ruffus.proxy_logger

Create proxy for logging for use with multiprocessing

These can be safely sent (marshalled) across process boundaries

Example 1

Set up logger from config file:

from proxy_logger import *
args={}
args["config_file"] = "/my/config/file"

(logger_proxy, 
 logging_mutex) = make_shared_logger_and_proxy (setup_std_shared_logger, 
                                                "my_logger", args)

Example 2

Log to file "/my/lg.log" in the specified format (Time / Log name / Event type / Message).

Delay file creation until first log.

Only log Debug messages

Other alternatives for the logging threshold (args["level"]) include

• logging.DEBUG
• logging.INFO
• logging.WARNING
• logging.ERROR
• logging.CRITICAL

from proxy_logger import *
args={}
args["file_name"] = "/my/lg.log"
args["formatter"] = "%(asctime)s - %(name)s - %(levelname)6s - %(message)s"
args["delay"]     = True
args["level"]     = logging.DEBUG

(logger_proxy, 
 logging_mutex) = make_shared_logger_and_proxy (setup_std_shared_logger, 
                                                "my_logger", args)

Example 3

Rotate log files every 20 Kb, with up to 10 backups.

from proxy_logger import *
args={}
args["file_name"] = "/my/lg.log"
args["rotating"] = True
args["maxBytes"]=20000
args["backupCount"]=10
(logger_proxy, 
 logging_mutex) = make_shared_logger_and_proxy (setup_std_shared_logger, 
                                                "my_logger", args)

To use:

(logger_proxy, 
 logging_mutex) = make_shared_logger_and_proxy (setup_std_shared_logger, 
                                                "my_logger", args)

with logging_mutex:
    my_log.debug('This is a debug message')
    my_log.info('This is an info message')
    my_log.warning('This is a warning message')
    my_log.error('This is an error message')
    my_log.critical('This is a critical error message')
    my_log.log(logging.DEBUG, 'This is a debug message')

Note that the logging function exception() is not included because python stack trace information is not well-marshalled (pickled) across processes.

Proxies for a log:

ruffus.proxy_logger.make_shared_logger_and_proxy(logger_factory, logger_name, args)

Make a logging object called “logger_name” by calling logger_factory(args)

This function will return a proxy to the shared logger which can be copied to jobs in other processes, as well as a mutex which can be used to prevent simultaneous logging from happening.

Parameters:

• logger_factory –

  functions which creates and returns an object with the logging interface. setup_std_shared_logger() is one example of a logger factory.

• logger_name – name of log
• args – parameters passed (as a single argument) to logger_factory

Returns:

a proxy to the shared logger which can be copied to jobs in other processes

Returns:

a mutex which can be used to prevent simultaneous logging from happening

Create a logging object

ruffus.proxy_logger.setup_std_shared_logger(logger_name, args)

This function is a simple around wrapper around the python logging module.

This logger_factory example creates logging objects which can then be managed by proxy via ruffus.proxy_logger.make_shared_logger_and_proxy()

This can be:

• a disk log file
• a automatically backed-up (rotating) log.
• any log specified in a configuration file

These are specified in the args dictionary forwarded by make_shared_logger_and_proxy()

Parameters:

• logger_name – name of log
• args –

  a dictionary of parameters forwarded from make_shared_logger_and_proxy()

  Valid entries include:

  "level"

  Sets the threshold for the logger.

  "config_file"

  The logging object is configured from this configuration file.

  "file_name"

  Sets disk log file name.

  "rotating"

  Chooses a (rotating) log.

  "maxBytes"

  Allows the file to rollover at a predetermined size

  "backupCount"

  If backupCount is non-zero, the system will save old log files by appending the extensions .1, .2, .3 etc., to the filename.

  "delay"

  Defer file creation until the log is written to.

  "formatter"

  Converts the message to a logged entry string. For example,

  "%(asctime)s - %(name)s - %(levelname)6s - %(message)s"