This patch adds the deoverlap function to range.hh, which takes in a
vector of possibly overlapping ranges and returns a vector of
non-overlapping ranges covering the same values.
Signed-off-by: Duarte Nunes <duarte@scylladb.com>
pending_endpoints_for is called frequently by
storage_proxy::create_write_response_handler when doing cql query.
Before this patch, each call to pending_endpoints_for involves
converting a multimap (std::unordered_multimap<range<token>,
inet_address>>) to map (std::unordered_map<range<token>,
std::unordered_set<inet_address>>).
To speed up the token to pending endpoint mapping search, a interval map
is introduced. It is faster than searching the map linearly and can
avoid caching the token/pending endpoint mapping.
With this patch, the operations per second drop during adding node
period gets much better.
Before:
45K to 10K
After:
45k to 38K
(The number is measured with the streaming code skipping to send data to
rule out the streaming factor.)
Refs: #1223
Since bytes is a very generic value that is returned from many calls,
it is easy to pass it by mistake to a function expecting a data_value,
and to get a wrong result. It is impossible for the data_value constructor
to know if the argument is a genuine bytes variable, a data_value of another
type, but serialized, or some other serialized data type.
To prevent misuse, make the data_value(bytes) constructor
(and complementary data_value(optional<bytes>) explicit.
