In a couple of places, where we already have a std::string_view, there
is no need to convert to to a std::string (which requires allocation).
One cool observation (by Piotr Sarna) is that map over std::string_view
is fine, when the strings in the map are always string constants.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
The source file alternator/executor.cc has grown too much, reaching almost
4,000 lines. In this patch I move about 400 lines out of executor.cc:
1. Some functions related to serialization of sets and lists were moved to
serialization.cc,
2. Functions related to evaluating parsed expressions were moved to
expressions.cc.
The header file expressions_eval.hh was also removed - the calculate_value()
functions now live in expressions.cc, so we can just define them in
expressions.hh, no need for a separate header files.
This patch just moves code around. It doesn't make any functional changes.
Refs #5783.
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
The header sits in many other headers, but there's a handy
schema_fwd.hh that's tiny and contains needed declarations
for other headers. So replace shema.hh with schema_fwd.hh
in most of the headers (and remove completely from some).
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Message-Id: <20200303102050.18462-1-xemul@scylladb.com>
We had a get_key_from_typed_value() utility function to decode a
JSON-encoded value with a known type (the JSON encoding is a map whose
key is the type, the value always a string because all possible key types -
string, bytes and number, are encoded as strings).
However, the function was less useful than it could have been - it was
missing one check for a malformed object (a check which only appeared in
one of its callers), it unnecessarily received the column's expected type
(all the callers passed it the given key column's type).
The cleaned up function will be more useful for the following patch
to support KeyConditionExpression, which wants to reuse it.
While at it, this patch also uses rjson::to_string_view(it->value)
instead of the less correct it->value.GetString() (the latter relies
on null-termination, which is actually true for JSON strings, but there
is no reason to rely on it).
Signed-off-by: Nadav Har'El <nyh@scylladb.com>
Message-Id: <20200213192509.32685-3-nyh@scylladb.com>
unwrap_number() is now a public function in serialization.hh instead
of a static function visible only in executor.cc.
Signed-off-by: Dejan Mircevski <dejan@scylladb.com>
Currently the only utility function for getting key bytes
from JSON was to parse a document with the following format:
"key_column_name" : { "key_column_type" : VALUE }.
However, it's also useful to parse only the inner document, i.e.:
{ "key_column_type" : VALUE }.
Profiling alternator implied that JSON parsing takes up a fair amount
of CPU, and as such should be optimized. libjsoncpp is a standard
library for handling JSON objects, but it also proves slower than
rapidjson, which is hereby used instead.
The results indicated that libjsoncpp used roughly 30% of CPU
for a single-shard alternator instance under stress, while rapidjson
dropped that usage to 18% without optimizations.
Future optimizations should include eliding object copying, string copying
and perhaps experimenting with different JSON allocators.
Attributes used to be written into the database in raw JSON format,
which is far from optimal. This patch introduces more robust
serializationi routines for simple alternator types: S, B, BOOL, N.
Serialization uses the first byte to encode attribute type
and follows with serializing data in binary form.
More complex types (sets, lists, etc.) are currently still
serialized in raw JSON and will be optimized in follow-up patches.
Message-Id: <10955606455bbe9165affb8ac8fba4d9e7c3705f.1559646761.git.sarna@scylladb.com>
