Constructor initialization and const fields

In constructors, initialize member fields in the initialization list
rather than constructor body where possible.  This allows more fields
to be const, provided they are never modified.

Also initialize POD fields in constructor, unless it's obvious they
don't need to be initialized.  In that case, put a comment instead.

Remove explicit clear() in destructors on fields that are now const.

Give AudioSessionRef a default constructor, so it's immutable fields can
be marked const.

Add comment about ~TrackBase() trick.

Initialize fields in declaration order to make it easier to confirm that
all fields are set.

Move initialization of mHardwareStatus from onFirstRef() to constructor.

Use NULL not 0 to initialize raw pointers in initialization list.

Rename field mClient to mAudioFlingerClient, and getter from client()
to audioFlingerClient().

Change-Id: Ib36cf6ed32f3cd19003f40a5d84046eb4c122052
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 76beeaf..ab5ec34 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -233,9 +233,9 @@
     private:
                             Client(const Client&);
                             Client& operator = (const Client&);
-        sp<AudioFlinger>    mAudioFlinger;
-        sp<MemoryDealer>    mMemoryDealer;
-        pid_t               mPid;
+        const sp<AudioFlinger> mAudioFlinger;
+        const sp<MemoryDealer> mMemoryDealer;
+        const pid_t         mPid;
     };
 
     // --- Notification Client ---
@@ -246,7 +246,7 @@
                                                 pid_t pid);
         virtual             ~NotificationClient();
 
-                sp<IAudioFlingerClient>    client() { return mClient; }
+                sp<IAudioFlingerClient> audioFlingerClient() const { return mAudioFlingerClient; }
 
                 // IBinder::DeathRecipient
                 virtual     void        binderDied(const wp<IBinder>& who);
@@ -255,9 +255,9 @@
                             NotificationClient(const NotificationClient&);
                             NotificationClient& operator = (const NotificationClient&);
 
-        sp<AudioFlinger>        mAudioFlinger;
-        pid_t                   mPid;
-        sp<IAudioFlingerClient> mClient;
+        const sp<AudioFlinger>  mAudioFlinger;
+        const pid_t             mPid;
+        const sp<IAudioFlingerClient> mAudioFlingerClient;
     };
 
     class TrackHandle;
@@ -367,8 +367,8 @@
             bool step();
             void reset();
 
-            wp<ThreadBase>      mThread;
-            sp<Client>          mClient;
+            const wp<ThreadBase> mThread;
+            /*const*/ sp<Client> mClient;   // see explanation at ~TrackBase() why not const
             sp<IMemory>         mCblkMemory;
             audio_track_cblk_t* mCblk;
             void*               mBuffer;
@@ -377,9 +377,9 @@
             // we don't really need a lock for these
             track_state         mState;
             int                 mClientTid;
-            audio_format_t      mFormat;
+            const audio_format_t mFormat;
             uint32_t            mFlags;
-            int                 mSessionId;
+            const int           mSessionId;
             uint8_t             mChannelCount;
             uint32_t            mChannelMask;
         };
@@ -532,7 +532,7 @@
 
                     const type_t            mType;
                     Condition               mWaitWorkCV;
-                    sp<AudioFlinger>        mAudioFlinger;
+                    const sp<AudioFlinger>  mAudioFlinger;
                     uint32_t                mSampleRate;
                     size_t                  mFrameCount;
                     uint32_t                mChannelMask;
@@ -553,7 +553,7 @@
                     char                    mName[kNameLength];
                     sp<IPowerManager>       mPowerManager;
                     sp<IBinder>             mWakeLockToken;
-                    sp<PMDeathRecipient>    mDeathRecipient;
+                    const sp<PMDeathRecipient> mDeathRecipient;
                     // list of suspended effects per session and per type. The first vector is
                     // keyed by session ID, the second by type UUID timeLow field
                     KeyedVector< int, KeyedVector< int, sp<SuspendedSessionDesc> > >  mSuspendedSessions;
@@ -671,7 +671,7 @@
                     bool        write(int16_t* data, uint32_t frames);
                     bool        bufferQueueEmpty() { return (mBufferQueue.size() == 0) ? true : false; }
                     bool        isActive() { return mActive; }
-            wp<ThreadBase>&     thread()  { return mThread; }
+            const wp<ThreadBase>& thread() { return mThread; }
 
         private:
 
@@ -688,7 +688,7 @@
             Vector < Buffer* >          mBufferQueue;
             AudioBufferProvider::Buffer mOutBuffer;
             bool                        mActive;
-            DuplicatingThread*          mSourceThread;
+            DuplicatingThread* const mSourceThread; // for waitTimeMs() in write()
         };  // end of OutputTrack
 
         PlaybackThread (const sp<AudioFlinger>& audioFlinger, AudioStreamOut* output, int id,
@@ -919,7 +919,7 @@
         virtual status_t onTransact(
             uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags);
     private:
-        sp<PlaybackThread::Track> mTrack;
+        const sp<PlaybackThread::Track> mTrack;
     };
 
     friend class Client;
@@ -1023,8 +1023,8 @@
                 int16_t                             *mRsmpInBuffer;
                 size_t                              mRsmpInIndex;
                 size_t                              mInputBytes;
-                int                                 mReqChannelCount;
-                uint32_t                            mReqSampleRate;
+                const int                           mReqChannelCount;
+                const uint32_t                      mReqSampleRate;
                 ssize_t                             mBytesRead;
     };
 
@@ -1038,7 +1038,7 @@
         virtual status_t onTransact(
             uint32_t code, const Parcel& data, Parcel* reply, uint32_t flags);
     private:
-        sp<RecordThread::RecordTrack> mRecordTrack;
+        const sp<RecordThread::RecordTrack> mRecordTrack;
     };
 
     //--- Audio Effect Management
@@ -1107,7 +1107,7 @@
         int16_t     *outBuffer() { return mConfig.outputCfg.buffer.s16; }
         void        setChain(const wp<EffectChain>& chain) { mChain = chain; }
         void        setThread(const wp<ThreadBase>& thread) { mThread = thread; }
-        wp<ThreadBase>& thread() { return mThread; }
+        const wp<ThreadBase>& thread() { return mThread; }
 
         status_t addHandle(const sp<EffectHandle>& handle);
         void disconnect(const wp<EffectHandle>& handle, bool unpiniflast);
@@ -1379,8 +1379,11 @@
     };
 
     struct AudioSessionRef {
-        int sessionid;
-        pid_t pid;
+        // FIXME rename parameter names when fields get "m" prefix
+        AudioSessionRef(int sessionid_, pid_t pid_) :
+            sessionid(sessionid_), pid(pid_), cnt(1) {}
+        const int sessionid;
+        const pid_t pid;
         int cnt;
     };