xbmc/threads/SharedSection.h

   1 /*
   2  *  Copyright (C) 2005-2018 Team Kodi
   3  *  This file is part of Kodi - https://kodi.tv
   4  *
   5  *  SPDX-License-Identifier: GPL-2.0-or-later
   6  *  See LICENSES/README.md for more information.
   7  */
   8
   9 #pragma once
  10
  11 #include "threads/Condition.h"
  12
  13 #include <mutex>
  14 #include <shared_mutex>
  15
  16 /**
  17  * A CSharedSection is a mutex that satisfies the Shared Lockable concept (see Lockables.h).
  18  */
  19 class CSharedSection
  20 {
  21   CCriticalSection sec;
  22   XbmcThreads::ConditionVariable actualCv;
  23
  24   unsigned int sharedCount = 0;
  25
  26 public:
  27   inline CSharedSection() = default;
  28
  29   inline void lock()
  30   {
  31     std::unique_lock<CCriticalSection> l(sec);
  32     while (sharedCount)
  33       actualCv.wait(l, [this]() { return sharedCount == 0; });
  34     sec.lock();
  35   }
  36   inline bool try_lock() { return (sec.try_lock() ? ((sharedCount == 0) ? true : (sec.unlock(), false)) : false); }
  37   inline void unlock() { sec.unlock(); }
  38
  39   inline void lock_shared()
  40   {
  41     std::unique_lock<CCriticalSection> l(sec);
  42     sharedCount++;
  43   }
  44   inline bool try_lock_shared() { return (sec.try_lock() ? sharedCount++, sec.unlock(), true : false); }
  45   inline void unlock_shared()
  46   {
  47     std::unique_lock<CCriticalSection> l(sec);
  48     sharedCount--;
  49     if (!sharedCount)
  50     {
  51       actualCv.notifyAll();
  52     }
  53   }
  54 };