Gin request process source code analysis

http service of the standard library

Handler接口就可以注册到标准库的http server中。然后就会启动一个web应用。http请求流程当发生一个http请求的时候，在内部处理的流程是下面这样的：开启一个协程进行请求处理在conn.serve中调用serverHandler.ServeHTTP 函数如果有自己注册的Handle，那么就会调用注册的Handle的ServeHTTP 方法。这里还要注意的2个点如果自己在启动的时候没有注册自己的Handle，那么会采用标准库默认的ServeMux，全局名称为DefaultServeMux。如果请求URI为*并且请求Method为OPTIONS，那么Handle行为会被改成默认的globalOptionsHandler。上述分析的源码为GO 1.18.3。Gin 处理请求的流程前面我们看到只要注册自己的Handle接口到标准库就可以接管请求的处理；那么我们来看一下gin的Handle接口实现。在gin中，handleHTTPRequest就是匹配路径和对应handle 的处理函数。流程大致是这样：获取请求的路径在trees中找到对应的methodTree

• methodTree中匹配对应路径的处理函数handle

• Execute the registered function through the Next method

Gin's Context source code

Before executing the registered function, we found that a sync was used in the ServeHTTP method .Pool, it is actually the reuse of gin.Context.



Let’s take a look at its structure:

// Context is the most important part of gin. It allows us to pass variables between middleware,
// manage the flow, validate the JSON of a request and render a JSON response for example.
type Context struct {
 writermem responseWriter
 Request   *http.Request
 Writer    ResponseWriter

 Params   Params
 handlers HandlersChain
 index    int8
 fullPath string

 engine       *Engine
 params       *Params
 skippedNodes *[]skippedNode

 // This mutex protects Keys map.
 mu sync.RWMutex
  ...
}

The official req and resp will be saved in Context in. And gin has added an extension to the official http.ResponseWriter function, that is, it has defined an interface gin.ResponseWriter

Others Some methods are packages for daily use to facilitate development.

Context's Bind class method analysis



In the source code, you can see that a total of Binding supports these ;The implementation is deserialization, the details will not be discussed one by one.

The key point is that after bind is completed, there is a validate method, which is actually used github.com/go-playground/validator/v10As a library for verifying data.



And use lazy loading to initialize, which means that if you don’t use it, the object will not be initialized.



For the development process of validating data, please see the detailed usage of validator^[1].

In the mode.go file of gin, there are controls for some behaviors. For example, DisableBindValidation can turn off the data validation function, which is Call this method before the service starts to shut down.



ginS folder

This folder defines a default internal global gin.Engine object.



And it is also initialized using lazy loading.



So if you want to use the global gin.Engine, you can use this package, so you don’t have to save your own global gin. Engine object.

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