[Chromecast] Add postprocessor registry to allow them to be built-in

Bug: internal b/167462029

Change-Id: Ic0880bc93996ddf1be6b8b2d2b8c1a9c3aefb348
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2389162
Commit-Queue: Kenneth MacKay <kmackay@chromium.org>
Reviewed-by: Yuchen Liu <yucliu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#803742}

chromecast/media/cma/backend/mixer/BUILD.gn

@@ -18,6 +18,17 @@ cast_source_set("post_processor_paths") {
   deps = [ "//base" ]
 }
 
+cast_source_set("post_processor_registry") {
+  sources = [
+    "post_processor_registry.cc",
+    "post_processor_registry.h",
+  ]
+  deps = [
+    "//base",
+    "//chromecast/public/media",
+  ]
+}
+
 cast_source_set("loopback") {
   sources = [
     "loopback_handler.cc",
@@ -67,6 +78,7 @@ cast_source_set("mixer") {
   deps = [
     ":loopback",
     ":post_processor_paths",
+    ":post_processor_registry",
     "//base",
     "//chromecast/base",
     "//chromecast/base:chromecast_switches",

chromecast/media/cma/backend/mixer/post_processor_factory.cc

@@ -14,6 +14,7 @@
 #include "base/strings/stringprintf.h"
 #include "chromecast/media/audio/audio_log.h"
 #include "chromecast/media/cma/backend/mixer/post_processor_paths.h"
+#include "chromecast/media/cma/backend/mixer/post_processor_registry.h"
 #include "chromecast/media/cma/backend/mixer/post_processors/post_processor_wrapper.h"
 #include "chromecast/public/media/audio_post_processor2_shlib.h"
 #include "chromecast/public/media/audio_post_processor_shlib.h"
@@ -63,6 +64,13 @@ std::unique_ptr<AudioPostProcessor2> PostProcessorFactory::CreatePostProcessor(
     const std::string& library_name,
     const std::string& config,
     int channels) {
+  std::unique_ptr<AudioPostProcessor2> builtin =
+      PostProcessorRegistry::Get()->Create(library_name, config, channels);
+  if (builtin) {
+    LOG(INFO) << "Loaded builtin " << library_name;
+    return builtin;
+  }
+
   base::FilePath path = FindLibrary(library_name);
   libraries_.push_back(std::make_unique<base::ScopedNativeLibrary>(path));
   CHECK(libraries_.back()->is_valid())

chromecast/media/cma/backend/mixer/post_processor_registry.cc

+// Copyright 2020 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 "chromecast/media/cma/backend/mixer/post_processor_registry.h"
+
+#include <utility>
+
+#include "base/no_destructor.h"
+#include "chromecast/public/media/audio_post_processor2_shlib.h"
+
+namespace chromecast {
+namespace media {
+
+// static
+PostProcessorRegistry* PostProcessorRegistry::Get() {
+  static base::NoDestructor<PostProcessorRegistry> g_registry;
+  return g_registry.get();
+}
+
+void PostProcessorRegistry::Register(const std::string& library_name,
+                                     CreateFunction create_function) {
+  creators_.emplace(library_name, std::move(create_function));
+}
+
+std::unique_ptr<AudioPostProcessor2> PostProcessorRegistry::Create(
+    const std::string& library_name,
+    const std::string& config,
+    int channels) {
+  auto it = creators_.find(library_name);
+  if (it == creators_.end()) {
+    return nullptr;
+  }
+  return it->second.Run(config, channels);
+}
+
+}  // namespace media
+}  // namespace chromecast

