OpenCore-Legacy-Patcher/resources/logging_handler.py

import logging
import sys
import threading
from pathlib import Path


class InitializeLoggingSupport:
    """
    Initialize logging framework for program

    Primary responsibilities:
    - Determine where to store log file
    - Clean log file if it's near the max file size
    - Initialize logging framework configuration
    - Implement custom traceback handler
    - Implement error handling for file write

    Usage:
    >>> from resources.logging_handler import InitializeLoggingSupport
    >>> InitializeLoggingSupport()

    """

    def __init__(self) -> None:
        self.log_filename: str  = "OpenCore-Patcher.log"
        self.log_filepath: Path = None

        self.original_excepthook:        sys       = sys.excepthook
        self.original_thread_excepthook: threading = threading.excepthook

        self.max_file_size:     int = 1024 * 1024 * 10  # 10 MB
        self.file_size_redline: int = 1024 * 1024 * 9   # 9 MB, when to start cleaning log file

        self._initialize_logging_path()
        self._clean_log_file()
        self._attempt_initialize_logging_configuration()
        self._implement_custom_traceback_handler()


    def __del__(self):
        self._restore_original_excepthook()


    def _initialize_logging_path(self):
        """
        Initialize logging framework storage path
        """

        self.log_filepath = Path(f"~/Library/Logs/{self.log_filename}").expanduser()

        if not self.log_filepath.parent.exists():
             # Likely in an installer environment, store in /Users/Shared
            self.log_filepath = Path("/Users/Shared") / self.log_filename

        print("- Initializing logging framework...")
        print(f"  - Log file: {self.log_filepath}")


    def _clean_log_file(self):
        """
        Determine if log file should be cleaned

        We check if we're near the max file size, and if so, we clean the log file
        """

        if not self.log_filepath.exists():
            return

        if self.log_filepath.stat().st_size < self.file_size_redline:
            return

        # Check if backup log file exists
        backup_log_filepath = self.log_filepath.with_suffix(".old.log")
        try:
            if backup_log_filepath.exists():
                backup_log_filepath.unlink()

            # Rename current log file to backup log file
            self.log_filepath.rename(backup_log_filepath)
        except Exception as e:
            print(f"- Failed to clean log file: {e}")


    def _initialize_logging_configuration(self, log_to_file: bool = True):
        """
        Initialize logging framework configuration

        StreamHandler's format is used to mimic the default behavior of print()
        While FileHandler's format is for more in-depth logging
        """

        logging.basicConfig(
            level=logging.NOTSET,
            format="%(asctime)s - %(filename)s (%(lineno)d): %(message)s",
            handlers=[
                logging.StreamHandler(stream = sys.stdout),
                logging.FileHandler(self.log_filepath) if log_to_file is True else logging.NullHandler()
            ],
        )
        logging.getLogger().setLevel(logging.INFO)
        logging.getLogger().handlers[0].setFormatter(logging.Formatter("%(message)s"))
        logging.getLogger().handlers[1].maxBytes = self.max_file_size

    def _attempt_initialize_logging_configuration(self):
        """
        Attempt to initialize logging framework configuration

        If we fail to initialize the logging framework, we will disable logging to file
        """

        try:
            self._initialize_logging_configuration()
        except Exception as e:
            print(f"- Failed to initialize logging framework: {e}")
            print("- Retrying without logging to file...")
            self._initialize_logging_configuration(log_to_file=False)


    def _implement_custom_traceback_handler(self):
        """
        Reroute traceback to logging module
        """

        def custom_excepthook(type, value, tb):
            """
            Reroute traceback in main thread to logging module
            """
            logging.error("Uncaught exception in main thread", exc_info=(type, value, tb))

        def custom_thread_excepthook(args):
            """
            Reroute traceback in spawned thread to logging module
            """
            logging.error("Uncaught exception in spawned thread", exc_info=(args))

        sys.excepthook = custom_excepthook
        threading.excepthook = custom_thread_excepthook

    def _restore_original_excepthook(self):
        """
        Restore original traceback handlers
        """

        sys.excepthook = self.original_excepthook
        threading.excepthook = self.original_thread_excepthook