mojo/public/cpp/utility/mutex.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef MOJO_PUBLIC_CPP_UTILITY_MUTEX_H_
   6 #define MOJO_PUBLIC_CPP_UTILITY_MUTEX_H_
   7
   8 #ifdef _WIN32
   9 #error "Not implemented: See crbug.com/342893."
  10 #endif
  11
  12 #include <pthread.h>
  13
  14 #include "mojo/public/cpp/system/macros.h"
  15
  16 namespace mojo {
  17
  18 #ifdef NDEBUG
  19 // Note: Make a C++ constant for |PTHREAD_MUTEX_INITIALIZER|. (We can't directly
  20 // use the C macro in an initializer list, since it might expand to |{ ... }|.)
  21 namespace internal {
  22 const pthread_mutex_t kPthreadMutexInitializer = PTHREAD_MUTEX_INITIALIZER;
  23 }
  24 #endif
  25
  26 class Mutex {
  27  public:
  28 #ifdef NDEBUG
  29   Mutex() : mutex_(internal::kPthreadMutexInitializer) {}
  30   ~Mutex() { pthread_mutex_destroy(&mutex_); }
  31
  32   void Lock() { pthread_mutex_lock(&mutex_); }
  33   void Unlock() { pthread_mutex_unlock(&mutex_); }
  34   bool TryLock() { return pthread_mutex_trylock(&mutex_) == 0; }
  35
  36   void AssertHeld() {}
  37 #else
  38   Mutex();
  39   ~Mutex();
  40
  41   void Lock();
  42   void Unlock();
  43   bool TryLock();
  44
  45   void AssertHeld();
  46 #endif
  47
  48  private:
  49   pthread_mutex_t mutex_;
  50
  51   MOJO_DISALLOW_COPY_AND_ASSIGN(Mutex);
  52 };
  53
  54 class MutexLock {
  55  public:
  56   explicit MutexLock(Mutex* mutex) : mutex_(mutex) { mutex_->Lock(); }
  57   ~MutexLock() { mutex_->Unlock(); }
  58
  59  private:
  60   Mutex* const mutex_;
  61
  62   MOJO_DISALLOW_COPY_AND_ASSIGN(MutexLock);
  63 };
  64
  65 // Catch bug where variable name is omitted (e.g., |MutexLock (&mu)|).
  66 #define MutexLock(x) static_assert(0, "MutexLock() missing variable name");
  67
  68 }  // namespace mojo
  69
  70 #endif  // MOJO_PUBLIC_CPP_UTILITY_MUTEX_H_