| // Copyright 2022 The Abseil Authors. |
| // |
| // Licensed 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 |
| // |
| // https://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. |
| // |
| // ----------------------------------------------------------------------------- |
| // File: log/internal/conditions.h |
| // ----------------------------------------------------------------------------- |
| // |
| // This file contains implementation of conditional log statements, like LOG_IF |
| // including all the ABSL_LOG_INTERNAL_..._CONDITION_... macros and |
| // various condition classes like LogEveryNState. |
| |
| #ifndef ABSL_LOG_INTERNAL_CONDITIONS_H_ |
| #define ABSL_LOG_INTERNAL_CONDITIONS_H_ |
| |
| #if defined(_WIN32) || defined(__hexagon__) |
| #include <cstdlib> |
| #else |
| #include <unistd.h> |
| #endif |
| #include <stdlib.h> |
| |
| #include <atomic> |
| #include <cstdint> |
| |
| #include "absl/base/attributes.h" |
| #include "absl/base/config.h" |
| #include "absl/log/internal/voidify.h" |
| |
| // `ABSL_LOG_INTERNAL_CONDITION` prefixes another macro that expands to a |
| // temporary `LogMessage` instantiation followed by zero or more streamed |
| // expressions. This definition is tricky to read correctly. It evaluates to |
| // either |
| // |
| // (void)0; |
| // |
| // or |
| // |
| // ::absl::log_internal::Voidify() && |
| // ::absl::log_internal::LogMessage(...) << "the user's message"; |
| // |
| // If the condition is evaluable at compile time, as is often the case, it |
| // compiles away to just one side or the other. |
| // |
| // Although this is not used anywhere a statement (e.g. `if`) could not go, |
| // the ternary expression does a better job avoiding spurious diagnostics |
| // (dangling else, missing switch case) and preserving noreturn semantics (e.g. |
| // on `LOG(FATAL)`) without requiring braces. |
| // |
| // The `switch` ensures that this expansion is the beginning of a statement (as |
| // opposed to an expression) and prevents shenanigans like |
| // `AFunction(LOG(INFO))` and `decltype(LOG(INFO))`. The apparently-redundant |
| // `default` case makes the condition more amenable to Clang dataflow analysis. |
| #define ABSL_LOG_INTERNAL_STATELESS_CONDITION(condition) \ |
| switch (0) \ |
| case 0: \ |
| default: \ |
| !(condition) ? (void)0 : ::absl::log_internal::Voidify()&& |
| |
| // `ABSL_LOG_INTERNAL_STATEFUL_CONDITION` applies a condition like |
| // `ABSL_LOG_INTERNAL_STATELESS_CONDITION` but adds to that a series of variable |
| // declarations, including a local static object which stores the state needed |
| // to implement the stateful macros like `LOG_EVERY_N`. |
| // |
| // `for`-loops are used to declare scoped variables without braces (to permit |
| // streaming into the macro's expansion) and without the dangling-`else` |
| // problems/diagnostics that come with `if`. |
| // |
| // Two more variables are declared in separate `for`-loops: |
| // |
| // * `COUNTER` implements a streamable token whose value when streamed is the |
| // number of times execution has passed through the macro. |
| // * A boolean flag is used to prevent any of the `for`-loops from ever actually |
| // looping. |
| #define ABSL_LOG_INTERNAL_STATEFUL_CONDITION(condition) \ |
| for (bool absl_log_internal_stateful_condition_do_log(condition); \ |
| absl_log_internal_stateful_condition_do_log; \ |
| absl_log_internal_stateful_condition_do_log = false) \ |
| ABSL_LOG_INTERNAL_STATEFUL_CONDITION_IMPL |
| #define ABSL_LOG_INTERNAL_STATEFUL_CONDITION_IMPL(kind, ...) \ |
| for (static ::absl::log_internal::Log##kind##State \ |
| absl_log_internal_stateful_condition_state; \ |
| absl_log_internal_stateful_condition_do_log && \ |
| absl_log_internal_stateful_condition_state.ShouldLog(__VA_ARGS__); \ |
| absl_log_internal_stateful_condition_do_log = false) \ |
| for (const uint32_t COUNTER ABSL_ATTRIBUTE_UNUSED = \ |
| absl_log_internal_stateful_condition_state.counter(); \ |
| absl_log_internal_stateful_condition_do_log; \ |
| absl_log_internal_stateful_condition_do_log = false) |
| |
| // `ABSL_LOG_INTERNAL_CONDITION_*` serve to combine any conditions from the |
| // macro (e.g. `LOG_IF` or `VLOG`) with inherent conditions (e.g. |
| // `ABSL_MIN_LOG_LEVEL`) into a single boolean expression. We could chain |
| // ternary operators instead, however some versions of Clang sometimes issue |
| // spurious diagnostics after such expressions due to a control flow analysis |
| // bug. |
| #ifdef ABSL_MIN_LOG_LEVEL |
| #define ABSL_LOG_INTERNAL_CONDITION_INFO(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION( \ |
| (condition) && ::absl::LogSeverity::kInfo >= \ |
| static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL)) |
| #define ABSL_LOG_INTERNAL_CONDITION_WARNING(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION( \ |
| (condition) && ::absl::LogSeverity::kWarning >= \ |
| static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL)) |
