"This simplifies implementation of mutation_partition merging by relaxing
exception guarantees it needs to provide. This allows reverters to be dropped.
Direct motivation for this is to make it easier to implement new semantics
for merging of clustering range continuity.
Implementation details:
We only need strong exception guarantees when applying to the memtable, which is
using MVCC. Instead of calling apply() with strong exception guarantees on the latest
version, we will move the incoming mutation to a new partition_version and then
use monotonic apply() to merge them. If that merging fails, we attach the version with
the remainder, which cannot fail. This way apply() always succeeds if the allocation
of partition_version object succeeds.
Results of `perf_simple_query_g -c1 -m1G --write` (high overwrite rate):
Before:
101011.13 tps
102498.07 tps
103174.68 tps
102879.55 tps
103524.48 tps
102794.56 tps
103565.11 tps
103018.51 tps
103494.37 tps
102375.81 tps
103361.65 tps
After:
101785.37 tps
101366.19 tps
103532.26 tps
100834.83 tps
100552.11 tps
100891.31 tps
101752.06 tps
101532.00 tps
100612.06 tps
102750.62 tps
100889.16 tps
Fixes #2012."
* tag 'tgrabiec/drop-reversible-apply-v1' of github.com:scylladb/seastar-dev:
mutation_partition: Drop apply_reversibly()
mutation_partition: Relax exception guarantees of apply()
mutation_partition: Introduce apply_weak()
tests: mvcc: Add test for atomicity of partition_entry::apply()
tests: Move failure_injecting_allocation_strategy to a header
tests: mutation_partition: Test exception guarantees of apply_monotonically()
mvcc: Use apply_monotonically() where sufficient
mvcc: partition_version: Use apply_monotonically() to provide atomicity
mvcc: Extract partition_entry::add_version()
mutation_partition: Introduce apply_monotonically()
mutation_partition: Introduce row::consume_with()
4cfcd8055e