LCOV - code coverage report
Current view: top level - include/llvm/Support - CrashRecoveryContext.h (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 28 31 90.3 %
Date: 2017-09-14 15:23:50 Functions: 61 81 75.3 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===--- CrashRecoveryContext.h - Crash Recovery ----------------*- C++ -*-===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : 
      10             : #ifndef LLVM_SUPPORT_CRASHRECOVERYCONTEXT_H
      11             : #define LLVM_SUPPORT_CRASHRECOVERYCONTEXT_H
      12             : 
      13             : #include "llvm/ADT/STLExtras.h"
      14             : 
      15             : namespace llvm {
      16             : class CrashRecoveryContextCleanup;
      17             : 
      18             : /// \brief Crash recovery helper object.
      19             : ///
      20             : /// This class implements support for running operations in a safe context so
      21             : /// that crashes (memory errors, stack overflow, assertion violations) can be
      22             : /// detected and control restored to the crashing thread. Crash detection is
      23             : /// purely "best effort", the exact set of failures which can be recovered from
      24             : /// is platform dependent.
      25             : ///
      26             : /// Clients make use of this code by first calling
      27             : /// CrashRecoveryContext::Enable(), and then executing unsafe operations via a
      28             : /// CrashRecoveryContext object. For example:
      29             : ///
      30             : ///    void actual_work(void *);
      31             : ///
      32             : ///    void foo() {
      33             : ///      CrashRecoveryContext CRC;
      34             : ///
      35             : ///      if (!CRC.RunSafely(actual_work, 0)) {
      36             : ///         ... a crash was detected, report error to user ...
      37             : ///      }
      38             : ///
      39             : ///      ... no crash was detected ...
      40             : ///    }
      41             : class CrashRecoveryContext {
      42             :   void *Impl;
      43             :   CrashRecoveryContextCleanup *head;
      44             : 
      45             : public:
      46        3487 :   CrashRecoveryContext() : Impl(nullptr), head(nullptr) {}
      47             :   ~CrashRecoveryContext();
      48             : 
      49             :   void registerCleanup(CrashRecoveryContextCleanup *cleanup);
      50             :   void unregisterCleanup(CrashRecoveryContextCleanup *cleanup);
      51             : 
      52             :   /// \brief Enable crash recovery.
      53             :   static void Enable();
      54             : 
      55             :   /// \brief Disable crash recovery.
      56             :   static void Disable();
      57             : 
      58             :   /// \brief Return the active context, if the code is currently executing in a
      59             :   /// thread which is in a protected context.
      60             :   static CrashRecoveryContext *GetCurrent();
      61             : 
      62             :   /// \brief Return true if the current thread is recovering from a
      63             :   /// crash.
      64             :   static bool isRecoveringFromCrash();
      65             : 
      66             :   /// \brief Execute the provide callback function (with the given arguments) in
      67             :   /// a protected context.
      68             :   ///
      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.
      73             :   bool RunSafely(function_ref<void()> Fn);
      74             :   bool RunSafely(void (*Fn)(void*), void *UserData) {
      75             :     return RunSafely([&]() { Fn(UserData); });
      76             :   }
      77             : 
      78             :   /// \brief Execute the provide callback function (with the given arguments) in
      79             :   /// a protected context which is run in another thread (optionally with a
      80             :   /// requested stack size).
      81             :   ///
      82             :   /// See RunSafely() and llvm_execute_on_thread().
      83             :   ///
      84             :   /// On Darwin, if PRIO_DARWIN_BG is set on the calling thread, it will be
      85             :   /// propagated to the new thread as well.
      86             :   bool RunSafelyOnThread(function_ref<void()>, unsigned RequestedStackSize = 0);
      87             :   bool RunSafelyOnThread(void (*Fn)(void*), void *UserData,
      88             :                          unsigned RequestedStackSize = 0) {
      89             :     return RunSafelyOnThread([&]() { Fn(UserData); }, RequestedStackSize);
      90             :   }
      91             : 
      92             :   /// \brief Explicitly trigger a crash recovery in the current process, and
      93             :   /// return failure from RunSafely(). This function does not return.
