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routine encapsulates and provides some easy-to-use, high-performance goroutine context access interfaces, which can help you access coroutine context information more elegantly, but you may also open Pandora's Box.

The Golang language has been sparing no effort to shield developers from the concept of coroutine context from the beginning of its design, including the acquisition of coroutine goid, the state of the coroutine within the process, and the storage of coroutine context.

If you have used other languages such as C++/Java/..., then you must be familiar with ThreadLocal, and after starting to use Golang, you will definitely feel confused and distressed by the lack of convenient functions similar to ThreadLocal . Of course, you can choose to use Context, let it carry all the context information, appear in the first input parameter of all functions, and then shuttle around in your system.

The core goal of routine is to open up another path: to introduce goroutine local storage into the world of Golang , and at the same time expose the coroutine information to meet the needs of some people.

This chapter briefly introduces how to install and use the routine library.

go get github.com/go-eden/routine

The following code simply demonstrates the use of routine.Goid():

package main

import (
	"fmt"
	"github.com/go-eden/routine"
	"time"
)

func main() {
	go func() {
		time.Sleep(time.Second)
	}()
	goid := routine.Goid()
	fmt.Printf("curr goid: %d\n", goid)
}

In this example, the main function starts a new coroutine, so Goid() returns the main coroutine 1:

curr goid: 1

The following code simply demonstrates NewLocalStorage(), Set(), Get(), and cross-coroutine propagation of LocalStorage:

package main

import (
	"fmt"
	"github.com/go-eden/routine"
	"time"
)

var nameVar = routine.NewLocalStorage()

func main() {
	nameVar.Set("hello world")
	fmt.Println("name: ", nameVar.Get())

	// other goroutine cannot read nameVar
	go func() {
		fmt.Println("name1: ", nameVar.Get())
	}()

	// but, the new goroutine could inherit/copy all local data from the current goroutine like this:
	routine.Go(func() {
		fmt.Println("name2: ", nameVar.Get())
	})

	// or, you could copy all local data manually
	ic := routine.BackupContext()
	go func() {
		routine.InheritContext(ic)
		fmt.Println("name3: ", nameVar.Get())
	}()

	time.Sleep(time.Second)
}

The results of the upper example are:

name:  hello world
name1:  <nil>
name3:  hello world
name2:  hello world

This chapter introduces in detail all the interfaces encapsulated by the routine library, as well as their core functions and implementation methods.

Get the goid of the current goroutine.

Create a new instance of LocalStorage, its design idea is very similar to the usage of ThreadLocal in other languages.

Back up the local storage data of the current coroutine context. It is just an immutable structure that facilitates the transfer of context data.

Actively inherit the backed-up context local storage data, it will copy the data of other coroutines BackupContext() into the current coroutine context, thus supporting the contextual data propagation across coroutines.

Start a new coroutine and automatically copy all the context local storage data of the current coroutine to the new coroutine. Its internal implementation consists of BackupContext() and InheritContext().

Represents the context variable of the coroutine, and the supported functions include:

• Get() (value interface{}): Get the variable value that has been set by the current coroutine.
• Set(v interface{}) interface{}: Set the value of the context variable of the current coroutine, and return the old value that has been set before.
• Del() (v interface{}): Delete the context variable value of the current coroutine and return the deleted old value.

Tip: The internal implementation of Get/Set/Del adopts a lock-free design. In most cases, its performance should be very stable and efficient.

Before the v1.0.0 version, routine will setup a backgrount timer to scan all go-routines intervally, and find the exited routine to clean the related LocalStorage data.

After the v1.0.0 version, routine will register a finalizer to listen the lifecycle of runtime.g.

After the coroutine exits, when runtime's GC running, the finalizer mechanism of runtime will actively remove the useless LocalStorage `Data clean up, So as to avoid memory leaks.

The internal model internal/g is from other repos, mainly two functions:

• G(), from https://github.com/huandu/go-tls
• G0(), from https://github.com/timandy/routine

MIT