// 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_