Flow -- Modern C++ toolkit for async loops, logs, config, benchmarking, and more

C++ power users, these days, are likely to use the standard library (a/k/a STL), Boost, and/or any number of third-party libraries. Nevertheless every large project or organization tends to need more reusable goodies, whether to add to STL/Boost/etc. or in some cases do something better, perhaps in a specialized way.

Flow is such a library (provided as both headers and an actual library). It's written in modern C++ (C++ 17 as of this writing) and is meant to be generally usable as opposed to particularly specialized. (One exception to this is the included, but wholly optional, NetFlow protocol, contained in flow::net_flow namespace. While still reusable in a general way, interest in this functionality is likely niche.)

We refrain from delving into any particulars as to what's in Flow, aside from the following brief list of its top-level modules. The documentation (see Documentation below) covers all of its contents in great detail. So, that said, Flow includes (alphabetically ordered):

• flow::async: Single-threaded and multi-threaded event loops, augmenting boost.asio so as to actually create boost.asio-powered threads and thread pools, schedule timers more easily, and other niceties.
• flow::cfg: Key-value configuration file parsing, augmenting a boost.program_options core with a large number of quality-of life additions including support for high-speed dynamically updated configuration structs.
• flow::error: A few niceties around the ubiquitous boost.system (now adopted by STL also) error-reporting system. It also adds a simple convention for reporting errors, used across Flow, wherein each error-reporting API handles reporting results via error code return or exception (whichever the caller prefers at the call-site).
• flow::log: A powerful and performant logging system. While it can actually output to console and files, if so configured, its loggers will also easily integrate with your own log system of choice.
• flow::perf: Benchmarking with multiple clock types and checkpoint-based accounting (if desired).
• flow::util: General goodies. Highlights: Blob (efficient and controlled vector<uint8_t> replacement with optional sharing and mem-pools), Linked_hash_{map|set} (hashed-lookup containers that maintain MRU-LRU iterator ordering as opposed to being unordered as in unordered_{map|set}), String_ostream (a sped-up ostringstream replacement leveraging boost.iostreams internally) plus ostream_op_string() function.

Documentation

A comprehensive Reference is available.

The project web site contains links to documentation for each individual release as well.

Obtaining the source code

• As a tarball/zip: The project web site links to individual releases with notes, docs, download links.
• Via Git: git clone [email protected]:Flow-IPC/flow.git

Installation

See INSTALL guide.

Contributing

See CONTRIBUTING guide.