commit f4158d855b941e5c7ffcc4f119f2bd146986b0c4
author Jean-Michel Trivi <jmtrivi@google.com> Tue Sep 25 12:43:58 2018 -0700
committer Jean-Michel Trivi <jmtrivi@google.com> Wed Oct 24 10:46:30 2018 -0700
tree cdd9cc09d90ff6d43ee200233f9fa16e6124f5b6
parent 0917fc25390c5f362332630e2d980480d1444e0d

AudioTrack: new transfer mode for Java offload support

New transfer mode for java AudioTrack using offload
  path, where data is provided through the write method,
  and the callback is used to notify the track owner
  more data can be written on the track.

Bug 86837964
Test: adb shell clof --source /sdcard/Music/my.mp3

Change-Id: I47c760b7fb8f1431945ca24ff4a26311b63cb761

media/libaudioclient/AudioTrack.cpp

diff --git a/media/libaudioclient/AudioTrack.cpp b/media/libaudioclient/AudioTrack.cpp
index c86d4ce..8b35a85 100644
--- a/media/libaudioclient/AudioTrack.cpp
+++ b/media/libaudioclient/AudioTrack.cpp
@@ -399,9 +399,10 @@
         }
         break;
     case TRANSFER_CALLBACK:
+    case TRANSFER_SYNC_NOTIF_CALLBACK:
         if (cbf == NULL || sharedBuffer != 0) {
-            ALOGE("%s(): Transfer type TRANSFER_CALLBACK but cbf == NULL || sharedBuffer != 0",
-                    __func__);
+            ALOGE("%s(): Transfer type %s but cbf == NULL || sharedBuffer != 0",
+                    convertTransferToText(transferType), __func__);
             status = BAD_VALUE;
             goto exit;
         }
@@ -1406,6 +1407,7 @@
         MEDIA_CASE_ENUM(TRANSFER_OBTAIN);
         MEDIA_CASE_ENUM(TRANSFER_SYNC);
         MEDIA_CASE_ENUM(TRANSFER_SHARED);
+        MEDIA_CASE_ENUM(TRANSFER_SYNC_NOTIF_CALLBACK);
         default:
             return "UNRECOGNIZED";
     }
@@ -1438,7 +1440,8 @@
             // use case 3: obtain/release mode
             (mTransfer == TRANSFER_OBTAIN) ||
             // use case 4: synchronous write
-            ((mTransfer == TRANSFER_SYNC) && mThreadCanCallJava);
+            ((mTransfer == TRANSFER_SYNC || mTransfer == TRANSFER_SYNC_NOTIF_CALLBACK)
+                    && mThreadCanCallJava);
 
         bool fastAllowed = sharedBuffer || transferAllowed;
         if (!fastAllowed) {
@@ -1795,7 +1798,7 @@
 
 ssize_t AudioTrack::write(const void* buffer, size_t userSize, bool blocking)
 {
-    if (mTransfer != TRANSFER_SYNC) {
+    if (mTransfer != TRANSFER_SYNC && mTransfer != TRANSFER_SYNC_NOTIF_CALLBACK) {
         return INVALID_OPERATION;
     }
 
@@ -1846,7 +1849,17 @@
 
     if (written > 0) {
         mFramesWritten += written / mFrameSize;
+
+        if (mTransfer == TRANSFER_SYNC_NOTIF_CALLBACK) {
+            const sp<AudioTrackThread> t = mAudioTrackThread;
+            if (t != 0) {
+                // causes wake up of the playback thread, that will callback the client for
+                // more data (with EVENT_CAN_WRITE_MORE_DATA) in processAudioBuffer()
+                t->wake();
+            }
+        }
     }
+
     return written;
 }
 
@@ -2100,8 +2113,8 @@
         if (ns < 0) ns = 0;
     }
 
-    // If not supplying data by EVENT_MORE_DATA, then we're done
-    if (mTransfer != TRANSFER_CALLBACK) {
+    // If not supplying data by EVENT_MORE_DATA or EVENT_CAN_WRITE_MORE_DATA, then we're done
+    if (mTransfer != TRANSFER_CALLBACK && mTransfer != TRANSFER_SYNC_NOTIF_CALLBACK) {
         return ns;
     }
 
@@ -2163,7 +2176,13 @@
         }
 
         size_t reqSize = audioBuffer.size;
-        mCbf(EVENT_MORE_DATA, mUserData, &audioBuffer);
+        if (mTransfer == TRANSFER_SYNC_NOTIF_CALLBACK) {
+            // when notifying client it can write more data, pass the total size that can be
+            // written in the next write() call, since it's not passed through the callback
+            audioBuffer.size += nonContig;
+        }
+        mCbf(mTransfer == TRANSFER_CALLBACK ? EVENT_MORE_DATA : EVENT_CAN_WRITE_MORE_DATA,
+                mUserData, &audioBuffer);
         size_t writtenSize = audioBuffer.size;
 
         // Sanity check on returned size
@@ -2174,6 +2193,14 @@
         }
 
         if (writtenSize == 0) {
+            if (mTransfer == TRANSFER_SYNC_NOTIF_CALLBACK) {
+                // The callback EVENT_CAN_WRITE_MORE_DATA was processed in the JNI of
+                // android.media.AudioTrack. The JNI is not using the callback to provide data,
+                // it only signals to the Java client that it can provide more data, which
+                // this track is read to accept now.
+                // The playback thread will be awaken at the next ::write()
+                return NS_WHENEVER;
+            }
             // The callback is done filling buffers
             // Keep this thread going to handle timed events and
             // still try to get more data in intervals of WAIT_PERIOD_MS