move to read only memory mapped files

CMakeLists.txt

@@ -58,7 +58,7 @@ target_link_libraries(solanaceae_ngcft1 PUBLIC
 add_library(solanaceae_sha1_ngcft1
 	# hacky deps
 	./solanaceae/ngc_ft1_sha1/mio.hpp
-	./solanaceae/ngc_ft1_sha1/file_rw_mapped.hpp
+	./solanaceae/ngc_ft1_sha1/file2_mapped.hpp
 	./solanaceae/ngc_ft1_sha1/file_constructor.hpp
 	./solanaceae/ngc_ft1_sha1/file_constructor.cpp
 

solanaceae/ngc_ft1_sha1/backends/sha1_mapped_filesystem.cpp

@@ -68,7 +68,7 @@ void SHA1MappedFilesystem::newFromFile(std::string_view file_name, std::string_v
 		file_path_ = std::string(file_path)
 	]() mutable {
 		// 0. open and fail
-		std::unique_ptr<File2I> file_impl = construct_file2_rw_mapped(file_path_, -1);
+		std::unique_ptr<File2I> file_impl = construct_file2_r_mapped(file_path_);
 		if (!file_impl->isGood()) {
 			{
 				std::lock_guard l{ibs->info_builder_queue_mutex};
@@ -124,7 +124,8 @@ void SHA1MappedFilesystem::newFromFile(std::string_view file_name, std::string_v
 			// executed on iterate thread
 
 			// reopen, cant move, since std::function needs to be copy consturctable (meh)
-			std::unique_ptr<File2I> file_impl = construct_file2_rw_mapped(file_path_, sha1_info.file_size);
+			std::unique_ptr<File2I> file_impl = construct_file2_r_mapped(file_path_);
+			//std::unique_ptr<File2I> file_impl = construct_file2_rw_mapped(file_path_, sha1_info.file_size);
 			if (!file_impl->isGood()) {
 				std::cerr << "SHA1MF error: failed opening file '" << file_path_ << "'!\n";
 				return;
@@ -234,15 +235,22 @@ std::unique_ptr<File2I> SHA1MappedFilesystem::file2(Object ov, FILE2_FLAGS flags
 		return nullptr;
 	}
 
-	// TODO: read-only one too
 	// since they are mapped, is this efficent to have multiple?
+	if (flags & FILE2_WRITE) {
 		auto res = construct_file2_rw_mapped(file_path, -1);
 		if (!res || !res->isGood()) {
-		std::cerr << "SHA1MF error: failed constructing mapped file '" << file_path << "'\n";
+			std::cerr << "SHA1MF error: failed constructing mapped RW file '" << file_path << "'\n";
 			return nullptr;
 		}
-
 		return res;
+	} else { // read
+		auto res = construct_file2_r_mapped(file_path);
+		if (!res || !res->isGood()) {
+			std::cerr << "SHA1MF error: failed constructing mapped R file '" << file_path << "'\n";
+			return nullptr;
+		}
+		return res;
+	}
 }
 
 } // Backends

solanaceae/ngc_ft1_sha1/file2_mapped.hpp

@@ -48,7 +48,8 @@ struct File2RWMapped : public File2I {
 		}
 	}
 
-	virtual ~File2RWMapped(void) override {}
+	virtual ~File2RWMapped(void) {
+	}
 
 	bool isGood(void) override {
 		return _file_map.is_mapped();
@@ -91,3 +92,55 @@ struct File2RWMapped : public File2I {
 	}
 };
 
+struct File2RMapped : public File2I {
+	mio::ummap_source _file_map;
+
+	File2RMapped(std::string_view file_path) : File2I(false, true) {
+		std::filesystem::path native_file_path{file_path};
+
+		if (!std::filesystem::exists(native_file_path)) {
+			std::cerr << "FileRMapped error: file does not exist\n";
+			return;
+		}
+
+		_file_size = std::filesystem::file_size(native_file_path);
+
+		std::error_code err;
+		_file_map.map(native_file_path.u8string(), err);
+
+		if (err) {
+			std::cerr << "FileRMapped error: mapping file failed: " << err.message() << " (" << err << ")\n";
+			return;
+		}
+
+		if (_file_size != _file_map.length()) {
+			std::cerr << "FileRMapped warning: file size and mapped file size mismatch.\n";
+			_file_size = _file_map.length();
+		}
+	}
+
+	virtual ~File2RMapped(void) {
+	}
+
+	bool isGood(void) override {
+		return _file_map.is_mapped();
+	}
+
+	bool write(const ByteSpan, int64_t = -1) override { return false; }
+
+	ByteSpanWithOwnership read(uint64_t size, int64_t pos = -1) override {
+		// TODO: support streaming read
+		if (pos < 0) {
+			assert(false && "streaming not implemented");
+			return ByteSpan{};
+		}
+
+		if (pos+size > _file_size) {
+			assert(false && "read past end");
+			return ByteSpan{};
+		}
+
+		// return non-owning
+		return ByteSpan{_file_map.data()+pos, size};
+	}
+};

solanaceae/ngc_ft1_sha1/file_constructor.cpp

@@ -1,8 +1,12 @@
 #include "./file_constructor.hpp"
 
-#include "./file_rw_mapped.hpp"
+#include "./file2_mapped.hpp"
 
 std::unique_ptr<File2I> construct_file2_rw_mapped(std::string_view file_path, int64_t file_size) {
 	return std::make_unique<File2RWMapped>(file_path, file_size);
 }
 
+std::unique_ptr<File2I> construct_file2_r_mapped(std::string_view file_path) {
+	return std::make_unique<File2RMapped>(file_path);
+}
+

solanaceae/ngc_ft1_sha1/file_constructor.hpp

@@ -6,4 +6,5 @@
 #include <string_view>
 
 std::unique_ptr<File2I> construct_file2_rw_mapped(std::string_view file_path, int64_t file_size = -1);
+std::unique_ptr<File2I> construct_file2_r_mapped(std::string_view file_path);