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      1 /*
      2  *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
      3  *
      4  *  Use of this source code is governed by a BSD-style license
      5  *  that can be found in the LICENSE file in the root of the source
      6  *  tree. An additional intellectual property rights grant can be found
      7  *  in the file PATENTS.  All contributing project authors may
      8  *  be found in the AUTHORS file in the root of the source tree.
      9  */
     10 
     11 #ifndef WEBRTC_VOICE_ENGINE_CHANNEL_MANAGER_H
     12 #define WEBRTC_VOICE_ENGINE_CHANNEL_MANAGER_H
     13 
     14 #include <vector>
     15 
     16 #include "webrtc/base/constructormagic.h"
     17 #include "webrtc/system_wrappers/interface/atomic32.h"
     18 #include "webrtc/system_wrappers/interface/critical_section_wrapper.h"
     19 #include "webrtc/system_wrappers/interface/scoped_ptr.h"
     20 #include "webrtc/typedefs.h"
     21 
     22 namespace webrtc {
     23 
     24 class Config;
     25 
     26 namespace voe {
     27 
     28 class Channel;
     29 
     30 // Shared-pointer implementation for keeping track of Channels. The underlying
     31 // shared instance will be dropped when no more ChannelOwners point to it.
     32 //
     33 // One common source of ChannelOwner instances are
     34 // ChannelManager::CreateChannel() and ChannelManager::GetChannel(...).
     35 // It has a similar use case to shared_ptr in C++11. Should this move to C++11
     36 // in the future, this class should be replaced by exactly that.
     37 //
     38 // To access the underlying Channel, use .channel().
     39 // IsValid() implements a convenience method as an alternative for checking
     40 // whether the underlying pointer is NULL or not.
     41 //
     42 // Channel channel_owner = channel_manager.GetChannel(channel_id);
     43 // if (channel_owner.IsValid())
     44 //   channel_owner.channel()->...;
     45 //
     46 class ChannelOwner {
     47  public:
     48   explicit ChannelOwner(Channel* channel);
     49   ChannelOwner(const ChannelOwner& channel_owner);
     50 
     51   ~ChannelOwner();
     52 
     53   ChannelOwner& operator=(const ChannelOwner& other);
     54 
     55   Channel* channel() { return channel_ref_->channel.get(); }
     56   bool IsValid() { return channel_ref_->channel.get() != NULL; }
     57  private:
     58   // Shared instance of a Channel. Copying ChannelOwners increase the reference
     59   // count and destroying ChannelOwners decrease references. Channels are
     60   // deleted when no references to them are held.
     61   struct ChannelRef {
     62     ChannelRef(Channel* channel);
     63     const scoped_ptr<Channel> channel;
     64     Atomic32 ref_count;
     65   };
     66 
     67   ChannelRef* channel_ref_;
     68 };
     69 
     70 class ChannelManager {
     71  public:
     72   ChannelManager(uint32_t instance_id, const Config& config);
     73 
     74   // Upon construction of an Iterator it will grab a copy of the channel list of
     75   // the ChannelManager. The iteration will then occur over this state, not the
     76   // current one of the ChannelManager. As the Iterator holds its own references
     77   // to the Channels, they will remain valid even if they are removed from the
     78   // ChannelManager.
     79   class Iterator {
     80    public:
     81     explicit Iterator(ChannelManager* channel_manager);
     82 
     83     Channel* GetChannel();
     84     bool IsValid();
     85 
     86     void Increment();
     87 
     88    private:
     89     size_t iterator_pos_;
     90     std::vector<ChannelOwner> channels_;
     91 
     92     DISALLOW_COPY_AND_ASSIGN(Iterator);
     93   };
     94 
     95   // CreateChannel will always return a valid ChannelOwner instance. The channel
     96   // is created either based on internal configuration, i.e. |config_|, by
     97   // calling CreateChannel(), or using and external configuration
     98   // |external_config| if the overloaded method
     99   // CreateChannel(const Config& external_config) is called.
    100   ChannelOwner CreateChannel();
    101   ChannelOwner CreateChannel(const Config& external_config);
    102 
    103   // ChannelOwner.channel() will be NULL if channel_id is invalid or no longer
    104   // exists. This should be checked with ChannelOwner::IsValid().
    105   ChannelOwner GetChannel(int32_t channel_id);
    106   void GetAllChannels(std::vector<ChannelOwner>* channels);
    107 
    108   void DestroyChannel(int32_t channel_id);
    109   void DestroyAllChannels();
    110 
    111   size_t NumOfChannels() const;
    112 
    113  private:
    114   // Create a channel given a configuration, |config|.
    115   ChannelOwner CreateChannelInternal(const Config& config);
    116 
    117   uint32_t instance_id_;
    118 
    119   Atomic32 last_channel_id_;
    120 
    121   scoped_ptr<CriticalSectionWrapper> lock_;
    122   std::vector<ChannelOwner> channels_;
    123 
    124   const Config& config_;
    125 
    126   DISALLOW_COPY_AND_ASSIGN(ChannelManager);
    127 };
    128 }  // namespace voe
    129 }  // namespace webrtc
    130 
    131 #endif  // WEBRTC_VOICE_ENGINE_CHANNEL_MANAGER_H
    132