audiohal: Make sure audio data transfer related commands go via FMQ

When outputting audio, the framework issues several HAL calls
from the same thread that writes into data FMQ. These calls
also need to be served on the same thread that writes audio data
to HAL. The same thing happens when audio input is commenced.

Add a command FMQ for passing different commands to the HAL thread.
This way, depending on the calling thread, the same call may go
either via hwbinder or via the command queue.

This dramatically reduces jitter in RTT measurements (although
doesn't improve the latency).

Bug: 30222631
Test: scripted RTT app
Change-Id: I04c826e2479d8210fd9c99756241156cda3143b6

1 files changed, 63 insertions, 23 deletions

diff --git a/audio/2.0/default/StreamOut.cpp b/audio/2.0/default/StreamOut.cpp
index 1948b68e2f..5f187c5ea4 100644
--- a/audio/2.0/default/StreamOut.cpp
+++ b/audio/2.0/default/StreamOut.cpp
@@ -36,6 +36,7 @@ class WriteThread : public Thread {
     // WriteThread's lifespan never exceeds StreamOut's lifespan.
     WriteThread(std::atomic<bool>* stop,
             audio_stream_out_t* stream,
+            StreamOut::CommandMQ* commandMQ,
             StreamOut::DataMQ* dataMQ,
             StreamOut::StatusMQ* statusMQ,
             EventFlag* efGroup,
@@ -43,6 +44,7 @@ class WriteThread : public Thread {
             : Thread(false /*canCallJava*/),
               mStop(stop),
               mStream(stream),
+              mCommandMQ(commandMQ),
               mDataMQ(dataMQ),
               mStatusMQ(statusMQ),
               mEfGroup(efGroup),
@@ -56,13 +58,19 @@ class WriteThread : public Thread {
   private:
     std::atomic<bool>* mStop;
     audio_stream_out_t* mStream;
+    StreamOut::CommandMQ* mCommandMQ;
     StreamOut::DataMQ* mDataMQ;
     StreamOut::StatusMQ* mStatusMQ;
     EventFlag* mEfGroup;
     ThreadPriority mThreadPriority;
     std::unique_ptr<uint8_t[]> mBuffer;
+    IStreamOut::WriteStatus mStatus;
 
     bool threadLoop() override;
+
+    void doGetLatency();
+    void doGetPresentationPosition();
+    void doWrite();
 };
 
 status_t WriteThread::readyToRun() {
@@ -75,6 +83,32 @@ status_t WriteThread::readyToRun() {
     return OK;
 }
 
