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/BlockingResourceBase.h"
  13
  14 #ifndef XP_WIN
  15 #  include <pthread.h>
  16 #endif
  17
  18 namespace mozilla {
  19
  20 class RecursiveMutex : public BlockingResourceBase {
  21  public:
  22   explicit RecursiveMutex(const char* aName);
  23   ~RecursiveMutex();
  24
  25 #ifdef DEBUG
  26   void Lock();
  27   void Unlock();
  28 #else
  29   void Lock() { LockInternal(); }
  30   void Unlock() { UnlockInternal(); }
  31 #endif
  32
  33 #ifdef DEBUG
  34   /**
  35    * AssertCurrentThreadIn
  36    **/
  37   void AssertCurrentThreadIn();
  38   /**
  39    * AssertNotCurrentThreadIn
  40    **/
  41   void AssertNotCurrentThreadIn() {
  42     // Not currently implemented. See bug 476536 for discussion.
  43   }
  44 #else
  45   void AssertCurrentThreadIn() {}
  46   void AssertNotCurrentThreadIn() {}
  47 #endif
  48
  49  private:
  50   RecursiveMutex() = delete;
  51   RecursiveMutex(const RecursiveMutex&) = delete;
  52   RecursiveMutex& operator=(const RecursiveMutex&) = delete;
  53
  54   void LockInternal();
  55   void UnlockInternal();
  56
  57 #ifdef DEBUG
  58   PRThread* mOwningThread;
  59   size_t mEntryCount;
  60 #endif
  61
  62 #if !defined(XP_WIN)
  63   pthread_mutex_t mMutex;
  64 #else
  65   // We eschew including windows.h and using CRITICAL_SECTION here so that files
  66   // including us don't also pull in windows.h.  Just use a type that's big
  67   // enough for CRITICAL_SECTION, and we'll fix it up later.
  68   void* mMutex[6];
  69 #endif
  70 };
  71
  72 class MOZ_RAII RecursiveMutexAutoLock {
  73  public:
  74   explicit RecursiveMutexAutoLock(RecursiveMutex& aRecursiveMutex)
  75       : mRecursiveMutex(&aRecursiveMutex) {
  76     NS_ASSERTION(mRecursiveMutex, "null mutex");
  77     mRecursiveMutex->Lock();
  78   }
  79
  80   ~RecursiveMutexAutoLock(void) { mRecursiveMutex->Unlock(); }
  81
  82  private:
  83   RecursiveMutexAutoLock() = delete;
  84   RecursiveMutexAutoLock(const RecursiveMutexAutoLock&) = delete;
  85   RecursiveMutexAutoLock& operator=(const RecursiveMutexAutoLock&) = delete;
  86   static void* operator new(size_t) noexcept(true);
  87
  88   mozilla::RecursiveMutex* mRecursiveMutex;
  89 };
  90
  91 class MOZ_RAII RecursiveMutexAutoUnlock {
  92  public:
  93   explicit RecursiveMutexAutoUnlock(RecursiveMutex& aRecursiveMutex)
  94       : mRecursiveMutex(&aRecursiveMutex) {
  95     NS_ASSERTION(mRecursiveMutex, "null mutex");
  96     mRecursiveMutex->Unlock();
  97   }
  98
  99   ~RecursiveMutexAutoUnlock(void) { mRecursiveMutex->Lock(); }
 100
 101  private:
 102   RecursiveMutexAutoUnlock() = delete;
 103   RecursiveMutexAutoUnlock(const RecursiveMutexAutoUnlock&) = delete;
 104   RecursiveMutexAutoUnlock& operator=(const RecursiveMutexAutoUnlock&) = delete;
 105   static void* operator new(size_t) noexcept(true);
 106
 107   mozilla::RecursiveMutex* mRecursiveMutex;
 108 };
 109
 110 }  // namespace mozilla
 111
 112 #endif  // mozilla_RecursiveMutex_h