The script logger.py is a logging utility written in Python 2.7 which logs
messages with a priority flag and time stamp and returns messages
for reading in priority flag and timestamp descending order.
No external or third-party packages are required to run the script. The logger
makes use of the following Python Standard Library modules:
Queue
datetime
time
calendar
threading
As such, only a Python environment is required to run logger.py.
The script makes use of the Python Queue base class, specifically its
PriorityQueue implementation, due to its multi-threading support.
Script functionality revolves around two distinct classes which separate
the logging and reading functions:
Logger
LogReader
The Logger class is responsible for logging messages. As it does so,
it checks for user-specified size-constraints/limitations and assigns a default
priority flag for incoming messages, if none are specified (defaulting to highest
priority). Warnings are raised if the log queue size approaches a critical (user
specificable limit) and no logs are accepted after capacity is reached.
The LogReader class fetches the log information (equivalent to popping) and
formats the time stamp to display in human-readable form from the original
capture of epoch-time.
The script seeds the log data with some pre-set sample messages and
priority flags. In addition, several threads are used in order to populate/
write to the log.
Salient user-specifiable constants are:
MAX_RECS - the maximum number of log records to queue
MAX_WARN - capacity percentage after which size warnings should be raised
NUM_THREADS - number of threads to spawn for writing to the log
Log messages may be written using the log method of the Logger object.
Messages must include at least the message content and, optionally,
a priority flag as follows:
Logger.log(flag,msg)
Sample instantiation and usage included in the script are as follows:
logger = Logger()
logger.log(1,"this is a message")
Log messages may be read individually using:
LogReader.get()
or the entire log may be read using:
LogReader.readAll()
The script and its sample data may simply be invoked by running:
logger.py
at the command line for Python-supported environments.