libsanitizer/sanitizer_common/sanitizer_mutex.h

   1 //===-- sanitizer_mutex.h ---------------------------------------*- C++ -*-===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is a part of ThreadSanitizer/AddressSanitizer runtime.
   9 //
  10 //===----------------------------------------------------------------------===//
  11
  12 #ifndef SANITIZER_MUTEX_H
  13 #define SANITIZER_MUTEX_H
  14
  15 #include "sanitizer_atomic.h"
  16 #include "sanitizer_internal_defs.h"
  17 #include "sanitizer_libc.h"
  18
  19 namespace __sanitizer {
  20
  21 class StaticSpinMutex {
  22  public:
  23   void Init() {
  24     atomic_store(&state_, 0, memory_order_relaxed);
  25   }
  26
  27   void Lock() {
  28     if (TryLock())
  29       return;
  30     LockSlow();
  31   }
  32
  33   bool TryLock() {
  34     return atomic_exchange(&state_, 1, memory_order_acquire) == 0;
  35   }
  36
  37   void Unlock() {
  38     atomic_store(&state_, 0, memory_order_release);
  39   }
  40
  41   void CheckLocked() {
  42     CHECK_EQ(atomic_load(&state_, memory_order_relaxed), 1);
  43   }
  44
  45  private:
  46   atomic_uint8_t state_;
  47
  48   void NOINLINE LockSlow() {
  49     for (int i = 0;; i++) {
  50       if (i < 10)
  51         proc_yield(10);
  52       else
  53         internal_sched_yield();
  54       if (atomic_load(&state_, memory_order_relaxed) == 0
  55           && atomic_exchange(&state_, 1, memory_order_acquire) == 0)
  56         return;
  57     }
  58   }
  59 };
  60
  61 class SpinMutex : public StaticSpinMutex {
  62  public:
  63   SpinMutex() {
  64     Init();
  65   }
  66
  67  private:
  68   SpinMutex(const SpinMutex&);
  69   void operator=(const SpinMutex&);
  70 };
  71
  72 class BlockingMutex {
  73  public:
  74 #if SANITIZER_WINDOWS
  75   // Windows does not currently support LinkerInitialized
  76   explicit BlockingMutex(LinkerInitialized);
  77 #else
  78   explicit constexpr BlockingMutex(LinkerInitialized)
  79       : opaque_storage_ {0, }, owner_(0) {}
  80 #endif
  81   BlockingMutex();
  82   void Lock();
  83   void Unlock();
  84
  85   // This function does not guarantee an explicit check that the calling thread
  86   // is the thread which owns the mutex. This behavior, while more strictly
  87   // correct, causes problems in cases like StopTheWorld, where a parent thread
  88   // owns the mutex but a child checks that it is locked. Rather than
  89   // maintaining complex state to work around those situations, the check only
  90   // checks that the mutex is owned, and assumes callers to be generally
  91   // well-behaved.
  92   void CheckLocked();
  93  private:
  94   uptr opaque_storage_[10];
  95   uptr owner_;  // for debugging
  96 };
  97
  98 // Reader-writer spin mutex.
  99 class RWMutex {
 100  public:
 101   RWMutex() {
 102     atomic_store(&state_, kUnlocked, memory_order_relaxed);
 103   }
 104
 105   ~RWMutex() {
 106     CHECK_EQ(atomic_load(&state_, memory_order_relaxed), kUnlocked);
 107   }
 108
 109   void Lock() {
 110     u32 cmp = kUnlocked;
 111     if (atomic_compare_exchange_strong(&state_, &cmp, kWriteLock,
 112                                        memory_order_acquire))
 113       return;
 114     LockSlow();
 115   }
 116
 117   void Unlock() {
 118     u32 prev = atomic_fetch_sub(&state_, kWriteLock, memory_order_release);
 119     DCHECK_NE(prev & kWriteLock, 0);
 120     (void)prev;
 121   }
 122
 123   void ReadLock() {
 124     u32 prev = atomic_fetch_add(&state_, kReadLock, memory_order_acquire);
 125     if ((prev & kWriteLock) == 0)
 126       return;
 127     ReadLockSlow();
 128   }
 129
 130   void ReadUnlock() {
 131     u32 prev = atomic_fetch_sub(&state_, kReadLock, memory_order_release);
 132     DCHECK_EQ(prev & kWriteLock, 0);
 133     DCHECK_GT(prev & ~kWriteLock, 0);
 134     (void)prev;
 135   }
 136
 137   void CheckLocked() {
 138     CHECK_NE(atomic_load(&state_, memory_order_relaxed), kUnlocked);
 139   }
 140
 141  private:
 142   atomic_uint32_t state_;
 143
 144   enum {
 145     kUnlocked = 0,
 146     kWriteLock = 1,
 147     kReadLock = 2
 148   };
 149
 150   void NOINLINE LockSlow() {
 151     for (int i = 0;; i++) {
 152       if (i < 10)
 153         proc_yield(10);
 154       else
 155         internal_sched_yield();
 156       u32 cmp = atomic_load(&state_, memory_order_relaxed);
 157       if (cmp == kUnlocked &&
 158           atomic_compare_exchange_weak(&state_, &cmp, kWriteLock,
 159                                        memory_order_acquire))
 160           return;
 161     }
 162   }
 163
 164   void NOINLINE ReadLockSlow() {
 165     for (int i = 0;; i++) {
 166       if (i < 10)
 167         proc_yield(10);
 168       else
 169         internal_sched_yield();
 170       u32 prev = atomic_load(&state_, memory_order_acquire);
 171       if ((prev & kWriteLock) == 0)
 172         return;
 173     }
 174   }
 175
 176   RWMutex(const RWMutex&);
 177   void operator = (const RWMutex&);
 178 };
 179
 180 template<typename MutexType>
 181 class GenericScopedLock {
 182  public:
 183   explicit GenericScopedLock(MutexType *mu)
 184       : mu_(mu) {
 185     mu_->Lock();
 186   }
 187
 188   ~GenericScopedLock() {
 189     mu_->Unlock();
 190   }
 191
 192  private:
 193   MutexType *mu_;
 194
 195   GenericScopedLock(const GenericScopedLock&);
 196   void operator=(const GenericScopedLock&);
 197 };
 198
 199 template<typename MutexType>
 200 class GenericScopedReadLock {
 201  public:
 202   explicit GenericScopedReadLock(MutexType *mu)
 203       : mu_(mu) {
 204     mu_->ReadLock();
 205   }
 206
 207   ~GenericScopedReadLock() {
 208     mu_->ReadUnlock();
 209   }
 210
 211  private:
 212   MutexType *mu_;
 213
 214   GenericScopedReadLock(const GenericScopedReadLock&);
 215   void operator=(const GenericScopedReadLock&);
 216 };
 217
 218 typedef GenericScopedLock<StaticSpinMutex> SpinMutexLock;
 219 typedef GenericScopedLock<BlockingMutex> BlockingMutexLock;
 220 typedef GenericScopedLock<RWMutex> RWMutexLock;
 221 typedef GenericScopedReadLock<RWMutex> RWMutexReadLock;
 222
 223 }  // namespace __sanitizer
 224
 225 #endif  // SANITIZER_MUTEX_H