[英]Observable.Interval executes a method twice at the same time
ExecuteSellAsync 方法同時被調用兩次,您可以在下面的日志中看到。 當我在Observable.Interval(TimeSpan.FromSeconds(15))
上放置 15 秒時,它工作正常。 我怎樣才能防止這種情況? 也許像鎖定或我不知道。
2021-02-12 19:04:09 [11] DEBUG LiveTradeManager Order ID: 263010769 | Pair: DOGEUSDT | Order side: Sell | Status: New | Price: 0.06783960 | Last filled price: 0.00000000 | Stop price: 0.00000000 | Quantity: 0.00000000 | Quote quantity: 0.00000000 | Commission: 0
2021-02-12 19:04:09 [11] DEBUG LiveTradeManager Order ID: 263010769 | Pair: DOGEUSDT | Order side: Sell | Status: Filled | Price: 0.06783960 | Last filled price: 0.06784260 | Stop price: 0.00000000 | Quantity: 5420.00000000 | Quote quantity: 367.70689200 | Commission: 0.00201210 BNB
2021-02-12 19:04:09 [11] DEBUG LiveTradeManager Sell order was filled | Close date: 2021/02/12 17:04:09 | Close rate (price): 0.06784260
2021-02-12 19:04:13 [9] INFO Wallets Wallets synced.
2021-02-12 19:04:14 [10] DEBUG LiveTradeManager Timer triggered. Price: 0.06783910 | Timestamp: 2/12/2021 5:03:00 PM | Close: 0.06790680
2021-02-12 19:04:17 [9] DEBUG BinanceSpotClient Limit sell order has failed | Error code: -2010 | Error message: Account has insufficient balance for requested action. | Pair: DOGEUSDT | Quantity: 0.00000000 | Price: 0.06782540
_throttlerObservable = Observable.Interval(TimeSpan.FromSeconds(5))
.SelectMany(_ => Observable.FromAsync(async () =>
{
var lastCandle = _candles.Last();
_logger.Debug($"Timer triggered. Price: {_ticker.LastPrice} | Open time: {lastCandle.Timestamp} | Close: {lastCandle.Close}");
if (_orderSide == OrderSide.Sell)
{
var trade = _trades.FirstOrDefault(e => e.Pair.Equals(_tradeOptions.Pair) && e.IsOpen);
if (trade.NotNull())
{
var shouldSell = _tradingStrategy.ShouldSell(trade, _ticker.LastPrice, _tradeAdvice);
if (shouldSell.SellFlag)
{
await ExecuteSellAsync(trade, lastCandle.Timestamp, shouldSell.SellType).ConfigureAwait(false);
}
}
}
}))
.Subscribe();
我知道問題出在哪里。 _tradingStrategy.ShouldSell 需要幾秒鍾來執行,下一次執行同時開始執行下一次檢查。 我可以在該邏輯中使用lock
嗎?
這就是解決它的方法,但我需要鎖定整個檢查:
bool test = false;
public (bool SellFlag, SellType SellType) ShouldSell(Trade trade, decimal rate, TradeAdvice tradeAdvice, decimal? low = null, decimal? high = null)
{
if (!test)
{
test = true;
// my logic is here. It takes a few seconds.
test = false;
}
return (false, SellType.None);
}
可測試的代碼。 Observable.Interval
每秒執行一次,ShouldSellAsync 的邏輯執行需要 5 秒。 一旦 _completed 變為true
,則不再打印該消息。 它執行消息 5 次,而我只希望它執行一次。
using System;
using System.Linq;
using System.Reactive.Linq;
using System.Threading.Tasks;
namespace RxNETDispose
{
class Program
{
private static bool _completed = false;
public static async Task ShouldSellAsync()
{
if (!_completed)
{
await Task.Delay(5000);
Console.WriteLine($"{DateTime.UtcNow} - ShouldSell called");
_completed = true;
}
}
static void Main(string[] args)
{
Observable.Interval(TimeSpan.FromSeconds(1))
.SelectMany(_ => Observable.FromAsync(async () =>
{
await ShouldSellAsync().ConfigureAwait(false);
}))
.Subscribe();
Console.ReadLine();
}
}
}
SelectMany
確實引入了並發性。 我們希望控制這種並發性,因此這里的答案是滾動您自己的運算符,以確保對ExecuteSellAsync
的調用之間存在固定的間隙。
值得慶幸的是,使用 Rx 調度程序有一個漂亮但不明顯的方法來做到這一點。
我們正在尋找的方法是這樣的:
public static IDisposable ScheduleAsync(this IScheduler scheduler, TimeSpan dueTime, Func<IScheduler, CancellationToken, Task<IDisposable>> action)
要使用此調用,需要將Func<IScheduler, CancellationToken, Task<IDisposable>> action
定義為遞歸的,以便在對ExecuteSellAsync
的調用完成后調用自身重新調度。
因此,要每2.0
秒執行一次,例如,我們這樣做:
Func<IScheduler, CancellationToken, Task<IDisposable>> handler = null;
handler = async (s, ct) =>
{
await ExecuteSellAsync();
return s.ScheduleAsync(TimeSpan.FromSeconds(2.0), handler);
};
我們可以通過調用它來啟動它:
IDisposable subscription = Scheduler.Default.ScheduleAsync(TimeSpan.Zero, handler);
當然,像所有好的 Rx 操作一樣,我們可以調用subscription.Dispose()
