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Merge pull request #5 from penglei0/4-read-write-improvement
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4 read write improvement
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@penglei0
penglei0 authored May 11, 2024
2 parents 8bbff3c + e5a57a4 commit 81be378
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Showing 2 changed files with 307 additions and 109 deletions.
171 changes: 112 additions & 59 deletions include/settings.h
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Original file line number Diff line number Diff line change
Expand Up @@ -46,7 +46,7 @@ using enable_if_supported_type = typename std::enable_if<
* @return T
*/
template <typename T, enable_if_supported_type<T> = 0>
T ConvertValue(const std::string& value, T default_value) {
T ConvertValue(const std::string& value, const T& default_value) {
if (value.empty()) {
return default_value;
}
Expand Down Expand Up @@ -135,6 +135,11 @@ class Settings {
}
return *ins;
}
// Tear down the singleton
static void DestroyInstance() {
Settings* ins = &GetInstance();
delete ins;
}
// disable copy and move
Settings(Settings const&) = delete;
Settings& operator=(Settings const&) = delete;
Expand All @@ -160,7 +165,7 @@ class Settings {
* @return T
*/
template <typename T, typename... Types, enable_if_supported_type<T> = 0>
T GetValue2(T default_value, const std::string& fmt, Types&&... args);
T GetValue2(const T& default_value, const std::string& fmt, Types&&... args);
/**
* @brief Get the value of the `key` from the `ini` file. If the `key` doesn't
* exist, return the `default_value`.
Expand All @@ -180,41 +185,77 @@ class Settings {
* @param value The value to be saved.
*/
template <typename T, enable_if_supported_type<T> = 0>
void SetValue(const std::string& key, T value);
void SetValue(const std::string& key, const T& value);

friend std::ostream& operator<<(std::ostream& os, const Settings& settings) {
for (auto& [key, value] : settings.content_tbl_) {
os << "*" << key << " = " << value << std::endl;
}
return os;
}
void DumpFile() {
std::ifstream ifs(IniFullPath);
if (!ifs.is_open()) {
std::cerr << "Failed to open file: " << IniFullPath << std::endl;
return;
}
std::string line;
while (std::getline(ifs, line)) {
std::cout << line << std::endl;
}
}

private:
Settings() = default;
virtual ~Settings() = default;

// *********** implementation ***********
bool LoadContentTbl();
bool StoreContentTbl();
void WriteIni(std::basic_ostream<char>& stream,
const StrStrMap& ini_content_tbl);
void ReadIni(std::basic_istream<char>& stream, StrStrMap& ini_content_tbl);
// protect read/write
std::mutex ini_rw_mutex_;
StrStrMap content_tbl_;
std::filesystem::file_time_type last_write_time_;
// stored in memory, and write back to the ini file when SetValue is called.
};

template <const char* IniFullPath>
template <typename T, typename... Types, enable_if_supported_type<T>>
T Settings<IniFullPath>::GetValue2(T default_value, const std::string& fmt,
Types&&... args) {
// lock ini_rw_mutex_
std::lock_guard<std::mutex> lock(ini_rw_mutex_);
if (!std::filesystem::exists(IniFullPath)) {
return default_value;
}
bool Settings<IniFullPath>::LoadContentTbl() {
std::basic_ifstream<char> stream(IniFullPath,
std::ios_base::out | std::ios_base::app);
if (!stream) {
// maybe permission denied
std::string err_msg = IniFullPath;
err_msg += " open failed";
throw std::runtime_error(err_msg);
return false;
}
StrStrMap kv_table;
stream.imbue(std::locale());
content_tbl_.clear();
// Read all the key-value pairs from the ini file
ReadIni(stream, kv_table);
ReadIni(stream, content_tbl_);
return true;
}

template <const char* IniFullPath>
bool Settings<IniFullPath>::StoreContentTbl() {
std::basic_ofstream<char> stream(IniFullPath);
if (!stream) {
return false;
}
stream.imbue(std::locale());
WriteIni(stream, content_tbl_);
last_write_time_ = std::filesystem::last_write_time(IniFullPath);
return true;
}

template <const char* IniFullPath>
template <typename T, typename... Types, enable_if_supported_type<T>>
T Settings<IniFullPath>::GetValue2(const T& default_value,
const std::string& fmt, Types&&... args) {
std::lock_guard<std::mutex> lock(ini_rw_mutex_);
if (!std::filesystem::exists(IniFullPath)) {
return default_value;
}

auto formatString = [](const std::string& __fmt, auto&&... __args) {
size_t args_size = snprintf(nullptr, 0, __fmt.c_str(),
Expand All @@ -225,9 +266,21 @@ T Settings<IniFullPath>::GetValue2(T default_value, const std::string& fmt,
std::forward<decltype(__args)>(__args)...);
return std::string(args_buf.get(), args_buf.get() + args_size - 1);
};

std::string key = formatString(fmt, std::forward<Types>(args)...);
return ConvertValue(kv_table[key], default_value);

