package main
import (
"net/http"
"github.com/gin-gonic/gin"
)
func main() {
r := gin.Default()
r.GET("/", func(c *gin.Context) {
c.String(200, "Hello!!!!")
})
}gin框架使用的是定制版本的httprouter，其路由的原理是大量使用公共前缀的树结构，它基本上是一个紧凑的Trie tree（或者只是Radix Tree）。具有公共前缀的节点也共享一个公共父节点。
获取请求方法树
在gin的路由中，每一个HTTP Method(GET、POST、PUT、DELETE…)都对应了一棵 radix tree，我们注册路由的时候会调用下面的addRoute函数：
func (group *RouterGroup) handle(httpMethod, relativePath string, handlers HandlersChain) IRoutes {
absolutePath := group.calculateAbsolutePath(relativePath)
handlers = group.combineHandlers(handlers)
group.engine.addRoute(httpMethod, absolutePath, handlers)
return group.returnObj()
}
func (engine *Engine) addRoute(method, path string, handlers HandlersChain) {
assert1(path[0] == '/', "path must begin with '/'")
assert1(method != "", "HTTP method can not be empty")
assert1(len(handlers) > 0, "there must be at least one handler")
debugPrintRoute(method, path, handlers)
// 获取请求方法对应的树
root := engine.trees.get(method)
if root == nil {// 如果没有就创建一个
root = new(node)
root.fullPath = "/"
engine.trees = append(engine.trees, methodTree{method: method, root: root})
}
root.addRoute(path, handlers)
// Update maxParams
if paramsCount := countParams(path); paramsCount > engine.maxParams {
engine.maxParams = paramsCount
}
if sectionsCount := countSections(path); sectionsCount > engine.maxSections {
engine.maxSections = sectionsCount
}
}在注册路由的时候都是先根据请求方法获取对应的树，也就是gin框架会为每一个请求方法创建一棵对应的树，gin框架中保存请求方法对应树关系使用的是slice；engine.trees的类型是methodTrees，其定义如下：
type methodTree struct {
method string
root *node
}
type methodTrees []methodTree获取请求方法对应树的get方法定义如下：---------->HTTP请求方法的数量是固定的，而且常用的就那几种，所以即使使用切片存储查询起来效率也足够了
func (trees methodTrees) get(method string) *node {
for _, tree := range trees {
if tree.method == method {
return tree.root
}
}
return nil
}所以tress初始化的时候就直接make申请了内存
func New() *Engine {
debugPrintWARNINGNew()
engine := &Engine{
RouterGroup: RouterGroup{
Handlers: nil,
basePath: "/",
root: true,
},
FuncMap: template.FuncMap{},
RedirectTrailingSlash: true,
RedirectFixedPath: false,
HandleMethodNotAllowed: false,
ForwardedByClientIP: true,
RemoteIPHeaders: []string{"X-Forwarded-For", "X-Real-IP"},
TrustedPlatform: defaultPlatform,
UseRawPath: false,
RemoveExtraSlash: false,
UnescapePathValues: true,
MaxMultipartMemory: defaultMultipartMemory,
// 初始化容量为9的切片（HTTP1.1请求方法共9种）
trees: make(methodTrees, 0, 9),
delims: render.Delims{Left: "{{", Right: "}}"},
secureJSONPrefix: "while(1);",
trustedProxies: []string{"0.0.0.0/0", "::/0"},
trustedCIDRs: defaultTrustedCIDRs,
}
engine.RouterGroup.engine = engine
engine.pool.New = func() any {
return engine.allocateContext(engine.maxParams)
}
return engine
}
获取请求方法树后---->执行注册路由
先看下路由树节点
路由树是由一个个节点构成的，gin框架路由树的节点由node结构体表示，它有以下字段：
r.GET("/search/", func2)
r.GET("/support/", func3)
type node struct {
path string// 节点路径，比如上面的s，earch，和upport
// 和children字段对应, 保存的是分裂的分支的第一个字符
// 例如search和support, 那么s节点的indices对应的"eu"
// 代表有两个分支, 分支的首字母分别是e和u
indices string
wildChild bool
// 节点类型，包括static, root, param, catchAll
// static: 静态节点（默认），比如上面的s，earch等节点
// root: 树的根节点
// catchAll: 有*匹配的节点
// param: 参数节点
nType nodeType
// 优先级，子节点、子子节点等注册的handler数量
priority uint32
children []*node // child nodes, at most 1 :param style node at the end of the array
handlers HandlersChain// 处理函数chain（切片）
fullPath string// 完整路径
}注册路由的逻辑主要有addRoute函数和insertChild方法。
root := engine.trees.get(method)
root.addRoute(path, handlers)
// addRoute adds a node with the given handle to the path.
