Switch from MessageBuffer to Queue for pipeline comms

1 files changed, 59 insertions, 0 deletions

diff --git a/src/audio/audio_element.cpp b/src/audio/audio_element.cpp
new file mode 100644
index 00000000..e1623c36
--- /dev/null
+++ b/src/audio/audio_element.cpp
@@ -0,0 +1,59 @@
+#include "audio_element.hpp"
+
+namespace audio {
+
+IAudioElement::IAudioElement()
+    : input_events_(xQueueCreate(kEventQueueSize, sizeof(StreamEvent))),
+      output_events_(nullptr),
+      unprocessed_output_chunks_(0),
+      buffered_output_(),
+      current_state_(STATE_RUN) {}
+
+IAudioElement::~IAudioElement() {
+  // Ensure we don't leak any memory from events leftover in the queue.
+  while (uxQueueSpacesAvailable(input_events_) < kEventQueueSize) {
+    StreamEvent* event;
+    if (xQueueReceive(input_events_, &event, 0)) {
+      free(event);
+    } else {
+      break;
+    }
+  }
+  // Technically there's a race here if someone is still adding to the queue,
+  // but hopefully the whole pipeline is stopped if an element is being
+  // destroyed.
+  vQueueDelete(input_events_);
+}
+
+auto IAudioElement::SendOrBufferEvent(std::unique_ptr<StreamEvent> event)
+    -> bool {
+  if (event->tag == StreamEvent::CHUNK_DATA) {
+    unprocessed_output_chunks_++;
+  }
+  if (!buffered_output_.empty()) {
+    // To ensure we send data in order, don't try to send if we've already
+    // failed to send something.
+    buffered_output_.push_back(std::move(event));
+    return false;
+  }
+  StreamEvent* raw_event = event.release();
+  if (!xQueueSend(output_events_, raw_event, 0)) {
+    buffered_output_.emplace_front(raw_event);
+    return false;
+  }
+  return true;
+}
+
+auto IAudioElement::FlushBufferedOutput() -> bool {
+  while (!buffered_output_.empty()) {
+    StreamEvent* raw_event = buffered_output_.front().release();
+    buffered_output_.pop_front();
+    if (!xQueueSend(output_events_, raw_event, 0)) {
+      buffered_output_.emplace_front(raw_event);
+      return false;
+    }
+  }
+  return true;
+}
+
+}  // namespace audio