Motown: Remove LPCM optimizations, fix prepare, add flush, add ActiveMultistreamSink model/stage

services/media/framework/stages/active_multistream_sink_stage.cc

Index: services/media/framework/stages/active_multistream_sink_stage.cc
diff --git a/services/media/framework/stages/active_multistream_sink_stage.cc b/services/media/framework/stages/active_multistream_sink_stage.cc
new file mode 100644
index 0000000000000000000000000000000000000000..cb3c4ad6e9129173c507cae95d5dbb15ff720819
--- /dev/null
+++ b/services/media/framework/stages/active_multistream_sink_stage.cc
@@ -0,0 +1,165 @@
+// 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/active_multistream_sink_stage.h"
+
+namespace mojo {
+namespace media {
+
+ActiveMultistreamSinkStage::ActiveMultistreamSinkStage(
+      std::shared_ptr<ActiveMultistreamSink> sink) : sink_(sink) {
+  DCHECK(sink_);
+  sink_->SetHost(this);
+  // Add one unallocated input so this stage isn't misidentified as a source.
+  ReleaseInput(AllocateInput());
+}
+
+ActiveMultistreamSinkStage::~ActiveMultistreamSinkStage() {
+  base::AutoLock lock(lock_);
+}
+
+size_t ActiveMultistreamSinkStage::input_count() const {
+  base::AutoLock lock(lock_);
+  return inputs_.size();
+};
+
+Input& ActiveMultistreamSinkStage::input(size_t index) {
+  base::AutoLock lock(lock_);
+  DCHECK_LT(index, inputs_.size());
+  return inputs_[index]->input_;
+}
+
+size_t ActiveMultistreamSinkStage::output_count() const {
+  return 0;
+}
+
+Output& ActiveMultistreamSinkStage::output(size_t index) {
+  CHECK(false) << "output requested from sink";
+  return *(static_cast<Output*>(nullptr));
+}
+
+PayloadAllocator* ActiveMultistreamSinkStage::PrepareInput(size_t index) {
+  return nullptr;
+}
+
+void ActiveMultistreamSinkStage::PrepareOutput(
+    size_t index,
+    PayloadAllocator* allocator,
+    const UpstreamCallback& callback) {
+  CHECK(false) << "PrepareOutput called on sink";
+}
+
+void ActiveMultistreamSinkStage::Prime() {
+  DCHECK(sink_);
+  sink_->Prime();
+}
+
+void ActiveMultistreamSinkStage::Update(Engine* engine) {
+  DCHECK(engine);
+  DCHECK(sink_);
+
+  base::AutoLock lock(lock_);
+
+  for (auto iter = pending_inputs_.begin(); iter != pending_inputs_.end(); ) {
+    DCHECK(*iter < inputs_.size());
+    StageInput* input = inputs_[*iter].get();
+    if (input->input_.packet_from_upstream()) {
+      input->demand_ = sink_->SupplyPacket(
+          input->index_,
+          std::move(input->input_.packet_from_upstream()));
+
+      if (input->demand_ == Demand::kNegative) {
+        auto remove_iter = iter;
+        ++iter;
+        pending_inputs_.erase(remove_iter);
+      }
+    } else {
+      ++iter;
+    }
+
+    input->input_.SetDemand(input->demand_, engine);
+  }
+}
+
+void ActiveMultistreamSinkStage::FlushInput(
+    size_t index,
+    const DownstreamCallback& callback) {
+  DCHECK(sink_);
+
+  sink_->Flush();
+
+  base::AutoLock lock(lock_);
+  inputs_[index]->demand_ = Demand::kNegative;
+  inputs_[index]->input_.Flush();
+
+  pending_inputs_.remove(index);
+}
+
+void ActiveMultistreamSinkStage::FlushOutput(size_t index) {
+  CHECK(false) << "FlushOutput called on sink";
+}
+
+size_t ActiveMultistreamSinkStage::AllocateInput() {
+  base::AutoLock lock(lock_);
+
+  StageInput* input;
+  if (unallocated_inputs_.empty()) {
+    input = new StageInput(inputs_.size());
+    inputs_.emplace_back(std::unique_ptr<StageInput>(input));
+  } else {
+    // Allocate lowest indices first.
+    auto iter = unallocated_inputs_.lower_bound(0);
+    input = inputs_[*iter].get();
+    DCHECK(!input->allocated_);
+    unallocated_inputs_.erase(iter);
+  }
+
+  input->allocated_ = true;
+
+  return input->index_;
+}
+
+size_t ActiveMultistreamSinkStage::ReleaseInput(size_t index) {
+  base::AutoLock lock(lock_);
+  DCHECK(index < inputs_.size());
+
+  StageInput* input = inputs_[index].get();
+  DCHECK(input);
+  DCHECK(input->allocated_);
+  DCHECK(!input->input_.connected());
+
+  input->allocated_ = false;
+
+  // Pop input if it's at the end of inputs_. Otherwise, add it to
+  // unallocated_inputs_. We never pop the last input so the stage can't be
+  // misidentified as a source.
+  if (index != 0 && index == inputs_.size() - 1) {
+    while (inputs_.size() > 1 && !inputs_.back()->allocated_) {
+      unallocated_inputs_.erase(inputs_.size() - 1);
+      inputs_.pop_back();
+    }
+  } else {
+    unallocated_inputs_.insert(input->index_);
+  }
+
+  return inputs_.size();
+}
+
+void ActiveMultistreamSinkStage::UpdateDemand(
+    size_t input_index,
+    Demand demand) {
+  lock_.Acquire();
+  DCHECK(input_index < inputs_.size());
+  DCHECK(demand != Demand::kNegative);
+
+  StageInput* input = inputs_[input_index].get();
+  DCHECK(input);
+  input->demand_ = demand;
+  pending_inputs_.push_back(input_index);
+  lock_.Release();
+  RequestUpdate();
+}
+
+}  // namespace media
+}  // namespace mojo