"
This series introduces frozen_mutation_fragment which can be used to
send mutation_fragments over the wire to a remote node. The main
intended user is going to be the new streaming implementation.
The first part of the series fixes some IDL issues related to empty
structures and variant being the first member of a structure. Both these
problems make the generated code fail to build and they do not, in any
way, affect the existing on-wire protocol.
Logic responsible for freezing and unfreezing of mutation_fragments is
heavily based on the existing code for freezing mutations and shares the
same drawbacks (for example, unnecessary copy during unfreezing). These
preexisting performance problems can be fixed incrementally.
Another performance problem (which affects frozen_mutations as well, but
to a lesser extent) is that since the batching is done at a different
layer each frozen mutation fragment is a separate bytes_ostream object
owning at least one memory buffer. If the mutation fragments are small
this will cause an excessive number of allocations. This could be solved
either by freezing fragments in batches (though it goes against the RPC
layer doing its own batching) or using bytes_ostream or an equivalent
object with a buffer allocation policy more suitable for such use cases.
This also is something that probably could be an incremental fix.
Tests: unit (release)
"
* tag 'frozen_mutation_fragment/v1-rebased' of https://github.com/pdziepak/scylla:
idl: add idl description of frozen_mutation_fragments
tests: add test for frozen_mutation_fragments
frozen_mutation: introduce frozen_mutation_fragment
tests/idl: test variant being the first member of a structure
idl: create variant state in root node
tests/idl: test serialising and deserialising empty structures
idl-compiler: avoid unused variable in empty struct deserialisers
tests/mutation_reader: disambiguate freeze() overload
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