+void WriteThread::doWrite() {
+    const size_t availToRead = mDataMQ->availableToRead();
+    mStatus.retval = Result::OK;
+    mStatus.reply.written = 0;
+    if (mDataMQ->read(&mBuffer[0], availToRead)) {
+        ssize_t writeResult = mStream->write(mStream, &mBuffer[0], availToRead);
+        if (writeResult >= 0) {
+            mStatus.reply.written = writeResult;
+        } else {
+            mStatus.retval = Stream::analyzeStatus("write", writeResult);
+        }
+    }
+}
+
+void WriteThread::doGetPresentationPosition() {
+    mStatus.retval = StreamOut::getPresentationPositionImpl(
+            mStream,
+            &mStatus.reply.presentationPosition.frames,
+            &mStatus.reply.presentationPosition.timeStamp);
+}
+
+void WriteThread::doGetLatency() {
+    mStatus.retval = Result::OK;
+    mStatus.reply.latencyMs = mStream->get_latency(mStream);
+}
+
 bool WriteThread::threadLoop() {
     // This implementation doesn't return control back to the Thread until it decides to stop,
     // as the Thread uses mutexes, and this can lead to priority inversion.
@@ -86,24 +120,26 @@ bool WriteThread::threadLoop() {
         if (!(efState & static_cast<uint32_t>(MessageQueueFlagBits::NOT_EMPTY))) {
             continue;  // Nothing to do.
         }
-
-        const size_t availToRead = mDataMQ->availableToRead();
-        IStreamOut::WriteStatus status;
-        status.writeRetval = Result::OK;
-        status.written = 0;
-        if (mDataMQ->read(&mBuffer[0], availToRead)) {
-            ssize_t writeResult = mStream->write(mStream, &mBuffer[0], availToRead);
-            if (writeResult >= 0) {
-                status.written = writeResult;
-            } else {
-                status.writeRetval = Stream::analyzeStatus("write", writeResult);
-            }
+        if (!mCommandMQ->read(&mStatus.replyTo)) {
+            continue;  // Nothing to do.
+        }
+        switch (mStatus.replyTo) {
+            case IStreamOut::WriteCommand::WRITE:
+                doWrite();
+                break;
+            case IStreamOut::WriteCommand::GET_PRESENTATION_POSITION:
+                doGetPresentationPosition();
+                break;
+            case IStreamOut::WriteCommand::GET_LATENCY:
+                doGetLatency();
+                break;
+            default:
+                ALOGE("Unknown write thread command code %d", mStatus.replyTo);
+                mStatus.retval = Result::NOT_SUPPORTED;
+                break;
         }
-        status.presentationPositionRetval = status.writeRetval == Result::OK ?
-                StreamOut::getPresentationPositionImpl(mStream, &status.frames, &status.timeStamp) :
-                Result::OK;
-        if (!mStatusMQ->write(&status)) {
-            ALOGW("status message queue write failed");
+        if (!mStatusMQ->write(&mStatus)) {
+            ALOGE("status message queue write failed");
         }
         mEfGroup->wake(static_cast<uint32_t>(MessageQueueFlagBits::NOT_FULL));
     }
@@ -259,17 +295,19 @@ Return<void> StreamOut::prepareForWriting(
     if (mDataMQ) {
         ALOGE("the client attempts to call prepareForWriting twice");
         _hidl_cb(Result::INVALID_STATE,
-                DataMQ::Descriptor(), StatusMQ::Descriptor());
+                CommandMQ::Descriptor(), DataMQ::Descriptor(), StatusMQ::Descriptor());
         return Void();
     }
+    std::unique_ptr<CommandMQ> tempCommandMQ(new CommandMQ(1));
     std::unique_ptr<DataMQ> tempDataMQ(
             new DataMQ(frameSize * framesCount, true /* EventFlag */));
     std::unique_ptr<StatusMQ> tempStatusMQ(new StatusMQ(1));
-    if (!tempDataMQ->isValid() || !tempStatusMQ->isValid()) {
+    if (!tempCommandMQ->isValid() || !tempDataMQ->isValid() || !tempStatusMQ->isValid()) {
+        ALOGE_IF(!tempCommandMQ->isValid(), "command MQ is invalid");
         ALOGE_IF(!tempDataMQ->isValid(), "data MQ is invalid");
         ALOGE_IF(!tempStatusMQ->isValid(), "status MQ is invalid");
         _hidl_cb(Result::INVALID_ARGUMENTS,
-                DataMQ::Descriptor(), StatusMQ::Descriptor());
+                CommandMQ::Descriptor(), DataMQ::Descriptor(), StatusMQ::Descriptor());
         return Void();
     }
     // TODO: Remove event flag management once blocking MQ is implemented. b/33815422
@@ -277,7 +315,7 @@ Return<void> StreamOut::prepareForWriting(
     if (status != OK || !mEfGroup) {
         ALOGE("failed creating event flag for data MQ: %s", strerror(-status));
         _hidl_cb(Result::INVALID_ARGUMENTS,
-                DataMQ::Descriptor(), StatusMQ::Descriptor());
+                CommandMQ::Descriptor(), DataMQ::Descriptor(), StatusMQ::Descriptor());
         return Void();
     }
 
@@ -285,6 +323,7 @@ Return<void> StreamOut::prepareForWriting(
     mWriteThread = new WriteThread(
             &mStopWriteThread,
             mStream,
+            tempCommandMQ.get(),
             tempDataMQ.get(),
             tempStatusMQ.get(),
             mEfGroup,
@@ -293,13 +332,14 @@ Return<void> StreamOut::prepareForWriting(
     if (status != OK) {
         ALOGW("failed to start writer thread: %s", strerror(-status));
         _hidl_cb(Result::INVALID_ARGUMENTS,
-                DataMQ::Descriptor(), StatusMQ::Descriptor());
+                CommandMQ::Descriptor(), DataMQ::Descriptor(), StatusMQ::Descriptor());
         return Void();
     }
 
+    mCommandMQ = std::move(tempCommandMQ);
     mDataMQ = std::move(tempDataMQ);
     mStatusMQ = std::move(tempStatusMQ);
-    _hidl_cb(Result::OK, *mDataMQ->getDesc(), *mStatusMQ->getDesc());
+    _hidl_cb(Result::OK, *mCommandMQ->getDesc(), *mDataMQ->getDesc(), *mStatusMQ->getDesc());
     return Void();
 }