class VersionedFile(object):
"""
Usage example:
versioned_file = VersionedFile(managed_file, backup_dir, max_versions)
versioned_file.checkpoint() # Called before an update is made
versioned_file.undo() # Recover a previous version
versioned_file.checkpoint() # Called before an update is made
versioned_file.redo() # Return to the version before the undo
"""
def __init__(self, filepath, backup_dir, max_versions):
"""
:param str filepath: File path to be managed
:param str backup_dir:
:param int max_versions:
"""
self._filepath = filepath
self._backup_dir = backup_dir
self._max_versions = max_versions
self._checkpoint_history = []
if not os.path.exists(backup_dir):
os.mkdir(backup_dir)
undo_pfx = self._filenamePrefix(UNDO_PREFIX)
self._undo_stack = FileStack(backup_dir, undo_pfx, self._max_versions)
redo_pfx = self._filenamePrefix(REDO_PREFIX)
self._redo_stack = FileStack(backup_dir, redo_pfx, self._max_versions)
def _filenamePrefix(self, pfx):
"""
:param str pfx: prefix in the file extension
Returns the filename prefix
"""
full_name = os.path.split(self._filepath)[1]
filename, ext = os.path.splitext(full_name)
filename_pfx = "%s.%s" % (filename, pfx)
return filename_pfx
def checkpoint(self, id=None):
"""
Create a checkpoint in the undo stack for the current version
of the managed file.
:param str id: record in the checkpoint
"""
self._undo_stack.push(self._filepath)
if not "_checkpoint_history" in dir(self):
self._checkpoint_history = []
self._checkpoint_history.append(id)
def clear(self):
"""
Empty the undo and redo stacks.
"""
self._undo_stack.clear()
self._redo_stack.clear()
def getFilepath(self):
"""
:returns str: filepath
"""
return self._filepath
def getDirectory(self):
"""
:returns str: directory path
"""
return self._backup_dir
def getCheckpointHistory(self):
return self._checkpoint_history
def getMaxVersions(self):
"""
:returns int: maximum depth
"""
return self._max_versions
def undo(self):
"""
Reinstates the last verion of the file
:raises RuntimeError: undo stack is empty
"""
if self._undo_stack.isEmpty():
raise RuntimeError("Undo stack is empty.")
self._redo_stack.push(self._filepath)
self._undo_stack.pop(self._filepath)
pass
def redo(self):
"""
Undoes the last undo
:raises RuntimeError: undo stack is empty
"""
if self._redo_stack.isEmpty():
raise RuntimeError("Redo stack is empty.")
self.checkpoint()
self._redo_stack.pop(self._filepath)
class TestFileStack(unittest.TestCase):
def setUp(self):
if os.path.exists(TEST_DIR):
shutil.rmtree(TEST_DIR)
os.mkdir(TEST_DIR)
self._writeManagedFile(0)
self.stack = FileStack(TEST_DIR, FILENAME_PFX,
max_depth=MAX_DEPTH)
def _writeManagedFile(self, value):
writeFile(TEST_FILEPATH, value)
def _populateStack(self, size):
"""
Creates the specified number of files in the stack
with values 1 through size.