| #define ABSL_LOG_INTERNAL_CONDITION_ERROR(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION( \ |
| (condition) && ::absl::LogSeverity::kError >= \ |
| static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL)) |
| // NOTE: Use ternary operators instead of short-circuiting to mitigate |
| // https://bugs.llvm.org/show_bug.cgi?id=51928. |
| #define ABSL_LOG_INTERNAL_CONDITION_FATAL(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION( \ |
| ((condition) \ |
| ? (::absl::LogSeverity::kFatal >= \ |
| static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL) \ |
| ? true \ |
| : (::absl::log_internal::AbortQuietly(), false)) \ |
| : false)) |
| // NOTE: Use ternary operators instead of short-circuiting to mitigate |
| // https://bugs.llvm.org/show_bug.cgi?id=51928. |
| #define ABSL_LOG_INTERNAL_CONDITION_QFATAL(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION( \ |
| ((condition) \ |
| ? (::absl::LogSeverity::kFatal >= \ |
| static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL) \ |
| ? true \ |
| : (::absl::log_internal::ExitQuietly(), false)) \ |
| : false)) |
| #define ABSL_LOG_INTERNAL_CONDITION_DFATAL(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION( \ |
| (ABSL_ASSUME(absl::kLogDebugFatal == absl::LogSeverity::kError || \ |
| absl::kLogDebugFatal == absl::LogSeverity::kFatal), \ |
| (condition) && \ |
| (::absl::kLogDebugFatal >= \ |
| static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL) || \ |
| (::absl::kLogDebugFatal == ::absl::LogSeverity::kFatal && \ |
| (::absl::log_internal::AbortQuietly(), false))))) |
| |
| #define ABSL_LOG_INTERNAL_CONDITION_LEVEL(severity) \ |
| for (int absl_log_internal_severity_loop = 1; \ |
| absl_log_internal_severity_loop; absl_log_internal_severity_loop = 0) \ |
| for (const absl::LogSeverity absl_log_internal_severity = \ |
| ::absl::NormalizeLogSeverity(severity); \ |
| absl_log_internal_severity_loop; absl_log_internal_severity_loop = 0) \ |
| ABSL_LOG_INTERNAL_CONDITION_LEVEL_IMPL |
| #define ABSL_LOG_INTERNAL_CONDITION_LEVEL_IMPL(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION(( \ |
| (condition) && \ |
| (absl_log_internal_severity >= \ |
| static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL) || \ |
| (absl_log_internal_severity == ::absl::LogSeverity::kFatal && \ |
| (::absl::log_internal::AbortQuietly(), false))))) |
| #else // ndef ABSL_MIN_LOG_LEVEL |
| #define ABSL_LOG_INTERNAL_CONDITION_INFO(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| #define ABSL_LOG_INTERNAL_CONDITION_WARNING(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| #define ABSL_LOG_INTERNAL_CONDITION_ERROR(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| #define ABSL_LOG_INTERNAL_CONDITION_FATAL(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| #define ABSL_LOG_INTERNAL_CONDITION_QFATAL(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| #define ABSL_LOG_INTERNAL_CONDITION_DFATAL(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| #define ABSL_LOG_INTERNAL_CONDITION_LEVEL(severity) \ |
| for (int absl_log_internal_severity_loop = 1; \ |
| absl_log_internal_severity_loop; absl_log_internal_severity_loop = 0) \ |
| for (const absl::LogSeverity absl_log_internal_severity = \ |
| ::absl::NormalizeLogSeverity(severity); \ |
| absl_log_internal_severity_loop; absl_log_internal_severity_loop = 0) \ |
| ABSL_LOG_INTERNAL_CONDITION_LEVEL_IMPL |
| #define ABSL_LOG_INTERNAL_CONDITION_LEVEL_IMPL(type, condition) \ |
| ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| #endif // ndef ABSL_MIN_LOG_LEVEL |
| |
| namespace absl { |
| ABSL_NAMESPACE_BEGIN |
| namespace log_internal { |
| |
| // Stateful condition class name should be "Log" + name + "State". |
| class LogEveryNState final { |
| public: |
| bool ShouldLog(int n); |
| uint32_t counter() { return counter_.load(std::memory_order_relaxed); } |
| |
| private: |
| std::atomic<uint32_t> counter_{0}; |
| }; |
| |
| class LogFirstNState final { |
| public: |
| bool ShouldLog(int n); |
| uint32_t counter() { return counter_.load(std::memory_order_relaxed); } |
| |
| private: |
| std::atomic<uint32_t> counter_{0}; |
| }; |
| |
| class LogEveryPow2State final { |
| public: |
| bool ShouldLog(); |
| uint32_t counter() { return counter_.load(std::memory_order_relaxed); } |
| |
| private: |
| std::atomic<uint32_t> counter_{0}; |
| }; |
| |
| class LogEveryNSecState final { |
| public: |
| bool ShouldLog(double seconds); |
| uint32_t counter() { return counter_.load(std::memory_order_relaxed); } |
| |
| private: |
| std::atomic<uint32_t> counter_{0}; |
| // Cycle count according to CycleClock that we should next log at. |
| std::atomic<int64_t> next_log_time_cycles_{0}; |
| }; |
| |
| // Helper routines to abort the application quietly |
| |
| ABSL_ATTRIBUTE_NORETURN inline void AbortQuietly() { abort(); } |
| ABSL_ATTRIBUTE_NORETURN inline void ExitQuietly() { _exit(1); } |
| } // namespace log_internal |
| ABSL_NAMESPACE_END |
| } // namespace absl |
| |
| #endif // ABSL_LOG_INTERNAL_CONDITIONS_H_ |