cpp-logger/src/loggers/file_appender.cxx

//
//  file_logger.cxx
//  logging
//
//  Created by Sam Jaffe on 4/1/19.
//

#include <fstream>

#include "expect/expect.hpp"
#include "resource_factory/prototype_factory.hpp"

#include "logger/detail/appender.h"
#include "logger/log_manager.h"
#include "logger/properties.h"

using namespace logging;

namespace logging {
  level level_from_string(std::string const & value);
}

class file_appender : public appender {
public:
  static std::shared_ptr<appender> create(properties const&);
  
  explicit file_appender(const std::string& fname, bool append);
  
  void write(std::string const & msg) override;
  void flush() override;
private:
  bool flush_immediately_{false};
  std::ofstream out_;
};

using namespace logging::property;
properties const DEFAULT_FILE_APPENDER{_obj({
  {"immediateFlush", _v(true)},
  {"threshold", _v("ERROR")},
  {"filename", {}}, // Will throw if accessed
  {"fileAppend", _v(true)}/*,
  {"bufferedIO", _v(false)},
  {"bufferSize", _v(8192)}*/
})};

std::shared_ptr<appender> file_appender::create(properties const & props) {
  properties const actual = DEFAULT_FILE_APPENDER.mergedWith(props);
  file_appender app(actual["filename"], actual["fileAppend"]);
  app.flush_immediately_ = actual["immediateFlush"];
  app.min_log_level = level_from_string(actual["threshold"]);
  return std::make_shared<file_appender>(std::move(app));
}

static std::ios_base::openmode mode(bool append) {
  return (append ? std::ios_base::app : 0) | std::ios_base::out;
}

file_appender::file_appender(const std::string& fname, bool append)
: out_(fname, mode(append)) {}

void file_appender::write(std::string const & msg) {
  out_ << msg;
  if (flush_immediately_) { flush(); }
}

void file_appender::flush() { out_.flush(); }

namespace {
  bool _ = appenders::instance().bind("File", file_appender::create);
}