* moved more generic code into `common` package

  * silently fail if cache fails
  * load the configuration on module load
  * produce a struct-based representation of the configuration
  * allowing full exception messages for OSErrors (default behavior)
  * added some dependencies specs

svn path=/trunk/packages/sipb-xen-base/; revision=778

diff --git a/debian/control b/debian/control
index 00396d8..59fea99 100644 (file)
--- a/debian/control
+++ b/debian/control
@@ -2,12 +2,12 @@ Source: sipb-xen-base
 Section: base
 Priority: extra
 Maintainer: SIPB Xen Project <sipb-xen@mit.edu>
-Build-Depends: cdbs (>= 0.4.23-1.1), debhelper (>= 4.1.0), python-json (>= 3.4-2), python-yaml (>= 3.05-1andersk1)
+Build-Depends: cdbs (>= 0.4.23-1.1), debhelper (>= 4.1.0)
 Standards-Version: 3.7.2
 
 Package: sipb-xen-base
 Architecture: all
-Depends: ${misc:Depends}, 
+Depends: ${misc:Depends}, python-json (>= 3.4-2), python-yaml (>= 3.05)
 Description: Base configuration required for all SIPB xen servers
  This package includes apt configuration, .k5login and other files that
  should be synchronized among all our servers.

diff --git a/files/usr/sbin/invirt-getconf b/files/usr/sbin/invirt-getconf
index d503dea..ce0dfa6 100755 (executable)
--- a/files/usr/sbin/invirt-getconf
+++ b/files/usr/sbin/invirt-getconf
@@ -1,13 +1,14 @@
 #!/usr/bin/env python
 
 """
-invirt-getconf [-f FILE] KEY prints the configuration the option named KEY from
-the invirt configuration file FILE.  Keys are dot-separated paths into the YAML
+invirt-getconf loads an invirt configuration file (either the original YAML
+source or the faster-to-load JSON cache) and prints the configuration option
+with the given name (key).  Keys are dot-separated paths into the YAML
 configuration tree.  List indexes (0-based) are also treated as path
 components.
 
 (Due to this path language, certain restrictions are placed on the keys used in
-the YAML configuration, e.g. they cannot contain dots.)
+the YAML configuration; e.g., they cannot contain dots.)
 
 Examples:
 
@@ -57,7 +58,7 @@ def main(argv):
             except IndexError: raise invirt_exception(
                     '%s: index %s out of range' % (progress, component))
         print conf
-    except (invirt_exception, OSError), ex:
+    except invirt_exception, ex:
         print >> stderr, ex
         return 1
 

diff --git a/files/usr/share/python-support/sipb-xen-base/invirt/common.py b/files/usr/share/python-support/sipb-xen-base/invirt/common.py
new file mode 100644 (file)
index 0000000..250078e
--- /dev/null
+++ b/files/usr/share/python-support/sipb-xen-base/invirt/common.py
@@ -0,0 +1,41 @@
+import unittest
+
+class struct(object):
+    'A simple namespace object.'
+    def __init__(self, d = {}):
+        'd is the dictionary to update my __dict__ with.'
+        self.__dict__.update(d)
+
+def dicts2struct(x):
+    """
+    Given a tree of lists/dicts, perform a deep traversal to transform all the
+    dicts to structs.
+    """
+    if type(x) == dict:
+        return struct((k, dicts2struct(v)) for k,v in x.iteritems())
+    elif type(x) == list:
+        return [dicts2struct(v) for v in x]
+    else:
+        return x
+
+def wrap(rsrc, func):
+    "Utility to that emulates with Python 2.5's `with closing(rsrc)`."
+    try: return func(rsrc)
+    finally: rsrc.close()
+
+class common_tests(unittest.TestCase):
+    def test_dicts2structs(self):
+        dicts = {
+                'atom': 0,
+                'dict': { 'atom': 'atom', 'list': [1,2,3] },
+                'list': [ 'atom', {'key': 'value'} ]
+                }
+        structs = dicts2struct(dicts)
+        self.assertEqual(structs.atom,        dicts['atom'])
+        self.assertEqual(structs.dict.atom,   dicts['dict']['atom'])
+        self.assertEqual(structs.dict.list,   dicts['dict']['list'])
+        self.assertEqual(structs.list[0],     dicts['list'][0])
+        self.assertEqual(structs.list[1].key, dicts['list'][1]['key'])
+
+if __name__ == '__main__':
+    unittest.main()

diff --git a/files/usr/share/python-support/sipb-xen-base/invirt/config.py b/files/usr/share/python-support/sipb-xen-base/invirt/config.py
index dab9f20..fad48fe 100644 (file)
--- a/files/usr/share/python-support/sipb-xen-base/invirt/config.py
+++ b/files/usr/share/python-support/sipb-xen-base/invirt/config.py
@@ -1,4 +1,5 @@
 import json, yaml
+from invirt.common import *
 from os import error, makedirs
 from os.path import dirname, getmtime
 
@@ -8,11 +9,6 @@ default_cache_path = '/var/lib/invirt/invirt.json'
 try:    default_loader = yaml.CSafeLoader
 except: default_loader = yaml.SafeLoader
 
-def wrap(rsrc, func):
-    "Utility to that emulates with Python 2.5's `with closing(rsrc)`."
-    try: return func(rsrc)
-    finally: rsrc.close()
-
 def load(src_path = default_src_path,
          cache_path = default_cache_path,
          force_refresh = False):
@@ -30,12 +26,19 @@ def load(src_path = default_src_path,
         except OSError: do_refresh  = True
         else:           do_refresh  = src_mtime > cache_mtime
 
+    if not do_refresh:
+        # try reading from the cache first
+        try: cfg = wrap(file(cache_path), lambda f: json.read(f.read()))
+        except: do_refresh = True
+
     if do_refresh:
         # reload the source and regenerate the cache
         cfg = wrap(file(src_path), lambda f: yaml.load(f, default_loader))
-        wrap(file(cache_path, 'w'), lambda f: f.write(json.write(cfg)))
-    else:
-        cfg = wrap(file(cache_path), lambda f: json.read(f.read()))
+        try: wrap(file(cache_path, 'w'), lambda f: f.write(json.write(cfg)))
+        except: pass # silent failure
     return cfg
 
+dicts = load()
+structs = dicts2struct(dicts)
+
 # vim:et:sw=4:ts=4