def open(self, mode = 'rb', agent = None):
"""Open the dentry for reading. Will raise an error if this
dentry is not a regular file.
:param str mode: open mode, must be either 'r' or 'rb'
:param PoolAgent agent: a pool agent to use for reading
:rtype: IOBase
"""
if agent is None:
agent = self.agent
io = DentryIO(readahead = agent.readahead(self.hashes))
if mode == 'rb':
return io
elif mode == 'r':
wrapper = TextIOWrapper(io)
wrapper._CHUNK_SIZE = self.chunk_size
return wrapper
else:
return RuntimeError("Unsupported open mode %r" % (mode,))
