http_cache.hpp

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#ifndef NEFORCE_NETWORK_HTTP_HTTP_CACHE_HPP__
#define NEFORCE_NETWORK_HTTP_HTTP_CACHE_HPP__

 
#include "NeForce/core/async/shared_mutex.hpp"
#include "NeForce/network/http/http_filter.hpp"
NEFORCE_BEGIN_NAMESPACE__
NEFORCE_BEGIN_HTTP__


struct cached_response {
    http_status status{http_status::S2_OK};
    string status_message;
    unordered_map<string, string> headers;
    string body;
    string etag;
    datetime cached_at;
    seconds max_age{60};
};

class NEFORCE_API response_cache {
public:
    seconds default_max_age{60};   
    size_t max_entries{10000};     
    byte_size max_body_size{1_MB}; 
 
    response_cache() = default;

    optional<cached_response> get(const string& key);

    void put(const string& key, const http_response& response, seconds max_age = -1_s);

    void remove(const string& key);

    void cleanup();

    void clear();

    size_t size() const {
        shared_lock<shared_mutex> lk(mutex_);
        return entries_.size();
    }

    static string generate_etag(string_view body);

    static string build_key(const http_method& method, string_view url);
 
private:
    struct entry {
        cached_response response;
        uint64_t last_access_ms;
    };
    mutable shared_mutex mutex_;
    unordered_map<string, entry> entries_;
 
    void evict_lru();
 
    // TODO: Distributed cache backends — Redis/Memcached as shared cache store for multi-instance deployments
    // TODO: Cache statistics — hit_rate, miss_count, eviction_count, cache_size_bytes for monitoring
    // TODO: Cache-control directive parsing — honor no-cache, no-store, max-age, s-maxage in addition to If-None-Match
};

class NEFORCE_API cache_filter final : public http_filter {
public:
    bool enabled{true};
    bool cache_only_get{true};
 
    cache_filter() = default;
    explicit cache_filter(response_cache* cache) :
    cache_(cache) {}
 
    void set_cache(response_cache* cache) { cache_ = cache; }
 
    bool pre_filter(http_request& request, http_response& response) override;
    void post_filter(http_request& request, http_response& response) override;
    void do_filter(http_request& request, http_response& response) override {}
    NEFORCE_NODISCARD string name() const override { return "cache_filter"; }
 
private:
    response_cache* cache_{nullptr};
};
 // HTTP
 
NEFORCE_END_HTTP__
NEFORCE_END_NAMESPACE__
#endif // NEFORCE_NETWORK_HTTP_HTTP_CACHE_HPP__