:param int size: number of stack files to create
"""
for idx in range(1, size+1):
filepath = self.stack._makeFilepath(idx)
writeFile(filepath, idx)
def testMakeFilepath(self):
filepath = self.stack._makeFilepath(1)
self.assertEqual(filepath, "/tmp/file_stack/file_stack.t01")
filepath = self.stack._makeFilepath(10)
self.assertEqual(filepath, "/tmp/file_stack/file_stack.t10")
def testGetFilepaths(self):
filepaths = self.stack._getFilepaths()
self.assertEqual(len(filepaths), 0)
self._populateStack(MAX_DEPTH)
filepaths = self.stack._getFilepaths()
self.assertEqual(len(filepaths), MAX_DEPTH)
filepath = self.stack._makeFilepath(3)
# Removing the 3rd file should cause files, 4, 5 to be deleted
os.remove(filepath)
filepaths = self.stack._getFilepaths()
self.assertEqual(len(filepaths), 2)
for sfx in range(3, MAX_DEPTH+1):
filepath = self.stack._makeFilepath(sfx)
self.assertFalse(os.path.exists(filepath))
def testGetTop(self):
filepath = self.stack._getTop()
self.assertIsNone(filepath)
self._populateStack(MAX_DEPTH)
filepath = self.stack._getTop()
expected_filepath = self.stack._makeFilepath(1)
self.assertEqual(filepath, expected_filepath)
def testClear(self):
self._populateStack(MAX_DEPTH)
filepaths = self.stack._getFilepaths()
self.assertEqual(len(filepaths), MAX_DEPTH)
self.stack.clear()
filepaths = self.stack._getFilepaths()
self.assertEqual(len(filepaths), 0)
def _testAdjustStackDown(self, size):
self.stack.clear()
self._populateStack(size)
self.stack._adjustStack(is_move_down=True)
filepaths = self.stack._getFilepaths()
if size > 0:
limit = min(size+1, MAX_DEPTH)
else:
limit = 0
self.assertEqual(len(filepaths), limit)
for idx in range(2, size+1):
filepath = self.stack._makeFilepath(idx)
self.assertTrue(checkFilepathValue(filepath, idx-1))
def testAdjustStackDown(self):
self._testAdjustStackDown(MAX_DEPTH-1)
self._testAdjustStackDown(MAX_DEPTH)
self._testAdjustStackDown(0)
self._testAdjustStackDown(2)
def _testAdjustStackUp(self, size):
self.stack.clear()
self._populateStack(size)
self.stack._adjustStack(is_move_down=False)
filepaths = self.stack._getFilepaths()
limit = max(0, size - 1)
self.assertEqual(len(filepaths), limit)
for idx in range(1, size-1):
filepath = self.stack._makeFilepath(idx)
self.assertTrue(checkFilepathValue(filepath, idx+1))
def testAdjustStackUp(self):
self._testAdjustStackUp(0)
self._testAdjustStackUp(MAX_DEPTH)
self._testAdjustStackUp(1)
def testGetDepth(self):
self._populateStack(0)
self.assertEqual(self.stack.getDepth(), 0)
self.stack.clear()
self._populateStack(MAX_DEPTH)
self.assertEqual(self.stack.getDepth(), MAX_DEPTH)
self.stack.clear()
self._populateStack(1)
self.assertEqual(self.stack.getDepth(), 1)
def testIsEmpty(self):
self.assertTrue(self.stack.isEmpty())
self._populateStack(1)
self.assertFalse(self.stack.isEmpty())
self._populateStack(MAX_DEPTH)
self.assertFalse(self.stack.isEmpty())
self.stack.clear()
self.assertTrue(self.stack.isEmpty())
def _testPop(self, size):
self.stack.clear()
self._populateStack(size)
self.stack.pop(TEST_FILEPATH)
self.assertTrue(checkFilepathValue(TEST_FILEPATH, 1))
filepaths = self.stack._getFilepaths()
limit = max(0, size-1)
self.assertEqual(len(filepaths), limit)
for idx in range(1, size):
filepath = self.stack._makeFilepath(idx)
self.assertTrue(checkFilepathValue(filepath, idx+1))
def testPop(self):
self._testPop(2)
with self.assertRaises(ValueError):
self._testPop(0)
self._testPop(MAX_DEPTH)
def _testPush(self, size):
self.stack.clear()
self._populateStack(size)
self.stack.push(TEST_FILEPATH)
self.assertTrue(checkFilepathValue(TEST_FILEPATH, 0))
filepaths = self.stack._getFilepaths()
limit = min(MAX_DEPTH, size+1)
self.assertEqual(len(filepaths), limit)
for idx in range(1, size):
filepath = self.stack._makeFilepath(idx)
self.assertTrue(checkFilepathValue(filepath, idx-1))
def testPush(self):
self._testPush(2)
self._testPush(0)
self._testPush(MAX_DEPTH)