c91b326d5a
Replace throwing `protocol_exception` with returning it as a result or an exceptional future in the transport server module. The goal is to improve performance. Most of the `protocol_exception` throws were made from `fragmented_temporary_buffer` module, by passing `exception_thrower()` to its `read*` methods. `fragmented_temporary_buffer` is changed so that it now accepts an exception creator, not exception thrower. `fragmented_temporary_buffer_concepts::ExceptionCreator` concept replaced `fragmented_temporary_buffer_concepts::ExceptionThrower` and all methods that have been throwing now return failed result of type `utils::result_with_eptr`. This change is then propagated to the callers. The scope of this patch is `protocol_exception`, so commitlog just calls `.value()` method on the result. If the result failed, that will throw the exception from the result, as defined by `utils::result_with_eptr_throw_policy`. This means that the behavior of commitlog module stays the same. transport server module handles results gracefully. All the caller functions that return non-future value `T` now return `utils::result_with_eptr<T>`. When the caller is a function that returns a future, and it receives failed result, `make_exception_future(std::move(failed_result).value())` is returned. The rest of the callstack up to the transport server `handle_error` function is already working without throwing, and that's how zero throws is achieved. cql3 module changes do the same as transport server module. Benchmark that is not yet merged has commit `67fbe35833e2d23a8e9c2dcb5e04580231d8ec96`, [GitHub diff view](https://github.com/scylladb/scylladb/compare/master...nuivall:scylladb:perf_cql_raw). It uses either read or write query. Command line used: ``` ./build/release/scylla perf-cql-raw --workdir ~/tmp/scylladir --smp 1 --developer-mode 1 --workload write --duration 300 --concurrency 1000 --username cassandra --password cassandra 2>/dev/null ``` The only thing changed across runs is `--workload write`/`--workload read`. Built and run on `release` target. <details> ``` throughput: mean= 36946.04 standard-deviation=1831.28 median= 37515.49 median-absolute-deviation=1544.52 maximum=39748.41 minimum=28443.36 instructions_per_op: mean= 108105.70 standard-deviation=965.19 median= 108052.56 median-absolute-deviation=53.47 maximum=124735.92 minimum=107899.00 cpu_cycles_per_op: mean= 70065.73 standard-deviation=2328.50 median= 69755.89 median-absolute-deviation=1250.85 maximum=92631.48 minimum=66479.36 ⏱ real=5:11.08 user=2:00.20 sys=2:25.55 cpu=85% ``` ``` throughput: mean= 40718.30 standard-deviation=2237.16 median= 41194.39 median-absolute-deviation=1723.72 maximum=43974.56 minimum=34738.16 instructions_per_op: mean= 117083.62 standard-deviation=40.74 median= 117087.54 median-absolute-deviation=31.95 maximum=117215.34 minimum=116874.30 cpu_cycles_per_op: mean= 58777.43 standard-deviation=1225.70 median= 58724.65 median-absolute-deviation=776.03 maximum=64740.54 minimum=55922.58 ⏱ real=5:12.37 user=27.461 sys=3:54.53 cpu=83% ``` ``` throughput: mean= 37107.91 standard-deviation=1698.58 median= 37185.53 median-absolute-deviation=1300.99 maximum=40459.85 minimum=29224.83 instructions_per_op: mean= 108345.12 standard-deviation=931.33 median= 108289.82 median-absolute-deviation=55.97 maximum=124394.65 minimum=108188.37 cpu_cycles_per_op: mean= 70333.79 standard-deviation=2247.71 median= 69985.47 median-absolute-deviation=1212.65 maximum=92219.10 minimum=65881.72 ⏱ real=5:10.98 user=2:40.01 sys=1:45.84 cpu=85% ``` ``` throughput: mean= 38353.12 standard-deviation=1806.46 median= 38971.17 median-absolute-deviation=1365.79 maximum=41143.64 minimum=32967.57 instructions_per_op: mean= 117270.60 standard-deviation=35.50 median= 117268.07 median-absolute-deviation=16.81 maximum=117475.89 minimum=117073.74 cpu_cycles_per_op: mean= 57256.00 standard-deviation=1039.17 median= 57341.93 median-absolute-deviation=634.50 maximum=61993.62 minimum=54670.77 ⏱ real=5:12.82 user=4:10.79 sys=11.530 cpu=83% ``` This shows ~240 instructions per op increase for reads and ~180 instructions per op increase for writes. Tests have been run multiple times, with almost identical results. Each run lasted 300 seconds. Number of operations executed is roughly 38k per second * 300 seconds = 11.4m ops. Update: I have repeated the benchmark with clean state - reboot computer, put in performance mode, rebuild, closed other apps that might affect CPU and disk usage. run count: 5 times before and 5 times after the patch duration: 300 seconds Average write throughput median before patch: 41155.99 Average write throughput median after patch: 42193.22 Median absolute deviation is also lower now, with