151 lines
4.0 KiB
Go
151 lines
4.0 KiB
Go
package main
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import (
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"fmt"
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"os"
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"net/http"
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"time"
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"io/ioutil"
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"encoding/json"
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)
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// a struct to hold the result from each request including an index
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// which will be used for sorting the results after they come in
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type result struct {
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id int
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status int
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err error
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}
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type check struct {
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// defining struct variables
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Url string `json:"url"`
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Id int `json:"id"`
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Computers_id int `json:"computers_id"`
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Status string `json:"status"`
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}
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// boundedParallelGet sends requests in parallel but only up to a certain
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// limit, and furthermore it's only parallel up to the amount of CPUs but
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// is always concurrent up to the concurrency limit
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func boundedParallelGet(Checks []check, concurrencyLimit int) []check {
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// this buffered channel will block at the concurrency limit
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semaphoreChan := make(chan struct{}, concurrencyLimit)
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// this channel will not block and collect the http request results
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resultsChan := make(chan *result)
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// make sure we close these channels when we're done with them
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defer func() {
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close(semaphoreChan)
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close(resultsChan)
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}()
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// keen an index and loop through every url we will send a request to
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for _,chck := range Checks {
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// start a go routine with the index and url in a closure
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go func(chck check) {
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var status int
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// this sends an empty struct into the semaphoreChan which
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// is basically saying add one to the limit, but when the
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// limit has been reached block until there is room
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semaphoreChan <- struct{}{}
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// send the request and put the response in a result struct
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// along with the index so we can sort them later along with
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// any error that might have occoured
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//fmt.Println(chck.Url)
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client := http.Client{
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Timeout: 7 * time.Second,
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}
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res, err := client.Get(chck.Url)
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status = 404
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if err == nil {
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status = res.StatusCode
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}
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result := &result{chck.Id, status, err}
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// now we can send the result struct through the resultsChan
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resultsChan <- result
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// once we're done it's we read from the semaphoreChan which
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// has the effect of removing one from the limit and allowing
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// another goroutine to start
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<-semaphoreChan
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}(chck)
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}
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// make a slice to hold the results we're expecting
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var results []result
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// start listening for any results over the resultsChan
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// once we get a result append it to the result slice
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for {
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result := <-resultsChan
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results = append(results, *result)
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// if we've reached the expected amount of urls then stop
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if len(results) == len(Checks) {
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break
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}
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}
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var ret []check
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for i := range results {
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ch := m[results[i].id]
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if results[i].status == 200 {
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ch.Status = "OK"
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ret = append(ret,*ch)
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}
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}
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// now we're done we return the results
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return ret
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}
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// we'll use the init function to set up the benchmark
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// by making a slice of 100 URLs to send requets to
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var urls []string
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var checks []check
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var m = make(map[int]*check)
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func init() {
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bytes, _ := ioutil.ReadAll(os.Stdin)
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json.Unmarshal(bytes , &checks)
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for i := range checks {
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m[checks[i].Id] = &checks[i]
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}
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}
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// the main function sets up an anonymous benchmark func
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// that will time how long it takes to get all the URLs
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// at the specified concurrency level
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//
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// and you should see something like the following printed
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// depending on how fast your computer and internet is
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//
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// 5 bounded parallel requests: 100/100 in 5.533223255
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// 10 bounded parallel requests: 100/100 in 2.5115351219
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// 25 bounded parallel requests: 100/100 in 1.189462884
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// 50 bounded parallel requests: 100/100 in 1.17430002
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// 75 bounded parallel requests: 100/100 in 1.001383863
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// 100 bounded parallel requests: 100/100 in 1.3769354
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func main() {
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//startTime := time.Now()
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results := boundedParallelGet(checks, 100)
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//seconds := time.Since(startTime).Seconds()
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//tmplate := "requests: %d/%d in %v"
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// fmt.Printf(tmplate, len(results), len(checks), seconds)
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val,_ := json.MarshalIndent(results, "", " ")
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fmt.Print(string(val))
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}
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