libcppa

Author

Dominik Charousset <dominik.charousset (at) haw-hamburg.de>

Introduction

This library provides an implementation of the actor model for C++. It uses a network transparent messaging system to ease development of both concurrent and distributed software.

libcppa uses a thread pool to schedule actors by default. A scheduled actor should not call blocking functions. Individual actors can be spawned (created) with a special flag to run in an own thread if one needs to make use of blocking APIs.

Writing applications in libcppa requires a minimum of gluecode and each context is an actor. Even main is implicitly converted to an actor if needed.

Getting Started

To build libcppa, you need GCC >= 4.7 or Clang >= 3.2, and CMake.

The usual build steps on Linux and Mac OS X are:

• mkdir build
• cd build
• cmake ..
• make

• make install (as root, optionally)

  Please run the unit tests as well to verify that libcppa works properly.

• ./bin/unit_tests

  Please submit a bug report that includes (a) your compiler version, (b) your OS, and (c) the output of the unit tests if an error occurs.

  Windows is not supported yet, because MVSC++ doesn't implement the C++11 features needed to compile libcppa.

  Please read the Manual for an introduction to libcppa. It is available online at http://neverlord.github.com/libcppa/manual/index.html or as PDF version at http://neverlord.github.com/libcppa/manual/libcppa_manual.pdf

Hello World Example

#include <string>
#include <iostream>
#include "cppa/cppa.hpp"

using namespace std;
using namespace cppa;

void mirror() {
    // wait for messages
    become (
        // invoke this lambda expression if we receive a string
        on_arg_match >> [](const string& what) {
            // prints "Hello World!" via aout (thread-safe cout wrapper)
            aout << what << endl;
            // replies "!dlroW olleH"
            reply(string(what.rbegin(), what.rend()));
            // terminates this actor ('become' otherwise loops forever)
            self->quit();
        }
    );
}

void hello_world(const actor_ptr& buddy) {
    // send "Hello World!" to our buddy ...
    sync_send(buddy, "Hello World!").then(
        // ... and wait for a response
        on_arg_match >> [](const string& what) {
            // prints "!dlroW olleH"
            aout << what << endl;
        }
    );
}

int main() {
    // create a new actor that calls 'mirror()'
    auto mirror_actor = spawn(mirror);
    // create another actor that calls 'hello_world(mirror_actor)'
    spawn(hello_world, mirror_actor);
    // wait until all other actors we have spawned are done
    await_all_others_done();
    // run cleanup code before exiting main
    shutdown();
}

More Examples

The Math Actor Example shows the usage of receive_loop and arg_match. The Dining Philosophers Example introduces event-based actors and includes a lot of libcppa features.