LibreOffice Module comphelper (master)  1
crashzone.hxx
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1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2 /*
3  * This file is part of the LibreOffice project.
4  *
5  * This Source Code Form is subject to the terms of the Mozilla Public
6  * License, v. 2.0. If a copy of the MPL was not distributed with this
7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
8  */
9 
10 #ifndef INCLUDED_COMPHELPER_CRASHZONE_H
11 #define INCLUDED_COMPHELPER_CRASHZONE_H
12 
13 #include <sal/config.h>
14 
15 #include <atomic>
16 #include <csignal>
17 #include <type_traits>
18 
20 {
23  int const mnAbortAfter;
24 };
25 
32 template <typename Dummy> class CrashZone
33 {
34 // gnEnterCount and gnLeaveCount are accessed both from multiple threads (cf.
35 // WatchdogThread::execute; so need to be of atomic type) and from signal handlers (cf.
36 // VCLExceptionSignal_impl; so need to be of lock-free atomic type). sig_atomic_t is chosen as
37 // the underlying type under the assumption that it is most likely to lead to an atomic type
38 // that is actually lock-free. However, gnEnterCount and gnLeaveCount are both monotonically
39 // increasing, so will eventually overflow, so the underlying type better be unsigned, which
40 // sig_atomic_t is not guaranteed to be:
41 #if !defined ARM32 || (defined ARM32 && defined __ARM_PCS_VFP)
42  using AtomicCounter = std::atomic<std::make_unsigned_t<std::sig_atomic_t>>;
43  static_assert(AtomicCounter::is_always_lock_free);
44 #else
45  using AtomicCounter = volatile std::make_unsigned_t<std::sig_atomic_t>;
46 #endif
47 
49  static inline AtomicCounter gnEnterCount = 0;
51  static inline AtomicCounter gnLeaveCount = 0;
52 
53 public:
54  CrashZone() { enter(); }
55  ~CrashZone() { leave(); }
56  static bool isInZone() { return gnEnterCount != gnLeaveCount; }
57  static const AtomicCounter& enterCount() { return gnEnterCount; }
58  // prefer creating instances to manually calling enter()/leave()
59  static void enter() { gnEnterCount++; }
60  static void leave() { gnLeaveCount++; }
61  // these should be implemented for each specific zone if needed
62  // static void hardDisable();
63  // static const CrashWatchdogTimingsValues& getCrashWatchdogTimingsValues();
64  // static void checkDebug(int nUnchanged, const CrashWatchdogTimingsValues& aTimingValues);
65  // static const char* name();
66 };
67 
68 #endif // INCLUDED_COMPHELPER_CRASHZONE_H
69 
70 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
static const AtomicCounter & enterCount()
Definition: crashzone.hxx:57
A generic class for detecting if a given crash or a lock-up came from a specific area of code (such a...
Definition: crashzone.hxx:32
int mnDisableEntries
delays to take various actions in 1/4 of a second increments.
Definition: crashzone.hxx:22
std::atomic< std::make_unsigned_t< std::sig_atomic_t >> AtomicCounter
Definition: crashzone.hxx:42
static AtomicCounter gnEnterCount
how many times have we entered a zone
Definition: crashzone.hxx:49
static bool isInZone()
Definition: crashzone.hxx:56
static void enter()
Definition: crashzone.hxx:59
static AtomicCounter gnLeaveCount
how many times have we left a new zone
Definition: crashzone.hxx:51
static void leave()
Definition: crashzone.hxx:60