Hash uniform name strings

Remove resource map and use std::shared_ptr<void>

src/base/hash.h

@@ -6,17 +6,15 @@
 
 namespace base {
 
-// Compile-time string hashing function.
 template <size_t N>
-constexpr inline size_t Hash(const char (&str)[N], size_t Len = N - 1) {
+constexpr inline size_t KR2Hash(const char (&str)[N], size_t Len = N - 1) {
   size_t hash_value = 0;
   for (int i = 0; str[i] != '\0'; ++i)
     hash_value = str[i] + 31 * hash_value;
   return hash_value;
 }
 
-// The same hashing function for run-time.
-inline size_t Hash(const std::string& str) {
+inline size_t KR2Hash(const std::string& str) {
   size_t hash_value = 0;
   for (std::string::value_type c : str)
     hash_value = c + 31 * hash_value;

src/base/thread_pool.cc

@@ -41,8 +41,6 @@ void ThreadPool::Shutdown() {
 }
 
 void ThreadPool::PostTask(Location from, Closure task, bool front) {
-  DCHECK((!threads_.empty()));
-
   task_runner_.PostTask(from, std::move(task), front);
   semaphore_.release();
 }
@@ -51,8 +49,6 @@ void ThreadPool::PostTaskAndReply(Location from,
                                   Closure task,
                                   Closure reply,
                                   bool front) {
-  DCHECK((!threads_.empty()));
-
   task_runner_.PostTaskAndReply(from, std::move(task), std::move(reply), front);
   semaphore_.release();
 }

src/engine/audio/audio_mixer.cc

@@ -17,6 +17,10 @@ using namespace base;
 
 namespace eng {
 
+AudioMixer::Resource::~Resource() {
+  DLOG(1) << "Destroying audio resource: " << uintptr_t(this);
+}
+
 AudioMixer::AudioMixer()
     : main_thread_task_runner_(TaskRunner::GetThreadLocalTaskRunner()),
 #if defined(__ANDROID__)
@@ -28,131 +32,102 @@ AudioMixer::AudioMixer()
   CHECK(res) << "Failed to initialize audio sink.";
 }
 
-AudioMixer::~AudioMixer() = default;
-
-uint64_t AudioMixer::CreateResource() {
-  uint64_t resource_id = ++last_resource_id_;
-  resources_[resource_id] = std::make_shared<Resource>();
-  return resource_id;
+AudioMixer::~AudioMixer() {
+  audio_sink_.reset();
 }
 
-void AudioMixer::DestroyResource(uint64_t resource_id) {
-  auto it = resources_.find(resource_id);
-  if (it == resources_.end())
-    return;
-
-  if (it->second->active) {
-    it->second->restart_cb = nullptr;
-    it->second->flags.fetch_or(kStopped, std::memory_order_relaxed);
-  }
-  resources_.erase(it);
+std::shared_ptr<void> AudioMixer::CreateResource() {
+  auto resource = std::make_shared<Resource>();
+  DLOG(1) << "Audio resource created: " << uintptr_t(resource.get());
+  return resource;
 }
 
-void AudioMixer::Play(uint64_t resource_id,
+void AudioMixer::Play(std::shared_ptr<void> resource,
                       std::shared_ptr<AudioBus> audio_bus,
                       float amplitude,
                       bool reset_pos) {
   if (!audio_enabled_)
     return;
 
-  auto it = resources_.find(resource_id);
-  if (it == resources_.end())
-    return;
+  auto resource_ptr = std::static_pointer_cast<Resource>(resource);
 
-  if (it->second->active) {
+  if (resource_ptr->active) {
     if (reset_pos)
-      it->second->flags.fetch_or(kStopped, std::memory_order_relaxed);
+      resource_ptr->flags.fetch_or(kStopped, std::memory_order_relaxed);
 
-    if (it->second->flags.load(std::memory_order_relaxed) & kStopped)
-      it->second->restart_cb = [&, resource_id, audio_bus, amplitude,
+    if (resource_ptr->flags.load(std::memory_order_relaxed) & kStopped)
+      resource_ptr->restart_cb = [&, resource, audio_bus, amplitude,
                                   reset_pos]() -> void {
-        Play(resource_id, audio_bus, amplitude, reset_pos);
+        Play(resource, audio_bus, amplitude, reset_pos);
       };
 
     return;
   }
 
   if (reset_pos) {
-    it->second->src_index = 0;
-    it->second->accumulator = 0;
+    resource_ptr->src_index = 0;
+    resource_ptr->accumulator = 0;
     audio_bus->ResetStream();
-  } else if (it->second->src_index >= audio_bus->samples_per_channel()) {
+  } else if (resource_ptr->src_index >= audio_bus->samples_per_channel()) {
     return;
   }
 
