seafile_ynh/sources/seafile-server-3.1.1/seahub/thirdpart/wsgidav/property_manager.py
Elie 0f063400be Add sources
Former-commit-id: 2e47976ec5
2014-08-06 22:42:37 -04:00

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Python

# (c) 2009-2011 Martin Wendt and contributors; see WsgiDAV http://wsgidav.googlecode.com/
# Original PyFileServer (c) 2005 Ho Chun Wei.
# Licensed under the MIT license: http://www.opensource.org/licenses/mit-license.php
"""
Implements two property managers: one in-memory (dict-based), and one
persistent low performance variant using shelve.
The properties dictionaray is built like::
{ ref-url1: {propname1: value1,
propname2: value2,
},
ref-url2: {propname1: value1,
propname2: value2,
},
}
See `Developers info`_ for more information about the WsgiDAV architecture.
.. _`Developers info`: http://docs.wsgidav.googlecode.com/hg/html/develop.html
"""
from wsgidav import util
import os
import sys
import shelve
from rw_lock import ReadWriteLock
# TODO: comment's from Ian Bicking (2005)
#@@: Use of shelve means this is only really useful in a threaded environment.
# And if you have just a single-process threaded environment, you could get
# nearly the same effect with a dictionary of threading.Lock() objects. Of course,
# it would be better to move off shelve anyway, probably to a system with
# a directory of per-file locks, using the file locking primitives (which,
# sadly, are not quite portable).
# @@: It would probably be easy to store the properties as pickle objects
# in a parallel directory structure to the files you are describing.
# Pickle is expedient, but later you could use something more readable
# (pickles aren't particularly readable)
__docformat__ = "reStructuredText"
_logger = util.getModuleLogger(__name__)
#===============================================================================
# PropertyManager
#===============================================================================
class PropertyManager(object):
"""
An in-memory property manager implementation using a dictionary.
This is obviously not persistent, but should be enough in some cases.
For a persistent implementation, see property_manager.ShelvePropertyManager().
"""
def __init__(self):
self._dict = None
self._loaded = False
self._lock = ReadWriteLock()
self._verbose = 2
def __repr__(self):
return "PropertyManager"
def __del__(self):
if __debug__ and self._verbose >= 2:
self._check()
self._close()
def _lazyOpen(self):
_logger.debug("_lazyOpen()")
self._lock.acquireWrite()
try:
self._dict = {}
self._loaded = True
finally:
self._lock.release()
def _sync(self):
pass
def _close(self):
_logger.debug("_close()")
self._lock.acquireWrite()
try:
self._dict = None
self._loaded = False
finally:
self._lock.release()
def _check(self, msg=""):
try:
if not self._loaded:
return True
# for k in self._dict.keys():
# print "%s" % k
# print " -> %s" % self._dict[k]
# self._dump()
for k, v in self._dict.items():
_ = "%s, %s" % (k, v)
# _logger.debug("%s checks ok %s" % (self.__class__.__name__, msg))
return True
except Exception:
_logger.exception("%s _check: ERROR %s" % (self.__class__.__name__, msg))
# traceback.print_exc()
# raise
# sys.exit(-1)
return False
def _dump(self, msg="", out=None):
if out is None:
out = sys.stdout
print >>out, "%s(%s): %s" % (self.__class__.__name__, self.__repr__(), msg)
if not self._loaded:
self._lazyOpen()
if self._verbose >= 2:
return # Already dumped in _lazyOpen
try:
for k, v in self._dict.items():
print >>out, " ", k
for k2, v2 in v.items():
try:
print >>out, " %s: '%s'" % (k2, v2)
except Exception, e:
print >>out, " %s: ERROR %s" % (k2, e)
out.flush()
except Exception, e:
util.warn("PropertyManager._dump() ERROR: %s" % e)
def getProperties(self, normurl):
_logger.debug("getProperties(%s)" % normurl)
self._lock.acquireRead()
try:
if not self._loaded:
self._lazyOpen()
returnlist = []
if normurl in self._dict:
for propdata in self._dict[normurl].keys():
returnlist.append(propdata)
return returnlist
finally:
self._lock.release()
def getProperty(self, normurl, propname):
_logger.debug("getProperty(%s, %s)" % (normurl, propname))
self._lock.acquireRead()
try:
if not self._loaded:
self._lazyOpen()
if normurl not in self._dict:
return None
# TODO: sometimes we get exceptions here: (catch or otherwise make more robust?)
try:
resourceprops = self._dict[normurl]
except Exception, e:
_logger.exception("getProperty(%s, %s) failed : %s" % (normurl, propname, e))
raise
return resourceprops.get(propname)
finally:
self._lock.release()
def writeProperty(self, normurl, propname, propertyvalue, dryRun=False):
# self._log("writeProperty(%s, %s, dryRun=%s):\n\t%s" % (normurl, propname, dryRun, propertyvalue))
assert normurl and normurl.startswith("/")
assert propname #and propname.startswith("{")
assert propertyvalue is not None
_logger.debug("writeProperty(%s, %s, dryRun=%s):\n\t%s" % (normurl, propname, dryRun, propertyvalue))
if dryRun:
return # TODO: can we check anything here?