      94             :   void HandleCrash();
      95             : };
      96             : 
      97             : class CrashRecoveryContextCleanup {
      98             : protected:
      99             :   CrashRecoveryContext *context;
     100             :   CrashRecoveryContextCleanup(CrashRecoveryContext *context)
     101       10953 :       : context(context), cleanupFired(false) {}
     102             : 
     103             : public:
     104             :   bool cleanupFired;
     105             : 
     106             :   virtual ~CrashRecoveryContextCleanup();
     107             :   virtual void recoverResources() = 0;
     108             : 
     109             :   CrashRecoveryContext *getContext() const {
     110             :     return context;
     111             :   }
     112             : 
     113             : private:
     114             :   friend class CrashRecoveryContext;
     115             :   CrashRecoveryContextCleanup *prev, *next;
     116             : };
     117             : 
     118             : template<typename DERIVED, typename T>
     119       10951 : class CrashRecoveryContextCleanupBase : public CrashRecoveryContextCleanup {
     120             : protected:
     121             :   T *resource;
     122       10951 :   CrashRecoveryContextCleanupBase(CrashRecoveryContext *context, T *resource)
     123       21902 :       : CrashRecoveryContextCleanup(context), resource(resource) {}
     124             : 
     125             : public:
     126       53804 :   static DERIVED *create(T *x) {
     127       53804 :     if (x) {
     128       45788 :       if (CrashRecoveryContext *context = CrashRecoveryContext::GetCurrent())
     129       21902 :         return new DERIVED(context, x);
     130             :     }
     131             :     return nullptr;
     132             :   }
     133             : };
     134             : 
     135             : template <typename T>
     136          62 : class CrashRecoveryContextDestructorCleanup : public
     137             :   CrashRecoveryContextCleanupBase<CrashRecoveryContextDestructorCleanup<T>, T> {
     138             : public:
     139             :   CrashRecoveryContextDestructorCleanup(CrashRecoveryContext *context,
     140             :                                         T *resource)
     141             :       : CrashRecoveryContextCleanupBase<
     142          62 :             CrashRecoveryContextDestructorCleanup<T>, T>(context, resource) {}
     143             : 
     144           0 :   virtual void recoverResources() {
     145           0 :     this->resource->~T();
     146           0 :   }
     147             : };
     148             : 
     149             : template <typename T>
     150       19962 : class CrashRecoveryContextDeleteCleanup : public
     151             :   CrashRecoveryContextCleanupBase<CrashRecoveryContextDeleteCleanup<T>, T> {
     152             : public:
     153             :   CrashRecoveryContextDeleteCleanup(CrashRecoveryContext *context, T *resource)
     154             :     : CrashRecoveryContextCleanupBase<
     155       19962 :         CrashRecoveryContextDeleteCleanup<T>, T>(context, resource) {}
     156             : 
     157          33 :   void recoverResources() override { delete this->resource; }
     158             : };
     159             : 
     160             : template <typename T>
     161        1878 : class CrashRecoveryContextReleaseRefCleanup : public
     162             :   CrashRecoveryContextCleanupBase<CrashRecoveryContextReleaseRefCleanup<T>, T>
     163             : {
     164             : public:
     165             :   CrashRecoveryContextReleaseRefCleanup(CrashRecoveryContext *context,
     166             :                                         T *resource)
     167             :     : CrashRecoveryContextCleanupBase<CrashRecoveryContextReleaseRefCleanup<T>,
     168        1878 :           T>(context, resource) {}
     169             : 
     170           3 :   void recoverResources() override { this->resource->Release(); }
     171             : };
     172             : 
     173             : template <typename T, typename Cleanup = CrashRecoveryContextDeleteCleanup<T> >
     174             : class CrashRecoveryContextCleanupRegistrar {
     175             :   CrashRecoveryContextCleanup *cleanup;
     176             : 
     177             : public:
     178       53804 :   CrashRecoveryContextCleanupRegistrar(T *x)
     179       53804 :     : cleanup(Cleanup::create(x)) {
     180       53804 :     if (cleanup)
     181       10951 :       cleanup->getContext()->registerCleanup(cleanup);
     182       53804 :   }
     183             : 
     184       53763 :   ~CrashRecoveryContextCleanupRegistrar() { unregister(); }
     185             : 
     186       53763 :   void unregister() {
     187       53763 :     if (cleanup && !cleanup->cleanupFired)
     188       10922 :       cleanup->getContext()->unregisterCleanup(cleanup);
     189       53763 :     cleanup = nullptr;
     190       53763 :   }
     191             : };
     192             : } // end namespace llvm
     193             : 
     194             : #endif // LLVM_SUPPORT_CRASHRECOVERYCONTEXT_H

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