Some subscribers are allocated statically, so it is a churn to make
shared pointers from them. And since registered subscribers have to be
unregister before been destroyed anyway there is no lifetime issue here
that require use of a smart pointer.
Starting with LZ4, the default compressor.
Stub functions were added to other compression algorithms, which should
eventually be replaced with an actual implementation.
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Reviewed-by: Nadav Har'El <nyh@cloudius-systems.com>
This automatically exposes them in partition_key and clustering_key too.
The iterators return bytes_view to components.
For example:
schema s;
partition_key k;
for (bytes_view component : boost::make_iterator_range(key.begin(s), key.end(s))) {
// ...
}
The 'bool' type doesn't hold any meaning on its own, which makes the
template instantiation sites not very readable:
tuple_type<true>
To improve that, we can introduce an enum class which is meaningful in
every context:
tuple_type<allow_prefixes::yes>
Origin is using CompositeType to serialize composite keys and that
type is using 16-bit integer to encode the length. If it's enough for
Origin, it's enough for us.
In Java it is possible to create an object by knowing its class name in
runtime. Replication strategies are created this way (I presume class
name comes from configuration somehow), so when I translated the code to
urchin I wrote replication_strategy_registry class to map a class name to
a factory function. Now I see that this is used in other places too (I
see that snitch class created in the same way), so instead of repeating
the same code for each class hierarchy that is created from its name in
origin this patch tries to introduce an infrastructure to do that easily.
Signed-off-by: Avi Kivity <avi@cloudius-systems.com>
This gives about 30% increase in tps in:
build/release/tests/perf/perf_simple_query -c1 --query-single-key
This patch switches query result format from a structured one to a
serialized one. The problems with structured format are:
- high level of indirection (vector of vectors of vectors of blobs), which
is not CPU cache friendly
- high allocation rate due to fine-grained object structure
On replica side, the query results are probably going to be serialized
in the transport layer anyway, so this change only subtracts
work. There is no processing of the query results on replica other
than concatenation in case of range queries. If query results are
collected in serialized form from different cores, we can concatenate
them without copying by simply appending the fragments into the
packet. This optimization is not implemented yet.
On coordinator side, the query results would have to be parsed from
the transport layer buffers anyway, so this also doesn't add work, but
again saves allocations and copying. The CQL server doesn't need
complex data structures to process the results, it just goes over it
linearly consuming it. This patch provides views, iterators and
visitors for consuming query results in serialized form. Currently the
iterators assume that the buffer is contiguous but we could easily
relax this in future so that we can avoid linearization of data
received from seastar sockets.
The coordinator side could be optimized even further for CQL queries
which do not need processing (eg. select * from cf where ...) we
could make the replica send the query results in the format which is
expected by the CQL binary protocol client. So in the typical case the
coordinator would just pass the data using zero-copy to the client,
prepending a header.
We do need structure for prefetched rows (needed by list
manipulations), and this change adds query result post-processing
which converts serialized query result into a structured one, tailored
particularly for prefetched rows needs.
This change also introduces partition_slice options. In some queries
(maybe even in typical ones), we don't need to send partition or
clustering keys back to the client, because they are already specified
in the query request, and not queried for. The query results hold now
keys as optional elements. Also, meta-data like cell timestamp and
ttl is now also optional. It is only needed if the query has
writetime() or ttl() functions in it, which it typically won't have.
