Gin [Discussion] abortIndex is too little?

How to reproduce

package main

import (
    "fmt"
    "log"
    "math"
    "net/http"

    "github.com/gin-gonic/gin"
)

func main() {
    r := gin.Default()
    r.Use(customMws()...)
    r.GET("/ping", func(c *gin.Context) {
        c.JSON(http.StatusOK, gin.H{
            "message": "pong",
        })
    })
    r.Run() // listen and serve on 0.0.0.0:8080 (for windows "localhost:8080")
}

func customMws() []gin.HandlerFunc {
    l := math.MaxInt8>>2 - 10
    res := make([]gin.HandlerFunc, 0)
    for i := 0; i < l; i++ {
        j := i
        res = append(res, func(c *gin.Context) {
            log.Println(fmt.Sprintf("req wrapper mw:%d", j))
            c.Next()
            log.Println(fmt.Sprintf("resp wrapper mw:%d aborted: %t", j, c.IsAborted()))
        })
        res = append(res, func(c *gin.Context) {
            log.Println(fmt.Sprintf("req mw:%d", j))
            c.Next()
            log.Println(fmt.Sprintf("resp mw:%d aborted: %t", j, c.IsAborted()))
        })
    }
    return res
}

See the source

func (c *Context) Next() {
    c.index++
    for c.index < int8(len(c.handlers)) {
        c.handlers[c.index](c)
        c.index++
    }
}

and

func (group *RouterGroup) combineHandlers(handlers HandlersChain) HandlersChain {
    finalSize := len(group.Handlers) + len(handlers)
    assert1(finalSize < int(abortIndex), "too many handlers")
    mergedHandlers := make(HandlersChain, finalSize)
    copy(mergedHandlers, group.Handlers)
    copy(mergedHandlers[len(group.Handlers):], handlers)
    return mergedHandlers
}

Expectations

$ curl localhost:8080/ping

c.IsAborted() is always false because i do not call Abort()

Actual result

resp mw:13 aborted: false
resp wrapper mw:13 aborted: false
resp mw:12 aborted: false
resp wrapper mw:12 aborted: false
resp mw:11 aborted: true
resp wrapper mw:11 aborted: true
resp mw:10 aborted: true
resp wrapper mw:10 aborted: true

Discussion

Maybe abortIndex is too little? The Boundary Index should not touch by index++. Or when handles over 63 should make some impact I do not know? Thank u

Environment

• go version: 1.17.2
• gin version (or commit ref): 1.8.1
• operating system: MacOS

Comment From: ywanbing

func (c *Context) Next() {
    c.index++
    for c.index < int8(len(c.handlers)) {
        c.handlers[c.index](c)
        c.index++
    }
}

Mainly here to make index increase. When calling the c.Next method to exec c.index++, when calling the c.Next method again in the middleware, c.index is increased again.

Then when the middleware exits it is called again

c.handlers[c.index](c)
// exit and call again
c.index++

If c.IsAborted() is not checked after c.Next(), it will not affect the execution of the registration middleware.