A job scheduler in C++

Not long ago I started writing some C++ code, and a task that I enjoyed implementing was a very basic job scheduler (idea from dailycodingproblem.com). I’m sure there are “holes” to be filled in my implementation regarding performance, concurrency, and general correctness. This is an early dive into the language and this post is mostly for me, to explain some things to myself.

The scheduler takes a job (function) and a time (in milliseconds) and runs the job after the given time.

The first thing was to define a function pointer as the job type.

using Job = void (*)();

 

Another callback that I’ll be using is one to report job errors, which takes an exception as an argument.

using Error = void (*)(const std::exception &);

 

The scheduler class constructor takes a size and an error callback (to report errors). The size is the maximum number of jobs accepted until scheduling blocks and waits for a job to be finished.
An error callback is required. The first measure to ensure this is to delete the constructor that takes null for the error callback, which performs a compile-time check. Explicitly passing null will not be allowed, but a pointer that is null will be checked at runtime.

Scheduler(size_t size, Error error);
Scheduler(size_t size, nullptr_t) = delete;

Continue reading A job scheduler in C++

Playing with PHP extensions: building a map

I’ve ran into PHP-CPP, a C++ library which helps you build your own PHP extensions in an easier way than writing them from scratch. And I decided to play a little bit. It has good documentation and examples.

Installing is not always out of the box depending on the environment. I like to keep things clean on my working machines so I wanted to have everything in a Docker container, but I quickly ran into an issue installing the library. Fortunately, I’ve found a solution pretty fast.

The first idea that came into my mind was a simple map. Nothing special, I’m not bringing any improvements, I just wanted to convert the following into an extension. Continue reading Playing with PHP extensions: building a map