重試後退,直到成功或達到最大嘗試次數
以下程式碼將嘗試執行 loadFromHttp()
最多 5 次(maxAttempts
),每次嘗試都會延遲多少秒。如果超過 maxAttempts
,Observable 就會放棄。
// assume loadFromHttp() returns a Promise, which might fail.
Rx.Observable.from(loadFromHttp())
.retryWhen((attempts) => {
let maxAttempts = 5;
Rx.Observable.range(1, maxAttempts+1).zip(attempts, (i, attempt) => [i, attempt])
.flatMap(([i, attempt]) => {
if (i <= maxAttempts) {
console.log(`Retrying in ${i} second(s)`);
return Rx.Observable.timer(i * 1000);
} else {
throw attempt;
}
})
})