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Merge pull request #187 from aojea/race_http
Improve startup latency
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,74 @@ | ||
| package controller | ||
|
|
||
| import ( | ||
| "context" | ||
| "crypto/tls" | ||
| "fmt" | ||
| "io" | ||
| "net/http" | ||
| "sync" | ||
| "time" | ||
|
|
||
| "k8s.io/klog/v2" | ||
| ) | ||
|
|
||
| func probeHTTP(ctx context.Context, address string) bool { | ||
| klog.Infof("probe HTTP address %s", address) | ||
| httpClient := &http.Client{ | ||
| Timeout: 2 * time.Second, | ||
| Transport: &http.Transport{ | ||
| TLSClientConfig: &tls.Config{InsecureSkipVerify: true}, | ||
| }, | ||
| } | ||
| req, err := http.NewRequest("GET", address, nil) | ||
| if err != nil { | ||
| return false | ||
| } | ||
| req = req.WithContext(ctx) | ||
| resp, err := httpClient.Do(req) | ||
| if err != nil { | ||
| klog.Infof("Failed to connect to HTTP address %s: %v", address, err) | ||
| return false | ||
| } | ||
| defer resp.Body.Close() | ||
| // drain the body | ||
| io.ReadAll(resp.Body) // nolint:errcheck | ||
| // we only want to verify connectivity so don't need to check the http status code | ||
| // as the apiserver may not be ready | ||
| return true | ||
| } | ||
|
|
||
| // firstSuccessfulProbe probes the given addresses in parallel and returns the first address to succeed, cancelling the other probes. | ||
| func firstSuccessfulProbe(ctx context.Context, addresses []string) (string, error) { | ||
| var wg sync.WaitGroup | ||
| resultChan := make(chan string, 1) | ||
|
|
||
| ctx, cancel := context.WithCancel(ctx) | ||
| defer cancel() | ||
|
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| for _, addr := range addresses { | ||
| wg.Add(1) | ||
| go func(address string) { | ||
| defer wg.Done() | ||
| if probeHTTP(ctx, address) { | ||
| select { | ||
| case resultChan <- address: | ||
| default: | ||
| } | ||
| cancel() | ||
| } | ||
| }(addr) | ||
| } | ||
|
|
||
| go func() { | ||
| wg.Wait() | ||
| close(resultChan) | ||
| }() | ||
|
|
||
| select { | ||
| case result := <-resultChan: | ||
| return result, nil | ||
| case <-ctx.Done(): | ||
| return "", fmt.Errorf("no address succeeded") | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,37 @@ | ||
| package controller | ||
|
|
||
| import ( | ||
| "context" | ||
| "net/http" | ||
| "net/http/httptest" | ||
| "testing" | ||
| "time" | ||
| ) | ||
|
|
||
| func Test_firstSuccessfulProbe(t *testing.T) { | ||
| reqCh := make(chan struct{}) | ||
| ts := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) { | ||
| t.Logf("received connection ") | ||
| close(reqCh) | ||
| })) | ||
| ts.EnableHTTP2 = true | ||
| ts.StartTLS() | ||
| defer ts.Close() | ||
| // use an address that is not likely to exist to avoid flakes | ||
| addresses := []string{"https://127.0.1.201:12349", ts.URL} | ||
| got, err := firstSuccessfulProbe(context.Background(), addresses) | ||
| if err != nil { | ||
| t.Errorf("firstSuccessfulProbe() error = %v", err) | ||
| return | ||
| } | ||
| if got != ts.URL { | ||
| t.Errorf("firstSuccessfulProbe() = %v, want %v", got, ts.URL) | ||
| } | ||
|
|
||
| select { | ||
| case <-reqCh: | ||
| case <-time.After(10 * time.Second): | ||
| t.Fatalf("test timed out, no request received") | ||
| } | ||
|
|
||
| } |