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# Copyright (C) 2012-2013 Aleksey Lim
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import os
import gzip
import zlib
import json
import logging
from cStringIO import StringIO
from types import GeneratorType
from os.path import exists, join, dirname, basename, splitext
from sugar_network import toolkit
from sugar_network.toolkit import coroutine, enforce
# Filename suffix to use for sneakernet synchronization files
_SNEAKERNET_SUFFIX = '.sneakernet'
# Leave at leat n bytes in fs whle calling `encode_to_file()`
_SNEAKERNET_RESERVED_SIZE = 1024 * 1024
_logger = logging.getLogger('node.sync')
def decode(stream):
packet = _PacketsIterator(stream)
while True:
packet.next()
if packet.name == 'last':
break
yield packet
def encode(packets, **header):
return _encode(None, packets, False, header, _EncodingStatus())
def limited_encode(limit, packets, **header):
return _encode(limit, packets, False, header, _EncodingStatus())
def package_decode(stream):
stream = _GzipStream(stream)
package_props = json.loads(stream.readline())
for packet in decode(stream):
packet.props.update(package_props)
yield packet
def package_encode(packets, **header):
# XXX Only for small amount of data
# TODO Support real streaming
buf = StringIO()
zipfile = gzip.GzipFile(mode='wb', fileobj=buf)
header['filename'] = toolkit.uuid() + _SNEAKERNET_SUFFIX
json.dump(header, zipfile)
zipfile.write('\n')
for chunk in _encode(None, packets, False, None, _EncodingStatus()):
zipfile.write(chunk)
zipfile.close()
yield buf.getvalue()
def sneakernet_decode(root, node=None, session=None):
for root, __, files in os.walk(root):
for filename in files:
if not filename.endswith(_SNEAKERNET_SUFFIX):
continue
zipfile = gzip.open(join(root, filename), 'rb')
try:
package_props = json.loads(zipfile.readline())
if node is not None and package_props.get('src') == node:
if package_props.get('session') == session:
_logger.debug('Skip session %r sneakernet package',
zipfile.name)
else:
_logger.debug('Remove outdate %r sneakernet package',
zipfile.name)
os.unlink(zipfile.name)
continue
for packet in decode(zipfile):
packet.props.update(package_props)
yield packet
finally:
zipfile.close()
def sneakernet_encode(packets, root=None, limit=None, path=None, **header):
if path is None:
if not exists(root):
os.makedirs(root)
filename = toolkit.uuid() + _SNEAKERNET_SUFFIX
path = toolkit.unique_filename(root, filename)
else:
filename = splitext(basename(path))[0] + _SNEAKERNET_SUFFIX
if 'filename' not in header:
header['filename'] = filename
if limit <= 0:
stat = os.statvfs(dirname(path))
limit = stat.f_bfree * stat.f_frsize - _SNEAKERNET_RESERVED_SIZE
_logger.debug('Creating %r sneakernet package, limit=%s header=%r',
path, limit, header)
status = _EncodingStatus()
with file(path, 'wb') as package:
zipfile = gzip.GzipFile(fileobj=package)
try:
json.dump(header, zipfile)
zipfile.write('\n')
pos = None
encoder = _encode(limit, packets, True, None, status)
while True:
try:
chunk = encoder.send(pos)
zipfile.write(chunk)
pos = zipfile.fileobj.tell()
coroutine.dispatch()
except StopIteration:
break
except Exception:
_logger.debug('Emergency removing %r package', path)
package.close()
os.unlink(path)
raise
else:
zipfile.close()
package.flush()
os.fsync(package.fileno())
return not status.aborted
class _EncodingStatus(object):
aborted = False
def _encode(limit, packets, download_blobs, header, status):
for packet, props, content in packets:
if status.aborted:
break
if props is None:
props = {}
if header:
props.update(header)
props['packet'] = packet
pos = (yield json.dumps(props) + '\n') or 0
if content is None:
continue
content = iter(content)
try:
record = next(content)
while True:
blob = None
blob_size = 0
if 'blob' in record:
blob = record.pop('blob')
blob_size = record['blob_size']
dump = json.dumps(record) + '\n'
if not status.aborted and limit is not None and \
pos + len(dump) + blob_size > limit:
status.aborted = True
if not isinstance(content, GeneratorType):
raise StopIteration()
record = content.throw(StopIteration())
continue
pos = (yield dump) or 0
if blob is not None:
for chunk in blob:
pos = (yield chunk) or 0
blob_size -= len(chunk)
enforce(blob_size == 0, EOFError,
'File size is not the same as declared')
record = next(content)
except StopIteration:
pass
yield json.dumps({'packet': 'last'}) + '\n'
class _PacketsIterator(object):
def __init__(self, stream):
if not hasattr(stream, 'readline'):
stream.readline = lambda: toolkit.readline(stream)
if hasattr(stream, 'seek'):
self._seek = stream.seek
self._stream = stream
self.props = {}
self._name = None
self._shift = True
@property
def name(self):
return self._name
def next(self):
if self._shift:
for __ in self:
pass
if self._name is None:
raise EOFError()
self._shift = True
def __repr__(self):
return '<SyncPacket %r>' % self.props
def __getitem__(self, key):
return self.props.get(key)
def __iter__(self):
blob = None
while True:
if blob is not None and blob.size_to_read:
self._seek(blob.size_to_read, 1)
blob = None
record = self._stream.readline()
if not record:
self._name = None
raise EOFError()
record = json.loads(record)
if 'packet' in record:
self._name = record['packet'] or ''
self.props = record
self._shift = False
break
blob_size = record.get('blob_size')
if blob_size:
blob = record['blob'] = _Blob(self._stream, blob_size)
yield record
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
pass
# pylint: disable-msg=E0202
def _seek(self, distance, where):
while distance:
chunk = self._stream.read(min(distance, toolkit.BUFFER_SIZE))
distance -= len(chunk)
class _Blob(object):
def __init__(self, stream, size):
self._stream = stream
self.size_to_read = size
def read(self, size=toolkit.BUFFER_SIZE):
chunk = self._stream.read(min(size, self.size_to_read))
self.size_to_read -= len(chunk)
return chunk
class _GzipStream(object):
def __init__(self, stream):
self._stream = stream
self._zip = zlib.decompressobj(16 + zlib.MAX_WBITS)
self._buffer = bytearray()
def read(self, size):
while True:
if size <= len(self._buffer):
result = self._buffer[:size]
self._buffer = self._buffer[size:]
return bytes(result)
chunk = self._stream.read(size)
if not chunk:
result, self._buffer = self._buffer, bytearray()
return result
self._buffer += self._zip.decompress(chunk)
def readline(self):
return toolkit.readline(self)
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