconds: float = sleep
     self._title: str = title
     self._message: str = ""
     self._cursor: str = " "
 
   def __enter__(self) -> None:
-    # Only enable the spinner if the output is an interactive terminal.
-    is_atty = hasattr(sys.stdout, "isatty") and sys.stdout.isatty()
-    if is_atty:
+    if self._is_atty:
       self._is_running = True
       threading.Thread(target=self._spin).start()
+    elif self._title:
+      # Write single title line.
+      self._write_message()
 
   def __exit__(self, exc_type, exc_value, traceback) -> None:
-    if self._is_running:
-      self._is_running = False
-      self._sleep()
+    self._is_running = False
 
   def _cursors(self) -> Iterable[str]:
     while True:
       yield from Spinner.CURSORS
 
   def _spin(self) -> None:
     for cursor in self._cursors():
-      self._cursor = cursor
       if not self._is_running:
         return
+      self._cursor = cursor
       self._write_message()
       self._sleep()
 
@@ -63,6 +64,12 @@ def title(self, title: str) -> None:
     self._write_message()
 
   def _write_message(self) -> None:
+    if self._is_atty:
+      self._write_interactive_message()
+    else:
+      print(f"{self._title}{self._message}")
+
+  def _write_interactive_message(self) -> None:
     stdout = sys.stdout
     stdout.write(f"{terminal.STORE_CURSOR_POS} {self._cursor} "
                  f"{self._title}{self._message}{terminal.CLEAR_END}"