fasthttp-routing

Description

fasthttp-routing is a Go package that is adapted from ozzo-routing to provide fast and powerful routing features for the high-performance fasthttp server. The package has the following features:

• middleware pipeline architecture, similar to that of the Express framework.
• extremely fast request routing with zero dynamic memory allocation
• modular code organization through route grouping
• flexible URL path matching, supporting URL parameters and regular expressions
• URL creation according to the predefined routes

Requirements

Go 1.5 or above.

Installation

Run the following command to install the package:

go get github.com/qiangxue/fasthttp-routing

Getting Started

Create a server.go file with the following content:

package main

import (
	"fmt"

	"github.com/qiangxue/fasthttp-routing"
	"github.com/valyala/fasthttp"
)

func main() {
	router := routing.New()
	
	router.Get("/", func(c *routing.Context) error {
		fmt.Fprintf(c, "Hello, world!")
		return nil
	})
	
	panic(fasthttp.ListenAndServe(":8080", router.HandleRequest))
}

Now run the following command to start the Web server:

go run server.go

You should be able to access URLs such as http://localhost:8080.

Routes

ozzo-routing works by building a routing table in a router and then dispatching HTTP requests to the matching handlers found in the routing table. An intuitive illustration of a routing table is as follows:

Routes	Handlers
GET /users	m1, m2, h1, ...
POST /users	m1, m2, h2, ...
PUT /users/<id>	m1, m2, h3, ...
DELETE /users/<id>	m1, m2, h4, ...

For an incoming request GET /users, the first route would match and the handlers m1, m2, and h1 would be executed. If the request is PUT /users/123, the third route would match and the corresponding handlers would be executed. Note that the token <id> can match any number of non-slash characters and the matching part can be accessed as a path parameter value in the handlers.

If an incoming request matches multiple routes in the table, the route added first to the table will take precedence. All other matching routes will be ignored.

The actual implementation of the routing table uses a variant of the radix tree data structure, which makes the routing process as fast as working with a hash table, thanks to the inspiration from httprouter.

To add a new route and its handlers to the routing table, call the To method like the following:

router := routing.New()
router.To("GET", "/users", m1, m2, h1)
router.To("POST", "/users", m1, m2, h2)

You can also use shortcut methods, such as Get, Post, Put, etc., which are named after the HTTP method names:

router.Get("/users", m1, m2, h1)
router.Post("/users", m1, m2, h2)

If you have multiple routes with the same URL path but different HTTP methods, like the above example, you can chain them together as follows,

router.Get("/users", m1, m2, h1).Post(m1, m2, h2)

If you want to use the same set of handlers to handle the same URL path but different HTTP methods, you can take the following shortcut:

router.To("GET,POST", "/users", m1, m2, h)

A route may contain parameter tokens which are in the format of <name:pattern>, where name stands for the parameter name, and pattern is a regular expression which the parameter value should match. A token <name> is equivalent to <name:[^/]*>, i.e., it matches any number of non-slash characters. At the end of a route, an asterisk character can be used to match any number of arbitrary characters. Below are some examples:

• /users/<username>: matches /users/admin
• /users/accnt-<id:\d+>: matches /users/accnt-123, but not /users/accnt-admin
• /users/<username>/*: matches /users/admin/profile/address

When a URL path matches a route, the matching parameters on the URL path can be accessed via Context.Param():

router := routing.New()

router.Get("/users/<username>", func (c *routing.Context) error {
	fmt.Fprintf(c, "Name: %v", c.Param("username"))
	return nil
})

Route Groups

Route group is a way of grouping together the routes which have the same route prefix. The routes in a group also share the same handlers that are registered with the group via its Use method. For example,

router := routing.New()
api := router.Group("/api")
api.Use(m1, m2)
api.Get("/users", h1).Post(h2)
api.Put("/users/<id>", h3).Delete(h4)

The above /api route group establishes the following routing table:

Routes	Handlers
GET /api/users	m1, m2, h1, ...
POST /api/users	m1, m2, h2, ...
PUT /api/users/<id>	m1, m2, h3, ...
DELETE /api/users/<id>	m1, m2, h4, ...

As you can see, all these routes have the same route prefix /api and the handlers m1 and m2. In other similar routing frameworks, the handlers registered with a route group are also called middlewares.

Route groups can be nested. That is, a route group can create a child group by calling the Group() method. The router serves as the top level route group. A child group inherits the handlers registered with its parent group. For example,

router := routing.New()
router.Use(m1)

api := router.Group("/api")
api.Use(m2)

users := group.Group("/users")
users.Use(m3)
users.Put("/<id>", h1)

Because the router serves as the parent of the api group which is the parent of the users group, the PUT /api/users/<id> route is associated with the handlers m1, m2, m3, and h1.

Router

Router manages the routing table and dispatches incoming requests to appropriate handlers. A router instance is created by calling the routing.New() method.

To hook up router with fasthttp, use the following code:

router := routing.New()
fasthttp.ListenAndServe(":8080", router.HandleRequest) 

Handlers

A handler is a function with the signature func(*routing.Context) error. A handler is executed by the router if the incoming request URL path matches the route that the handler is associated with. Through the routing.Context parameter, you can access the request information in handlers.

A route may be associated with multiple handlers. These handlers will be executed in the order that they are registered to the route. The execution sequence can be terminated in the middle using one of the following two methods:

• A handler returns an error: the router will skip the rest of the handlers and handle the returned error.
• A handler calls Context.Abort(): the router will simply skip the rest of the handlers. There is no error to be handled.

A handler can call Context.Next() to explicitly execute the rest of the unexecuted handlers and take actions after they finish execution. For example, a response compression handler may start the output buffer, call Context.Next(), and then compress and send the output to response.

Context

For each incoming request, a routing.Context object is passed through the relevant handlers. Because routing.Context embeds fasthttp.RequestCtx, you can access all properties and methods provided by the latter.

Additionally, the Context.Param() method allows handlers to access the URL path parameters that match the current route. Using Context.Get() and Context.Set(), handlers can share data between each other. For example, an authentication handler can store the authenticated user identity by calling Context.Set(), and other handlers can retrieve back the identity information by calling Context.Get().

Context also provides a handy WriteData() method that can be used to write data of arbitrary type to the response. The WriteData() method can also be overridden (by replacement) to achieve more versatile response data writing.

Error Handling

A handler may return an error indicating some erroneous condition. Sometimes, a handler or the code it calls may cause a panic. Both should be handled properly to ensure best user experience. It is recommended that you use the fault.Recover handler or a similar error handler to handle these errors.

If an error is not handled by any handler, the router will handle it by calling its handleError() method which simply sets an appropriate HTTP status code and writes the error message to the response.

When an incoming request has no matching route, the router will call the handlers registered via the Router.NotFound() method. All the handlers registered via Router.Use() will also be called in advance. By default, the following two handlers are registered with Router.NotFound():

• routing.MethodNotAllowedHandler: a handler that sends an Allow HTTP header indicating the allowed HTTP methods for a requested URL
• routing.NotFoundHandler: a handler triggering 404 HTTP error