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>
This overload alows searching the elements by an arbitrary key as long as it is "hashable"
to the same values as the default key and if there is a comparator for
this new key.
Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
This class implements an key-value container that is populated
using the provided asynchronous callback.
The value is loaded when there are active references to the value for the given key.
Container ensures that only one entry is loaded per key at any given time.
The returned value is a lw_shared_ptr to the actual value.
The value for a specific key is immediately evicted when there are no
more references to it.
The container is based on the boost::intrusive::unordered_set and is rehashed (grown) if needed
every time a new value is added (asynchronously loaded).
The container has a rehash() method that would grow or shrink the container as needed
in order to get the load factor into the [0.25, 0.75] range.
Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>
