Kaido Kert | b108943 | 2024-03-18 19:46:49 -0700 | [diff] [blame] | 1 | // Copyright 2022 The Abseil Authors. |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // https://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | // |
| 15 | // ----------------------------------------------------------------------------- |
| 16 | // File: log/internal/conditions.h |
| 17 | // ----------------------------------------------------------------------------- |
| 18 | // |
| 19 | // This file contains implementation of conditional log statements, like LOG_IF |
| 20 | // including all the ABSL_LOG_INTERNAL_..._CONDITION_... macros and |
| 21 | // various condition classes like LogEveryNState. |
| 22 | |
| 23 | #ifndef ABSL_LOG_INTERNAL_CONDITIONS_H_ |
| 24 | #define ABSL_LOG_INTERNAL_CONDITIONS_H_ |
| 25 | |
| 26 | #ifdef _WIN32 |
| 27 | #include <cstdlib> |
| 28 | #else |
| 29 | #include <unistd.h> |
| 30 | #endif |
| 31 | #include <stdlib.h> |
| 32 | |
| 33 | #include <atomic> |
| 34 | #include <cstdint> |
| 35 | |
| 36 | #include "absl/base/attributes.h" |
| 37 | #include "absl/base/config.h" |
| 38 | #include "absl/log/internal/voidify.h" |
| 39 | |
| 40 | // `ABSL_LOG_INTERNAL_CONDITION` prefixes another macro that expands to a |
| 41 | // temporary `LogMessage` instantiation followed by zero or more streamed |
| 42 | // expressions. This definition is tricky to read correctly. It evaluates to |
| 43 | // either |
| 44 | // |
| 45 | // (void)0; |
| 46 | // |
| 47 | // or |
| 48 | // |
| 49 | // ::absl::log_internal::Voidify() && |
| 50 | // ::absl::log_internal::LogMessage(...) << "the user's message"; |
| 51 | // |
| 52 | // If the condition is evaluable at compile time, as is often the case, it |
| 53 | // compiles away to just one side or the other. |
| 54 | // |
| 55 | // Although this is not used anywhere a statement (e.g. `if`) could not go, |
| 56 | // the ternary expression does a better job avoiding spurious diagnostics |
| 57 | // (dangling else, missing switch case) and preserving noreturn semantics (e.g. |
| 58 | // on `LOG(FATAL)`) without requiring braces. |
| 59 | #define ABSL_LOG_INTERNAL_STATELESS_CONDITION(condition) \ |
| 60 | switch (0) \ |
| 61 | case 0: \ |
| 62 | !(condition) ? (void)0 : ::absl::log_internal::Voidify()&& |
| 63 | |
| 64 | // `ABSL_LOG_INTERNAL_STATEFUL_CONDITION` applies a condition like |
| 65 | // `ABSL_LOG_INTERNAL_CONDITION` but adds to that a series of variable |
| 66 | // declarations, including a local static object which stores the state needed |
| 67 | // to implement the stateful macros like `LOG_EVERY_N`. |
| 68 | // |
| 69 | // `for`-loops are used to declare scoped variables without braces (to permit |
| 70 | // streaming into the macro's expansion) and without the dangling-`else` |
| 71 | // problems/diagnostics that come with `if`. |
| 72 | // |
| 73 | // Two more variables are declared in separate `for`-loops: |
| 74 | // |
| 75 | // * `COUNTER` implements a streamable token whose value when streamed is the |
| 76 | // number of times execution has passed through the macro. |
| 77 | // * A boolean flag is used to prevent any of the `for`-loops from ever actually |
| 78 | // looping. |
| 79 | #define ABSL_LOG_INTERNAL_STATEFUL_CONDITION(condition) \ |
| 80 | for (bool absl_log_internal_stateful_condition_do_log(condition); \ |
| 81 | absl_log_internal_stateful_condition_do_log; \ |
| 82 | absl_log_internal_stateful_condition_do_log = false) \ |
