Event loops, simplified

Event-driven IO handlers are an efficient mechanism for implementing network servers and clients. Excellent libraries like libevent and libuv provide portable event loop implementations that abstract away platform-specific details of monitoring sockets or file descriptors for events. These APIs, however, have considerable complexity can can be awkward to use in modern C++ programs. What The Event? offers an alternative, providing a C++ asynchronous IO interface aimed at multithreaded server and client applications.

Feature highlights

What The Event? wraps a subset of the functionality of libevent and exposes similar concepts:

Manual or continuously driven event loops
Buffered asynchronous stream IO
Convenience blocking interfaces
Socket listener for server applications
Arbitrary deferred task execution
Safe for use in multithreaded programs
Cross-platform (Windows, OS X, Linux) support

The echo server demonstrates a small server application based on this library.

WTE is a work in progress; refer to the TODO list for future functionality.

Supported platforms

What The Event? supports Linux, OS X, and Windows 64-bit platforms. It could in principal be extended to any combination of operating system and architecture that libevent supports.

Building

The WTE build system is CMake-based, so an installation of CMake 2.8+ is required. On Linux systems, we recommend using a system-provided installation of libevent if possible; on Windows this dependency will be resolved automatically.

WTE uses C++11 features and requires a supported compiler. It is known to work with at least the following compilers:

GCC 4.8
Apple LLVM 6.1.0 (Xcode 6.4)
MSVC 12 (Visual Studio 2013)

Linux and OSX

Building on Linux and OSX is straightforward:

mkdir build
cd build
cmake ..
make

To select a specific compiler, pass the full path to CMake via cmake -DCMAKE_CXX_COMPILER=<path> ...

Windows

The WTE library requires MSVC 12+; depending on your build environment you may need to define a target environment by passing -G <target> to cmake:

mkdir build
cd build
cmake -G "Visual Studio 12"
msbuild what-the-event.sln

By default both dynamic and static libraries will be built. Note that if you want to link wte_s.lib statically, you will also need to add the libevent.lib static library to the link command.

Related projects

What The Event? uses the excellent libevent library for cross-platform monitoring of IO events.

Facebook's Folly library includes an asynchronous IO component that is similar in several respects to WTE (libevent-based, exposes stream-like interfaces for reading and writing). Facebook's async io support may be a better choice if your target platforms are limited to Linux and OS X or if you are using other components of the Folly library.

License

Licensed under the MIT License.

flandr/what-the-event