// no updates, use the memory content_tbl_
if (last_write_time_ != std::filesystem::last_write_time(IniFullPath)) {
if (!LoadContentTbl()) {
std::string err_msg = IniFullPath;
err_msg += " open failed, maybe permission denied.";
throw std::runtime_error(err_msg);
}
last_write_time_ = std::filesystem::last_write_time(IniFullPath);
}
if (content_tbl_.find(key) == content_tbl_.end()) {
return default_value;
}
return ConvertValue(content_tbl_.at(key), default_value);
}

template <const char* IniFullPath>
Expand All @@ -237,25 +290,24 @@ T Settings<IniFullPath>::GetValue(const std::string& key, T default_value) {
if (!std::filesystem::exists(IniFullPath)) {
return default_value;
}
std::basic_ifstream<char> stream(IniFullPath,
std::ios_base::out | std::ios_base::app);
if (!stream) {
// maybe permission denied
std::string err_msg = IniFullPath;
err_msg += " open failed";
throw std::runtime_error(err_msg);
// no updates, use the memory content_tbl_
if (last_write_time_ != std::filesystem::last_write_time(IniFullPath)) {
if (!LoadContentTbl()) {
std::string err_msg = IniFullPath;
err_msg += " open failed, maybe permission denied.";
throw std::runtime_error(err_msg);
}
last_write_time_ = std::filesystem::last_write_time(IniFullPath);
}
StrStrMap kv_table;
stream.imbue(std::locale());

// Read all the key-value pairs from the ini file
ReadIni(stream, kv_table);
return ConvertValue(kv_table[key], default_value);
if (content_tbl_.find(key) == content_tbl_.end()) {
return default_value;
}
return ConvertValue(content_tbl_.at(key), default_value);
}

template <const char* IniFullPath>
template <typename T, enable_if_supported_type<T>>
void Settings<IniFullPath>::SetValue(const std::string& key, T value) {
void Settings<IniFullPath>::SetValue(const std::string& key, const T& value) {
std::lock_guard<std::mutex> lock(ini_rw_mutex_);
if (!std::filesystem::exists(IniFullPath)) {
std::cout << IniFullPath << " doesn't exist, create a new one."
Expand All @@ -265,7 +317,7 @@ void Settings<IniFullPath>::SetValue(const std::string& key, T value) {
std::cout << "Create directory: " << ini_parent_path << std::endl;
if (!std::filesystem::create_directories(ini_parent_path)) {
// maybe permission denied
throw std::runtime_error("File create failed");
throw std::runtime_error("Path create failed");
}
}
auto create_ini_file = [](const std::string& ini_path) -> bool {
Expand All @@ -280,38 +332,33 @@ void Settings<IniFullPath>::SetValue(const std::string& key, T value) {
throw std::runtime_error("File create failed");
}
std::cout << "Create regular file: " << IniFullPath << std::endl;
last_write_time_ = std::filesystem::last_write_time(IniFullPath);
}

StrStrMap kv_table;
{
std::basic_ifstream<char> stream(IniFullPath,
std::ios_base::out | std::ios_base::app);
if (!stream) {
// maybe permission denied
// load before write
if (last_write_time_ != std::filesystem::last_write_time(IniFullPath)) {
if (!LoadContentTbl()) {
std::string err_msg = IniFullPath;
err_msg += " open failed";
err_msg += " open failed, maybe permission denied.";
throw std::runtime_error(err_msg);
}
stream.imbue(std::locale());
// Read all the key-value pairs from the ini file
ReadIni(stream, kv_table);
}
std::stringstream ss;

std::string value_string;
ss << value;
ss >> value_string;
auto it = kv_table.find(key);
if (it != kv_table.end()) {
it = kv_table.erase(it);
if constexpr (!std::is_same<typename std::decay<T>::type,
std::string>::value) {
value_string = std::to_string(value);
} else {
value_string = value;
}
kv_table.insert(std::make_pair(key, value_string));
// write back to the ini file
std::basic_ofstream<char> out(IniFullPath);
if (!out) {
throw std::runtime_error("File open failed");

// insert or update
content_tbl_.insert_or_assign(key, value_string);
if (!StoreContentTbl()) {
std::string err_msg = IniFullPath;
err_msg += " write failed, maybe permission denied.";
throw std::runtime_error(err_msg);
}
out.imbue(std::locale());
WriteIni(out, kv_table);
}
/**
* @brief Write the `ini_content_tbl` to the `stream`.
Expand All @@ -325,6 +372,10 @@ void Settings<IniFullPath>::WriteIni(std::basic_ostream<char>& stream,
const StrStrMap& ini_content_tbl) {
std::set<std::string> sec_name_set;
for (auto& [combined_key, value] : ini_content_tbl) {
if (value.empty()) {
// always ignore empty value. it make no sense.
continue;
}
auto combined_key_vec = Split(combined_key, ".");
if (combined_key_vec.size() < 2) {
// no section or key: invalid data
Expand Down Expand Up @@ -373,7 +424,9 @@ void Settings<IniFullPath>::ReadIni(std::basic_istream<char>& stream,
// For all lines
while (stream.good()) {
std::getline(stream, line);
if (!stream.good() && !stream.eof()) {
// "eof": true if an end-of-file has occurred, false otherwise.
// "good": true if the stream error flags are all false, false otherwise.
if (!stream.good() || stream.eof()) {
break;
}
// If line is non-empty
Expand Down Expand Up @@ -418,7 +471,7 @@ void Settings<IniFullPath>::ReadIni(std::basic_istream<char>& stream,
if (ini_content_tbl.find(combined_key) != ini_content_tbl.end()) {
std::cerr << "Duplicated key name " << combined_key << std::endl;
}
ini_content_tbl.insert(std::make_pair(combined_key, (data)));
ini_content_tbl.insert_or_assign(combined_key, (data));
}
}
}
Expand Down
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