wgtmac commented on code in PR #723: URL: https://github.com/apache/iceberg-cpp/pull/723#discussion_r3426361820
########## src/iceberg/logging/logger.cc: ########## @@ -0,0 +1,146 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +#include "iceberg/logging/logger.h" + +#include <atomic> +#include <cstdint> +#include <memory> +#include <mutex> +#include <utility> + +namespace iceberg { + +namespace { + +/// \brief Logger that drops every record. +class NoopLogger final : public Logger { + public: + bool ShouldLog(LogLevel /*level*/) const override { return false; } + void Log(LogMessage&& /*message*/) noexcept override {} + void SetLevel(LogLevel /*level*/) override {} + LogLevel level() const override { return LogLevel::kOff; } + bool IsNoop() const override { return true; } +}; + +/// \brief Construct the process default logger for this build configuration. +/// +/// This block ships only the interface and the no-op logger; the concrete +/// std::cerr and spdlog sinks (and the build-config selection between them) +/// arrive in later blocks, which update this factory. +std::shared_ptr<Logger> MakeDefaultLogger() { return std::make_shared<NoopLogger>(); } + +/// \brief The process-global default-logger slot. +struct DefaultSlot { + std::mutex mtx; + std::shared_ptr<Logger> logger; + // Seeded to 1 so a fresh thread (tls_gen == 0) always refreshes on first use. + std::atomic<uint64_t> gen{1}; + + DefaultSlot() : logger(MakeDefaultLogger()) {} +}; + +/// \brief Immortal (leaked, hence reachable -> LSan-clean) accessor for the slot. +DefaultSlot& Slot() { + static auto* slot = new DefaultSlot(); + return *slot; +} + +} // namespace + +std::shared_ptr<Logger> Logger::Noop() { + // Intentionally leaked: reachable via the function-local static (LSan-clean) + // and never destroyed, so logging during static teardown stays safe. + static auto* instance = new std::shared_ptr<Logger>(std::make_shared<NoopLogger>()); + return *instance; +} + +std::shared_ptr<Logger> GetDefaultLogger() { + DefaultSlot& slot = Slot(); + std::lock_guard<std::mutex> lock(slot.mtx); + return slot.logger; +} + +void SetDefaultLogger(std::shared_ptr<Logger> logger) { + if (!logger) { + logger = Logger::Noop(); + } + DefaultSlot& slot = Slot(); + std::lock_guard<std::mutex> lock(slot.mtx); + slot.logger = std::move(logger); + // Publish the swap; the mutex provides the happens-before, gen is a detector. + slot.gen.fetch_add(1, std::memory_order_relaxed); +} + +void SetDefaultLevel(LogLevel level) { + DefaultSlot& slot = Slot(); + std::lock_guard<std::mutex> lock(slot.mtx); + slot.logger->SetLevel(level); +} + +namespace detail { + +const std::shared_ptr<Logger>& CurrentLogger() noexcept { Review Comment: I think this is still not safe for thread_local teardown. One case: a thread creates another thread_local object first. Then it calls CurrentLogger() in normal code. At thread exit, alive is destroyed before that earlier object. If that earlier object logs in its destructor, we read alive.value after alive is already destroyed. This is UB. The test only checks first use from a TLS destructor. Maybe we need a design without destructible TLS state, or leak the per-thread cache. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
