scan_cache.hpp

Go to the documentation of this file.

#pragma once
 
// Persistent plugin scan cache.
//
// Stores PluginInfo results keyed by (path, mtime, size). On the second scan
// of an unchanged plugin file, the cache returns the stored PluginInfo
// without re-inspecting the plugin binary. Entries auto-invalidate when the
// underlying file changes.
//
// Format: JSON file. Schema versioned so future changes can force a flush.
// Usage:
//   HostScanCache cache;
//   cache.load_from("/path/to/cache.json");          // best-effort; silent on miss
//   if (auto info = cache.get("/path/to/plugin.vst3")) { ... }
//   else { PluginInfo fresh = ...; cache.put("/path/to/plugin.vst3", fresh); }
//   cache.save_to("/path/to/cache.json");
 
#include <pulp/host/scanner.hpp>
 
#include <optional>
#include <string>
#include <unordered_map>
 
namespace pulp::host {
 
struct ScanCacheEntry {
    int64_t mtime = 0;   // seconds since epoch; 0 means "unknown" (never matches)
    int64_t size = 0;    // bytes
    PluginInfo info;
};
 
class HostScanCache {
public:
    static constexpr int kSchemaVersion = 1;

    std::optional<PluginInfo> get(const std::string& path) const;

    void put(const std::string& path, const PluginInfo& info);

    void erase(const std::string& path);

    std::size_t size() const { return entries_.size(); }

    void clear() { entries_.clear(); }

    bool save_to(const std::string& file_path) const;

    bool load_from(const std::string& file_path);
 
    // ── Serialization helpers exposed for unit tests ──────────────────────
    std::string to_json() const;
    bool from_json(const std::string& json);
 
    // ── Raw access for tests / diagnostics ────────────────────────────────
    const std::unordered_map<std::string, ScanCacheEntry>& entries() const {
        return entries_;
    }
 
private:
    std::unordered_map<std::string, ScanCacheEntry> entries_;
};
 
} // namespace pulp::host