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gcloud sdk go と context(cancel, timeout)の動作
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package main | |
import ( | |
"cloud.google.com/go/bigquery" | |
"context" | |
"fmt" | |
"google.golang.org/api/iterator" | |
"log" | |
"os" | |
"time" | |
) | |
func main() { | |
doneCh := make(chan bool) | |
ctx := context.Background() | |
log.Println("start") | |
// 3sec後にtimeout | |
subCtx, cancelFunc := context.WithTimeout(ctx, time.Duration(3)*time.Second) | |
defer cancelFunc() | |
// // 以下のgoroutineを有効にすると、`context canceled` で終了 | |
// go func() { | |
// // 2sec後にcancel | |
// time.Sleep(time.Duration(2) * time.Second) | |
// cancelFunc() | |
// }() | |
go func(subCtx context.Context) { | |
projectID := os.Getenv("GCP_PROJECT") | |
client, err := bigquery.NewClient(subCtx, projectID) | |
if err != nil { | |
message := fmt.Sprintf("Failed to create client: %v\n", err) | |
log.Println(message) | |
return | |
} | |
// timeout待ち | |
time.Sleep(time.Duration(5) * time.Second) | |
it := client.Datasets(subCtx) | |
for { | |
ds, err := it.Next() | |
if err == iterator.Done { | |
log.Println("iterator done.") | |
break | |
} | |
if err != nil { | |
log.Printf("iterate Dataset err: %v", err) | |
break | |
} else { | |
fmt.Println("Dataset:", ds.DatasetID) | |
} | |
} | |
select { | |
case <-subCtx.Done(): | |
log.Println("subCtx Done") | |
default: | |
log.Println("default end.") | |
} | |
doneCh <- true | |
}(subCtx) | |
select { | |
case <-doneCh: | |
log.Println("doneCh end.") | |
} | |
} |
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GCP_PROJECT="****" GOOGLE_APPLICATION_CREDENTIALS=****.json go run main.go 2020/02/23 13:28:17 start 2020/02/23 13:28:22 iterate Dataset err: context deadline exceeded 2020/02/23 13:28:22 subCtx Done 2020/02/23 13:28:22 doneCh end.