Line data    Source code

       1             : /*
       2             :  *  Copyright (C) 2004-2024 Savoir-faire Linux Inc.
       3             :  *
       4             :  *  This program is free software: you can redistribute it and/or modify
       5             :  *  it under the terms of the GNU General Public License as published by
       6             :  *  the Free Software Foundation, either version 3 of the License, or
       7             :  *  (at your option) any later version.
       8             :  *
       9             :  *  This program is distributed in the hope that it will be useful,
      10             :  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
      11             :  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
      12             :  *  GNU General Public License for more details.
      13             :  *
      14             :  *  You should have received a copy of the GNU General Public License
      15             :  *  along with this program. If not, see <https://www.gnu.org/licenses/>.
      16             :  */
      17             : 
      18             : #ifndef RING_TYPES_H_
      19             : #define RING_TYPES_H_
      20             : 
      21             : #include <type_traits>
      22             : #include <memory>
      23             : #include <mutex>
      24             : #include <cstddef> // for size_t
      25             : 
      26             : #include <ciso646> // fix windows compiler bug
      27             : 
      28             : namespace jami {
      29             : 
      30             : 
      31             : static constexpr size_t SIZEBUF = 16000; /** About 62.5ms of buffering at 48kHz */
      32             : 
      33             : /**
      34             :  * This meta-function is used to enable a template overload
      35             :  * only if given class T is a base of class U
      36             :  */
      37             : template<class T, class U>
      38             : using enable_if_base_of = typename std::enable_if<std::is_base_of<T, U>::value, T>::type;
      39             : 
      40             : /**
      41             :  * Return a shared pointer on an auto-generated global instance of class T.
      42             :  * This instance is created only at usage and destroyed when not,
      43             :  * as we keep only a weak reference on it.
      44             :  * But when created it's always the same object until all holders release
      45             :  * their sharing.
      46             :  * An optional MaxRespawn positive integer can be given to limit the number
      47             :  * of time the object can be created (i.e. different instance).
      48             :  * Any negative values (default) block this effect (unlimited respawn).
      49             :  * This function is thread-safe.
      50             :  */
      51             : template<class T, signed MaxRespawn = -1>
      52             : std::shared_ptr<T>
      53         974 : getGlobalInstance()
      54             : {
      55             :     static std::recursive_mutex mutex; // recursive as instance calls recursively
      56         974 :     static std::weak_ptr<T> wlink;
      57             : 
      58         974 :     std::unique_lock<std::recursive_mutex> lock(mutex);
      59             : 
      60         974 :     if (wlink.expired()) {
      61             :         static signed counter {MaxRespawn};
      62         271 :         if (not counter)
      63           0 :             return nullptr;
      64         271 :         auto link = std::make_shared<T>();
      65         271 :         wlink = link;
      66         271 :         if (counter > 0)
      67           0 :             --counter;
      68         271 :         return link;
      69         271 :     }
      70             : 
      71         703 :     return wlink.lock();
      72         974 : }
      73             : 
      74             : } // namespace jami
      75             : 
      76             : #endif // RING_TYPES_H_