1 //===--- CrashRecoveryContext.h - Crash Recovery ----------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #ifndef LLVM_SUPPORT_CRASHRECOVERYCONTEXT_H
11 #define LLVM_SUPPORT_CRASHRECOVERYCONTEXT_H
18 class CrashRecoveryContextCleanup;
20 /// \brief Crash recovery helper object.
22 /// This class implements support for running operations in a safe context so
23 /// that crashes (memory errors, stack overflow, assertion violations) can be
24 /// detected and control restored to the crashing thread. Crash detection is
25 /// purely "best effort", the exact set of failures which can be recovered from
26 /// is platform dependent.
28 /// Clients make use of this code by first calling
29 /// CrashRecoveryContext::Enable(), and then executing unsafe operations via a
30 /// CrashRecoveryContext object. For example:
32 /// void actual_work(void *);
35 /// CrashRecoveryContext CRC;
37 /// if (!CRC.RunSafely(actual_work, 0)) {
38 /// ... a crash was detected, report error to user ...
41 /// ... no crash was detected ...
44 /// Crash recovery contexts may not be nested.
45 class CrashRecoveryContext {
47 CrashRecoveryContextCleanup *head;
50 CrashRecoveryContext() : Impl(0), head(0) {}
51 ~CrashRecoveryContext();
53 void registerCleanup(CrashRecoveryContextCleanup *cleanup);
54 void unregisterCleanup(CrashRecoveryContextCleanup *cleanup);
56 /// \brief Enable crash recovery.
59 /// \brief Disable crash recovery.
60 static void Disable();
62 /// \brief Return the active context, if the code is currently executing in a
63 /// thread which is in a protected context.
64 static CrashRecoveryContext *GetCurrent();
66 /// \brief Execute the provide callback function (with the given arguments) in
67 /// a protected context.
69 /// \return True if the function completed successfully, and false if the
70 /// function crashed (or HandleCrash was called explicitly). Clients should
71 /// make as little assumptions as possible about the program state when
72 /// RunSafely has returned false. Clients can use getBacktrace() to retrieve
73 /// the backtrace of the crash on failures.
74 bool RunSafely(void (*Fn)(void*), void *UserData);
76 /// \brief Execute the provide callback function (with the given arguments) in
77 /// a protected context which is run in another thread (optionally with a
78 /// requested stack size).
80 /// See RunSafely() and llvm_execute_on_thread().
81 bool RunSafelyOnThread(void (*Fn)(void*), void *UserData,
82 unsigned RequestedStackSize = 0);
84 /// \brief Explicitly trigger a crash recovery in the current process, and
85 /// return failure from RunSafely(). This function does not return.
88 /// \brief Return a string containing the backtrace where the crash was
89 /// detected; or empty if the backtrace wasn't recovered.
91 /// This function is only valid when a crash has been detected (i.e.,
92 /// RunSafely() has returned false.
93 const std::string &getBacktrace() const;
96 class CrashRecoveryContextCleanup {
98 virtual ~CrashRecoveryContextCleanup();
99 virtual void recoverResources() = 0;
101 template <typename T> static CrashRecoveryContextCleanup *create(T *);
104 friend class CrashRecoveryContext;
105 CrashRecoveryContextCleanup *prev, *next;
108 template <typename T>
109 class CrashRecoveryContextDestructorCleanup
110 : public CrashRecoveryContextCleanup
114 CrashRecoveryContextDestructorCleanup(T *resource) : resource(resource) {}
115 virtual void recoverResources() {
120 template <typename T>
121 struct CrashRecoveryContextTrait {
122 static inline CrashRecoveryContextCleanup *createCleanup(T *resource) {
123 return new CrashRecoveryContextDestructorCleanup<T>(resource);
128 inline CrashRecoveryContextCleanup* CrashRecoveryContextCleanup::create(T *x) {
129 return CrashRecoveryContext::GetCurrent() ?
130 CrashRecoveryContextTrait<T>::createCleanup(x) :
134 class CrashRecoveryContextCleanupRegistrar {
135 CrashRecoveryContext *context;
136 CrashRecoveryContextCleanup *cleanup;
138 CrashRecoveryContextCleanupRegistrar(CrashRecoveryContextCleanup *cleanup)
139 : context(CrashRecoveryContext::GetCurrent()),
142 if (context && cleanup)
143 context->registerCleanup(cleanup);
145 ~CrashRecoveryContextCleanupRegistrar() {
148 context->unregisterCleanup(cleanup);