Fixes#4713
Modifying config files to use sharded storage misses the fact
that extensions are allowed to add non-member config fields to
the main configuration, typically from "extra" config_file
objects.
Unless those "extra" files are broadcast when main file broadcast,
the values will not be readable from other shards.
This patch propagates the broadcast to all other config files
whose entries are in the top level object. This ensures we
always keep data up to date on config reload.
Message-Id: <20190715135851.19948-1-calle@scylladb.com>
Replace the per-shard value we store with an updateable_value_source, which
allows updating it dynamically and allows users to track changes.
The broadcast_to_all_shards() function is augmented to apply modifications
when called on a live system.
Since some of our values are not atomic (strings) and the administrative
information needed to track references to values is also not atomic, we will
need to store them per-shard. To do that we add a vector of per-shard data
to config_file, where each element is itself a vector of configuration items.
Since we need to operate generically on items (copying them from shard to shard)
we store them in a type-erased form.
Only mutable state is stored per-shard.
Currently, the REST API does its own conversion of named_value into json.
This requires it to use the _make_config_values macro to perform iteration
of all config items, since it needs to preserve the concrete type of the item
while iterating, so it can select the correct json conversion.
Since we want to remove that macro, we need to provide a different way to
convert a config item to json. So this patch adds a value_as_json().
To hide json_return_value from the rest of the system, we extend config_type
with a conversion function to handle the details. This usually calls
the json_return_type constructor directly, but when it doesn't have default
translation, it interposes a conversion into a type that json recognizes.
I didn't bother maintaining the existing type names, since they're C++
names which don't make sense for the UI.
Replace stdx::optional and stdx::string_view with the C++ std
counterparts.
Some instances of boost::variant were also replaced with std::variant,
namely those that called seastar::visit.
Scylla now requires GCC 8 to compile.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
Message-Id: <20190108111141.5369-1-duarte@scylladb.com>
Handling all the boost::commandline + YAML stuff.
This patch only provides an external version of these functions,
it does not modify the db::config object. That is for a follow-up
patch.