values in range 350-550, while the previous runs' values were in range 750-1350. </details> Built and run on `release` target. <details> ./build/release/scylla perf-simple-query --smp 1 --duration 300 --concurrency 1000 --enable-cache false --bypass-cache 2>/dev/null ``` throughput: mean= 14910.90 standard-deviation=477.72 median= 14956.73 median-absolute-deviation=294.16 maximum=16061.18 minimum=13198.68 instructions_per_op: mean= 659591.63 standard-deviation=495.85 median= 659595.46 median-absolute-deviation=324.91 maximum=661184.94 minimum=658001.49 cpu_cycles_per_op: mean= 213301.49 standard-deviation=2724.27 median= 212768.64 median-absolute-deviation=1403.85 maximum=225837.15 minimum=208110.12 ⏱ real=5:19.26 user=5:00.22 sys=15.827 cpu=98% ``` ./build/release/scylla perf-simple-query --smp 1 --duration 300 --concurrency 1000 --enable-cache false 2>/dev/null ``` throughput: mean= 93345.45 standard-deviation=4499.00 median= 93915.52 median-absolute-deviation=2764.41 maximum=104343.64 minimum=79816.66 instructions_per_op: mean= 65556.11 standard-deviation=97.42 median= 65545.11 median-absolute-deviation=71.51 maximum=65806.75 minimum=65346.25 cpu_cycles_per_op: mean= 34160.75 standard-deviation=803.02 median= 33927.16 median-absolute-deviation=453.08 maximum=39285.19 minimum=32547.13 ⏱ real=5:03.23 user=4:29.46 sys=29.255 cpu=98% ``` ./build/release/scylla perf-simple-query --smp 1 --duration 300 --concurrency 1000 --enable-cache true 2>/dev/null ``` throughput: mean= 206982.18 standard-deviation=15894.64 median= 208893.79 median-absolute-deviation=9923.41 maximum=232630.14 minimum=127393.34 instructions_per_op: mean= 35983.27 standard-deviation=6.12 median= 35982.75 median-absolute-deviation=3.75 maximum=36008.24 minimum=35952.14 cpu_cycles_per_op: mean= 17374.87 standard-deviation=985.06 median= 17140.81 median-absolute-deviation=368.86 maximum=26125.38 minimum=16421.99 ⏱ real=5:01.23 user=4:57.88 sys=0.124 cpu=98% ``` ./build/release/scylla perf-simple-query --smp 1 --duration 300 --concurrency 1000 --enable-cache false --bypass-cache 2>/dev/null ``` throughput: mean= 16198.26 standard-deviation=902.41 median= 16094.02 median-absolute-deviation=588.58 maximum=17890.10 minimum=13458.74 instructions_per_op: mean= 659752.73 standard-deviation=488.08 median= 659789.16 median-absolute-deviation=334.35 maximum=660881.69 minimum=658460.82 cpu_cycles_per_op: mean= 216070.70 standard-deviation=3491.26 median= 215320.37 median-absolute-deviation=1678.06 maximum=232396.48 minimum=209839.86 ⏱ real=5:17.33 user=4:55.87 sys=18.425 cpu=99% ``` ./build/release/scylla perf-simple-query --smp 1 --duration 300 --concurrency 1000 --enable-cache false 2>/dev/null ``` throughput: mean= 97067.79 standard-deviation=2637.79 median= 97058.93 median-absolute-deviation=1477.30 maximum=106338.97 minimum=87457.60 instructions_per_op: mean= 65695.66 standard-deviation=58.43 median= 65695.93 median-absolute-deviation=37.67 maximum=65947.76 minimum=65547.05 cpu_cycles_per_op: mean= 34300.20 standard-deviation=704.66 median= 34143.92 median-absolute-deviation=321.72 maximum=38203.68 minimum=33427.46 ⏱ real=5:03.22 user=4:31.56 sys=29.164 cpu=99% ``` ./build/release/scylla perf-simple-query --smp 1 --duration 300 --concurrency 1000 --enable-cache true 2>/dev/null ``` throughput: mean= 223495.91 standard-deviation=6134.95 median= 224825.90 median-absolute-deviation=3302.09 maximum=234859.90 minimum=193209.69 instructions_per_op: mean= 35981.41 standard-deviation=3.16 median= 35981.13 median-absolute-deviation=2.12 maximum=35991.46 minimum=35972.55 cpu_cycles_per_op: mean= 17482.26 standard-deviation=281.82 median= 17424.08 median-absolute-deviation=143.91 maximum=19120.68 minimum=16937.43 ⏱ real=5:01.23 user=4:58.54 sys=0.136 cpu=99% ``` </details> Fixes: #24567 This PR is a continuation of #24738 [transport: remove throwing protocol_exception on connection start](https://github.com/scylladb/scylladb/pull/24738). This PR does not solve a burning issue, but is rather an improvement in the same direction. As it is just an enhancement, it should not be backported. Closes scylladb/scylladb#25408 * github.com:scylladb/scylladb: test/cqlpy: add protocol exception tests test/cqlpy: `test_protocol_exceptions.py` refactor message frame building test/cqlpy: `test_protocol_exceptions.py` refactor duplicate code transport: replace `make_frame` throw with return result cql3: remove throwing `protocol_exception` transport: replace throw in validate_utf8 with result_with_exception_ptr return transport: replace throwing protocol_exception with returns utils: add result_with_exception_ptr test/cqlpy: add unknown compression algorithm test case
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