solanaceae_ngc_ft1/solanaceae/ngc_ft1_sha1/file_rw_mapped.hpp

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#pragma once
#include <solanaceae/file/file2.hpp>
#include "./mio.hpp"
#include <filesystem>
#include <fstream>
#include <iostream>
#include <cstring>
struct File2RWMapped : public File2I {
mio::ummap_sink _file_map;
// TODO: add truncate support?
// TODO: rw always true?
File2RWMapped(std::string_view file_path, int64_t file_size = -1) : File2I(true, true) {
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std::filesystem::path native_file_path{file_path};
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if (!std::filesystem::exists(native_file_path)) {
std::ofstream(native_file_path) << '\0'; // force create the file
}
_file_size = std::filesystem::file_size(native_file_path);
if (file_size >= 0 && _file_size != file_size) {
_file_size = file_size;
std::filesystem::resize_file(native_file_path, file_size); // ensure size, usually sparse
}
std::error_code err;
// sink, is also read
_file_map.map(native_file_path.u8string(), 0, _file_size, err);
if (err) {
std::cerr << "FileRWMapped error: mapping file failed " << err << "\n";
return;
}
}
virtual ~File2RWMapped(void) override {}
bool isGood(void) override {
return _file_map.is_mapped();
}
bool write(const ByteSpan data, int64_t pos = -1) override {
// TODO: support streaming write
if (pos < 0) {
return false;
}
if (data.empty()) {
return true; // false?
}
// file size is fix for mmaped files
if (pos+data.size > _file_size) {
return false;
}
std::memcpy(_file_map.data()+pos, data.ptr, data.size);
return true;
}
ByteSpanWithOwnership read(uint64_t size, int64_t pos = -1) override {
if (pos+size > _file_size) {
//assert(false && "read past end");
return ByteSpan{};
}
// return non-owning
return ByteSpan{_file_map.data()+pos, size};
}
};