| 83 | ABSL_LOG_INTERNAL_STATEFUL_CONDITION_IMPL |
| 84 | #define ABSL_LOG_INTERNAL_STATEFUL_CONDITION_IMPL(kind, ...) \ |
| 85 | for (static ::absl::log_internal::Log##kind##State \ |
| 86 | absl_log_internal_stateful_condition_state; \ |
| 87 | absl_log_internal_stateful_condition_do_log && \ |
| 88 | absl_log_internal_stateful_condition_state.ShouldLog(__VA_ARGS__); \ |
| 89 | absl_log_internal_stateful_condition_do_log = false) \ |
| 90 | for (const uint32_t COUNTER ABSL_ATTRIBUTE_UNUSED = \ |
| 91 | absl_log_internal_stateful_condition_state.counter(); \ |
| 92 | absl_log_internal_stateful_condition_do_log; \ |
| 93 | absl_log_internal_stateful_condition_do_log = false) |
| 94 | |
| 95 | // `ABSL_LOG_INTERNAL_CONDITION_*` serve to combine any conditions from the |
| 96 | // macro (e.g. `LOG_IF` or `VLOG`) with inherent conditions (e.g. |
| 97 | // `ABSL_MIN_LOG_LEVEL`) into a single boolean expression. We could chain |
| 98 | // ternary operators instead, however some versions of Clang sometimes issue |
| 99 | // spurious diagnostics after such expressions due to a control flow analysis |
| 100 | // bug. |
| 101 | #ifdef ABSL_MIN_LOG_LEVEL |
| 102 | #define ABSL_LOG_INTERNAL_CONDITION_INFO(type, condition) \ |
| 103 | ABSL_LOG_INTERNAL_##type##_CONDITION( \ |
| 104 | (condition) && ::absl::LogSeverity::kInfo >= \ |
| 105 | static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL)) |
| 106 | #define ABSL_LOG_INTERNAL_CONDITION_WARNING(type, condition) \ |
| 107 | ABSL_LOG_INTERNAL_##type##_CONDITION( \ |
| 108 | (condition) && ::absl::LogSeverity::kWarning >= \ |
| 109 | static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL)) |
| 110 | #define ABSL_LOG_INTERNAL_CONDITION_ERROR(type, condition) \ |
| 111 | ABSL_LOG_INTERNAL_##type##_CONDITION( \ |
| 112 | (condition) && ::absl::LogSeverity::kError >= \ |
| 113 | static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL)) |
| 114 | // NOTE: Use ternary operators instead of short-circuiting to mitigate |
| 115 | // https://bugs.llvm.org/show_bug.cgi?id=51928. |
| 116 | #define ABSL_LOG_INTERNAL_CONDITION_FATAL(type, condition) \ |
| 117 | ABSL_LOG_INTERNAL_##type##_CONDITION( \ |
| 118 | ((condition) \ |
| 119 | ? (::absl::LogSeverity::kFatal >= \ |
| 120 | static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL) \ |
| 121 | ? true \ |
| 122 | : (::absl::log_internal::AbortQuietly(), false)) \ |
| 123 | : false)) |
| 124 | // NOTE: Use ternary operators instead of short-circuiting to mitigate |
| 125 | // https://bugs.llvm.org/show_bug.cgi?id=51928. |
| 126 | #define ABSL_LOG_INTERNAL_CONDITION_QFATAL(type, condition) \ |
| 127 | ABSL_LOG_INTERNAL_##type##_CONDITION( \ |
| 128 | ((condition) \ |
| 129 | ? (::absl::LogSeverity::kFatal >= \ |
| 130 | static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL) \ |
| 131 | ? true \ |
| 132 | : (::absl::log_internal::ExitQuietly(), false)) \ |
| 133 | : false)) |
| 134 | |
| 135 | #define ABSL_LOG_INTERNAL_CONDITION_LEVEL(severity) \ |
| 136 | for (int log_internal_severity_loop = 1; log_internal_severity_loop; \ |
| 137 | log_internal_severity_loop = 0) \ |
| 138 | for (const absl::LogSeverity log_internal_severity = \ |
| 139 | ::absl::NormalizeLogSeverity(severity); \ |
| 140 | log_internal_severity_loop; log_internal_severity_loop = 0) \ |
| 141 | ABSL_LOG_INTERNAL_CONDITION_LEVEL_IMPL |
| 142 | #define ABSL_LOG_INTERNAL_CONDITION_LEVEL_IMPL(type, condition) \ |
