How swoole implements coroutines

Swoole has built-in coroutine capabilities since 2.0, and provides IO interfaces with coroutine capabilities (unified in the namespace Swoole\Coroutine\*).

When enabling coroutines, please add the --enable-coroutine compilation option when compiling.

Coroutines can be understood as pure user-mode threads, which switch through collaboration rather than preemption. Compared with processes or threads, all operations of coroutines can be completed in user mode, and creation and switching costs are lower. (Recommended learning: swoole video tutorial)

Swoole can create a corresponding coroutine for each request and reasonably schedule the coroutine according to the IO status, which will bring the following advantages ：

Developers can use synchronous code writing to achieve the effect and performance of asynchronous IO without any awareness, avoiding the discrete code logic caused by traditional asynchronous callbacks and being trapped in multiple layers of callbacks, resulting in unmaintainable code. .

At the same time, because swoole encapsulates the coroutine at the bottom layer, compared with the traditional PHP layer coroutine framework, developers do not need to use the yield keyword to identify a coroutine IO operation, so there is no need to specify yield. The semantics are deeply understood and the calls at each level are modified to yield, which greatly improves development efficiency.

The coroutine API currently targets client encapsulation of mainstream protocols such as TCP and UDP, including:

UDP

TCP

HTTP

Mysql

Redis

can meet the needs of most developers. For private protocols, developers can use the TCP or UDP interface of the coroutine for convenient encapsulation.

Enable

Prerequisite:

PHP version requirements: >= 5.5, including 5.5, 5.6, 7.0, 7.1

Develop based on swoole_server or swoole_http_server, Currently, coroutines are only supported in onRequet, onReceive, onConnect and other event callback functions.

swoole_server and swoole_http_server will create corresponding coroutines for each request. Developers can use coroutine clients in onRequet, onReceive, and onConnect event callbacks.

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