NetEq: Dependency injection through one struct instead of many params

webrtc/modules/audio_coding/neteq/neteq_impl.h

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 48 matching lines @@
 class NetEqImpl : public webrtc::NetEq {
  public:
   enum class OutputType {
     kNormalSpeech,
     kPLC,
     kCNG,
     kPLCCNG,
     kVadPassive
   };
 
+  struct Dependencies {
+    // The constructor populates the Dependencies struct with the default
+    // implementations of the objects. They can all be replaced by the user
+    // before sending the struct to the NetEqImpl constructor. However, there
+    // are dependencies between some of the classes inside the struct, so
+    // swapping out one may make it necessary to re-create another one.
+    explicit Dependencies(const NetEq::Config& config);
+    ~Dependencies();
+
+    std::unique_ptr<TickTimer> tick_timer;
+    std::unique_ptr<BufferLevelFilter> buffer_level_filter;
+    std::unique_ptr<DecoderDatabase> decoder_database;
+    std::unique_ptr<DelayPeakDetector> delay_peak_detector;
+    std::unique_ptr<DelayManager> delay_manager;
+    std::unique_ptr<DtmfBuffer> dtmf_buffer;
+    std::unique_ptr<DtmfToneGenerator> dtmf_tone_generator;
+    std::unique_ptr<PacketBuffer> packet_buffer;
+    std::unique_ptr<PayloadSplitter> payload_splitter;
+    std::unique_ptr<TimestampScaler> timestamp_scaler;
+    std::unique_ptr<AccelerateFactory> accelerate_factory;
+    std::unique_ptr<ExpandFactory> expand_factory;
+    std::unique_ptr<PreemptiveExpandFactory> preemptive_expand_factory;
+  };
+
   // Creates a new NetEqImpl object. The object will assume ownership of all
   // injected dependencies, and will delete them when done.

[kwiberg-webrtc, 2016/04/26 13:00:04]

You no longer need the second sentence in this comment; the use of unique_ptrs
makes it obvious that this is the case.

[hlundin-webrtc, 2016/04/26 13:20:38]

Done.

   NetEqImpl(const NetEq::Config& config,
-            std::unique_ptr<TickTimer> tick_timer,
-            BufferLevelFilter* buffer_level_filter,
-            DecoderDatabase* decoder_database,
-            DelayManager* delay_manager,
-            DelayPeakDetector* delay_peak_detector,
-            DtmfBuffer* dtmf_buffer,
-            DtmfToneGenerator* dtmf_tone_generator,
-            PacketBuffer* packet_buffer,
-            PayloadSplitter* payload_splitter,
-            TimestampScaler* timestamp_scaler,
-            AccelerateFactory* accelerate_factory,
-            ExpandFactory* expand_factory,
-            PreemptiveExpandFactory* preemptive_expand_factory,
+            Dependencies&& deps,
             bool create_components = true);
 
   ~NetEqImpl() override;
 
   // Inserts a new packet into NetEq. The |receive_timestamp| is an indication
   // of the time when the packet was received, and should be measured with
   // the same tick rate as the RTP timestamp of the current payload.
   // Returns 0 on success, -1 on failure.
   int InsertPacket(const WebRtcRTPHeader& rtp_header,
                    rtc::ArrayView<const uint8_t> payload,
@@ skipping 297 matching lines @@
   bool nack_enabled_ GUARDED_BY(crit_sect_);
   AudioFrame::VADActivity last_vad_activity_ GUARDED_BY(crit_sect_) =
       AudioFrame::kVadPassive;
 
  private:
   RTC_DISALLOW_COPY_AND_ASSIGN(NetEqImpl);
 };
 
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_AUDIO_CODING_NETEQ_NETEQ_IMPL_H_