cpp-pubsub

cpp-pubsub is a fast, lightweight, and thread-safe header-only C++17 library for Publish-Subscribe messaging.

Features

• Header-Only: Simply include cpppubsub.hpp in your project.
• Thread-Safe by Design: Uses standard C++ primitives (<mutex>, <condition_variable>) to guarantee safe multi-threaded dispatching. Multiple publishers and subscribers can operate simultaneously without data races.
• Robust Memory Management: Deep integration with C++ smart pointers guarantees memory safety. The broker safely manages Subscriber lifecycles (no manual unsubscribe needed) and strictly respects std::shared_ptr reference counts to prevent memory leaks even when unread messages are dropped from full queues.
• Background Workers: Includes a robust Worker and Selector system for asynchronous background processing of multiple topics simultaneously.
• Type-Safe Topics: Topics and subscribers strictly enforce the type of the messages being passed.

Integration

You can easily integrate this into your project via CMake's add_subdirectory or FetchContent. The target cpppubsub::cpppubsub is an INTERFACE library.

FetchContent

include(FetchContent)
FetchContent_Declare(
  cpppubsub
  GIT_REPOSITORY https://github.com/jonoton/cpp-pubsub.git
  GIT_TAG main
)
FetchContent_MakeAvailable(cpppubsub)

target_link_libraries(your_target PRIVATE cpppubsub::cpppubsub)

Add Subdirectory

Alternatively, if you cloned the repository locally as a submodule:

add_subdirectory(path/to/cpppubsub)

target_link_libraries(your_target PRIVATE cpppubsub::cpppubsub)

Quick Start

#include "cpppubsub.hpp"
#include <iostream>
#include <string>

int main() {
    cpppubsub::PubSub broker;

    // 1. Subscribe to a topic
    auto sub = broker.Subscribe<std::string>("system_events");

    // 2. Publish to the topic
    broker.Publish("system_events", std::string("Hello World!"));

    // 3. Receive the message
    if (auto msg = sub->try_receive()) {
        std::cout << "Received: " << *msg << std::endl;
    }

    return 0;
}

Documentation

For full API documentation and advanced usage (like the Worker class), please refer to our GitHub Pages Documentation Site.

Examples

Check out the examples/ directory for full compilable examples demonstrating:

• Basic multi-threaded publish/subscribe (basic_pubsub.cpp)
• Worker multiplexing (worker_pubsub.cpp)
• Structured event loops and multi-topic coordination (advanced_pubsub.cpp)

Building and Testing

By default, building the project will compile the examples. You can also build and run the unit tests powered by Google Test.

mkdir build && cd build
cmake .. -DCPPPUBSUB_BUILD_TESTS=ON
cmake --build .

# Run the tests
ctest --output-on-failure

# Run an example
./advanced_pubsub