Architecture & Under the Hood

cpp-pubsub is explicitly designed for high performance, low latency, and zero-headache memory management across threads.

OS-Level Events for Efficient Multiplexing

Instead of relying on CPU-heavy spinlocking or basic condition variables for Selector multiplexing, cpp-pubsub uses highly optimized OS-native handles:

POSIX: Uses anonymous pipe and poll.
Windows: Uses CreateEvent and WaitForMultipleObjects.

This allows the Selector and Worker to sleep natively and wake instantly when a message arrives on any monitored topic, ensuring minimal CPU usage while idle.

Automatic Cleanup & Robust Memory Management

The broker tracks subscribers internally using std::weak_ptr. When your Subscriber object goes out of scope and is destroyed, the broker automatically cleans up the dead subscription during its next publish cycle. You never have to manually “unsubscribe”!

Zero-Leak Message Queues: cpp-pubsub is deeply integrated with C++ smart pointers. If you publish a std::shared_ptr<T> as a message, and that message is dropped from a subscriber’s queue (e.g., due to the DropOldest policy or because the subscriber is destroyed), its reference count is automatically and safely decremented. You don’t have to worry about memory leaks from unread messages!

Strict Type Safety

Topics strictly enforce type-matching. Because cpp-pubsub uses template types combined with std::dynamic_pointer_cast internally, attempting to subscribe to an existing topic with the wrong data type will throw a std::invalid_argument exception.

Examples & Testing

We provide complete, compilable examples in the examples directory of the repository to demonstrate the API in real-world scenarios:

basic_pubsub.cpp: Demonstrates multi-threaded publish/subscribe between producer and consumer threads.
advanced_pubsub.cpp: Demonstrates sensor systems, structured event loops, and multi-topic coordination.
worker_pubsub.cpp: Demonstrates the Worker multiplexing mechanics with multiple topics.

Building and Running the Examples

The examples are built by default. To compile and run them from the project root:

mkdir build && cd build
cmake ..
cmake --build .

# Run the basic example
./basic_pubsub

# Run the advanced example
./advanced_pubsub

# Run the worker example
./worker_pubsub

Running the Unit Tests

cpp-pubsub includes a suite of unit tests powered by Google Test. To build and run the tests:

mkdir build && cd build
cmake .. -DCPPPUBSUB_BUILD_TESTS=ON
cmake --build .
ctest --output-on-failure

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