kamcheungting-db commented on code in PR #723: URL: https://github.com/apache/iceberg-cpp/pull/723#discussion_r3447688468
########## src/iceberg/logging/logger.h: ########## @@ -0,0 +1,213 @@ +/* + * 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. + */ + +#pragma once + +/// \file iceberg/logging/logger.h +/// \brief Pluggable logging interface, the process-global default logger, and +/// the logging macros. +/// +/// This header is backend-agnostic: it never includes the build-generated +/// backend configuration header and never references the spdlog feature macro, +/// so consumers see one stable API regardless of how the backend was configured. + +#include <cstdlib> +#include <format> +#include <memory> +#include <source_location> +#include <string> +#include <string_view> +#include <unordered_map> +#include <utility> +#include <vector> + +#include "iceberg/iceberg_export.h" +#include "iceberg/logging/log_level.h" +#include "iceberg/result.h" + +namespace iceberg { + +/// \brief A structured key/value attribute attached to a log record. +/// +/// Both key and value are owned so a sink may retain the record safely. +/// Unused in v1; reserved so structured logging can be added without an ABI +/// break to LogMessage. +struct LogAttribute { + std::string key; + std::string value; +}; + +/// \brief A single log record handed to a Logger. +/// +/// The formatted message is owned (moved in by the logging macros), so a sink +/// may safely retain the record beyond the Log() call. The member set must not +/// depend on the build's logging backend (the spdlog backend never appears here). +struct LogMessage { + LogLevel level = LogLevel::kOff; + std::string message; + std::source_location location = std::source_location::current(); + std::vector<LogAttribute> attributes; +}; + +/// \brief Well-known Logger::Initialize() property keys. +/// +/// `level` is honored by the base Logger::Initialize (parsed via +/// LogLevelFromString). `pattern` is honored by the formatting sinks +/// (CerrLogger, SpdLogger). +inline constexpr std::string_view kLevelProperty = "level"; +inline constexpr std::string_view kPatternProperty = "pattern"; + +/// \brief Pluggable logging sink. +/// +/// ShouldLog() is the single authority for runtime filtering -- the macros call +/// it on every (compile-time-enabled) statement, so level changes by any path +/// take effect immediately. Implementations must be thread-safe and must not +/// throw. They must also obey: +/// - No reentrancy: Log()/Flush() must not call the logging macros or +/// GetDefaultLogger() (UB -- deadlock with mutex-based sinks). +/// - level() is an accessor consistent with ShouldLog (used by SetDefaultLevel +/// and introspection); ShouldLog may implement finer logic than a level compare. +class ICEBERG_EXPORT Logger { + public: + virtual ~Logger() = default; + + /// \brief Property-based setup, called by Loggers::Load() before first use. + /// + /// The base implementation applies the "level" property (parsed via + /// LogLevelFromString); an unrecognized value is an InvalidArgument error. + /// Formatting sinks override this to also apply "pattern" and then delegate + /// to this base for "level". + virtual Status Initialize( + const std::unordered_map<std::string, std::string>& properties) { + if (auto it = properties.find(std::string(kLevelProperty)); it != properties.end()) { + auto parsed = LogLevelFromString(it->second); + if (!parsed) return std::unexpected(parsed.error()); + SetLevel(*parsed); + } + return {}; + } + + /// \brief Cheap check whether a record at \p level would be emitted. + virtual bool ShouldLog(LogLevel level) const = 0; + + /// \brief Emit one (already-formatted) record, taking ownership. Must not throw. + virtual void Log(LogMessage&& message) noexcept = 0; + + /// \brief Set the minimum level this logger emits. + virtual void SetLevel(LogLevel level) = 0; + + /// \brief Return the minimum level this logger emits. + virtual LogLevel level() const = 0; + + /// \brief Flush any buffered output. Must not throw; best-effort on the fatal path. + virtual void Flush() noexcept {} + + /// \brief Return true if this logger is a no-op. + virtual bool IsNoop() const { return false; } + + /// \brief Return a shared, immortal no-op logger singleton. + static std::shared_ptr<Logger> Noop(); +}; + +/// \brief Return the process-global default logger (never null). +/// +/// Off the hot path -- acquires the slot lock and returns an owning copy. The +/// logging macros use the cheaper internal hot-path accessor instead. +ICEBERG_EXPORT std::shared_ptr<Logger> GetDefaultLogger(); Review Comment: Done -- This is an automated message from the Apache Git Service. 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