index: TempFileMover now handles the case that the file to move does not exist more gracefully

Added BlockingLockFile which may be used to wait for the lock according to some criteria

2 files changed, 51 insertions, 4 deletions

diff --git a/lib/git/index.py b/lib/git/index.py
index 64a25a70..991c77da 100644
--- a/lib/git/index.py
+++ b/lib/git/index.py
@@ -57,7 +57,11 @@ class _TemporaryFileSwap(object):
 	def __init__(self, file_path):
 		self.file_path = file_path
 		self.tmp_file_path = self.file_path + tempfile.mktemp('','','')
-		os.rename(self.file_path, self.tmp_file_path)
+		# it may be that the source does not exist
+		try:
+			os.rename(self.file_path, self.tmp_file_path)
+		except OSError:
+			pass
 		
 	def __del__(self):
 		if os.path.isfile(self.tmp_file_path):
@@ -556,6 +560,7 @@ class IndexFile(LazyMixin, diff.Diffable):
 			repo.git.read_tree(*arg_list, **kwargs)
 			index = cls(repo, tmp_index)
 			index.entries		# force it to read the file as we will delete the temp-file
+			del(index_handler)	# release as soon as possible
 		finally:
 			if os.path.exists(tmp_index):
 				os.remove(tmp_index)
@@ -763,9 +768,6 @@ class IndexFile(LazyMixin, diff.Diffable):
 		Returns
 			Tree object representing this index
 		"""
-		index_path = self._index_path()
-		tmp_index_mover = _TemporaryFileSwap(index_path)
-		
 		# IMPORTANT: If we have TREE extension data, it will actually 
 		# ignore the index and write the stored tree instead. Hence we 
 		# temporarily forget about it, and in fact I don't know what git 
@@ -776,9 +778,14 @@ class IndexFile(LazyMixin, diff.Diffable):
 			self._extension_data = ''
 		# END extension data special handling
 		
+		index_path = self._index_path()
+		tmp_index_mover = _TemporaryFileSwap(index_path)
+		
 		self.write(index_path)
 		tree_sha = self.repo.git.write_tree(missing_ok=missing_ok)
 		
+		del(tmp_index_mover)	# as soon as possible
+		
 		if stored_ext_data:
 			self._extension_data = stored_ext_data
 		# END reset stored exstension data
diff --git a/lib/git/utils.py b/lib/git/utils.py
index 1a624ca2..b5364c4c 100644
--- a/lib/git/utils.py
+++ b/lib/git/utils.py
@@ -6,6 +6,7 @@
 
 import os
 import sys
+import time
 import tempfile
 
 try:
@@ -172,6 +173,45 @@ class LockFile(object):
 		os.remove(self._lock_file_path())
 		self._owns_lock = False
 
+class BlockingLockFile(LockFile):
+	"""The lock file will block until a lock could be obtained, or fail after 
+	a specified timeout"""
+	__slots__ = ("_check_interval", "_max_block_time")
+	def __init__(self, file_path, check_interval_s=0.3, max_block_time_s=sys.maxint):
+		"""Configure the instance
+		
+		``check_interval_s``
+			Period of time to sleep until the lock is checked the next time.
+			By default, it waits a nearly unlimited time
+		
+		``max_block_time_s``
+			Maximum amount of seconds we may lock
+		"""
+		super(BlockingLockFile, self).__init__(file_path)
+		self._check_interval = check_interval_s
+		self._max_block_time = max_block_time_s
+		
+	def _obtain_lock(self):
+		"""This method blocks until it obtained the lock, or raises IOError if 
+		it ran out of time.
+		If this method returns, you are guranteed to own the lock"""
+		starttime = time.time()
+		maxtime = starttime + float(self._max_block_time)
+		while True:
+			try:
+				self._obtain_lock_or_raise()
+			except IOError:
+				curtime = time.time()
+				if curtime >= maxtime:
+					msg = "Waited %f seconds for lock at %r" % ( maxtime - starttime, self._lock_file_path())
+					raise IOError(msg)
+				# END abort if we wait too long
+				time.sleep(self._check_interval)
+			else:
+				break
+		# END endless loop
+	
+	
 
 class ConcurrentWriteOperation(LockFile):
 	"""