Move LazyMixin type to gitdb, index reading now uses file_contents_ro from gitdb as well

Author: Byron

lib/git/ext/gitdb

@@ -6,7 +6,6 @@
 """Module containing Index implementation, allowing to perform all kinds of index
 manipulations such as querying and merging. """
 import binascii
-import mmap
 import tempfile
 import os
 import sys
@@ -44,7 +43,8 @@
 							IndexFileSHA1Writer, 
 							LazyMixin, 
 							LockedFD, 
-							join_path_native
+							join_path_native, 
+							file_contents_ro
 						)
 
 
@@ -91,19 +91,15 @@ def _set_cache_(self, attr):
 			# try memory map for speed
 			lfd = LockedFD(self._file_path)
 			try:
-				stream = lfd.open(write=False, stream=True)
+				fd = lfd.open(write=False, stream=False)
 			except OSError:
 				lfd.rollback()
 				# in new repositories, there may be no index, which means we are empty
 				self.entries = dict()
 				return
 			# END exception handling
 
-			try:
-				stream = mmap.mmap(stream.fileno(), 0, access=mmap.ACCESS_READ)
-			except Exception:
-				pass
-			# END memory mapping
+			stream = file_contents_ro(fd, stream=True, allow_mmap=True)
 
 			try:
 				self._deserialize(stream)

lib/git/index/base.py

@@ -13,7 +13,9 @@
 	stream_copy,
 	make_sha, 
 	FDStreamWrapper,
-	LockedFD
+	LockedFD, 
+	file_contents_ro, 
+	LazyMixin
 	)
 
 
@@ -274,36 +276,6 @@ def _obtain_lock(self):
 		# END endless loop
 
 
-class LazyMixin(object):
-	"""
-	Base class providing an interface to lazily retrieve attribute values upon 
-	first access. If slots are used, memory will only be reserved once the attribute
-	is actually accessed and retrieved the first time. All future accesses will 
-	return the cached value as stored in the Instance's dict or slot.
-	"""
-	__slots__ = tuple()
-	
-	def __getattr__(self, attr):
-		"""
-		Whenever an attribute is requested that we do not know, we allow it 
-		to be created and set. Next time the same attribute is reqeusted, it is simply
-		returned from our dict/slots.
-		"""
-		self._set_cache_(attr)
-		# will raise in case the cache was not created
-		return object.__getattribute__(self, attr)
-
-	def _set_cache_(self, attr):
-		""" This method should be overridden in the derived class. 
-		It should check whether the attribute named by attr can be created
-		and cached. Do nothing if you do not know the attribute or call your subclass
-		
-		The derived class may create as many additional attributes as it deems 
-		necessary in case a git command returns more information than represented 
-		in the single attribute."""
-		pass
-
-
 class IterableList(list):
 	"""
 	List of iterable objects allowing to query an object by id or by named index::