| 143 | ABSL_LOG_INTERNAL_##type##_CONDITION( \ |
| 144 | (condition) && \ |
| 145 | (log_internal_severity >= \ |
| 146 | static_cast<::absl::LogSeverity>(ABSL_MIN_LOG_LEVEL) || \ |
| 147 | (log_internal_severity == ::absl::LogSeverity::kFatal && \ |
| 148 | (::absl::log_internal::AbortQuietly(), false)))) |
| 149 | #else // ndef ABSL_MIN_LOG_LEVEL |
| 150 | #define ABSL_LOG_INTERNAL_CONDITION_INFO(type, condition) \ |
| 151 | ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| 152 | #define ABSL_LOG_INTERNAL_CONDITION_WARNING(type, condition) \ |
| 153 | ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| 154 | #define ABSL_LOG_INTERNAL_CONDITION_ERROR(type, condition) \ |
| 155 | ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| 156 | #define ABSL_LOG_INTERNAL_CONDITION_FATAL(type, condition) \ |
| 157 | ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| 158 | #define ABSL_LOG_INTERNAL_CONDITION_QFATAL(type, condition) \ |
| 159 | ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| 160 | #define ABSL_LOG_INTERNAL_CONDITION_LEVEL(severity) \ |
| 161 | for (int log_internal_severity_loop = 1; log_internal_severity_loop; \ |
| 162 | log_internal_severity_loop = 0) \ |
| 163 | for (const absl::LogSeverity log_internal_severity = \ |
| 164 | ::absl::NormalizeLogSeverity(severity); \ |
| 165 | log_internal_severity_loop; log_internal_severity_loop = 0) \ |
| 166 | ABSL_LOG_INTERNAL_CONDITION_LEVEL_IMPL |
| 167 | #define ABSL_LOG_INTERNAL_CONDITION_LEVEL_IMPL(type, condition) \ |
| 168 | ABSL_LOG_INTERNAL_##type##_CONDITION(condition) |
| 169 | #endif // ndef ABSL_MIN_LOG_LEVEL |
| 170 | |
| 171 | namespace absl { |
| 172 | ABSL_NAMESPACE_BEGIN |
| 173 | namespace log_internal { |
| 174 | |
| 175 | // Stateful condition class name should be "Log" + name + "State". |
| 176 | class LogEveryNState final { |
| 177 | public: |
| 178 | bool ShouldLog(int n); |
| 179 | uint32_t counter() { return counter_.load(std::memory_order_relaxed); } |
| 180 | |
| 181 | private: |
| 182 | std::atomic<uint32_t> counter_{0}; |
| 183 | }; |
| 184 | |
| 185 | class LogFirstNState final { |
| 186 | public: |
| 187 | bool ShouldLog(int n); |
| 188 | uint32_t counter() { return counter_.load(std::memory_order_relaxed); } |
| 189 | |
| 190 | private: |
| 191 | std::atomic<uint32_t> counter_{0}; |
| 192 | }; |
| 193 | |
| 194 | class LogEveryPow2State final { |
| 195 | public: |
| 196 | bool ShouldLog(); |
| 197 | uint32_t counter() { return counter_.load(std::memory_order_relaxed); } |
| 198 | |
| 199 | private: |
| 200 | std::atomic<uint32_t> counter_{0}; |
| 201 | }; |
| 202 | |
| 203 | class LogEveryNSecState final { |
| 204 | public: |
| 205 | bool ShouldLog(double seconds); |
| 206 | uint32_t counter() { return counter_.load(std::memory_order_relaxed); } |
| 207 | |
| 208 | private: |
| 209 | std::atomic<uint32_t> counter_{0}; |
| 210 | // Cycle count according to CycleClock that we should next log at. |
| 211 | std::atomic<int64_t> next_log_time_cycles_{0}; |
| 212 | }; |
| 213 | |
| 214 | // Helper routines to abort the application quietly |
| 215 | |
| 216 | ABSL_ATTRIBUTE_NORETURN inline void AbortQuietly() { abort(); } |
| 217 | ABSL_ATTRIBUTE_NORETURN inline void ExitQuietly() { _exit(1); } |
| 218 | } // namespace log_internal |
| 219 | ABSL_NAMESPACE_END |
| 220 | } // namespace absl |
| 221 | |
| 222 | #endif // ABSL_LOG_INTERNAL_CONDITIONS_H_ |