xpcom/threads/RecursiveMutex.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 // A lock that can be acquired multiple times on the same thread.
   8
   9 #ifndef mozilla_RecursiveMutex_h
  10 #define mozilla_RecursiveMutex_h
  11
  12 #include "mozilla/ThreadSafety.h"
  13 #include "mozilla/BlockingResourceBase.h"
  14
  15 #ifndef XP_WIN
  16 #  include <pthread.h>
  17 #endif
  18
  19 namespace mozilla {
  20
  21 class MOZ_CAPABILITY("recursive mutex") RecursiveMutex
  22     : public BlockingResourceBase {
  23  public:
  24   explicit RecursiveMutex(const char* aName);
  25   ~RecursiveMutex();
  26
  27 #ifdef DEBUG
  28   void Lock() MOZ_CAPABILITY_ACQUIRE();
  29   void Unlock() MOZ_CAPABILITY_RELEASE();
  30 #else
  31   void Lock() MOZ_CAPABILITY_ACQUIRE() { LockInternal(); }
  32   void Unlock() MOZ_CAPABILITY_RELEASE() { UnlockInternal(); }
  33 #endif
  34
  35 #ifdef DEBUG
  36   /**
  37    * AssertCurrentThreadIn
  38    **/
  39   void AssertCurrentThreadIn() const MOZ_ASSERT_CAPABILITY(this);
  40   /**
  41    * AssertNotCurrentThreadIn
  42    **/
  43   void AssertNotCurrentThreadIn() const MOZ_EXCLUDES(this) {
  44     // Not currently implemented. See bug 476536 for discussion.
  45   }
  46 #else
  47   void AssertCurrentThreadIn() const MOZ_ASSERT_CAPABILITY(this) {}
  48   void AssertNotCurrentThreadIn() const MOZ_EXCLUDES(this) {}
  49 #endif
  50
  51  private:
  52   RecursiveMutex() = delete;
  53   RecursiveMutex(const RecursiveMutex&) = delete;
  54   RecursiveMutex& operator=(const RecursiveMutex&) = delete;
  55
  56   void LockInternal();
  57   void UnlockInternal();
  58
  59 #ifdef DEBUG
  60   PRThread* mOwningThread;
  61   size_t mEntryCount;
  62 #endif
  63
  64 #if !defined(XP_WIN)
  65   pthread_mutex_t mMutex;
  66 #else
  67   // We eschew including windows.h and using CRITICAL_SECTION here so that files
  68   // including us don't also pull in windows.h.  Just use a type that's big
  69   // enough for CRITICAL_SECTION, and we'll fix it up later.
  70   void* mMutex[6];
  71 #endif
  72 };
  73
  74 class MOZ_RAII MOZ_SCOPED_CAPABILITY RecursiveMutexAutoLock {
  75  public:
  76   explicit RecursiveMutexAutoLock(RecursiveMutex& aRecursiveMutex)
  77       MOZ_CAPABILITY_ACQUIRE(aRecursiveMutex)
  78       : mRecursiveMutex(&aRecursiveMutex) {
  79     NS_ASSERTION(mRecursiveMutex, "null mutex");
  80     mRecursiveMutex->Lock();
  81   }
  82
  83   ~RecursiveMutexAutoLock(void) MOZ_CAPABILITY_RELEASE() {
  84     mRecursiveMutex->Unlock();
  85   }
  86
  87  private:
  88   RecursiveMutexAutoLock() = delete;
  89   RecursiveMutexAutoLock(const RecursiveMutexAutoLock&) = delete;
  90   RecursiveMutexAutoLock& operator=(const RecursiveMutexAutoLock&) = delete;
  91   static void* operator new(size_t) noexcept(true);
  92
  93   mozilla::RecursiveMutex* mRecursiveMutex;
  94 };
  95
  96 class MOZ_RAII MOZ_SCOPED_CAPABILITY RecursiveMutexAutoUnlock {
  97  public:
  98   explicit RecursiveMutexAutoUnlock(RecursiveMutex& aRecursiveMutex)
  99       MOZ_SCOPED_UNLOCK_RELEASE(aRecursiveMutex)
 100       : mRecursiveMutex(&aRecursiveMutex) {
 101     NS_ASSERTION(mRecursiveMutex, "null mutex");
 102     mRecursiveMutex->Unlock();
 103   }
 104
 105   ~RecursiveMutexAutoUnlock(void) MOZ_SCOPED_UNLOCK_REACQUIRE() {
 106     mRecursiveMutex->Lock();
 107   }
 108
 109  private:
 110   RecursiveMutexAutoUnlock() = delete;
 111   RecursiveMutexAutoUnlock(const RecursiveMutexAutoUnlock&) = delete;
 112   RecursiveMutexAutoUnlock& operator=(const RecursiveMutexAutoUnlock&) = delete;
 113   static void* operator new(size_t) noexcept(true);
 114
 115   mozilla::RecursiveMutex* mRecursiveMutex;
 116 };
 117
 118 }  // namespace mozilla
 119
 120 #endif  // mozilla_RecursiveMutex_h