That's helpful for the purpose of testing, and leveled compaction may
also end up using size-tiered compaction strategy for selecting
candidates.
Signed-off-by: Raphael S. Carvalho <raphaelsc@cloudius-systems.com>
Instead of requiring the user to subclass a "sstable_creator" class to
specify how to create a new sstable (or in the future, several of them),
switch to an std::function.
In practice, it is much easier to specify a lambda than a class, especialy
since C++11 made it easy to capture variables into lambdas - but not into
local classes.
The "commit()" function is also unnecessary. Then intention there was to
provide a function to "commit" the new sstables (i.e., rename them).
But the caller doesn't need to supply this function - it can just wait
for the future of the end of compaction, and do his own committing code
right then.
Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
This patch adds the basic compaction function sstables::compact_sstables,
which takes a list of input sstables, and creates several (currently one)
merged sstable. This implementation is pretty simple once we have all
the infrastructure in place (combining reader, writer, and a pipe between
them to reduce context switches).
This is already working compaction, but not quite complete: We'll need
to add compaction strategies (which sstables to compact, and when),
better cardinality estimator, sstable management and renaming, and a lot
of other details, and we'll probably still need to change the API.
But we can already write a test for compacting existing sstables (see
the next patch), and I wanted to get this patch out of the way, so we can
start working on applying compaction in a real use case.
Signed-off-by: Nadav Har'El <nyh@cloudius-systems.com>
