libsanitizer/tsan/tsan_mutexset.h

   1 //===-- tsan_mutexset.h -----------------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file is a part of ThreadSanitizer (TSan), a race detector.
  10 //
  11 // MutexSet holds the set of mutexes currently held by a thread.
  12 //===----------------------------------------------------------------------===//
  13 #ifndef TSAN_MUTEXSET_H
  14 #define TSAN_MUTEXSET_H
  15
  16 #include "tsan_defs.h"
  17
  18 namespace __tsan {
  19
  20 class MutexSet {
  21  public:
  22   // Holds limited number of mutexes.
  23   // The oldest mutexes are discarded on overflow.
  24   static constexpr uptr kMaxSize = 16;
  25   struct Desc {
  26     uptr addr;
  27     StackID stack_id;
  28     u32 seq;
  29     u32 count;
  30     bool write;
  31
  32     Desc() { internal_memset(this, 0, sizeof(*this)); }
  33     Desc(const Desc& other) { *this = other; }
  34     Desc& operator=(const MutexSet::Desc& other) {
  35       internal_memcpy(this, &other, sizeof(*this));
  36       return *this;
  37     }
  38   };
  39
  40   MutexSet();
  41   void Reset();
  42   void AddAddr(uptr addr, StackID stack_id, bool write);
  43   void DelAddr(uptr addr, bool destroy = false);
  44   uptr Size() const;
  45   Desc Get(uptr i) const;
  46
  47  private:
  48 #if !SANITIZER_GO
  49   u32 seq_ = 0;
  50   uptr size_ = 0;
  51   Desc descs_[kMaxSize];
  52
  53   void RemovePos(uptr i);
  54 #endif
  55 };
  56
  57 // MutexSet is too large to live on stack.
  58 // DynamicMutexSet can be use used to create local MutexSet's.
  59 class DynamicMutexSet {
  60  public:
  61   DynamicMutexSet();
  62   ~DynamicMutexSet();
  63   MutexSet* operator->() { return ptr_; }
  64   operator MutexSet*() { return ptr_; }
  65   DynamicMutexSet(const DynamicMutexSet&) = delete;
  66   DynamicMutexSet& operator=(const DynamicMutexSet&) = delete;
  67
  68  private:
  69   MutexSet* ptr_;
  70 #if SANITIZER_GO
  71   MutexSet set_;
  72 #endif
  73 };
  74
  75 // Go does not have mutexes, so do not spend memory and time.
  76 // (Go sync.Mutex is actually a semaphore -- can be unlocked
  77 // in different goroutine).
  78 #if SANITIZER_GO
  79 MutexSet::MutexSet() {}
  80 void MutexSet::Reset() {}
  81 void MutexSet::AddAddr(uptr addr, StackID stack_id, bool write) {}
  82 void MutexSet::DelAddr(uptr addr, bool destroy) {}
  83 uptr MutexSet::Size() const { return 0; }
  84 MutexSet::Desc MutexSet::Get(uptr i) const { return Desc(); }
  85 DynamicMutexSet::DynamicMutexSet() : ptr_(&set_) {}
  86 DynamicMutexSet::~DynamicMutexSet() {}
  87 #endif
  88
  89 }  // namespace __tsan
  90
  91 #endif  // TSAN_MUTEXSET_H