gpu_audio_provider_pool.hpp

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#pragma once
 
#include <cstddef>
#include <cstdint>
#include <memory>
#include <string>
 
#include <pulp/gpu_audio/gpu_wavenet.hpp>
 
namespace pulp::gpu_audio {
 
namespace detail {
struct GpuAudioProviderPoolTestAccess;
class WaveNetRealtimeChannel;
} // namespace detail

class GpuAudioProviderPool {
  public:
    struct Config {
        std::uint64_t keep_warm_ns = 30'000'000'000;
        std::uint32_t capacity = 4;
        std::uint64_t release_budget_ns = 250'000'000;
    };
    struct Stats {
        std::uint64_t hits = 0;         // prepare() borrowed a warm provider
        std::uint64_t misses = 0;       // prepare() found no matching provider
        std::uint64_t returned = 0;     // release() kept a provider warm
        std::uint64_t evictions = 0;    // providers destroyed by age, capacity or clear()
        std::uint32_t warm_entries = 0; // providers held now
    };
 
    GpuAudioProviderPool();
    explicit GpuAudioProviderPool(const Config& config);
    ~GpuAudioProviderPool();
    GpuAudioProviderPool(const GpuAudioProviderPool&) = delete;
    GpuAudioProviderPool& operator=(const GpuAudioProviderPool&) = delete;
    GpuAudioProviderPool(GpuAudioProviderPool&&) = delete;
    GpuAudioProviderPool& operator=(GpuAudioProviderPool&&) = delete;

    void evict_expired() noexcept;
    void clear() noexcept;
    Stats stats() const noexcept;
 
  private:
    friend class GpuWaveNetRealtimeNode;
    friend struct detail::GpuAudioProviderPoolTestAccess;
    // Node-facing. A null result is a miss; the caller creates a provider.
    // `provider_key` names the provider kind and revision; providers found
    // lost on the way are released within `release_budget_ns` in total (zero:
    // Config::release_budget_ns).
    std::unique_ptr<detail::WaveNetRealtimeChannel>
    acquire(const GpuWaveNetSession::Config&, const std::string& provider_key,
            std::uint64_t release_budget_ns) noexcept;
    // Takes a drained, resumable channel; false hands it back to the caller.
    bool give(const GpuWaveNetSession::Config&, const std::string& provider_key,
              std::unique_ptr<detail::WaveNetRealtimeChannel>&) noexcept;
 
    struct Impl;
    std::unique_ptr<Impl> impl_;
};
 
} // namespace pulp::gpu_audio