cpp-playground

Cpp samples for testing and learning C++ 11/14/17/20

LLVM Clang Linux/WSL

install llvm version 18

wget https://apt.llvm.org/llvm.sh
chmod +x llvm.sh
sudo ./llvm.sh 18
sudo apt install libomp-18-dev // for openmp

Useful Commands

mkdir build
cd build
cmake ..
make
make test

We use catch2 testing framework in this repo, the corresponding executable is test-algorithms. run below command to check how to list and filter tests.

test-algorithms --help

On Windows GitBash

mkdir build
cd build
cmake ..
cmake --build . --parallel 4 --config Debug
cmake --build . --target RUN_TESTS --config Debug

Learning notes

Asynchrous programming

Standalone asio and continuable libraries are the best libraries to handle the async programming. Both asio and continuable still use the pattern of callback and future-then pattern respectively. The drawback is that if a function requires callback/future-then/coroutine then the caller function also needs to provide a callback/then/coroutine, personally I do not really like this requirement. It behaves like a virus. We need to change the whole app that might cross many layers of the whole application. In order to mutigate this, we still would like to block the caller to wait for the async results, e.g. future.get(), however it will block the caller's thread. Threads are expensive resources, thus this solution is not scalable. How to solve this? The boost::fiber to rescue. fiber is user-land thread and thus it is cheaper to block, e.g. fiber's yeild which will let the fiber scheduler to run other ready fibers, there is no os thread context switch and won't block the os thread.

The drawback of using boost is that your application will have to compile the boost on different platforms which are not portable. Boost does not provide a way of compile boost with cmake. We should try to avoid using boost library at the first place. There is no other alternative similar to boost::fiber that shares the same quality. boost::fiber also includes bounded channel and unbounded channel as channels in golang which is really an elegant way when writing a pipeline with different stages.

Now I solve how to use boost fiber in your project by inventing your own cmakelists.txt to compile the boost fiber and easily reference it in your app, see fiber_shared_work.cpp for example.

• continuable example in continuable_asio.cpp if you want to go with continuable.

• fiber example in fiber_shared_work.cpp.