-  it->second->active = true;
-  it->second->flags.fetch_and(~kStopped, std::memory_order_relaxed);
-  it->second->audio_bus = audio_bus;
+  resource_ptr->active = true;
+  resource_ptr->flags.fetch_and(~kStopped, std::memory_order_relaxed);
+  resource_ptr->audio_bus = audio_bus;
   if (amplitude >= 0)
-    it->second->amplitude = amplitude;
+    resource_ptr->amplitude = amplitude;
 
   std::lock_guard<std::mutex> scoped_lock(lock_);
-  play_list_[0].push_back(it->second);
+  play_list_[0].push_back(resource_ptr);
 }
 
-void AudioMixer::Stop(uint64_t resource_id) {
-  auto it = resources_.find(resource_id);
-  if (it == resources_.end())
-    return;
-
-  if (it->second->active) {
-    it->second->restart_cb = nullptr;
-    it->second->flags.fetch_or(kStopped, std::memory_order_relaxed);
+void AudioMixer::Stop(std::shared_ptr<void> resource) {
+  auto resource_ptr = std::static_pointer_cast<Resource>(resource);
+  if (resource_ptr->active) {
+    resource_ptr->restart_cb = nullptr;
+    resource_ptr->flags.fetch_or(kStopped, std::memory_order_relaxed);
   }
 }
 
-void AudioMixer::SetLoop(uint64_t resource_id, bool loop) {
-  auto it = resources_.find(resource_id);
-  if (it == resources_.end())
-    return;
-
+void AudioMixer::SetLoop(std::shared_ptr<void> resource, bool loop) {
+  auto resource_ptr = std::static_pointer_cast<Resource>(resource);
   if (loop)
-    it->second->flags.fetch_or(kLoop, std::memory_order_relaxed);
+    resource_ptr->flags.fetch_or(kLoop, std::memory_order_relaxed);
   else
-    it->second->flags.fetch_and(~kLoop, std::memory_order_relaxed);
+    resource_ptr->flags.fetch_and(~kLoop, std::memory_order_relaxed);
 }
 
-void AudioMixer::SetSimulateStereo(uint64_t resource_id, bool simulate) {
-  auto it = resources_.find(resource_id);
-  if (it == resources_.end())
-    return;
-
+void AudioMixer::SetSimulateStereo(std::shared_ptr<void> resource,
+                                   bool simulate) {
+  auto resource_ptr = std::static_pointer_cast<Resource>(resource);
   if (simulate)
-    it->second->flags.fetch_or(kSimulateStereo, std::memory_order_relaxed);
+    resource_ptr->flags.fetch_or(kSimulateStereo, std::memory_order_relaxed);
   else
-    it->second->flags.fetch_and(~kSimulateStereo, std::memory_order_relaxed);
+    resource_ptr->flags.fetch_and(~kSimulateStereo, std::memory_order_relaxed);
 }
 
-void AudioMixer::SetResampleStep(uint64_t resource_id, size_t step) {
-  auto it = resources_.find(resource_id);
-  if (it == resources_.end())
-    return;
-
-  it->second->step.store(step + 100, std::memory_order_relaxed);
+void AudioMixer::SetResampleStep(std::shared_ptr<void> resource, size_t step) {
+  auto resource_ptr = std::static_pointer_cast<Resource>(resource);
+  resource_ptr->step.store(step + 100, std::memory_order_relaxed);
 }
 
-void AudioMixer::SetMaxAmplitude(uint64_t resource_id, float max_amplitude) {
-  auto it = resources_.find(resource_id);
-  if (it == resources_.end())
-    return;
-
-  it->second->max_amplitude.store(max_amplitude, std::memory_order_relaxed);
+void AudioMixer::SetMaxAmplitude(std::shared_ptr<void> resource,
+                                 float max_amplitude) {
+  auto resource_ptr = std::static_pointer_cast<Resource>(resource);
+  resource_ptr->max_amplitude.store(max_amplitude, std::memory_order_relaxed);
 }
 
