audio: utils: Lessen number of errors in pipe providers

Lessen the number of errors in pipe providers (PipeReader and
PipeWriter) by sleeping the equivalent time of the provider's
buffer size. That helps to keep on retrying to get buffers
from a provider that may be in a bad state (e.g. underrun)
and to give chance to other threads to run.

Change-Id: Ia643b681ed4ffca2958dd3808515c3bbc91acbad
Signed-off-by: Misael Lopez Cruz <misael.lopez@ti.com>

1 files changed, 20 insertions, 3 deletions

diff --git a/audio/utils/src/MonoPipe.cpp b/audio/utils/src/MonoPipe.cpp
index 9889c7a..48380ae 100644
--- a/audio/utils/src/MonoPipe.cpp
+++ b/audio/utils/src/MonoPipe.cpp
@@ -143,6 +143,7 @@ int PipeReader::getNextBuffer(BufferProvider::Buffer *buffer)
 
     int8_t *buf = mBuffer.i8;
     int pending = buffer->frameCount;
+    bool xrun = false;
 
     while (pending > 0) {
         int read = mPipe->read(buf, pending);
@@ -151,7 +152,7 @@ int PipeReader::getNextBuffer(BufferProvider::Buffer *buffer)
             buffer->frameCount = 0;
             return read;
         } else if (read == 0) {
-            ALOGW("PipeReader: underrun!");
+            xrun = true;
             break;
         } else {
             pending -= read;
@@ -159,7 +160,8 @@ int PipeReader::getNextBuffer(BufferProvider::Buffer *buffer)
         }
     }
 
-    ALOGW_IF(pending, "PipeReader: unexpected %u pending frames", pending);
+    ALOGW_IF(pending, "PipeReader: %s %u pending frames",
+             xrun ? "underrun!" : "unexpected", pending);
 
     buffer->frameCount -= pending;
     buffer->raw = mBuffer.raw;
@@ -172,7 +174,14 @@ int PipeReader::getNextBuffer(BufferProvider::Buffer *buffer)
 
 void PipeReader::releaseBuffer(BufferProvider::Buffer *buffer)
 {
-    /* Nothing to do to release the buffer, but must be implemented */
+    uint32_t rate = mPipe->getParams().sampleRate;
+
+    if (!buffer->frameCount) {
+        /* Lessen the number of errors */
+        ALOGV("PipeReader: release an empty buffer");
+        uint32_t usecs = (mBuffer.frameCount * 1000 * 1000) / rate;
+        usleep(usecs);
+    }
 }
 
 /* ---------------------------------------------------------------------------------------- */
@@ -216,6 +225,14 @@ void PipeWriter::releaseBuffer(BufferProvider::Buffer *buffer)
     int8_t *buf = buffer->i8;
     int pending = buffer->frameCount;
     uint32_t frameSize = mPipe->getParams().frameSize();
+    uint32_t rate = mPipe->getParams().sampleRate;
+
+    if (!pending) {
+        /* Lessen the number of errors */
+        ALOGV("PipeWriter: release an empty buffer");
+        uint32_t usecs = (mBuffer.frameCount * 1000 * 1000) / rate;
+        usleep(usecs);
+    }
 
     while (pending > 0) {
         int written = mPipe->write(buf, pending);