PLC/Config.py

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