-void AudioMixer::SetAmplitudeInc(uint64_t resource_id, float amplitude_inc) {
-  auto it = resources_.find(resource_id);
-  if (it == resources_.end())
-    return;
-
-  it->second->amplitude_inc.store(amplitude_inc, std::memory_order_relaxed);
+void AudioMixer::SetAmplitudeInc(std::shared_ptr<void> resource,
+                                 float amplitude_inc) {
+  auto resource_ptr = std::static_pointer_cast<Resource>(resource);
+  resource_ptr->amplitude_inc.store(amplitude_inc, std::memory_order_relaxed);
 }
 
-void AudioMixer::SetEndCallback(uint64_t resource_id, base::Closure cb) {
-  auto it = resources_.find(resource_id);
-  if (it == resources_.end())
-    return;
-
-  it->second->end_cb = std::move(cb);
+void AudioMixer::SetEndCallback(std::shared_ptr<void> resource,
+                                base::Closure cb) {
+  auto resource_ptr = std::static_pointer_cast<Resource>(resource);
+  resource_ptr->end_cb = std::move(cb);
 }
 
 void AudioMixer::Suspend() {
@@ -177,8 +152,8 @@ void AudioMixer::RenderAudio(float* output_buffer, size_t num_frames) {
   memset(output_buffer, 0, sizeof(float) * num_frames * kChannelCount);
 
   for (auto it = play_list_[1].begin(); it != play_list_[1].end();) {
-    auto audio_bus = it->get()->audio_bus.get();
-    unsigned flags = it->get()->flags.load(std::memory_order_relaxed);
+    auto audio_bus = (*it)->audio_bus.get();
+    unsigned flags = (*it)->flags.load(std::memory_order_relaxed);
     bool marked_for_removal = false;
 
     if (flags & kStopped) {
@@ -190,14 +165,14 @@ void AudioMixer::RenderAudio(float* output_buffer, size_t num_frames) {
         src[1] = src[0];  // mono.
 
       size_t num_samples = audio_bus->samples_per_channel();
-      size_t src_index = it->get()->src_index;
-      size_t step = it->get()->step.load(std::memory_order_relaxed);
-      size_t accumulator = it->get()->accumulator;
-      float amplitude = it->get()->amplitude;
+      size_t src_index = (*it)->src_index;
+      size_t step = (*it)->step.load(std::memory_order_relaxed);
+      size_t accumulator = (*it)->accumulator;
+      float amplitude = (*it)->amplitude;
       float amplitude_inc =
-          it->get()->amplitude_inc.load(std::memory_order_relaxed);
+          (*it)->amplitude_inc.load(std::memory_order_relaxed);
       float max_amplitude =
-          it->get()->max_amplitude.load(std::memory_order_relaxed);
+          (*it)->max_amplitude.load(std::memory_order_relaxed);
       size_t channel_offset =
           (flags & kSimulateStereo) ? audio_bus->sample_rate() / 10 : 0;
 
@@ -237,11 +212,9 @@ void AudioMixer::RenderAudio(float* output_buffer, size_t num_frames) {
             break;
           }
 
-          if (!it->get()->streaming_in_progress.load(
-                  std::memory_order_acquire)) {
+          if (!(*it)->streaming_in_progress.load(std::memory_order_acquire)) {
             src_index %= num_samples;
-            it->get()->streaming_in_progress.store(true,
-                                                   std::memory_order_relaxed);
+            (*it)->streaming_in_progress.store(true, std::memory_order_relaxed);
 
             // Swap buffers and start streaming in background.
             audio_bus->SwapBuffers();
@@ -261,9 +234,9 @@ void AudioMixer::RenderAudio(float* output_buffer, size_t num_frames) {
         }
       }
 
-      it->get()->src_index = src_index;
-      it->get()->accumulator = accumulator;
-      it->get()->amplitude = amplitude;
+      (*it)->src_index = src_index;
+      (*it)->accumulator = accumulator;
+      (*it)->amplitude = amplitude;
     }
 
     if (marked_for_removal) {
@@ -275,7 +248,7 @@ void AudioMixer::RenderAudio(float* output_buffer, size_t num_frames) {
   }
 
   for (auto it = end_list_.begin(); it != end_list_.end();) {
-    if (!it->get()->streaming_in_progress.load(std::memory_order_relaxed)) {
+    if (!(*it)->streaming_in_progress.load(std::memory_order_relaxed)) {
       main_thread_task_runner_->PostTask(
           HERE, std::bind(&AudioMixer::EndCallback, this, *it));
       it = end_list_.erase(it);

src/engine/audio/audio_mixer.h

@@ -5,7 +5,6 @@
 #include <list>
 #include <memory>
 #include <mutex>
-#include <unordered_map>
 
