PLC/Config.py

   1 #
   2 # PLCAPI configuration store. Supports XML-based configuration file
   3 # format exported by MyPLC.
   4 #
   5 # Mark Huang <mlhuang@cs.princeton.edu>
   6 # Copyright (C) 2004-2006 The Trustees of Princeton University
   7 #
   8
   9 import os
  10 import sys
  11
  12 from PLC.Faults import *
  13 from PLC.Debug import profile
  14
  15 # If we have been checked out into a directory at the same
  16 # level as myplc, where plc_config.py lives. If we are in a
  17 # MyPLC environment, plc_config.py has already been installed
  18 # in site-packages.
  19 myplc = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))) + \
  20         os.sep + "myplc"
  21
  22 class Config:
  23     """
  24     Parse the bash/Python/PHP version of the configuration file. Very
  25     fast but no type conversions.
  26     """
  27
  28     def __init__(self, file = "/etc/planetlab/plc_config"):
  29         # Load plc_config
  30         try:
  31             exec(compile(open(file).read(), file, 'exec'), self.__dict__)
  32         except:
  33             # Try myplc directory
  34             try:
  35                 exec(compile(open(myplc + os.sep + "plc_config").read(), myplc + os.sep + "plc_config", 'exec'), self.__dict__)
  36             except:
  37                 raise PLCAPIError("Could not find plc_config in " + \
  38                                   file + ", " + \
  39                                   myplc + os.sep + "plc_config")
  40
  41 class XMLConfig:
  42     """
  43     Parse the XML configuration file directly. Takes longer but is
  44     presumably more accurate.
  45     """
  46
  47     def __init__(self, file = "/etc/planetlab/plc_config.xml"):
  48         try:
  49             from plc_config import PLCConfiguration
  50         except:
  51             sys.path.append(myplc)
  52             from plc_config import PLCConfiguration
  53
  54         # Load plc_config.xml
  55         try:
  56             cfg = PLCConfiguration(file)
  57         except:
  58             # Try myplc directory
  59             try:
  60                 cfg = PLCConfiguration(myplc + os.sep + "plc_config.xml")
  61             except:
  62                 raise PLCAPIError("Could not find plc_config.xml in " + \
  63                                   file + ", " + \
  64                                   myplc + os.sep + "plc_config.xml")
  65
  66         for (category, variablelist) in list(cfg.variables().values()):
  67             for variable in list(variablelist.values()):
  68                 # Try to cast each variable to an appropriate Python
  69                 # type.
  70                 if variable['type'] == "int":
  71                     value = int(variable['value'])
  72                 elif variable['type'] == "double":
  73                     value = float(variable['value'])
  74                 elif variable['type'] == "boolean":
  75                     if variable['value'] == "true":
  76                         value = True
  77                     else:
  78                         value = False
  79                 else:
  80                     value = variable['value']
  81
  82                 # Variables are split into categories such as
  83                 # "plc_api", "plc_db", etc. Within each category are
  84                 # variables such as "host", "port", etc. For backward
  85                 # compatibility, refer to variables by their shell
  86                 # names.
  87                 shell_name = category['id'].upper() + "_" + variable['id'].upper()
  88                 setattr(self, shell_name, value)
  89
  90 if __name__ == '__main__':
  91     import pprint
  92     pprint = pprint.PrettyPrinter()
  93     pprint.pprint(list(Config().__dict__.items()))