shader_cache.hpp

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#pragma once
 
#include "shader_reflection.hpp"
 
#include <cstddef>
#include <future>
#include <memory>
#include <mutex>
#include <optional>
#include <string>
#include <toast/assets/core_types.hpp>
#include <toast/assets/shader.hpp>
#include <toast/events/event.hpp>
#include <toast/events/listener.hpp>
#include <toast/uid.hpp>
#include <unordered_map>
#include <unordered_set>
#include <vector>
 
namespace event {
 
struct ShaderRecompiled : public Event<ShaderRecompiled> {
  toast::UID uid;
 
  explicit ShaderRecompiled(toast::UID uid) : uid(uid) { }
};
 
}
 
namespace renderer {
 
class TOAST_API ShaderCache {
public:
  struct Entry {
    std::vector<std::byte> spirv;
    ShaderReflection reflection;
    uint64_t hash = 0;
    std::string source_uri;
    std::vector<std::string> dependencies;
  };
 
  static auto get() -> ShaderCache&;
 
  void compileAllAtStartup();

  auto acquire(toast::UID uid) -> std::shared_ptr<const Entry>;
 
  auto ensureCompiled(toast::UID uid) -> bool;
 
  auto onShaderSourceReloaded(toast::UID uid) -> bool;
 
  static auto fnv1a(const void* data, size_t size) -> uint64_t;
 
private:
  using EntryPtr = std::shared_ptr<const Entry>;
 
  ShaderCache();

  auto loadOrCompile(toast::UID uid) -> EntryPtr;
  auto compile(toast::UID uid, const std::string& source) -> EntryPtr;
  static auto loadFromDisk(toast::UID uid) -> EntryPtr;
  auto isDiskCacheFresh(toast::UID uid, uint64_t source_hash) -> bool;
  auto sourceOf(toast::UID uid) -> std::optional<std::string>;
 
  void loadHashIndexLocked();
  void saveHashIndexLocked();
  auto sourceHandleLocked(toast::UID uid) -> assets::Handle<assets::Shader>&;

  std::mutex m_mutex;
  std::unordered_map<uint64_t, EntryPtr> m_entries;
  std::unordered_map<uint64_t, std::shared_future<EntryPtr>> m_in_flight;
  std::unordered_map<uint64_t, assets::Handle<assets::Shader>> m_sources;
  std::unordered_map<uint64_t, std::unordered_set<uint64_t>> m_reverse_deps;
  nlohmann::json m_hash_index;
  bool m_hash_index_loaded = false;
 
  event::Listener m_listener;
};
 
}