Thanks to Petteri Räty <betelgeuse@gentoo.org> for this new cache module which

uses extended attributes (via pyxattr) to attach metadata cache directly to
the ebuild files themselves.

svn path=/main/trunk/; revision=12737

diff --git a/pym/portage/cache/ebuild_xattr.py b/pym/portage/cache/ebuild_xattr.py
new file mode 100644 (file)
index 0000000..83ed8a7
--- /dev/null
+++ b/pym/portage/cache/ebuild_xattr.py
@@ -0,0 +1,163 @@
+# -*- coding: UTF8 -*-
+# Copyright: 2009 Gentoo Foundation
+# Author(s): Petteri Räty (betelgeuse@gentoo.org)
+# License: GPL2
+# $Id$
+
+__all__ = ['database']
+
+from portage.cache import fs_template
+from portage.versions import catsplit
+from portage import cpv_getkey
+from portage.util import writemsg
+import os
+import xattr
+from errno import ENODATA,ENOSPC,E2BIG
+
+class NoValueException(Exception):
+       pass
+
+class database(fs_template.FsBased):
+
+       autocommits = True
+
+       def __init__(self, *args, **config):
+               super(database,self).__init__(*args, **config)
+               self.portdir = self.label
+               self.ns = xattr.NS_USER + '.gentoo.cache'
+               self.keys = set(self._known_keys)
+               self.keys.add('_mtime_')
+               self.keys.add('_eclasses_')
+               # xattrs have an upper length
+               self.max_len = self.__get_max()
+
+       def __get_max(self):
+               path = os.path.join(self.portdir,'profiles/repo_name')
+               try:
+                       return int(self.__get(path,'value_max_len'))
+               except NoValueException,e:
+                       max = self.__calc_max(path)
+                       self.__set(path,'value_max_len',str(max))
+                       return max
+
+       def __calc_max(self,path):
+               """ Find out max attribute length supported by the file system """
+
+               hundred = ''
+               for i in range(100):
+                       hundred+='a'
+
+               s=hundred
+
+               # Could use finally but needs python 2.5 then
+               try:
+                       while True:
+                               self.__set(path,'test_max',s)
+                               s+=hundred
+               except IOError,e:
+                       # ext based give wrong errno
+                       # http://bugzilla.kernel.org/show_bug.cgi?id=12793
+                       if e.errno in (E2BIG,ENOSPC):
+                               result = len(s)-100
+                       else:
+                               raise e
+
+               try:
+                       self.__remove(path,'test_max')
+               except IOError,e:
+                       if e.errno is not ENODATA:
+                               raise e
+
+               return result
+
+       def __get_path(self,cpv):
+               cat,pn = catsplit(cpv_getkey(cpv))
+               return os.path.join(self.portdir,cat,pn,os.path.basename(cpv) + ".ebuild")
+
+       def __has_cache(self,path):
+               try:
+                       self.__get(path,'_mtime_')
+               except NoValueException,e:
+                       return False
+
+               return True
+
+       def __get(self,path,key,default=None):
+               try:
+                       return xattr.get(path,key,namespace=self.ns)
+               except IOError,e:
+                       if not default is None and ENODATA == e.errno:
+                               return default
+                       else:
+                               raise NoValueException()
+
+       def __remove(self,path,key):
+               xattr.remove(path,key,namespace=self.ns)
+
+       def __set(self,path,key,value):
+               xattr.set(path,key,value,namespace=self.ns)
+
+       def _getitem(self, cpv):
+               values = {}
+               path = self.__get_path(cpv)
+               all = {}
+               for tuple in xattr.get_all(path,namespace=self.ns):
+                       key,value = tuple
+                       all[key] = value
+
+               if not '_mtime_' in all:
+                       raise KeyError(cpv)
+
+               # We default to '' like other caches
+               for key in self.keys:
+                       attr_value = all.get(key,'1:')
+                       parts,sep,value = attr_value.partition(':')
+                       parts = int(parts)
+                       if parts > 1:
+                               for i in range(1,parts):
+                                       value += all.get(key+str(i))
+                       values[key] = value
+
+               return values
+
+       def _setitem(self, cpv, values):
+               path = self.__get_path(cpv)
+               max = self.max_len
+               for key,value in values.iteritems():
+                       # mtime comes in as long so need to convert to strings
+                       s = str(value)
+                       # We need to split long values
+                       value_len = len(s)
+                       parts = 0
+                       if value_len > max:
+                               # Find out how many parts we need
+                               parts = value_len/max
+                               if value_len % max > 0:
+                                       parts += 1
+
+                               # Only the first entry carries the number of parts
+                               self.__set(path,key,'%s:%s'%(parts,s[0:max]))
+
+                               # Write out the rest
+                               for i in range(1,parts):
+                                       start = i * max
+                                       val = s[start:start+max]
+                                       self.__set(path,key+str(i),val)
+                       else:
+                               self.__set(path,key,"%s:%s"%(1,s))
+
+       def _delitem(self, cpv):
+               pass # Will be gone with the ebuild
+
+       def __contains__(self, cpv):
+               return os.path.exists(self.__get_path(cpv))
+
+       def __iter__(self):
+               for root,dirs,files in os.walk(self.portdir):
+                       for file in files:
+                               if file[-7:] == '.ebuild':
+                                       cat = os.path.basename(os.path.dirname(root))
+                                       pn_pv = file[:-7]
+                                       path = os.path.join(root,file)
+                                       if self.__has_cache(path):
+                                               yield "%s/%s/%s" % (cat,os.path.basename(root),file[:-7])