Motown in-proc streaming framework used to implement media services.

services/media/framework/stages/distributor_stage.cc

Index: services/media/framework/stages/distributor_stage.cc
diff --git a/services/media/framework/stages/distributor_stage.cc b/services/media/framework/stages/distributor_stage.cc
new file mode 100644
index 0000000000000000000000000000000000000000..749de98c35e1ab314375d7995a707bac7905d2e5
--- /dev/null
+++ b/services/media/framework/stages/distributor_stage.cc
@@ -0,0 +1,91 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "services/media/framework/stages/distributor_stage.h"
+
+namespace mojo {
+namespace media {
+
+DistributorStage::DistributorStage(
+    MultiStreamPacketSourcePtr packet_source) :
+    packet_source_(packet_source),
+    ended_streams_(0) {
+  DCHECK(packet_source);
+  outputs_.resize(packet_source->stream_count());
+}
+
+DistributorStage::~DistributorStage() {}
+
+uint32_t DistributorStage::input_count() const {
+  return 0;
+};
+
+StageInput& DistributorStage::input(uint32_t index) {
+  NOTREACHED();
+  static StageInput result;
+  return result;
+}
+
+uint32_t DistributorStage::output_count() const {
+  return outputs_.size();
+}
+
+StageOutput& DistributorStage::output(uint32_t index) {
+  DCHECK(index < outputs_.size());
+  return outputs_[index];
+}
+
+bool DistributorStage::Prepare(UpdateCallback update_callback) {
+  for (StageOutput& output : outputs_) {
+    output.Prepare(false);
+  }
+  return false;
+}
+
+void DistributorStage::Update(Engine* engine) {
+  DCHECK(engine);
+
+  bool has_positive_demand = false;
+  for (StageOutput& output : outputs_) {
+    if (output.demand() == Demand::kPositive) {
+      has_positive_demand = true;
+      break;
+    }
+  }
+
+  while (true) {
+    if (cached_packet_ && has_positive_demand) {
+      DCHECK(cached_packet_output_index_ < outputs_.size());
+      StageOutput& output = outputs_[cached_packet_output_index_];
+
+      if (output.demand() != Demand::kNegative) {
+        // cached_packet_ is intended for an output which will accept packets.
+        output.SupplyPacket(std::move(cached_packet_), engine);
+      } else {
+      }
+    }
+
+    if (cached_packet_) {
+      // There's still a cached packet. We're done for now.
+      return;
+    }
+
+    if (ended_streams_ == outputs_.size()) {
+      // We've seen end-of-stream for all streams. All done.
+      return;
+    }
+
+    // Pull a packet from the source.
+    cached_packet_ = packet_source_->PullPacket(&cached_packet_output_index_);
+    DCHECK(cached_packet_);
+    DCHECK(cached_packet_output_index_ < outputs_.size());
+
+    if (cached_packet_->end_of_stream()) {
+      ended_streams_++;
+    }
+  }
+}
+
+}  // namespace media
+}  // namespace mojo