| //===-- xray_recursion_guard.h ---------------------------------*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // 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 { |
| atomic_uint8_t &Running; |
| const bool Valid; |
| |
| public: |
| explicit inline RecursionGuard(atomic_uint8_t &R) |
| : Running(R), Valid(!atomic_exchange(&R, 1, memory_order_acq_rel)) {} |
| |
| inline RecursionGuard(const RecursionGuard &) = delete; |
| inline RecursionGuard(RecursionGuard &&) = delete; |
| inline RecursionGuard &operator=(const RecursionGuard &) = delete; |
| inline RecursionGuard &operator=(RecursionGuard &&) = delete; |
| |
| explicit inline operator bool() const { return Valid; } |
| |
| inline ~RecursionGuard() noexcept { |
| if (Valid) |
| atomic_store(&Running, 0, memory_order_release); |
| } |
| }; |
| |
| } // namespace __xray |
| |
| #endif // XRAY_XRAY_RECURSION_GUARD_H |