Imported existing code

indra/lib/python/indra/base/config.py

@@ -0,0 +1,266 @@
+"""\
+@file config.py
+@brief Utility module for parsing and accessing the indra.xml config file.
+
+$LicenseInfo:firstyear=2006&license=mit$
+
+Copyright (c) 2006-2009, Linden Research, Inc.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+$/LicenseInfo$
+"""
+
+import copy
+import errno
+import os
+import traceback
+import time
+import types
+
+from os.path import dirname, getmtime, join, realpath
+from indra.base import llsd
+
+_g_config = None
+
+class IndraConfig(object):
+    """
+    IndraConfig loads a 'indra' xml configuration file
+    and loads into memory.  This representation in memory
+    can get updated to overwrite values or add new values.
+
+    The xml configuration file is considered a live file and changes
+    to the file are checked and reloaded periodically.  If a value had
+    been overwritten via the update or set method, the loaded values
+    from the file are ignored (the values from the update/set methods
+    override)
+    """
+    def __init__(self, indra_config_file):
+        self._indra_config_file = indra_config_file
+        self._reload_check_interval = 30 # seconds
+        self._last_check_time = 0
+        self._last_mod_time = 0
+
+        self._config_overrides = {}
+        self._config_file_dict = {}
+        self._combined_dict = {}
+
+        self._load()
+
+    def _load(self):
+        # if you initialize the IndraConfig with None, no attempt
+        # is made to load any files
+        if self._indra_config_file is None:
+            return
+
+        config_file = open(self._indra_config_file)
+        self._config_file_dict = llsd.parse(config_file.read())
+        self._combine_dictionaries()
+        config_file.close()
+
+        self._last_mod_time = self._get_last_modified_time()
+        self._last_check_time = time.time() # now
+
+    def _get_last_modified_time(self):
+        """
+        Returns the mtime (last modified time) of the config file,
+        if such exists.
+        """
+        if self._indra_config_file is not None:
+            return os.path.getmtime(self._indra_config_file)
+
+        return 0
+
+    def _combine_dictionaries(self):
+        self._combined_dict = {}
+        self._combined_dict.update(self._config_file_dict)
+        self._combined_dict.update(self._config_overrides)
+
+    def _reload_if_necessary(self):
+        now = time.time()
+
+        if (now - self._last_check_time) > self._reload_check_interval:
+            self._last_check_time = now
+            try:
+                modtime = self._get_last_modified_time()
+                if modtime > self._last_mod_time:
+                    self._load()
+            except OSError, e:
+                if e.errno == errno.ENOENT: # file not found
+                    # someone messed with our internal state
+                    # or removed the file
+
+                    print 'WARNING: Configuration file has been removed ' + (self._indra_config_file)
+                    print 'Disabling reloading of configuration file.'
+
+                    traceback.print_exc()
+
+                    self._indra_config_file = None
+                    self._last_check_time = 0
+                    self._last_mod_time = 0
+                else:
+                    raise  # pass the exception along to the caller
+
+    def __getitem__(self, key):
+        self._reload_if_necessary()
+
+        return self._combined_dict[key]
+
+    def get(self, key, default = None):
+        try:
+            return self.__getitem__(key)
+        except KeyError:
+            return default
+
+    def __setitem__(self, key, value):
+        """
+        Sets the value of the config setting of key to be newval
+
+        Once any key/value pair is changed via the set method,
+        that key/value pair will remain set with that value until
+        change via the update or set method
+        """
+        self._config_overrides[key] = value
+        self._combine_dictionaries()
+
+    def set(self, key, newval):
+        return self.__setitem__(key, newval)
+
+    def update(self, new_conf):
+        """
+        Load an XML file and apply its map as overrides or additions
+        to the existing config.  Update can be a file or a dict.
+
+        Once any key/value pair is changed via the update method,
+        that key/value pair will remain set with that value until
+        change via the update or set method
+        """
+        if isinstance(new_conf, dict):
+            overrides = new_conf
+        else:
+            # assuming that it is a filename
+            config_file = open(new_conf)
+            overrides = llsd.parse(config_file.read())
+            config_file.close()
+  
+        self._config_overrides.update(overrides)
+        self._combine_dictionaries()
+
+    def as_dict(self):
+        """
+        Returns immutable copy of the IndraConfig as a dictionary
+        """
+        return copy.deepcopy(self._combined_dict)
+
+def load(config_xml_file = None):
+    global _g_config
+
+    load_default_files = config_xml_file is None
+    if load_default_files:
+        ## going from:
+        ## "/opt/linden/indra/lib/python/indra/base/config.py"
+        ## to:
+        ## "/opt/linden/etc/indra.xml"
+        config_xml_file = realpath(
+            dirname(realpath(__file__)) + "../../../../../../etc/indra.xml")
+
+    try:
+        _g_config = IndraConfig(config_xml_file)
+    except IOError:
+        # Failure to load passed in file
+        # or indra.xml default file
+        if load_default_files:
+            try:
+                config_xml_file = realpath(
+                    dirname(realpath(__file__)) + "../../../../../../etc/globals.xml")
+                _g_config = IndraConfig(config_xml_file)
+                return
+            except IOError:
+                # Failure to load globals.xml
+                # fall to code below
+                pass
+
+        # Either failed to load passed in file
+        # or failed to load all default files
+        _g_config = IndraConfig(None)
+
+def dump(indra_xml_file, indra_cfg = None, update_in_mem=False):
+    '''
+    Dump config contents into a file
+    Kindof reverse of load.
+    Optionally takes a new config to dump.
+    Does NOT update global config unless requested.
+    '''
+    global _g_config
+
+    if not indra_cfg:
+        if _g_config is None:
+            return
+
+        indra_cfg = _g_config.as_dict()
+
+    if not indra_cfg:
+        return
+
+    config_file = open(indra_xml_file, 'w')
+    _config_xml = llsd.format_xml(indra_cfg)
+    config_file.write(_config_xml)
+    config_file.close()
+
+    if update_in_mem:
+        update(indra_cfg)
+
+def update(new_conf):
+    global _g_config
+
+    if _g_config is None:
+        # To keep with how this function behaved
+        # previously, a call to update
+        # before the global is defined
+        # make a new global config which does not
+        # load data from a file.
+        _g_config = IndraConfig(None)
+
+    return _g_config.update(new_conf)
+
+def get(key, default = None):
+    global _g_config
+
+    if _g_config is None:
+        load()
+
+    return _g_config.get(key, default)
+
+def set(key, newval):
+    """
+    Sets the value of the config setting of key to be newval
+
+    Once any key/value pair is changed via the set method,
+    that key/value pair will remain set with that value until
+    change via the update or set method or program termination
+    """
+    global _g_config
+
+    if _g_config is None:
+        _g_config = IndraConfig(None)
+
+    _g_config.set(key, newval)
+
+def get_config():
+    global _g_config
+    return _g_config