util.py

#!/usr/bin/env python
"""
Gearman Client Utils
"""
import errno
import select as select_lib
import time
import sys

from gearman.constants import DEFAULT_GEARMAN_PORT

class Stopwatch(object):
    """Timer class that keeps track of time remaining"""
    def __init__(self, time_remaining):
        if time_remaining is not None:
            self.stop_time = time.time() + time_remaining
        else:
            self.stop_time = None

    def get_time_remaining(self):
        if self.stop_time is None:
            return None

        current_time = time.time()
        if not self.has_time_remaining(current_time):
            return 0.0

        time_remaining = self.stop_time - current_time
        return time_remaining

    def has_time_remaining(self, time_comparison=None):
        time_comparison = time_comparison or self.get_time_remaining()
        if self.stop_time is None:
            return True

        return bool(time_comparison < self.stop_time)

def disambiguate_server_parameter(hostport_tuple):
    """Takes either a tuple of (address, port) or a string of 'address:port' and disambiguates them for us"""
    if type(hostport_tuple) is tuple:
        gearman_host, gearman_port = hostport_tuple
    elif ':' in hostport_tuple:
        gearman_host, gearman_possible_port = hostport_tuple.split(':')
        gearman_port = int(gearman_possible_port)
    else:
        gearman_host = hostport_tuple
        gearman_port = DEFAULT_GEARMAN_PORT

    return gearman_host, gearman_port

def select(rlist, wlist, xlist, timeout=None):
    """Behave similar to select.select, except ignoring certain types of exceptions"""
    rd_list = []
    wr_list = []
    ex_list = []

    select_args = [rlist, wlist, xlist]
    if timeout is not None:
        select_args.append(timeout)

    try:
        rd_list, wr_list, ex_list = select_lib.select(*select_args)
    except select_lib.error as exc:
        # Ignore interrupted system call, reraise anything else
        print("Interrupted system call. Exiting - Gearman")
        sys.exit()
        if exc[0] != errno.EINTR:
            raise

    return rd_list, wr_list, ex_list

def unlist(given_list):
    """Convert the (possibly) single item list into a single item"""
    list_size = len(given_list)
    if list_size == 0:
        return None
    elif list_size == 1:
        return given_list[0]
    else:
        raise ValueError(list_size)