Documentation

Introduction

PHP is a nice langage: it has been designed to be easy and fast but lacks concurrent programming capabilities. It is a sequential language.

Developers sometimes want to achieve concurrent programming with PHP and often end up using external technologies like workers. Those workers have many benefits but sometime they are too heavy to just handle simple tasks.

Concurrent programming

When talking about concurrent programming it's useful to distinguish two methods:

• Parallel computing
• Concurrent computing

To sum-up the difference between those two paradigm, let's look at some diagram.

Parellel computing means two tasks will run in parallel without blocking each other:

    +- - - - - - - - - - -+
    |                     |
- - +                     + - - >
    |                     |
    +- - - - - - - - - - -+

Concurrent programming is a bit different: two tasks will race together and each time a task is paused, the main program will switch context and work on the other task:

    +- - -       - -     -+
    |                     |
- - +                     + - - >
    |                     |
    +-     - - -     - - -+

Async generators

Async generators try to solve this issue by allowing developers to implement concurrent programming. Thanks to the yield keyword, we can make PHP pause processing something and switch to another task.

The library provides some low-level functions grouped in logical namespaces to make things easier:

• Runtime: this namespace provides generic functions to work with concurrency
• Time: this namespace provides functions to work with time
• Pipe: this namespace provides functions to work with pipes
• Loop: this namespace provides functions to make concurrent loops
• Stream: this namespace provides functions to work with streams
• Socket: this namespace provides functions to work with sockets