 #include "base/closure.h"
 #include "engine/audio/audio_sink.h"
@@ -26,21 +25,20 @@ class AudioMixer : public AudioSink::Delegate {
   AudioMixer();
   ~AudioMixer();
 
-  uint64_t CreateResource();
-  void DestroyResource(uint64_t resource_id);
+  std::shared_ptr<void> CreateResource();
 
-  void Play(uint64_t resource_id,
+  void Play(std::shared_ptr<void> resource,
             std::shared_ptr<AudioBus> audio_bus,
             float amplitude,
             bool reset_pos);
-  void Stop(uint64_t resource_id);
+  void Stop(std::shared_ptr<void> resource);
 
-  void SetLoop(uint64_t resource_id, bool loop);
-  void SetSimulateStereo(uint64_t resource_id, bool simulate);
-  void SetResampleStep(uint64_t resource_id, size_t step);
-  void SetMaxAmplitude(uint64_t resource_id, float max_amplitude);
-  void SetAmplitudeInc(uint64_t resource_id, float amplitude_inc);
-  void SetEndCallback(uint64_t resource_id, base::Closure cb);
+  void SetLoop(std::shared_ptr<void> resource, bool loop);
+  void SetSimulateStereo(std::shared_ptr<void> resource, bool simulate);
+  void SetResampleStep(std::shared_ptr<void> resource, size_t step);
+  void SetMaxAmplitude(std::shared_ptr<void> resource, float max_amplitude);
+  void SetAmplitudeInc(std::shared_ptr<void> resource, float amplitude_inc);
+  void SetEndCallback(std::shared_ptr<void> resource, base::Closure cb);
 
   void SetEnableAudio(bool enable) { audio_enabled_ = enable; }
 
@@ -74,10 +72,9 @@ class AudioMixer : public AudioSink::Delegate {
 
     // Accessed by audio thread and decoder thread.
     std::atomic<bool> streaming_in_progress{false};
-  };
 
-  std::unordered_map<uint64_t, std::shared_ptr<Resource>> resources_;
-  uint64_t last_resource_id_ = 0;
+    ~Resource();
+  };
 
   std::list<std::shared_ptr<Resource>> play_list_[2];
   std::mutex lock_;

src/engine/renderer/opengl/renderer_opengl.cc

@@ -5,6 +5,7 @@
 #include <sstream>
 #include <unordered_set>
 
+#include "base/hash.h"
 #include "base/log.h"
 #include "base/vecmath.h"
 #include "engine/asset/image.h"
@@ -615,22 +616,29 @@ bool RendererOpenGL::BindAttributeLocation(GLuint id,
 GLint RendererOpenGL::GetUniformLocation(
     GLuint id,
     const std::string& name,
-    std::unordered_map<std::string, GLuint>& uniforms) {
+    std::vector<std::pair<size_t, GLuint>>& uniforms) {
   // Check if we've encountered this uniform before.
-  auto i = uniforms.find(name);
+  auto hash = KR2Hash(name);
+  auto it = std::find_if(uniforms.begin(), uniforms.end(),
+                         [&](auto& r) { return hash == std::get<0>(r); });
   GLint index;
-  if (i != uniforms.end()) {
+  if (it != uniforms.end()) {
     // Yes, we already have the mapping.
-    index = i->second;
+    index = std::get<1>(*it);
   } else {
     // No, ask the driver for the mapping and save it.
     index = glGetUniformLocation(id, name.c_str());
-    if (index >= 0)
-      uniforms[name] = index;
-    else
+    if (index >= 0) {
+      DCHECK(std::find_if(uniforms.begin(), uniforms.end(),
+                          [&](auto& r) { return hash == std::get<0>(r); }) ==
+             uniforms.end())
+          << "Hash collision";
+      uniforms.emplace_back(std::make_pair(hash, index));
+    } else {
       LOG(0) << "Cannot find uniform " << name.c_str() << " (shader: " << id
              << ")";
     }
+  }
   return index;
 }
 

src/engine/renderer/opengl/renderer_opengl.h

@@ -4,6 +4,7 @@
 #include <memory>
 #include <string>
 #include <unordered_map>
+#include <utility>
 #include <vector>
 
