8//===----------------------------------------------------------------------===//
9//
10// This file is a part of XRay, a dynamic runtime instrumentation system.
11//
12//===----------------------------------------------------------------------===//
13#ifndef XRAY_XRAY_RECURSION_GUARD_H
14#define XRAY_XRAY_RECURSION_GUARD_H
15
16#include "sanitizer_common/sanitizer_atomic.h"
17
18namespace __xray {
19
20/// The RecursionGuard is useful for guarding against signal handlers which are
21/// also potentially calling XRay-instrumented functions. To use the
22/// RecursionGuard, you'll typically need a thread_local atomic_uint8_t:
23///
24/// thread_local atomic_uint8_t Guard{0};
25///
26/// // In a handler function:
27/// void handleArg0(int32_t F, XRayEntryType T) {
28/// RecursionGuard G(Guard);
29/// if (!G)
30/// return; // Failed to acquire the guard.
31/// ...
32/// }
33///
34class RecursionGuard {
35 atomic_uint8_t &Running;
36 const bool Valid;
37
38public:
39 explicit inline RecursionGuard(atomic_uint8_t &R)
40 : Running(R), Valid(!atomic_exchange(&R, 1, memory_order_acq_rel)) {}
41
42 inline RecursionGuard(const RecursionGuard &) = delete;
43 inline RecursionGuard(RecursionGuard &&) = delete;
44 inline RecursionGuard &operator=(const RecursionGuard &) = delete;
45 inline RecursionGuard &operator=(RecursionGuard &&) = delete;
46
47 explicit inline operator bool() const { return Valid; }
48
49 inline ~RecursionGuard() noexcept {
50 if (Valid)
51 atomic_store(&Running, 0, memory_order_release);
52 }
53};
54
55} // namespace __xray
56
57#endif // XRAY_XRAY_RECURSION_GUARD_H
| 7//===----------------------------------------------------------------------===//
8//
9// This file is a part of XRay, a dynamic runtime instrumentation system.
10//
11//===----------------------------------------------------------------------===//
12#ifndef XRAY_XRAY_RECURSION_GUARD_H
13#define XRAY_XRAY_RECURSION_GUARD_H
14
15#include "sanitizer_common/sanitizer_atomic.h"
16
17namespace __xray {
18
19/// The RecursionGuard is useful for guarding against signal handlers which are
20/// also potentially calling XRay-instrumented functions. To use the
21/// RecursionGuard, you'll typically need a thread_local atomic_uint8_t:
22///
23/// thread_local atomic_uint8_t Guard{0};
24///
25/// // In a handler function:
26/// void handleArg0(int32_t F, XRayEntryType T) {
27/// RecursionGuard G(Guard);
28/// if (!G)
29/// return; // Failed to acquire the guard.
30/// ...
31/// }
32///
33class RecursionGuard {
34 atomic_uint8_t &Running;
35 const bool Valid;
36
37public:
38 explicit inline RecursionGuard(atomic_uint8_t &R)
39 : Running(R), Valid(!atomic_exchange(&R, 1, memory_order_acq_rel)) {}
40
41 inline RecursionGuard(const RecursionGuard &) = delete;
42 inline RecursionGuard(RecursionGuard &&) = delete;
43 inline RecursionGuard &operator=(const RecursionGuard &) = delete;
44 inline RecursionGuard &operator=(RecursionGuard &&) = delete;
45
46 explicit inline operator bool() const { return Valid; }
47
48 inline ~RecursionGuard() noexcept {
49 if (Valid)
50 atomic_store(&Running, 0, memory_order_release);
51 }
52};
53
54} // namespace __xray
55
56#endif // XRAY_XRAY_RECURSION_GUARD_H
|