What is the meaning of Go/Gin debug output - (x handlers) - go

Question

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)

Answer 1

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).