// Copyright 2024 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.

#ifndef ABSL_BASE_INTERNAL_TRACING_H_

#define ABSL_BASE_INTERNAL_TRACING_H_

#include "absl/base/config.h"

namespace absl {

ABSL_NAMESPACE_BEGIN

namespace base_internal {

// Well known Abseil object types that have causality.

enum class ObjectKind { kUnknown, kBlockingCounter, kNotification };

// `TraceWait` and `TraceContinue` record the start and end of a potentially

// blocking wait operation on `object`. `object` typically represents a higher

// level synchronization object such as `absl::Notification`.

void TraceWait(const void* object, ObjectKind kind);

void TraceContinue(const void* object, ObjectKind kind);

// `TraceSignal` records a signal on `object`.

void TraceSignal(const void* object, ObjectKind kind);

// `TraceObserved` records the non-blocking observation of a signaled object.

void TraceObserved(const void* object, ObjectKind kind);

// ---------------------------------------------------------------------------

// Weak implementation detail:

//

// We define the weak API as extern "C": in some build configurations we pass

// `--detect-odr-violations` to the gold linker. This causes it to flag weak

// symbol overrides as ODR violations. Because ODR only applies to C++ and not

// C, `--detect-odr-violations` ignores symbols not mangled with C++ names.

// By changing our extension points to be extern "C", we dodge this check.

// ---------------------------------------------------------------------------

extern "C" {

  void ABSL_INTERNAL_C_SYMBOL(AbslInternalTraceWait)(const void* object,

                                                     ObjectKind kind);

  void ABSL_INTERNAL_C_SYMBOL(AbslInternalTraceContinue)(const void* object,

                                                         ObjectKind kind);

  void ABSL_INTERNAL_C_SYMBOL(AbslInternalTraceSignal)(const void* object,

                                                       ObjectKind kind);

  void ABSL_INTERNAL_C_SYMBOL(AbslInternalTraceObserved)(const void* object,

                                                         ObjectKind kind);

}  // extern "C"

inline void TraceWait(const void* object, ObjectKind kind) {

  ABSL_INTERNAL_C_SYMBOL(AbslInternalTraceWait)(object, kind);

}

inline void TraceContinue(const void* object, ObjectKind kind) {

  ABSL_INTERNAL_C_SYMBOL(AbslInternalTraceContinue)(object, kind);

}

inline void TraceSignal(const void* object, ObjectKind kind) {

  ABSL_INTERNAL_C_SYMBOL(AbslInternalTraceSignal)(object, kind);

}

inline void TraceObserved(const void* object, ObjectKind kind) {

  ABSL_INTERNAL_C_SYMBOL(AbslInternalTraceObserved)(object, kind);

}

}  // namespace base_internal

ABSL_NAMESPACE_END

}  // namespace absl

#endif  // ABSL_BASE_INTERNAL_TRACING_H_