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e277f747bd
Introduce `read_from_collection_cell_view()` which reads a `collection_mutation` directly from the IDL representation of a collection (`ser::collection_cell_view`). This cuts down the number of allocations required drastically compared to the current method of:
IDL -> collection_mutatio_description -> collection_mutation
Reduces the number of allocations to unfreeze a collection from O(collection_cell_count) -> O(1) (actually, due to buffer fragmentation, it is O(collection_size)).
The new method is used when unfreezing frozen mutations and frozen mutation fragments. This is on the hot path: all writes with collections benefit.
Add a `--collection` flag to `perf-simple-query` to allow measuring the performance improvement of this PR.
With `dbuild -it -- build/release/scylla perf-simple-query --collection=16 -c1 -m2G --default-log-level=error --write` the number of allocations drop from ~123 to 102, which is a significant amount of allocations shaved off.
Refs: https://github.com/scylladb/scylladb/issues/3602 (solves one use-case out of the many listed therein)
Fixes: SCYLLADB-1046
Fixes: SCYLLADB-1077
Backport: this is an optimization so normally not a backport candidate, but we may have to backport to relieve certain customers
Closes scylladb/scylladb#29033
* github.com:scylladb/scylladb:
test/perf/perf_simple_query: add --collection=N
test/boost/frozen_mutation_test: add freeze/unfreeze test for large collections
mutation/mutation_partition_view: use read_from_collection_cell_view() to read collections
mutation/collection_mutation: introduce read_from_collection_cell_view()
mutation/atomic_cell: atomic_cell_type: add write*() and *serialized_size()
mutation/collection_mutation: generalize serialize_collection_mutation
mutation/mutation_partition_view: avoid copying collection
mutation/mutation_partition_view: accept collection_mutation in the consume API
partition_builder: add move variant of accept_*_cell() collection overloads