Different uses of the Go language channel

This is a creation in Article, where the information may have evolved or changed.

1. return value using Channel

Func Main () {//generate random numbers as a serviceRandservice: =Randgenerator ()//read random numbers from the service and printFmt. Printf ("%d\n", <-Randservice)} Func randgenerator () Chanint {    //Create a channel     out: = Make (chanint)    //Create a co-processgo func () { for {            //writes data to the channel and waits if no one reads             out<-Rand. Int ()}} ()return  out}

2. Parameters using Channels

//a query structure bodyType querystruct {    //parameter ChannelSQL Chanstring    //Results ChannelResult Chanstring}//Execute Queryfunc ExecQuery (q query) {//Start the processgo func () {//Get inputsql: = <-Q.sql//Accessing the database, outputting the result channelQ.result <-"Get"+SQL} ()}func main () {//Initialize QueryQ: = Query{make (chanstring,1), make (chanstring,1)}    //Execute Query, note that there is no need to prepare parameters when executingExecQuery (q)//Prepare ParametersQ.sql <-"select * FROM table"    //Get ResultsFmt. Println (<-Q.result)}

3. Concurrent Loops

Func dosomething (numint) (sumint) {     forI: =1; I <=Ten; i++{fmt. Printf ("%d +%d =%d\n", num, num + i, num + num +i) Sum= sum + num +i}returnSum}func Testloop () {//set up a counter with a channel size of CPU cores    varNUMCPU =Runtime. NUMCPU () fmt. Printf ("numcpu =%d\n", NUMCPU) SEM:=make (chanint, NUMCPU); //For loop bodyData: = []int{1, One, +, to, A,Wuyi, A, in,Bayi, the}     for_,v:=Range Data {//establish a co-processGo func (Vint) {fmt. Printf ("dosomething (%d) ... \ n", v) sum:=dosomething (v); //CountSEM <-sum;    } (v); }    //wait for the loop to end    varTotalint=0     forI: =0; I < len (data); i++{temp:= <-sem fmt. Printf ("%d <-sem\n", temp) Total= Total +temp} fmt. Printf ("Total =%d\n", Total)} Func Main () {Testloop ()}

4. Using channel to calculate prime numbers

//Send the sequence 2, 3, 4, ... to channel ' in '.Func Generate (Ch chanint) {     forI: =2; ; i++{ch<-I//Send ' i ' to Channel ' in '.    }}//Copy the values from channel ' on ' to channel ' out ',//removing those divisible by ' prime '.Func Filter (inchChanint, outChanint, primeint) {     for{i:= <-inch //Receive valuefrom ' in '.        ifI%prime! =0 {             out<-I//Send ' i ' to ' out '.}}}func Main () {inch: = Make (chanint) Go Generate (inch)//Launch Generate goroutine.     forI: =0; I < -; i++{prime:= <-inchprint (Prime,"\ n")         out: = Make (chanint) Go Filter (inch, out, Prime)inch= out    }}

5. Read and write shared variables

//shared variables consist of a read channel and a write channelType Shardedvarstruct{Reader Chanintwriter Chanint}//Shared Variable Maintenance co-processfunc Whachdog (v shardedvar) {go func () {//Initial value        varValueint=0         for {            //listen to read and write channels, complete service            Select {             CaseValue = <-V.writer: CaseV.reader <-Value:}} } ()}func main () {//Initialize and start the maintenance processV: = Shardedvar{make (chanint), make (chanint)} whachdog (v)//Read initial valueFmt. Println (<-V.reader)//Write a valueV.writer <-1    //read the newly written valueFmt. Println (<-V.reader)}

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