llvm/compiler-rt/lib/xray/xray_recursion_guard.h

//===-- xray_recursion_guard.h ---------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is a part of XRay, a dynamic runtime instrumentation system.
//
//===----------------------------------------------------------------------===//
#ifndef XRAY_XRAY_RECURSION_GUARD_H
#define XRAY_XRAY_RECURSION_GUARD_H

#include "sanitizer_common/sanitizer_atomic.h"

namespace __xray {

/// The RecursionGuard is useful for guarding against signal handlers which are
/// also potentially calling XRay-instrumented functions. To use the
/// RecursionGuard, you'll typically need a thread_local atomic_uint8_t:
///
///   thread_local atomic_uint8_t Guard{0};
///
///   // In a handler function:
///   void handleArg0(int32_t F, XRayEntryType T) {
///     RecursionGuard G(Guard);
///     if (!G)
///       return;  // Failed to acquire the guard.
///     ...
///   }
///
class RecursionGuard { … };

} // namespace __xray

#endif // XRAY_XRAY_RECURSION_GUARD_H