self._lock.acquireWrite()
try:
if not self._loaded:
self._lazyOpen()
if normurl in self._dict:
locatordict = self._dict[normurl]
else:
locatordict = {} #dict([])
locatordict[propname] = propertyvalue
# This re-assignment is important, so Shelve realizes the change:
self._dict[normurl] = locatordict
self._sync()
if __debug__ and self._verbose >= 2:
self._check()
finally:
self._lock.release()
def removeProperty(self, normurl, propname, dryRun=False):
"""
Specifying the removal of a property that does not exist is NOT an error.
"""
_logger.debug("removeProperty(%s, %s, dryRun=%s)" % (normurl, propname, dryRun))
if dryRun:
# TODO: can we check anything here?
return
self._lock.acquireWrite()
try:
if not self._loaded:
self._lazyOpen()
if normurl in self._dict:
locatordict = self._dict[normurl]
if propname in locatordict:
del locatordict[propname]
# This re-assignment is important, so Shelve realizes the change:
self._dict[normurl] = locatordict
self._sync()
if __debug__ and self._verbose >= 2:
self._check()
finally:
self._lock.release()
def removeProperties(self, normurl):
_logger.debug("removeProperties(%s)" % normurl)
self._lock.acquireWrite()
try:
if not self._loaded:
self._lazyOpen()
if normurl in self._dict:
del self._dict[normurl]
self._sync()
finally:
self._lock.release()
def copyProperties(self, srcurl, desturl):
_logger.debug("copyProperties(%s, %s)" % (srcurl, desturl))
self._lock.acquireWrite()
try:
if __debug__ and self._verbose >= 2:
self._check()
if not self._loaded:
self._lazyOpen()
if srcurl in self._dict:
self._dict[desturl] = self._dict[srcurl].copy()
self._sync()
if __debug__ and self._verbose >= 2:
self._check("after copy")
finally:
self._lock.release()
def moveProperties(self, srcurl, desturl, withChildren):
_logger.debug("moveProperties(%s, %s, %s)" % (srcurl, desturl, withChildren))
self._lock.acquireWrite()
try:
if __debug__ and self._verbose >= 2:
self._check()
if not self._loaded:
self._lazyOpen()
if withChildren:
# Move srcurl\*
for url in self._dict.keys():
if util.isEqualOrChildUri(srcurl, url):
d = url.replace(srcurl, desturl)
self._dict[d] = self._dict[url]
del self._dict[url]
# print "moveProperties:", url, d
elif srcurl in self._dict:
# Move srcurl only
self._dict[desturl] = self._dict[srcurl]
del self._dict[srcurl]
self._sync()
if __debug__ and self._verbose >= 2:
self._check("after move")
finally:
self._lock.release()
#===============================================================================
# ShelvePropertyManager
#===============================================================================
class ShelvePropertyManager(PropertyManager):
"""
A low performance property manager implementation using shelve
"""
def __init__(self, storagePath):
self._storagePath = os.path.abspath(storagePath)
super(ShelvePropertyManager, self).__init__()
def __repr__(self):
return "ShelvePropertyManager(%s)" % self._storagePath
def _lazyOpen(self):
_logger.debug("_lazyOpen(%s)" % self._storagePath)
self._lock.acquireWrite()
try:
# Test again within the critical section
if self._loaded:
return True
# Open with writeback=False, which is faster, but we have to be
# careful to re-assign values to _dict after modifying them
self._dict = shelve.open(self._storagePath,
writeback=False)
self._loaded = True
if __debug__ and self._verbose >= 2:
self._check("After shelve.open()")
self._dump("After shelve.open()")
finally:
self._lock.release()
def _sync(self):
"""Write persistent dictionary to disc."""
_logger.debug("_sync()")
self._lock.acquireWrite() # TODO: read access is enough?
try:
if self._loaded:
self._dict.sync()
finally:
self._lock.release()
def _close(self):
_logger.debug("_close()")
self._lock.acquireWrite()
try:
if self._loaded:
self._dict.close()
self._dict = None
self._loaded = False
finally:
self._lock.release()