tahoe-lafs/allmydata/bucketstore.py
2006-12-03 03:01:43 -07:00

141 lines
4.2 KiB
Python

import os
from foolscap import Referenceable
from twisted.application import service
from twisted.python.failure import Failure
from allmydata.util import idlib
from zope.interface import implements
from allmydata.interfaces import RIBucketWriter, RIBucketReader
from amdlib.util.assertutil import precondition, _assert
class NoSuchBucketError(Failure):
pass
class BucketStore(service.MultiService, Referenceable):
def __init__(self, store_dir):
precondition(os.path.isdir(store_dir))
service.MultiService.__init__(self)
self._store_dir = store_dir
self._leases = set() # should do weakref dances.
def _get_bucket_dir(self, verifierid):
avid = idlib.b2a(verifierid)
return os.path.join(self._store_dir, avid)
def has_bucket(self, verifierid):
return os.path.exists(self._get_bucket_dir(verifierid))
def allocate_bucket(self, verifierid, bucket_num, size, leaser_credentials):
bucket_dir = self._get_bucket_dir(verifierid)
precondition(not os.path.exists(bucket_dir))
precondition(isinstance(bucket_num, int))
bucket = WriteBucket(bucket_dir, verifierid, bucket_num, size)
bucket.set_leaser(leaser_credentials)
lease = Lease(verifierid, leaser_credentials, bucket)
self._leases.add(lease)
return lease
def get_buckets(self, verifierid):
# for now, only returns those created by this process, in this run
bucket_dir = self._get_bucket_dir(verifierid)
if os.path.exists(bucket_dir):
b = ReadBucket(bucket_dir, verifierid)
br = BucketReader(b)
return [(b.get_bucket_num(), br)]
else:
return []
class Lease(Referenceable):
implements(RIBucketWriter)
def __init__(self, verifierid, leaser, bucket):
self._leaser = leaser
self._verifierid = verifierid
self._bucket = bucket
def get_bucket(self):
return self._bucket
def remote_write(self, data):
self._bucket.write(data)
def remote_close(self):
self._bucket.close()
class BucketReader(Referenceable):
implements(RIBucketReader)
def __init__(self, bucket):
self._bucket = bucket
def remote_get_bucket_num(self):
return self._bucket.get_bucket_num()
def remote_read(self):
return self._bucket.read()
class Bucket:
def __init__(self, bucket_dir, verifierid):
self._bucket_dir = bucket_dir
self._verifierid = verifierid
def _write_attr(self, name, val):
f = file(os.path.join(self._bucket_dir, name), 'wb')
f.write(val)
f.close()
def _read_attr(self, name):
f = file(os.path.join(self._bucket_dir, name), 'rb')
data = f.read()
f.close()
return data
def is_complete(self):
return os.path.exists(os.path.join(self._bucket_dir, 'closed'))
class WriteBucket(Bucket):
def __init__(self, bucket_dir, verifierid, bucket_num, size):
Bucket.__init__(self, bucket_dir, verifierid)
precondition(not os.path.exists(bucket_dir))
os.mkdir(bucket_dir)
self._size = size
self._data = file(os.path.join(self._bucket_dir, 'data'), 'wb')
self._bytes_written = 0
self._write_attr('bucket_num', str(bucket_num))
def set_leaser(self, leaser):
self._write_attr('leases', leaser)
def write(self, data):
precondition(len(data) + self._bytes_written <= self._size)
self._data.write(data)
self._data.flush()
self._bytes_written += len(data)
def close(self):
precondition(self._bytes_written == self._size)
self._data.close()
self._write_attr('closed', '')
def is_complete(self):
complete = Bucket.is_complete(self)
if complete:
_assert(os.path.getsize(os.path.join(self._bucket_dir, 'data')) == self._size)
return complete
class ReadBucket(Bucket):
def __init__(self, bucket_dir, verifierid):
Bucket.__init__(self, bucket_dir, verifierid)
precondition(self.is_complete()) # implicitly asserts bucket_dir exists
def get_bucket_num(self):
return int(self._read_attr('bucket_num'))
def read(self):
return self._read_attr('data')