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"""
fs.wrapfs.limitsizefs
=====================
An FS wrapper class for limiting the size of the underlying FS.
This module provides the class LimitSizeFS, an FS wrapper that can limit the
total size of files stored in the wrapped FS.
"""
from __future__ import with_statement
from fs.errors import *
from fs.path import *
from fs.base import FS, threading, synchronize
from fs.wrapfs import WrapFS
from fs.filelike import FileWrapper
class LimitSizeFS(WrapFS):
"""FS wrapper class to limit total size of files stored."""
def __init__(self, fs, max_size):
super(LimitSizeFS,self).__init__(fs)
if max_size < 0:
try:
max_size = fs.getmeta("total_space") + max_size
except NoMetaError:
msg = "FS doesn't report total_size; "\
"can't use negative max_size"
raise ValueError(msg)
self.max_size = max_size
self._size_lock = threading.Lock()
self._file_sizes = PathMap()
self.cur_size = self._get_cur_size()
def __getstate__(self):
state = super(LimitSizeFS,self).__getstate__()
del state["cur_size"]
del state["_size_lock"]
del state["_file_sizes"]
return state
def __setstate__(self, state):
super(LimitSizeFS,self).__setstate__(state)
self._size_lock = threading.Lock()
self._file_sizes = PathMap()
self.cur_size = self._get_cur_size()
def _get_cur_size(self,path="/"):
return sum(self.getsize(f) for f in self.walkfiles(path))
def getsyspath(self, path, allow_none=False):
# If people could grab syspaths, they could route around our
# size protection; no dice!
if not allow_none:
raise NoSysPathError(path)
return None
def open(self, path, mode='r', buffering=-1, encoding=None, errors=None, newline=None, line_buffering=False, **kwargs):
path = relpath(normpath(path))
with self._size_lock:
try:
size = self.getsize(path)
except ResourceNotFoundError:
size = 0
f = super(LimitSizeFS,self).open(path,
mode=mode,
buffering=buffering,
errors=errors,
newline=newline,
line_buffering=line_buffering,
**kwargs)
if "w" not in mode:
self._set_file_size(path,None,1)
else:
self.cur_size -= size
size = 0
self._set_file_size(path,0,1)
return LimitSizeFile(f,mode,size,self,path)
def _set_file_size(self,path,size,incrcount=None):
try:
(cursize,count) = self._file_sizes[path]
except KeyError:
count = 0
try:
cursize = self.getsize(path)
except ResourceNotFoundError:
cursize = 0
if size is None:
size = cursize
if count is not None:
count += 1
if count == 0:
del self._file_sizes[path]
else:
self._file_sizes[path] = (size,count)
def setcontents(self, path, data, chunk_size=64*1024):
f = None
try:
f = self.open(path, 'wb')
if hasattr(data, 'read'):
chunk = data.read(chunk_size)
while chunk:
f.write(chunk)
chunk = data.read(chunk_size)
else:
f.write(data)
finally:
if f is not None:
f.close()
def _file_closed(self, path):
self._set_file_size(path,None,-1)
def _ensure_file_size(self, path, size, shrink=False):
with self._size_lock:
try:
(cur_size,_) = self._file_sizes[path]
except KeyError:
try:
cur_size = self.getsize(path)
except ResourceNotFoundError:
cur_size = 0
self._set_file_size(path,cur_size,1)
diff = size - cur_size
if diff > 0:
if self.cur_size + diff > self.max_size:
raise StorageSpaceError("write")
self.cur_size += diff
self._set_file_size(path,size)
return size
elif diff < 0 and shrink:
self.cur_size += diff
self._set_file_size(path,size)
return size
else:
return cur_size
# We force use of several base FS methods,
# since they will fall back to writing out each file
# and thus will route through our size checking logic.
def copy(self, src, dst, **kwds):
FS.copy(self,src,dst,**kwds)
def copydir(self, src, dst, **kwds):
FS.copydir(self,src,dst,**kwds)
def move(self, src, dst, **kwds):
if self.getmeta("atomic.rename",False):
if kwds.get("overwrite",False) or not self.exists(dst):
try:
self.rename(src,dst)
return
except FSError:
pass
FS.move(self, src, dst, **kwds)
def movedir(self, src, dst, **kwds):
overwrite = kwds.get("overwrite",False)
if self.getmeta("atomic.rename",False):
if kwds.get("overwrite",False) or not self.exists(dst):
try:
self.rename(src,dst)
return
except FSError:
pass
FS.movedir(self,src,dst,**kwds)
def rename(self, src, dst):
if self.getmeta("atomic.rename",False):
try:
dst_size = self._get_cur_size(dst)
except ResourceNotFoundError:
dst_size = 0
super(LimitSizeFS,self).rename(src,dst)
with self._size_lock:
self.cur_size -= dst_size
self._file_sizes.pop(src,None)
else:
if self.isdir(src):
self.movedir(src,dst)
else:
self.move(src,dst)
def remove(self, path):
with self._size_lock:
try:
(size,_) = self._file_sizes[path]
except KeyError:
size = self.getsize(path)
super(LimitSizeFS,self).remove(path)
self.cur_size -= size
self._file_sizes.pop(path,None)
def removedir(self, path, recursive=False, force=False):
# Walk and remove directories by hand, so they we
# keep the size accounting precisely up to date.
for nm in self.listdir(path):
if not force:
raise DirectoryNotEmptyError(path)
cpath = pathjoin(path,nm)
try:
if self.isdir(cpath):
self.removedir(cpath,force=True)
else:
self.remove(cpath)
except ResourceNotFoundError:
pass
super(LimitSizeFS,self).removedir(path,recursive=recursive)
def getinfo(self, path):
info = super(LimitSizeFS,self).getinfo(path)
try:
info["size"] = max(self._file_sizes[path][0],info["size"])
except KeyError:
pass
return info
def getsize(self, path):
size = super(LimitSizeFS,self).getsize(path)
try:
size = max(self._file_sizes[path][0],size)
except KeyError:
pass
return size
class LimitSizeFile(FileWrapper):
"""Filelike wrapper class for use by LimitSizeFS."""
def __init__(self, file, mode, size, fs, path):
super(LimitSizeFile,self).__init__(file,mode)
self.size = size
self.fs = fs
self.path = path
self._lock = fs._lock
@synchronize
def _write(self, data, flushing=False):
pos = self.wrapped_file.tell()
new_size = self.fs._ensure_file_size(self.path, pos+len(data))
res = super(LimitSizeFile,self)._write(data, flushing)
self.size = new_size
return res
@synchronize
def _truncate(self, size):
new_size = self.fs._ensure_file_size(self.path,size,shrink=True)
res = super(LimitSizeFile,self)._truncate(size)
self.size = new_size
return res
@synchronize
def close(self):
super(LimitSizeFile,self).close()
self.fs._file_closed(self.path)
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