來停止它的運行。
這是一個完整的例子:
async Task Main()
{
Func<IScheduler, CancellationToken, Task<IDisposable>> handler = null;
handler = async (s, ct) =>
{
await ExecuteSellAsync();
return s.ScheduleAsync(TimeSpan.FromSeconds(2.0), handler);
};
IDisposable subscription = Scheduler.Default.ScheduleAsync(TimeSpan.Zero, handler);
await Task.Delay(TimeSpan.FromSeconds(9.0));
subscription.Dispose();
}
private DateTime then = DateTime.Now;
private int __counter = 0;
async Task ExecuteSellAsync()
{
var counter = Interlocked.Increment(ref __counter);
Console.WriteLine($"ExecuteSellAsync() Start {counter} - {DateTime.Now.Subtract(then).TotalSeconds}");
await Task.Delay(TimeSpan.FromSeconds(2.0));
Console.WriteLine($"ExecuteSellAsync() End {counter} - {DateTime.Now.Subtract(then).TotalSeconds}");
}
當我運行它時,我得到了這個 output:
ExecuteSellAsync() Start 1 - 0.0019952
ExecuteSellAsync() End 1 - 2.0095866
ExecuteSellAsync() Start 2 - 4.0185182
ExecuteSellAsync() End 2 - 6.0199157
ExecuteSellAsync() Start 3 - 8.0303588
ExecuteSellAsync() End 3 - 10.0417079
請注意, ExecuteSellAsync()
不會合作取消,因此它會運行到完成。 不難改成async Task ExecuteSellAsync(CancellationToken ct)
讓其協同取消。
現在,可以擴展它以使其成為一個很好的可觀察對象。
嘗試這個:
IObservable<Unit> query =
Observable.Create<Unit>(o =>
{
Func<IScheduler, CancellationToken, Task<IDisposable>> handler = null;
handler = async (s, ct) =>
{
if (ct.IsCancellationRequested)
{
o.OnCompleted();
}
else
{
await ExecuteSellAsync();
o.OnNext(Unit.Default);
}
return s.ScheduleAsync(TimeSpan.FromSeconds(2.0), handler);
};
return Scheduler.Default.ScheduleAsync(TimeSpan.Zero, handler);
});
IDisposable subscription = query.Take(3).Subscribe(x => Console.WriteLine("U"), () => Console.WriteLine("C"));
await Task.Delay(TimeSpan.FromSeconds(11.0));
subscription.Dispose();
這有以下 output:
ExecuteSellAsync() Start 1 - 0.0009972
ExecuteSellAsync() End 1 - 2.0115375
U
ExecuteSellAsync() Start 2 - 4.0128375
ExecuteSellAsync() End 2 - 6.0282818
U
ExecuteSellAsync() Start 3 - 8.0370135
ExecuteSellAsync() End 3 - 10.0521106
U
C
注意它完成。 如果你調用subscription.Dispose();
在它自然完成之前,它會正常運行並且不會發出OnComplete
通知。
讓我們將其包裝在一組不錯的擴展方法中:
public static class ObservableEx
{
public static IObservable<Unit> IntervalAsync(TimeSpan period, Func<Task> actionAsync, IScheduler scheduler) =>
TimerAsync(period, period, actionAsync, scheduler);
public static IObservable<T> IntervalAsync<T>(TimeSpan period, Func<Task<T>> functionAsync, IScheduler scheduler) =>
TimerAsync(period, period, functionAsync, scheduler);
public static IObservable<Unit> TimerAsync(TimeSpan dueTime, TimeSpan period, Func<Task> actionAsync, IScheduler scheduler) =>
Observable.Create<Unit>(o =>
{
Func<IScheduler, CancellationToken, Task<IDisposable>> handler = null;
handler = async (s, ct) =>
{
if (ct.IsCancellationRequested)
{
o.OnCompleted();
}
else
{
await actionAsync();
o.OnNext(Unit.Default);
}
return s.ScheduleAsync(period, handler);
};
return scheduler.ScheduleAsync(dueTime, handler);
});
public static IObservable<T> TimerAsync<T>(TimeSpan dueTime, TimeSpan period, Func<Task<T>> functionAsync, IScheduler scheduler) =>
Observable.Create<T>(o =>
{
Func<IScheduler, CancellationToken, Task<IDisposable>> handler = null;
handler = async (s, ct) =>
{
if (ct.IsCancellationRequested)
{
o.OnCompleted();
}
else
{
o.OnNext(await functionAsync());
}
return s.ScheduleAsync(period, handler);
};
return scheduler.ScheduleAsync(dueTime, handler);
});
}
現在,很明顯有一堆我沒有寫的重載——使用默認調度程序的和允許合作取消的——但我希望你明白這一點。
現在使用這些擴展方法,我可以做到這一點:
IDisposable subscription =
ObservableEx
.IntervalAsync(TimeSpan.FromSeconds(2.0), () => ExecuteSellAsync(), Scheduler.Default)
.Take(3)
.Subscribe(x => Console.WriteLine("U"), () => Console.WriteLine("C"));
我得到了和以前一樣的 output。
我還沒有完全測試擴展方法。 他們可能需要更多的愛和關注。
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