// Not concurrency-safe!
func (n *node) addRoute(path string, handlers HandlersChain) {
fullPath := path
n.priority++
// Empty tree 空树就直接插入当前节点
if len(n.path) == 0 && len(n.children) == 0 {
n.insertChild(path, fullPath, handlers)
n.nType = root
return
}
parentFullPathIndex := 0
walk:
for {
// Find the longest common prefix.
// This also implies that the common prefix contains no ':' or '*'
// since the existing key can't contain those chars.
// 找到最长的通用前缀
// 这也意味着公共前缀不包含“:”"或“*” /
// 因为现有键不能包含这些字符。
i := longestCommonPrefix(path, n.path)
// Split edge
// 分裂边缘（此处分裂的是当前树节点）
// 例如一开始path是search，新加入support，s是他们通用的最长前缀部分
// 那么会将s拿出来作为parent节点，增加earch和upport作为child节点
if i < len(n.path) {
child := node{
path: n.path[i:], // 公共前缀后的部分作为子节点
wildChild: n.wildChild,
nType: static,
indices: n.indices,
children: n.children,
handlers: n.handlers,
priority: n.priority - 1,//子节点优先级-1
fullPath: n.fullPath,
}
n.children = []*node{&child}
// []byte for proper unicode char conversion, see #65
n.indices = bytesconv.BytesToString([]byte{n.path[i]})
n.path = path[:i]
n.handlers = nil
n.wildChild = false
n.fullPath = fullPath[:parentFullPathIndex+i]
}
// Make new node a child of this node
// 将新来的节点插入新的parent节点作为子节点
if i < len(path) {
path = path[i:]
c := path[0]
// '/' after param 处理参数后加斜线情况
if n.nType == param && c == '/' && len(n.children) == 1 {
parentFullPathIndex += len(n.path)
n = n.children[0]
n.priority++
continue walk
}
// Check if a child with the next path byte exists
// 检查路path下一个字节的子节点是否存在
// 比如s的子节点现在是earch和upport，indices为eu
// 如果新加一个路由为super，那么就是和upport有匹配的部分u，将继续分列现在的upport节点
for i, max := 0, len(n.indices); i < max; i++ {
if c == n.indices[i] {
parentFullPathIndex += len(n.path)
i = n.incrementChildPrio(i)
n = n.children[i]
continue walk
}
}
// Otherwise insert it 否则就插入
if c != ':' && c != '*' && n.nType != catchAll {
// []byte for proper unicode char conversion, see #65
// 注意这里是直接拼接第一个字符到n.indices
n.indices += bytesconv.BytesToString([]byte{c})
child := &node{
fullPath: fullPath,
}
// 追加子节点
n.addChild(child)
n.incrementChildPrio(len(n.indices) - 1)
n = child
} else if n.wildChild {// 如果是参数节点
// inserting a wildcard node, need to check if it conflicts with the existing wildcard
n = n.children[len(n.children)-1]
n.priority++
// Check if the wildcard matches 检查通配符是否匹配
if len(path) >= len(n.path) && n.path == path[:len(n.path)] &&
// Adding a child to a catchAll is not possible
n.nType != catchAll &&
// Check for longer wildcard, e.g. :name and :names
(len(n.path) >= len(path) || path[len(n.path)] == '/') {
continue walk
}
// Wildcard conflict
pathSeg := path
if n.nType != catchAll {
pathSeg = strings.SplitN(pathSeg, "/", 2)[0]
}
prefix := fullPath[:strings.Index(fullPath, pathSeg)] + n.path
panic("'" + pathSeg +
"' in new path '" + fullPath +
"' conflicts with existing wildcard '" + n.path +
"' in existing prefix '" + prefix +
"'")
}
n.insertChild(path, fullPath, handlers)
return
}
// Otherwise add handle to current node 已经注册过的节点
if n.handlers != nil {
panic("handlers are already registered for path '" + fullPath + "'")
}
n.handlers = handlers
n.fullPath = fullPath
return
}
}- 第一次注册路由，例如注册search
- 继续注册一条没有公共前缀的路由，例如blog
- 注册一条与先前注册的路由有公共前缀的路由，例如support
