def __init__(self):
super(PureMemoryDB, self).__init__()
self._db = PureLooseObjectODB("path/doesnt/matter")
# maps 20 byte shas to their OStream objects
self._cache = dict()
class PureMemoryDB(PureObjectDBR, PureObjectDBW):
"""A memory database stores everything to memory, providing fast IO and object
retrieval. It should be used to buffer results and obtain SHAs before writing
it to the actual physical storage, as it allows to query whether object already
exists in the target storage before introducing actual IO
:note: memory is currently not threadsafe, hence the async methods cannot be used
for storing"""
def __init__(self):
super(PureMemoryDB, self).__init__()
self._db = PureLooseObjectODB("path/doesnt/matter")
# maps 20 byte shas to their OStream objects
self._cache = dict()
def set_ostream(self, stream):
raise UnsupportedOperation("PureMemoryDB's always stream into memory")
def store(self, istream):
zstream = ZippedStoreShaWriter()
self._db.set_ostream(zstream)
istream = self._db.store(istream)
zstream.close() # close to flush
zstream.seek(0)
# don't provide a size, the stream is written in object format, hence the
# header needs decompression
decomp_stream = DecompressMemMapReader(zstream.getvalue(), close_on_deletion=False)
self._cache[istream.binsha] = OStream(istream.binsha, istream.type, istream.size, decomp_stream)
return istream
def store_async(self, reader):
raise UnsupportedOperation("PureMemoryDBs cannot currently be used for async write access")
def has_object(self, sha):
return sha in self._cache
def info(self, sha):
# we always return streams, which are infos as well
return self.stream(sha)
def stream(self, sha):
try:
ostream = self._cache[sha]
# rewind stream for the next one to read
ostream.stream.seek(0)
return ostream
except KeyError:
raise BadObject(sha)
# END exception handling
def size(self):
return len(self._cache)
def sha_iter(self):
return self._cache.iterkeys()
# { Interface
def stream_copy(self, sha_iter, odb):
"""Copy the streams as identified by sha's yielded by sha_iter into the given odb
The streams will be copied directly
:note: the object will only be written if it did not exist in the target db
:return: amount of streams actually copied into odb. If smaller than the amount
of input shas, one or more objects did already exist in odb"""
count = 0
for sha in sha_iter:
if odb.has_object(sha):
continue
# END check object existance
ostream = self.stream(sha)
# compressed data including header
sio = StringIO(ostream.stream.data())
istream = IStream(ostream.type, ostream.size, sio, sha)
odb.store(istream)
count += 1
# END for each sha
return count