chromecast/media/cma/backend/mixer/post_processor_registry.h

+// Copyright 2020 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.
+
+#ifndef CHROMECAST_MEDIA_CMA_BACKEND_MIXER_POST_PROCESSOR_REGISTRY_H_
+#define CHROMECAST_MEDIA_CMA_BACKEND_MIXER_POST_PROCESSOR_REGISTRY_H_
+
+#include <memory>
+#include <string>
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/containers/flat_map.h"
+
+namespace chromecast {
+namespace media {
+
+class AudioPostProcessor2;
+
+// Global registry for built-in postprocessors.
+class PostProcessorRegistry {
+ public:
+  using CreateFunction = base::RepeatingCallback<std::unique_ptr<
+      AudioPostProcessor2>(const std::string& config, int channels)>;
+
+  // Returns the global registry instance for the current process.
+  static PostProcessorRegistry* Get();
+
+  PostProcessorRegistry();
+  ~PostProcessorRegistry();
+
+  PostProcessorRegistry(const PostProcessorRegistry&) = delete;
+  PostProcessorRegistry& operator=(const PostProcessorRegistry&) = delete;
+
+  // Registers a function to create a postprocessor for the given
+  // |library_name|, which should match the name used for the shlib for that
+  // postprocessor.
+  void Register(const std::string& library_name,
+                CreateFunction create_function);
+
+  // Creates a postprocessor instance for the given |library_name|, if it has
+  // been registered. Returns nullptr if no creation function has been
+  // registered for that name.
+  std::unique_ptr<AudioPostProcessor2> Create(const std::string& library_name,
+                                              const std::string& config,
+                                              int channels);
+
+ private:
+  base::flat_map<std::string /* library_name */, CreateFunction> creators_;
+};
+
+inline PostProcessorRegistry::PostProcessorRegistry() = default;
+inline PostProcessorRegistry::~PostProcessorRegistry() = default;
+
+// Helper class and macro for auto-registering postprocessors with simple
+// constructors.
+template <typename PostProcessor>
+struct PostProcessorCreator {
+  PostProcessorCreator(const std::string& library_name) {
+    PostProcessorRegistry::Get()->Register(
+        library_name, base::BindRepeating(&PostProcessorCreator::Create));
+  }
+
+  static std::unique_ptr<AudioPostProcessor2> Create(const std::string& config,
+                                                     int channels) {
+    return std::make_unique<PostProcessor>(config, channels);
+  }
+};
+
+#define REGISTER_POSTPROCESSOR(Type, library_name)                       \
+  static PostProcessorCreator<Type>* static_postprocessor_registration = \
+      new PostProcessorCreator<Type>(library_name)
+
+}  // namespace media
+}  // namespace chromecast
+
+#endif  // CHROMECAST_MEDIA_CMA_BACKEND_MIXER_POST_PROCESSOR_REGISTRY_H_

chromecast/media/cma/backend/mixer/post_processors/BUILD.gn

@@ -42,6 +42,7 @@ cast_source_set("governor") {
     "//chromecast/base",
     "//chromecast/media/base",
     "//chromecast/media/base:slew_volume",
+    "//chromecast/media/cma/backend/mixer:post_processor_registry",
     "//chromecast/public/media",
   ]
   public_configs = [ "//chromecast/public:public_config" ]
@@ -73,6 +74,7 @@ cast_source_set("saturated_gain") {
     "//chromecast/base",
     "//chromecast/media/base",
     "//chromecast/media/base:slew_volume",
+    "//chromecast/media/cma/backend/mixer:post_processor_registry",
     "//chromecast/public/media",
   ]
   public_configs = [ "//chromecast/public:public_config" ]

chromecast/media/cma/backend/mixer/post_processors/governor.cc

@@ -13,6 +13,7 @@
 #include "base/values.h"
 #include "chromecast/base/serializers.h"
 #include "chromecast/media/base/slew_volume.h"
+#include "chromecast/media/cma/backend/mixer/post_processor_registry.h"
 
 namespace chromecast {
 namespace media {
@@ -89,5 +90,7 @@ void Governor::SetSlewTimeMsForTest(int slew_time_ms) {
   slew_volume_.SetMaxSlewTimeMs(slew_time_ms);
 }
 
+REGISTER_POSTPROCESSOR(Governor, "libcast_governor_2.0.so");
+
 }  // namespace media
 }  // namespace chromecast

chromecast/media/cma/backend/mixer/post_processors/saturated_gain.cc

@@ -11,6 +11,7 @@
 #include "base/values.h"
 #include "chromecast/base/serializers.h"
 #include "chromecast/media/base/slew_volume.h"
+#include "chromecast/media/cma/backend/mixer/post_processor_registry.h"
 
 namespace chromecast {
 namespace media {
@@ -68,5 +69,7 @@ bool SaturatedGain::UpdateParameters(const std::string& message) {
   return false;
 }
 
+REGISTER_POSTPROCESSOR(SaturatedGain, "libcast_saturated_gain_2.0.so");
+
 }  // namespace media
 }  // namespace chromecast