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18f43fa00e
Introduces a utility function which allows obtaining a pointer to the exception data held behind an std::exception_ptr if the data matches the requested type. It can be used to implement manual but concise try..catch chains. The `try_catch` has the best performance when used with libstdc++ as it uses the stdlib specific functions for simulating a try..catch without having to actually throw. For other stdlibs, the implementation falls back to a throw surrounded by an actual try..catch.
111 lines
2.9 KiB
C++
111 lines
2.9 KiB
C++
/*
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* Copyright 2016-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: AGPL-3.0-or-later
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*/
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#pragma once
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#include <cstddef>
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#if defined(__GLIBCXX__) && (defined(__x86_64__) || defined(__aarch64__))
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#define OPTIMIZED_EXCEPTION_HANDLING_AVAILABLE
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#endif
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#if !defined(NO_OPTIMIZED_EXCEPTION_HANDLING)
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#if defined(OPTIMIZED_EXCEPTION_HANDLING_AVAILABLE)
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#define USE_OPTIMIZED_EXCEPTION_HANDLING
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#else
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#warn "Fast implementation of some of the exception handling routines is not available for this platform. Expect poor exception handling performance."
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#endif
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#endif
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#include <seastar/core/sstring.hh>
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#include <seastar/core/on_internal_error.hh>
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#include <functional>
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#include <system_error>
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#include <type_traits>
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namespace seastar { class logger; }
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typedef std::function<bool (const std::system_error &)> system_error_lambda_t;
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bool check_exception(system_error_lambda_t f);
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bool is_system_error_errno(int err_no);
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bool is_timeout_exception(std::exception_ptr e);
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class storage_io_error : public std::exception {
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private:
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std::error_code _code;
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std::string _what;
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public:
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storage_io_error(std::system_error& e) noexcept
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: _code{e.code()}
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, _what{std::string("Storage I/O error: ") + std::to_string(e.code().value()) + ": " + e.what()}
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{ }
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virtual const char* what() const noexcept override {
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return _what.c_str();
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}
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const std::error_code& code() const { return _code; }
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};
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// Rethrow exception if not null
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//
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// Helps with the common coroutine exception-handling idiom:
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//
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// std::exception_ptr ex;
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// try {
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// ...
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// } catch (...) {
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// ex = std::current_exception();
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// }
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//
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// // release resource(s)
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// maybe_rethrow_exception(std::move(ex));
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//
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// return result;
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//
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inline void maybe_rethrow_exception(std::exception_ptr ex) {
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if (ex) {
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std::rethrow_exception(std::move(ex));
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}
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}
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namespace utils::internal {
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#if defined(OPTIMIZED_EXCEPTION_HANDLING_AVAILABLE)
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void* try_catch_dynamic(std::exception_ptr& eptr, const std::type_info* catch_type) noexcept;
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#endif
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} // utils::internal
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/// If the exception_ptr holds an exception which would match on a `catch (T&)`
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/// clause, returns a pointer to it. Otherwise, returns `nullptr`.
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///
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/// The exception behind the pointer is valid as long as the exception
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/// behind the exception_ptr is valid.
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template<typename T>
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inline T* try_catch(std::exception_ptr& eptr) noexcept {
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static_assert(!std::is_pointer_v<T>, "catching pointers is not supported");
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static_assert(!std::is_lvalue_reference_v<T> && !std::is_rvalue_reference_v<T>,
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"T must not be a reference");
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#if defined(USE_OPTIMIZED_EXCEPTION_HANDLING)
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void* opt_ptr = utils::internal::try_catch_dynamic(eptr, &typeid(std::remove_const_t<T>));
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return reinterpret_cast<T*>(opt_ptr);
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#else
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try {
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std::rethrow_exception(eptr);
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} catch (T& t) {
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return &t;
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} catch (...) {
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}
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return nullptr;
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#endif
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}
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