 #include "engine/renderer/opengl/opengl.h"
@@ -94,7 +95,10 @@ class RendererOpenGL final : public Renderer {
 
   struct ShaderOpenGL {
     GLuint id = 0;
-    std::unordered_map<std::string, GLuint> uniforms;
+    std::vector<std::pair<size_t,  // Uniform name hash
+                          GLuint   // Uniform index
+                          >>
+        uniforms;
     bool enable_depth_test = false;
   };
 
@@ -140,7 +144,7 @@ class RendererOpenGL final : public Renderer {
   bool BindAttributeLocation(GLuint id, const VertexDescription& vd);
   GLint GetUniformLocation(GLuint id,
                            const std::string& name,
-                           std::unordered_map<std::string, GLuint>& uniforms);
+                           std::vector<std::pair<size_t, GLuint>>& uniforms);
 };
 
 }  // namespace eng

src/engine/renderer/vulkan/renderer_vulkan.cc

@@ -5,6 +5,7 @@
 #include <sstream>
 #include <utility>
 
+#include "base/hash.h"
 #include "base/log.h"
 #include "base/vecmath.h"
 #include "engine/asset/image.h"
@@ -1876,19 +1877,27 @@ bool RendererVulkan::CreatePipelineLayout(
 
       size_t offset = 0;
       for (uint32_t j = 0; j < pconstants_vertex[0]->member_count; j++) {
+        DCHECK(std::find_if(
+                   shader.variables.begin(), shader.variables.end(),
+                   [hash = KR2Hash(pconstants_vertex[0]->members[j].name)](
+                       auto& r) { return hash == std::get<0>(r); }) ==
+               shader.variables.end())
+            << "Hash collision";
+
         DLOG(0) << __func__
                 << " name: " << pconstants_vertex[0]->members[j].name
                 << " size: " << pconstants_vertex[0]->members[j].size
                 << " padded_size: "
                 << pconstants_vertex[0]->members[j].padded_size;
 
-        shader.variables[pconstants_vertex[0]->members[j].name] = {
-            pconstants_vertex[0]->members[j].size, offset};
+        shader.variables.emplace_back(
+            std::make_tuple(KR2Hash(pconstants_vertex[0]->members[j].name),
+                            pconstants_vertex[0]->members[j].size, offset));
         offset += pconstants_vertex[0]->members[j].padded_size;
       }
     }
 
-    // Use the same layout for all decriptor sets.
+    // Use the same layout for all descriptor sets.
     std::vector<VkDescriptorSetLayout> desc_set_layouts;
     for (size_t i = 0; i < binding_count; ++i)
       desc_set_layouts.push_back(descriptor_set_layout_);
@@ -2032,17 +2041,21 @@ template <typename T>
 bool RendererVulkan::SetUniformInternal(ShaderVulkan& shader,
                                         const std::string& name,
                                         T val) {
-  auto it = shader.variables.find(name);
+  auto hash = KR2Hash(name);
+  auto it = std::find_if(shader.variables.begin(), shader.variables.end(),
+                         [&](auto& r) { return hash == std::get<0>(r); });
   if (it == shader.variables.end()) {
     DLOG(0) << "No variable found with name " << name;
     return false;
   }
-  if (it->second[0] != sizeof(val)) {
+
+  if (std::get<1>(*it) != sizeof(val)) {
     DLOG(0) << "Size mismatch for variable " << name;
     return false;
   }
 
-  auto* dst = reinterpret_cast<T*>(shader.push_constants.get() + it->second[1]);
+  auto* dst =
+      reinterpret_cast<T*>(shader.push_constants.get() + std::get<2>(*it));
   *dst = val;
   return true;
 }

src/engine/renderer/vulkan/renderer_vulkan.h

@@ -106,7 +106,11 @@ class RendererVulkan final : public Renderer {
   };
 
   struct ShaderVulkan {
-    std::unordered_map<std::string, std::array<size_t, 2>> variables;
+    std::vector<std::tuple<size_t,  // Variable name hash
+                           size_t,  // Variable size
+                           size_t   // Push constant offset
+                           >>
+        variables;
     std::unique_ptr<char[]> push_constants;
     size_t push_constants_size = 0;
     std::vector<std::string> sampler_uniform_names;

src/engine/sound_player.cc

@@ -11,10 +11,10 @@ using namespace base;
 namespace eng {
 
 SoundPlayer::SoundPlayer()
-    : resource_id_(Engine::Get().GetAudioMixer()->CreateResource()) {}
+    : resource_(Engine::Get().GetAudioMixer()->CreateResource()) {}
 
