CSV Writing

The library provides functionality for asynchronously writing CSV files. Formatting and I/O operations are managed by the backend thread, allowing for efficient and minimal-overhead CSV file writing on the hot path. This feature can be used alongside regular logging.

The CsvWriter class is a utility designed to facilitate asynchronous CSV file writing.

CSV Writing To File

 1#include "quill/Backend.h"
 2#include "quill/CsvWriter.h"
 3#include "quill/LogMacros.h"
 4#include "quill/core/FrontendOptions.h"
 5#include "quill/sinks/ConsoleSink.h"
 6
 7/**
 8 * This example shows how to define a CSV schema, instantiate a CsvWriter object, and append rows to
 9 * the CSV file. The logging operations are handled asynchronously by the backend worker thread.
10 */
11
12struct OrderCsvSchema
13{
14  static constexpr char const* header = "order_id,symbol,quantity,price,side";
15  static constexpr char const* format = "{},{},{},{:.2f},{}";
16};
17
18int main()
19{
20  quill::BackendOptions backend_options;
21  quill::Backend::start(backend_options);
22
23  quill::Logger* logger = quill::Frontend::create_or_get_logger(
24    "root", quill::Frontend::create_or_get_sink<quill::ConsoleSink>("sink_id_1"));
25
26  LOG_INFO(logger, "CSV writing example");
27
28  quill::CsvWriter<OrderCsvSchema, quill::FrontendOptions> csv_writer{"orders.csv"};
29  csv_writer.append_row(13212123, "AAPL", 100, 210.32321, "BUY");
30  csv_writer.append_row(132121123, "META", 300, 478.32321, "SELL");
31  csv_writer.append_row(13212123, "AAPL", 120, 210.42321, "BUY");
32}

Csv output (orders.csv):

order_id,symbol,quantity,price,side
13212123,AAPL,100,210.32,BUY
132121123,META,300,478.32,SELL
13212123,AAPL,120,210.42,BUY

CSV Writing To Existing Sink

It is possible to pass an existing Sink, or a custom user-created Sink, to the CSV file for output. The following example shows how to use the console sink

 1#include "quill/Backend.h"
 2#include "quill/CsvWriter.h"
 3#include "quill/LogMacros.h"
 4#include "quill/core/FrontendOptions.h"
 5#include "quill/sinks/ConsoleSink.h"
 6
 7struct OrderCsvSchema
 8{
 9  static constexpr char const* header = "order_id,symbol,quantity,price,side";
10  static constexpr char const* format = "{},{},{},{:.2f},{}";
11};
12
13int main()
14{
15  quill::Backend::start();
16
17  quill::Logger* logger = quill::Frontend::create_or_get_logger(
18    "root", quill::Frontend::create_or_get_sink<quill::ConsoleSink>("sink_id_1"));
19
20  LOG_INFO(logger, "CSV writing example");
21
22  // Pass the existing ConsoleSink to the CsvWritter, this will output the csv to console
23  quill::CsvWriter<OrderCsvSchema, quill::FrontendOptions> csv_writer{
24    "orders.csv", quill::Frontend::get_sink("sink_id_1")};
25
26  csv_writer.append_row(13212123, "AAPL", 100, 210.32321, "BUY");
27  csv_writer.append_row(132121123, "META", 300, 478.32321, "SELL");
28  csv_writer.append_row(13212123, "AAPL", 120, 210.42321, "BUY");
29}