This PR gets rid of exception throws/rethrows on the replica side for writes and single-partition reads. This goal is achieved without using `boost::outcome` but rather by replacing the parts of the code which throw with appropriate seastar idioms and by introducing two helper functions:
1.`try_catch` allows to inspect the type and value behind an `std::exception_ptr`. When libstdc++ is used, this function does not need to throw the exception and avoids the very costly unwind process. This based on the "How to catch an exception_ptr without even try-ing" proposal mentioned in https://github.com/scylladb/scylla/issues/10260.
This function allows to replace the current `try..catch` chains which inspect the exception type and account it in the metrics.
Example:
```c++
// Before
try {
std::rethrow_exception(eptr);
} catch (std::runtime_exception& ex) {
// 1
} catch (...) {
// 2
}
// After
if (auto* ex = try_catch<std::runtime_exception>(eptr)) {
// 1
} else {
// 2
}
```
2. `make_nested_exception_ptr` which is meant to be a replacement for `std::throw_with_nested`. Unlike the original function, it does not require an exception being currently thrown and does not throw itself - instead, it takes the nested exception as an `std::exception_ptr` and produces another `std::exception_ptr` itself.
Apart from the above, seastar idioms such as `make_exception_future`, `co_await as_future`, `co_return coroutine::exception()` are used to propagate exceptions without throwing. This brings the number of exception throws to zero for single partition reads and writes (tested with scylla-bench, --mode=read and --mode=write).
Results from `perf_simple_query`:
```
Before (719724e4df):
Writes:
Normal:
127841.40 tps ( 56.2 allocs/op, 13.2 tasks/op, 50042 insns/op, 0 errors)
Timeouts:
94770.81 tps ( 53.1 allocs/op, 5.1 tasks/op, 78678 insns/op, 1000000 errors)
Reads:
Normal:
138902.31 tps ( 65.1 allocs/op, 12.1 tasks/op, 43106 insns/op, 0 errors)
Timeouts:
62447.01 tps ( 49.7 allocs/op, 12.1 tasks/op, 135984 insns/op, 936846 errors)
After (d8ac4c02bfb7786dc9ed30d2db3b99df09bf448f):
Writes:
Normal:
127359.12 tps ( 56.2 allocs/op, 13.2 tasks/op, 49782 insns/op, 0 errors)
Timeouts:
163068.38 tps ( 52.1 allocs/op, 5.1 tasks/op, 40615 insns/op, 1000000 errors)
Reads:
Normal:
151221.15 tps ( 65.1 allocs/op, 12.1 tasks/op, 43028 insns/op, 0 errors)
Timeouts:
192094.11 tps ( 41.2 allocs/op, 12.1 tasks/op, 33403 insns/op, 960604 errors)
```
Closes#10368
* github.com:scylladb/scylla:
database: avoid rethrows when handling exceptions from commitlog
database: convert throw_commitlog_add_error to use make_nested_exception_ptr
utils: add make_nested_exception_ptr
storage_proxy: don't rethrow when inspecting replica exceptions on write path
database: don't rethrow rate_limit_exception
storage_proxy: don't rethrow the exception in abstract_read_resolver::error
utils/exceptions.cc: don't rethrow in is_timeout_exception
utils/exceptions: add try_catch
utils: add abi/eh_ia64.hh
storage_proxy: don't rethrow exceptions from replicas when accounting read stats
message: get rid of throws in send_message{,_timeout,_abortable}
database/{query,query_mutations}: don't rethrow read semaphore exceptions
957bf48eb2