Skip to content

LogFormatter

File: base/log/log_formatter.py

This file implements a basic log formatter that formats log messages defaulting to a specified pattern used by the GLog library (C++).

Classes:

  • LogFormatter –

    A class for formatting log messages with customizable patterns.

LogFormatter

A class for formatting log messages with customizable patterns.

This formatter allows developers to define a custom log message prefix format, similar to the GLog library. The format can include placeholders for date, time, severity, file name, and line number.

Attributes:

  • format_pattern (str) –

    The pattern for formatting log messages. If None, a default pattern is used that mimics GLog.

Methods:

  • __init__ –

    Initializes the LogFormatter with a given format pattern.

  • format –

    Formats a log message with the specified severity and message.

Source code in kern_comm_lib/base/log/log_formatter.py 
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
class LogFormatter:
  """A class for formatting log messages with customizable patterns.

  This formatter allows developers to define a custom log message prefix
  format, similar to the GLog library. The format can include placeholders
  for date, time, severity, file name, and line number.

  Attributes:
    format_pattern (str): The pattern for formatting log messages. If None,
        a default pattern is used that mimics GLog.
  """

  def __init__(self, format_pattern: str | None = None) -> None:
    """Initializes the LogFormatter with a given format pattern.

    Args:
      format_pattern (default: None): The pattern for formatting log messages.

    Notes:
      Default pattern mimics GLog:
        - %severity% -> First letter of severity (e.g., I, W, E, F)
        - %Y%m%d -> Full date (year, month, day)
        - %H:%M:%S.%f -> Time with microseconds
        - [%F:%L] -> File name and line number of the log call
    """
    if format_pattern is None:
      format_pattern = "%severity%%Y%m%d %H:%M:%S.%f [%F:%L] "
    self.format_pattern = format_pattern

  def format(self, severity: log_severity.LogSeverity, message: str) -> str:
    """Formats a log message with the specified severity and message.

    This method generates a log message prefix based on the format pattern
    and replaces placeholders with actual values such as the current date,
    time, severity, file name, and line number.

    Args:
      severity: The severity level of the log message.
      message: The log message to be formatted.

    Returns:
      The formatted log message with the prefix.

    Notes:
      - The file name and line number are determined using the `inspect` module.
      - If the stack depth is insufficient, "unknown" and -1 are used as defaults
        for the file name and line number, respectively.
    """
    now = datetime.datetime.now()
    stack = inspect.stack()

    # Determine the caller's file name and line number
    if len(stack) > 5:
      caller_frame = stack[5]
      filename = caller_frame.filename.split("/")[-1]
      lineno = caller_frame.lineno
    else:
      filename = "unknown"
      lineno = -1

    # Mapping of placeholders to their corresponding values
    mapping = {
        "%Y": f"{now.year:04d}",  # Year (4 digits)
        "%m": f"{now.month:02d}",  # Month (2 digits)
        "%d": f"{now.day:02d}",  # Day (2 digits)
        "%H": f"{now.hour:02d}",  # Hour (2 digits)
        "%M": f"{now.minute:02d}",  # Minute (2 digits)
        "%S": f"{now.second:02d}",  # Second (2 digits)
        "%f": f"{now.microsecond:06d}",  # Microsecond (6 digits)
        "%severity%": severity.name[0]
        if severity.name
        else "?",  # First letter of severity
        "%F": filename,  # File name
        "%L": str(lineno),  # Line number
    }

    # Replace placeholders in the format pattern with actual values
    formatted_prefix = self.format_pattern
    for key, value in mapping.items():
      formatted_prefix = formatted_prefix.replace(key, value)

    # Return the formatted log message
    return f"{formatted_prefix}{message}"

__init__ 

__init__(format_pattern: str | None = None) -> None

Initializes the LogFormatter with a given format pattern.

Parameters:

  • format_pattern (default, default: None ) –

    None): The pattern for formatting log messages.

Notes

Default pattern mimics GLog: - %severity% -> First letter of severity (e.g., I, W, E, F) - %Y%m%d -> Full date (year, month, day) - %H:%M:%S.%f -> Time with microseconds - [%F:%L] -> File name and line number of the log call

Source code in kern_comm_lib/base/log/log_formatter.py 
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
def __init__(self, format_pattern: str | None = None) -> None:
  """Initializes the LogFormatter with a given format pattern.

  Args:
    format_pattern (default: None): The pattern for formatting log messages.

  Notes:
    Default pattern mimics GLog:
      - %severity% -> First letter of severity (e.g., I, W, E, F)
      - %Y%m%d -> Full date (year, month, day)
      - %H:%M:%S.%f -> Time with microseconds
      - [%F:%L] -> File name and line number of the log call
  """
  if format_pattern is None:
    format_pattern = "%severity%%Y%m%d %H:%M:%S.%f [%F:%L] "
  self.format_pattern = format_pattern

format 

format(severity: LogSeverity, message: str) -> str

Formats a log message with the specified severity and message.

This method generates a log message prefix based on the format pattern and replaces placeholders with actual values such as the current date, time, severity, file name, and line number.

Parameters:

  • severity (LogSeverity) –

    The severity level of the log message.

  • message (str) –

    The log message to be formatted.

Returns:

  • str –

    The formatted log message with the prefix.

Notes
  • The file name and line number are determined using the inspect module.
  • If the stack depth is insufficient, "unknown" and -1 are used as defaults for the file name and line number, respectively.
Source code in kern_comm_lib/base/log/log_formatter.py 
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
def format(self, severity: log_severity.LogSeverity, message: str) -> str:
  """Formats a log message with the specified severity and message.

  This method generates a log message prefix based on the format pattern
  and replaces placeholders with actual values such as the current date,
  time, severity, file name, and line number.

  Args:
    severity: The severity level of the log message.
    message: The log message to be formatted.

  Returns:
    The formatted log message with the prefix.

  Notes:
    - The file name and line number are determined using the `inspect` module.
    - If the stack depth is insufficient, "unknown" and -1 are used as defaults
      for the file name and line number, respectively.
  """
  now = datetime.datetime.now()
  stack = inspect.stack()

  # Determine the caller's file name and line number
  if len(stack) > 5:
    caller_frame = stack[5]
    filename = caller_frame.filename.split("/")[-1]
    lineno = caller_frame.lineno
  else:
    filename = "unknown"
    lineno = -1

  # Mapping of placeholders to their corresponding values
  mapping = {
      "%Y": f"{now.year:04d}",  # Year (4 digits)
      "%m": f"{now.month:02d}",  # Month (2 digits)
      "%d": f"{now.day:02d}",  # Day (2 digits)
      "%H": f"{now.hour:02d}",  # Hour (2 digits)
      "%M": f"{now.minute:02d}",  # Minute (2 digits)
      "%S": f"{now.second:02d}",  # Second (2 digits)
      "%f": f"{now.microsecond:06d}",  # Microsecond (6 digits)
      "%severity%": severity.name[0]
      if severity.name
      else "?",  # First letter of severity
      "%F": filename,  # File name
      "%L": str(lineno),  # Line number
  }

  # Replace placeholders in the format pattern with actual values
  formatted_prefix = self.format_pattern
  for key, value in mapping.items():
    formatted_prefix = formatted_prefix.replace(key, value)

  # Return the formatted log message
  return f"{formatted_prefix}{message}"