Fix logging in Jupyter and Colab (#542)

This PR:

- Enables colors in Jupyter and Colab
- Makes it possible to enable/disable logging colors on the fly
- Addresses the issue with duplicate log lines on Colab in case of `use_hivemind_log_handler("in_root_logger")`

hivemind/utils/logging.py

@@ -3,20 +3,32 @@ import os
 import sys
 import threading
 from enum import Enum
-from typing import Optional, Union
+from typing import Any, Optional, Union
 
-logging.addLevelName(logging.WARNING, "WARN")
 
+def in_ipython() -> bool:
+    """Check if the code is run in IPython, Jupyter, or Colab"""
+
+    try:
+        __IPYTHON__
+        return True
+    except NameError:
+        return False
+
+
+logging.addLevelName(logging.WARNING, "WARN")
 loglevel = os.getenv("HIVEMIND_LOGLEVEL", "INFO")
 
+TRUE_CONSTANTS = ["TRUE", "1"]
+
 _env_colors = os.getenv("HIVEMIND_COLORS")
 if _env_colors is not None:
-    use_colors = _env_colors.lower() == "true"
+    use_colors = _env_colors.upper() in TRUE_CONSTANTS
 else:
-    use_colors = sys.stderr.isatty()
+    use_colors = sys.stderr.isatty() or in_ipython()
 
-_env_log_caller = os.getenv("HIVEMIND_ALWAYS_LOG_CALLER")
-always_log_caller = _env_log_caller is not None and _env_log_caller.lower() == "true"
+_env_log_caller = os.getenv("HIVEMIND_ALWAYS_LOG_CALLER", "0")
+always_log_caller = _env_log_caller.upper() in TRUE_CONSTANTS
 
 
 class HandlerMode(Enum):
@@ -30,7 +42,14 @@ _current_mode = HandlerMode.IN_HIVEMIND
 _default_handler = None
 
 
-class TextStyle:
+class _DisableIfNoColors(type):
+    def __getattribute__(self, name: str) -> Any:
+        if name.isupper() and not use_colors:
+            return ""
+        return super().__getattribute__(name)
+
+
+class TextStyle(metaclass=_DisableIfNoColors):
     """
     ANSI escape codes. Details: https://en.wikipedia.org/wiki/ANSI_escape_code#Colors
     """
@@ -42,11 +61,6 @@ class TextStyle:
     PURPLE = "\033[35m"
     ORANGE = "\033[38;5;208m"  # From 8-bit palette
 
-    if not use_colors:
-        # Set the constants above to empty strings
-        _codes = locals()
-        _codes.update({_name: "" for _name in list(_codes) if _name.isupper()})
-
 
 class CustomFormatter(logging.Formatter):
     """
@@ -115,14 +129,21 @@ def get_logger(name: Optional[str] = None) -> logging.Logger:
     return logging.getLogger(name)
 
 
-def _enable_default_handler(name: str) -> None:
+def _enable_default_handler(name: Optional[str]) -> None:
     logger = get_logger(name)
+
+    # Remove the extra default handler in the Colab's default logger before adding a new one
+    if isinstance(logger, logging.RootLogger):
+        for handler in list(logger.handlers):
+            if isinstance(handler, logging.StreamHandler) and handler.stream is sys.stderr:
+                logger.removeHandler(handler)
+
     logger.addHandler(_default_handler)
     logger.propagate = False
     logger.setLevel(loglevel)
 
 
-def _disable_default_handler(name: str) -> None:
+def _disable_default_handler(name: Optional[str]) -> None:
     logger = get_logger(name)
     logger.removeHandler(_default_handler)
     logger.propagate = True