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
13 #include "llvm/ADT/STLExtras.h"
17 class CrashRecoveryContextCleanup;
19 /// \brief Crash recovery helper object.
21 /// This class implements support for running operations in a safe context so
22 /// that crashes (memory errors, stack overflow, assertion violations) can be
23 /// detected and control restored to the crashing thread. Crash detection is
24 /// purely "best effort", the exact set of failures which can be recovered from
25 /// is platform dependent.
27 /// Clients make use of this code by first calling
28 /// CrashRecoveryContext::Enable(), and then executing unsafe operations via a
29 /// CrashRecoveryContext object. For example:
31 /// void actual_work(void *);
34 /// CrashRecoveryContext CRC;
36 /// if (!CRC.RunSafely(actual_work, 0)) {
37 /// ... a crash was detected, report error to user ...
40 /// ... no crash was detected ...
42 class CrashRecoveryContext {
44 CrashRecoveryContextCleanup *head;
47 CrashRecoveryContext() : Impl(nullptr), head(nullptr) {}
48 ~CrashRecoveryContext();
50 void registerCleanup(CrashRecoveryContextCleanup *cleanup);
51 void unregisterCleanup(CrashRecoveryContextCleanup *cleanup);
53 /// \brief Enable crash recovery.
56 /// \brief Disable crash recovery.
57 static void Disable();
59 /// \brief Return the active context, if the code is currently executing in a
60 /// thread which is in a protected context.
61 static CrashRecoveryContext *GetCurrent();
63 /// \brief Return true if the current thread is recovering from a
65 static bool isRecoveringFromCrash();
67 /// \brief Execute the provide callback function (with the given arguments) in
68 /// a protected context.
70 /// \return True if the function completed successfully, and false if the
71 /// function crashed (or HandleCrash was called explicitly). Clients should
72 /// make as little assumptions as possible about the program state when
73 /// RunSafely has returned false. Clients can use getBacktrace() to retrieve
74 /// the backtrace of the crash on failures.
75 bool RunSafely(function_ref<void()> Fn);
76 bool RunSafely(void (*Fn)(void*), void *UserData) {
77 return RunSafely([&]() { Fn(UserData); });
80 /// \brief Execute the provide callback function (with the given arguments) in
81 /// a protected context which is run in another thread (optionally with a
82 /// requested stack size).
84 /// See RunSafely() and llvm_execute_on_thread().
86 /// On Darwin, if PRIO_DARWIN_BG is set on the calling thread, it will be
87 /// propagated to the new thread as well.
88 bool RunSafelyOnThread(function_ref<void()>, unsigned RequestedStackSize = 0);
89 bool RunSafelyOnThread(void (*Fn)(void*), void *UserData,
90 unsigned RequestedStackSize = 0) {
91 return RunSafelyOnThread([&]() { Fn(UserData); }, RequestedStackSize);
94 /// \brief Explicitly trigger a crash recovery in the current process, and
95 /// return failure from RunSafely(). This function does not return.
98 /// \brief Return a string containing the backtrace where the crash was
99 /// detected; or empty if the backtrace wasn't recovered.
101 /// This function is only valid when a crash has been detected (i.e.,
102 /// RunSafely() has returned false.
103 const std::string &getBacktrace() const;
106 class CrashRecoveryContextCleanup {
108 CrashRecoveryContext *context;
109 CrashRecoveryContextCleanup(CrashRecoveryContext *context)
110 : context(context), cleanupFired(false) {}
114 virtual ~CrashRecoveryContextCleanup();
115 virtual void recoverResources() = 0;
117 CrashRecoveryContext *getContext() const {
122 friend class CrashRecoveryContext;
123 CrashRecoveryContextCleanup *prev, *next;
126 template<typename DERIVED, typename T>
127 class CrashRecoveryContextCleanupBase : public CrashRecoveryContextCleanup {
130 CrashRecoveryContextCleanupBase(CrashRecoveryContext *context, T* resource)
131 : CrashRecoveryContextCleanup(context), resource(resource) {}
133 static DERIVED *create(T *x) {
135 if (CrashRecoveryContext *context = CrashRecoveryContext::GetCurrent())
136 return new DERIVED(context, x);
142 template <typename T>
143 class CrashRecoveryContextDestructorCleanup : public
144 CrashRecoveryContextCleanupBase<CrashRecoveryContextDestructorCleanup<T>, T> {
146 CrashRecoveryContextDestructorCleanup(CrashRecoveryContext *context,
148 : CrashRecoveryContextCleanupBase<
149 CrashRecoveryContextDestructorCleanup<T>, T>(context, resource) {}
151 virtual void recoverResources() {
152 this->resource->~T();
156 template <typename T>
157 class CrashRecoveryContextDeleteCleanup : public
158 CrashRecoveryContextCleanupBase<CrashRecoveryContextDeleteCleanup<T>, T> {
160 CrashRecoveryContextDeleteCleanup(CrashRecoveryContext *context, T *resource)
161 : CrashRecoveryContextCleanupBase<
162 CrashRecoveryContextDeleteCleanup<T>, T>(context, resource) {}
164 void recoverResources() override { delete this->resource; }
167 template <typename T>
168 class CrashRecoveryContextReleaseRefCleanup : public
169 CrashRecoveryContextCleanupBase<CrashRecoveryContextReleaseRefCleanup<T>, T>
172 CrashRecoveryContextReleaseRefCleanup(CrashRecoveryContext *context,
174 : CrashRecoveryContextCleanupBase<CrashRecoveryContextReleaseRefCleanup<T>,
175 T>(context, resource) {}
177 void recoverResources() override { this->resource->Release(); }
180 template <typename T, typename Cleanup = CrashRecoveryContextDeleteCleanup<T> >
181 class CrashRecoveryContextCleanupRegistrar {
182 CrashRecoveryContextCleanup *cleanup;
184 CrashRecoveryContextCleanupRegistrar(T *x)
185 : cleanup(Cleanup::create(x)) {
187 cleanup->getContext()->registerCleanup(cleanup);
190 ~CrashRecoveryContextCleanupRegistrar() {
195 if (cleanup && !cleanup->cleanupFired)
196 cleanup->getContext()->unregisterCleanup(cleanup);