 SoundPlayer::~SoundPlayer() {
-  Engine::Get().GetAudioMixer()->DestroyResource(resource_id_);
+  Engine::Get().GetAudioMixer()->Stop(resource_);
 }
 
 void SoundPlayer::SetSound(const std::string& asset_name) {
@@ -30,15 +30,15 @@ void SoundPlayer::Play(bool loop, float fade_in_duration) {
     return;
 
   int step = variate_ ? Engine::Get().GetRandomGenerator().Roll(3) - 2 : 0;
-  Engine::Get().GetAudioMixer()->SetResampleStep(resource_id_, step * 12);
-  Engine::Get().GetAudioMixer()->SetLoop(resource_id_, loop);
+  Engine::Get().GetAudioMixer()->SetResampleStep(resource_, step * 12);
+  Engine::Get().GetAudioMixer()->SetLoop(resource_, loop);
   if (fade_in_duration > 0)
     Engine::Get().GetAudioMixer()->SetAmplitudeInc(
-        resource_id_, 1.0f / (sound_->sample_rate() * fade_in_duration));
+        resource_, 1.0f / (sound_->sample_rate() * fade_in_duration));
   else
-    Engine::Get().GetAudioMixer()->SetAmplitudeInc(resource_id_, 0);
+    Engine::Get().GetAudioMixer()->SetAmplitudeInc(resource_, 0);
   Engine::Get().GetAudioMixer()->Play(
-      resource_id_, sound_, fade_in_duration > 0 ? 0 : max_amplitude_, true);
+      resource_, sound_, fade_in_duration > 0 ? 0 : max_amplitude_, true);
 }
 
 void SoundPlayer::Resume(float fade_in_duration) {
@@ -47,8 +47,8 @@ void SoundPlayer::Resume(float fade_in_duration) {
 
   if (fade_in_duration > 0)
     Engine::Get().GetAudioMixer()->SetAmplitudeInc(
-        resource_id_, 1.0f / (sound_->sample_rate() * fade_in_duration));
-  Engine::Get().GetAudioMixer()->Play(resource_id_, sound_,
+        resource_, 1.0f / (sound_->sample_rate() * fade_in_duration));
+  Engine::Get().GetAudioMixer()->Play(resource_, sound_,
                                       fade_in_duration > 0 ? 0 : -1, false);
 }
 
@@ -58,9 +58,9 @@ void SoundPlayer::Stop(float fade_out_duration) {
 
   if (fade_out_duration > 0)
     Engine::Get().GetAudioMixer()->SetAmplitudeInc(
-        resource_id_, -1.0f / (sound_->sample_rate() * fade_out_duration));
+        resource_, -1.0f / (sound_->sample_rate() * fade_out_duration));
   else
-    Engine::Get().GetAudioMixer()->Stop(resource_id_);
+    Engine::Get().GetAudioMixer()->Stop(resource_);
 }
 
 void SoundPlayer::SetVariate(bool variate) {
@@ -68,16 +68,16 @@ void SoundPlayer::SetVariate(bool variate) {
 }
 
 void SoundPlayer::SetSimulateStereo(bool simulate) {
-  Engine::Get().GetAudioMixer()->SetSimulateStereo(resource_id_, simulate);
+  Engine::Get().GetAudioMixer()->SetSimulateStereo(resource_, simulate);
 }
 
 void SoundPlayer::SetMaxAplitude(float max_amplitude) {
   max_amplitude_ = max_amplitude;
-  Engine::Get().GetAudioMixer()->SetMaxAmplitude(resource_id_, max_amplitude);
+  Engine::Get().GetAudioMixer()->SetMaxAmplitude(resource_, max_amplitude);
 }
 
 void SoundPlayer::SetEndCallback(base::Closure cb) {
-  Engine::Get().GetAudioMixer()->SetEndCallback(resource_id_, cb);
+  Engine::Get().GetAudioMixer()->SetEndCallback(resource_, cb);
 }
 
 }  // namespace eng

src/engine/sound_player.h

@@ -37,7 +37,7 @@ class SoundPlayer {
   void SetEndCallback(base::Closure cb);
 
  private:
-  uint64_t resource_id_ = 0;
+  std::shared_ptr<void> resource_;
   std::shared_ptr<AudioBus> sound_;
 
   float max_amplitude_ = 1.0f;