51995af258
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_exception_ptr`. 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_exception_ptr_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_exception_ptr<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. Fixes: #24567
18 KiB
18 KiB