With the changes introduced in #2981 and #3189, the lifetime management
of the objects used by index_reader became more complicated.
This patchset addresses the immediate problems caused by lack of proper
handling.
The more holistic approach to this will take more time and is to be
implemented under #3220. The current fix, however, should be good
enought as a stop-gap solution.
* 'issues/3213/v3' of https://github.com/argenet/scylla:
Close promoted index streams when closing index_readers.
Support proper closing of prepended_input_stream.
buffer_input_stream is a simple input_stream wrapping a single
temporary_buffer.
prepended_input_stream suits for the case when some data has been read
into a buffer and the rest is still in a stream. It accepts a buffer and
a data_source and first reads from the buffer and then, when it ends,
proceeds reading from the data_source.
Signed-off-by: Vladimir Krivopalov <vladimir@scylladb.com>
