add file index to static file handler

static_file_handler.hpp

@@ -6,11 +6,14 @@
 #include <string>
 #include <string_view>
 #include <unordered_map>
+#include <unordered_set>
 #include <fstream>
 #include <filesystem>
 #include <chrono>
+#include <shared_mutex>
 #include <zlib.h>
 #include <cstring>
+#include <mutex>
 
 using std::string_view;
 using std::string;
@@ -21,8 +24,31 @@ private:
 	string url_prefix_;
 	string root_path_;
 	std::unordered_map<string, std::pair<string, std::chrono::time_point<std::chrono::file_clock>>> cache_;
+	std::unordered_set<string> file_index_;
+	mutable std::shared_mutex index_mutex_;
 	size_t max_cache_size_ = 50 * 1024 * 1024; // 50MB cache limit
 
+	void build_file_index() {
+		std::unique_lock lock(index_mutex_);
+		file_index_.clear();
+		
+		if (!fs::exists(root_path_) || !fs::is_directory(root_path_)) {
+			return;
+		}
+
+		for (const auto& entry : fs::recursive_directory_iterator(root_path_)) {
+			if (entry.is_regular_file()) {
+				auto rel_path = fs::relative(entry.path(), root_path_);
+				file_index_.insert(rel_path.string());
+			}
+		}
+	}
+
+	bool file_exists_fast(const string& relative_path) const {
+		std::shared_lock lock(index_mutex_);
+		return file_index_.count(relative_path) > 0;
+	}
+
 	string compress_gzip(const string& data) const {
 		z_stream zs;
 		memset(&zs, 0, sizeof(zs));
@@ -79,6 +105,11 @@ public:
 		if (!url_prefix_.empty() && url_prefix_.back() != '/') {
 			url_prefix_ += '/';
 		}
+		build_file_index();
+	}
+
+	void refresh_index() {
+		build_file_index();
 	}
 
 	bool handle(const Request& req, Response& res) {
@@ -101,19 +132,22 @@ public:
 			return false;
 		}
 
-		string file_path = root_path_;
+		string relative_path;
 		if (file_path_part.empty() || file_path_part == "/") {
-			file_path += "index.html";
+			relative_path = "index.html";
 		} else {
 			// Remove leading slash if present
 			if (file_path_part[0] == '/') file_path_part = file_path_part.substr(1);
-			file_path += string(file_path_part);
+			relative_path = string(file_path_part);
 		}
 
-		if (!fs::exists(file_path) || !fs::is_regular_file(file_path)) {
+		// Fast file existence check
+		if (!file_exists_fast(relative_path)) {
 			return false;
 		}
 
+		string file_path = root_path_ + relative_path;
+
 		// Get file info
 		auto last_write = fs::last_write_time(file_path);
 		auto file_size = fs::file_size(file_path);
@@ -163,4 +197,4 @@ public:
 
 		return true;
 	}
-};
+};