What is the meaning of Go/Gin debug output

In the following Go/Gin debug output, what is the meaning of (5 handlers). As you can see, I obviously have more than 5 handlers.

[GIN-debug] GET    /                         --> .../handlers.APIDetail (5 handlers)
[GIN-debug] POST   /signup                   --> .../handlers.SignUp (5 handlers)
[GIN-debug] POST   /signin                   --> .../handlers.SignIn (5 handlers)
[GIN-debug] POST   /refresh-token            --> .../handlers.RefreshToken (5 handlers)
[GIN-debug] POST   /verify-email             --> .../handlers.VerifyEmailVerificationToken (5 handlers)
[GIN-debug] POST   /resend-verification-email --> .../handlers.ResendEmailVerificationEmail (5 handlers)
[GIN-debug] POST   /reset-password           --> .../handlers.ResetPassword (5 handlers)
[GIN-debug] POST   /change-password          --> .../handlers.ChangePassword (5 handlers)
[GIN-debug] PATCH  /users/me                 --> .../handlers.UpdateProfile (5 handlers)
[GIN-debug] POST   /signout                  --> .../handlers.SignOut (5 handlers)
[GIN-debug] GET    /orgs/:id                 --> .../handlers.GetOrganizations (5 handlers)
[GIN-debug] GET    /orgs                     --> .../handlers.GetOrganizations (5 handlers)

CodePudding user response：

It should be the number of handlers in each route's handler chain, i.e. the maximum number of handlers, including middleware, that will be executed when a request is routed to a certain endpoint.

Relevant code from Gin sources @latest:

func debugPrintRoute(httpMethod, absolutePath string, handlers HandlersChain) {
    if IsDebugging() {
        nuHandlers := len(handlers)
        handlerName := nameOfFunction(handlers.Last())
        if DebugPrintRouteFunc == nil {
            debugPrint("%-6s %-25s --> %s (%d handlers)\n", httpMethod, absolutePath, handlerName, nuHandlers)
        } else {
            DebugPrintRouteFunc(httpMethod, absolutePath, handlerName, nuHandlers)
        }
    }
}

If you are setting a few global middlewares, e.g. with router.Use, before declaring the routes, and no route has per-route middlewares, that explains why the number is always the same.

For example, consider the following:

    r.Use(func(*gin.Context) { fmt.Println("FIRST") })
    r.GET("/foo", func(c *gin.Context) {
        c.Status(http.StatusOK)
    })

    r.Use(func(*gin.Context) { fmt.Println("SECOND") })
    r.GET("/bar", func(c *gin.Context) {
        c.Status(http.StatusOK)
    })

This prints:

[GIN-debug] GET    /foo    --> main.main.func2 (2 handlers)
[GIN-debug] GET    /bar    --> main.main.func4 (3 handlers)

Because /foo's chain has the FIRST middleware, and the handler itself (2), and /bar's chain has both FIRST and SECOND middleware, plus the handler itself (3).