ppapi/utility/non_thread_safe_ref_count.h

   1 // Copyright (c) 2011 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 PPAPI_UTILITY_NON_THREAD_SAFE_REF_COUNT_H_
   6 #define PPAPI_UTILITY_NON_THREAD_SAFE_REF_COUNT_H_
   7
   8 #include "ppapi/cpp/core.h"
   9 #include "ppapi/cpp/logging.h"
  10 #include "ppapi/cpp/module.h"
  11
  12 /// @file
  13 /// This file defines the APIs for maintaining a reference counter.
  14 namespace pp {
  15
  16 /// A simple reference counter that is not thread-safe. <strong>Note:</strong>
  17 /// in Debug mode, it checks that it is either called on the main thread, or
  18 /// always called on another thread.
  19 class NonThreadSafeRefCount {
  20  public:
  21   /// Default constructor. In debug mode, this checks that the object is being
  22   /// created on the main thread.
  23   NonThreadSafeRefCount()
  24       : ref_(0) {
  25 #ifndef NDEBUG
  26     is_main_thread_ = Module::Get()->core()->IsMainThread();
  27 #endif
  28   }
  29
  30   /// Destructor.
  31   ~NonThreadSafeRefCount() {
  32     PP_DCHECK(is_main_thread_ == Module::Get()->core()->IsMainThread());
  33   }
  34
  35   /// AddRef() increments the reference counter.
  36   ///
  37   /// @return An int32_t with the incremented reference counter.
  38   int32_t AddRef() {
  39     PP_DCHECK(is_main_thread_ == Module::Get()->core()->IsMainThread());
  40     return ++ref_;
  41   }
  42
  43   /// Release() decrements the reference counter.
  44   ///
  45   /// @return An int32_t with the decremeneted reference counter.
  46   int32_t Release() {
  47     PP_DCHECK(is_main_thread_ == Module::Get()->core()->IsMainThread());
  48     return --ref_;
  49   }
  50
  51  private:
  52   int32_t ref_;
  53 #ifndef NDEBUG
  54   bool is_main_thread_;
  55 #endif
  56 };
  57
  58 }  // namespace pp
  59
  60 #endif  // PPAPI_UTILITY_NON_THREAD_SAFE_REF_COUNT_H_