Immune buildout on any networkcache issues.

As fallback shall be always possible make binding really immune to any problems
in networkcache including name errors, api changes, syntax errors, etc.

src/zc/buildout/buildout.py

@@ -51,11 +51,18 @@ import zc.buildout.easy_install
 
 
 try:
-  import slapos.libnetworkcache
-except ImportError:
-  LIBNETWORKCACHE_ENABLED = False
-else:
-  LIBNETWORKCACHE_ENABLED = True
+    try:
+        import slapos.libnetworkcache
+    except ImportError:
+        LIBNETWORKCACHE_ENABLED = False
+    else:
+        LIBNETWORKCACHE_ENABLED = True
+except:
+    import traceback
+    print 'There was problem while trying to import slapos.libnetworkcache:'\
+        '\n%s' % traceback.format_exc()
+    LIBNETWORKCACHE_ENABLED = False
+    print 'Networkcache forced to be disabled.'
 
 realpath = zc.buildout.easy_install.realpath
 

src/zc/buildout/networkcache.py

@@ -19,14 +19,21 @@ import posixpath
 import re
 import shutil
 import urlparse
+import traceback
 
 try:
-    from slapos.libnetworkcache import NetworkcacheClient, UploadError, \
-      DirectoryNotFound
-except ImportError:
+    try:
+        from slapos.libnetworkcache import NetworkcacheClient, UploadError, \
+          DirectoryNotFound
+    except ImportError:
+        LIBNETWORKCACHE_ENABLED = False
+    else:
+        LIBNETWORKCACHE_ENABLED = True
+except:
+    print 'There was problem while trying to import slapos.libnetworkcache:'\
+        '\n%s' % traceback.format_exc()
     LIBNETWORKCACHE_ENABLED = False
-else:
-    LIBNETWORKCACHE_ENABLED = True
+    print 'Networkcache forced to be disabled.'
 
 _md5_re = re.compile(r'md5=([a-f0-9]+)')
 
@@ -37,7 +44,23 @@ def _get_md5_from_url(url):
     return match.group(1)
   return None
 
+def fallback_call(function):
+    """Decorator which disallow to have any problem while calling method"""
+    def wrapper(self, *args, **kwd):
+        """
+        Log the call, and the result of the call
+        """
+        try:
+            return function(self, *args, **kwd)
+        except: # indeed, *any* exception is swallowed
+            print 'There was problem while calling method %r:\n%s' % (
+                function.__name__, traceback.format_exc())
+            return False
+    wrapper.__doc__ = function.__doc__
+    return wrapper
+
 
+@fallback_call
 def get_directory_key(url):
     """Returns directory hash based on url.
 
@@ -51,6 +74,7 @@ def get_directory_key(url):
     return 'slapos-buildout-%s' % urlmd5
 
 
+@fallback_call
 def download_network_cached(dir_url, cache_url, path, url, logger,
                             signature_certificate_list, md5sum=None):
     """Downloads from a network cache provider
@@ -104,6 +128,7 @@ def download_network_cached(dir_url, cache_url, path, url, logger,
     return True
 
 
+@fallback_call
 def upload_network_cached(dir_url, cache_url, external_url, path, logger,
    signature_private_key_file, shacache_cert_file, shacache_key_file,
    shadir_cert_file, shadir_key_file):
@@ -158,6 +183,7 @@ def upload_network_cached(dir_url, cache_url, external_url, path, logger,
     return True
 
 
+@fallback_call
 def get_filename_from_url(url):
     """Inspired how pip get filename from url.
     """